Merge branch 'jt/fetch-pack-wanted-refs-optim'
[gitweb.git] / sequencer.c
index d0c2277455007a6a9e8bbaefc01a5741ec01f878..546f28189851875b4a881ef9ff8876528e5dc9f9 100644 (file)
@@ -2,6 +2,7 @@
 #include "config.h"
 #include "lockfile.h"
 #include "dir.h"
+#include "object-store.h"
 #include "object.h"
 #include "commit.h"
 #include "sequencer.h"
 #include "worktree.h"
 #include "oidmap.h"
 #include "oidset.h"
+#include "commit-slab.h"
 #include "alias.h"
+#include "commit-reach.h"
+#include "rebase-interactive.h"
 
 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
 
@@ -50,7 +54,9 @@ static GIT_PATH_FUNC(rebase_path, "rebase-merge")
  * the lines are processed, they are removed from the front of this
  * file and written to the tail of 'done'.
  */
-static GIT_PATH_FUNC(rebase_path_todo, "rebase-merge/git-rebase-todo")
+GIT_PATH_FUNC(rebase_path_todo, "rebase-merge/git-rebase-todo")
+GIT_PATH_FUNC(rebase_path_todo_backup, "rebase-merge/git-rebase-todo.backup")
+
 /*
  * The rebase command lines that have already been processed. A line
  * is moved here when it is first handled, before any associated user
@@ -61,12 +67,12 @@ static GIT_PATH_FUNC(rebase_path_done, "rebase-merge/done")
  * The file to keep track of how many commands were already processed (e.g.
  * for the prompt).
  */
-static GIT_PATH_FUNC(rebase_path_msgnum, "rebase-merge/msgnum");
+static GIT_PATH_FUNC(rebase_path_msgnum, "rebase-merge/msgnum")
 /*
  * The file to keep track of how many commands are to be processed in total
  * (e.g. for the prompt).
  */
-static GIT_PATH_FUNC(rebase_path_msgtotal, "rebase-merge/end");
+static GIT_PATH_FUNC(rebase_path_msgtotal, "rebase-merge/end")
 /*
  * The commit message that is planned to be used for any changes that
  * need to be committed following a user interaction.
@@ -138,11 +144,12 @@ static GIT_PATH_FUNC(rebase_path_refs_to_delete, "rebase-merge/refs-to-delete")
 
 /*
  * The following files are written by git-rebase just after parsing the
- * command-line (and are only consumed, not modified, by the sequencer).
+ * command-line.
  */
 static GIT_PATH_FUNC(rebase_path_gpg_sign_opt, "rebase-merge/gpg_sign_opt")
 static GIT_PATH_FUNC(rebase_path_orig_head, "rebase-merge/orig-head")
 static GIT_PATH_FUNC(rebase_path_verbose, "rebase-merge/verbose")
+static GIT_PATH_FUNC(rebase_path_quiet, "rebase-merge/quiet")
 static GIT_PATH_FUNC(rebase_path_signoff, "rebase-merge/signoff")
 static GIT_PATH_FUNC(rebase_path_head_name, "rebase-merge/head-name")
 static GIT_PATH_FUNC(rebase_path_onto, "rebase-merge/onto")
@@ -150,6 +157,7 @@ static GIT_PATH_FUNC(rebase_path_autostash, "rebase-merge/autostash")
 static GIT_PATH_FUNC(rebase_path_strategy, "rebase-merge/strategy")
 static GIT_PATH_FUNC(rebase_path_strategy_opts, "rebase-merge/strategy_opts")
 static GIT_PATH_FUNC(rebase_path_allow_rerere_autoupdate, "rebase-merge/allow_rerere_autoupdate")
+static GIT_PATH_FUNC(rebase_path_reschedule_failed_exec, "rebase-merge/reschedule-failed-exec")
 
 static int git_sequencer_config(const char *k, const char *v, void *cb)
 {
@@ -175,6 +183,7 @@ static int git_sequencer_config(const char *k, const char *v, void *cb)
                        warning(_("invalid commit message cleanup mode '%s'"),
                                  s);
 
+               free((char *)s);
                return status;
        }
 
@@ -222,13 +231,16 @@ static const char *get_todo_path(const struct replay_opts *opts)
  * Returns 3 when sob exists within conforming footer as last entry
  */
 static int has_conforming_footer(struct strbuf *sb, struct strbuf *sob,
-       int ignore_footer)
+       size_t ignore_footer)
 {
+       struct process_trailer_options opts = PROCESS_TRAILER_OPTIONS_INIT;
        struct trailer_info info;
-       int i;
+       size_t i;
        int found_sob = 0, found_sob_last = 0;
 
-       trailer_info_get(&info, sb->buf);
+       opts.no_divider = 1;
+
+       trailer_info_get(&info, sb->buf, &opts);
 
        if (info.trailer_start == info.trailer_end)
                return 0;
@@ -304,7 +316,7 @@ static const char *action_name(const struct replay_opts *opts)
        case REPLAY_INTERACTIVE_REBASE:
                return N_("rebase -i");
        }
-       die(_("Unknown action: %d"), opts->action);
+       die(_("unknown action: %d"), opts->action);
 }
 
 struct commit_message {
@@ -344,7 +356,8 @@ static void free_message(struct commit *commit, struct commit_message *msg)
        unuse_commit_buffer(commit, msg->message);
 }
 
-static void print_advice(int show_hint, struct replay_opts *opts)
+static void print_advice(struct repository *r, int show_hint,
+                        struct replay_opts *opts)
 {
        char *msg = getenv("GIT_CHERRY_PICK_HELP");
 
@@ -355,7 +368,7 @@ static void print_advice(int show_hint, struct replay_opts *opts)
                 * (typically rebase --interactive) wants to take care
                 * of the commit itself so remove CHERRY_PICK_HEAD
                 */
-               unlink(git_path_cherry_pick_head());
+               unlink(git_path_cherry_pick_head(r));
                return;
        }
 
@@ -428,14 +441,14 @@ static int read_oneliner(struct strbuf *buf,
        return 1;
 }
 
-static struct tree *empty_tree(void)
+static struct tree *empty_tree(struct repository *r)
 {
-       return lookup_tree(the_hash_algo->empty_tree);
+       return lookup_tree(r, the_hash_algo->empty_tree);
 }
 
-static int error_dirty_index(struct replay_opts *opts)
+static int error_dirty_index(struct repository *repo, struct replay_opts *opts)
 {
-       if (read_cache_unmerged())
+       if (repo_read_index_unmerged(repo))
                return error_resolve_conflict(_(action_name(opts)));
 
        error(_("your local changes would be overwritten by %s."),
@@ -460,15 +473,18 @@ static void update_abort_safety_file(void)
                write_file(git_path_abort_safety_file(), "%s", "");
 }
 
-static int fast_forward_to(const struct object_id *to, const struct object_id *from,
-                       int unborn, struct replay_opts *opts)
+static int fast_forward_to(struct repository *r,
+                          const struct object_id *to,
+                          const struct object_id *from,
+                          int unborn,
+                          struct replay_opts *opts)
 {
        struct ref_transaction *transaction;
        struct strbuf sb = STRBUF_INIT;
        struct strbuf err = STRBUF_INIT;
 
-       read_cache();
-       if (checkout_fast_forward(from, to, 1))
+       repo_read_index(r);
+       if (checkout_fast_forward(r, from, to, 1))
                return -1; /* the callee should have complained already */
 
        strbuf_addf(&sb, _("%s: fast-forward"), _(action_name(opts)));
@@ -494,24 +510,26 @@ static int fast_forward_to(const struct object_id *to, const struct object_id *f
        return 0;
 }
 
-void append_conflicts_hint(struct strbuf *msgbuf)
+void append_conflicts_hint(struct index_state *istate,
+                          struct strbuf *msgbuf)
 {
        int i;
 
        strbuf_addch(msgbuf, '\n');
        strbuf_commented_addf(msgbuf, "Conflicts:\n");
-       for (i = 0; i < active_nr;) {
-               const struct cache_entry *ce = active_cache[i++];
+       for (i = 0; i < istate->cache_nr;) {
+               const struct cache_entry *ce = istate->cache[i++];
                if (ce_stage(ce)) {
                        strbuf_commented_addf(msgbuf, "\t%s\n", ce->name);
-                       while (i < active_nr && !strcmp(ce->name,
-                                                       active_cache[i]->name))
+                       while (i < istate->cache_nr &&
+                              !strcmp(ce->name, istate->cache[i]->name))
                                i++;
                }
        }
 }
 
-static int do_recursive_merge(struct commit *base, struct commit *next,
+static int do_recursive_merge(struct repository *r,
+                             struct commit *base, struct commit *next,
                              const char *base_label, const char *next_label,
                              struct object_id *head, struct strbuf *msgbuf,
                              struct replay_opts *opts)
@@ -522,12 +540,12 @@ static int do_recursive_merge(struct commit *base, struct commit *next,
        char **xopt;
        struct lock_file index_lock = LOCK_INIT;
 
-       if (hold_locked_index(&index_lock, LOCK_REPORT_ON_ERROR) < 0)
+       if (repo_hold_locked_index(r, &index_lock, LOCK_REPORT_ON_ERROR) < 0)
                return -1;
 
-       read_cache();
+       repo_read_index(r);
 
-       init_merge_options(&o);
+       init_merge_options(&o, r);
        o.ancestor = base ? base_label : "(empty tree)";
        o.branch1 = "HEAD";
        o.branch2 = next ? next_label : "(empty tree)";
@@ -536,8 +554,8 @@ static int do_recursive_merge(struct commit *base, struct commit *next,
        o.show_rename_progress = 1;
 
        head_tree = parse_tree_indirect(head);
-       next_tree = next ? get_commit_tree(next) : empty_tree();
-       base_tree = base ? get_commit_tree(base) : empty_tree();
+       next_tree = next ? get_commit_tree(next) : empty_tree(r);
+       base_tree = base ? get_commit_tree(base) : empty_tree(r);
 
        for (xopt = opts->xopts; xopt != opts->xopts + opts->xopts_nr; xopt++)
                parse_merge_opt(&o, *xopt);
@@ -554,7 +572,7 @@ static int do_recursive_merge(struct commit *base, struct commit *next,
                return clean;
        }
 
-       if (write_locked_index(&the_index, &index_lock,
+       if (write_locked_index(r->index, &index_lock,
                               COMMIT_LOCK | SKIP_IF_UNCHANGED))
                /*
                 * TRANSLATORS: %s will be "revert", "cherry-pick" or
@@ -564,34 +582,35 @@ static int do_recursive_merge(struct commit *base, struct commit *next,
                        _(action_name(opts)));
 
        if (!clean)
-               append_conflicts_hint(msgbuf);
+               append_conflicts_hint(r->index, msgbuf);
 
        return !clean;
 }
 
-static struct object_id *get_cache_tree_oid(void)
+static struct object_id *get_cache_tree_oid(struct index_state *istate)
 {
-       if (!active_cache_tree)
-               active_cache_tree = cache_tree();
+       if (!istate->cache_tree)
+               istate->cache_tree = cache_tree();
 
-       if (!cache_tree_fully_valid(active_cache_tree))
-               if (cache_tree_update(&the_index, 0)) {
+       if (!cache_tree_fully_valid(istate->cache_tree))
+               if (cache_tree_update(istate, 0)) {
                        error(_("unable to update cache tree"));
                        return NULL;
                }
 
-       return &active_cache_tree->oid;
+       return &istate->cache_tree->oid;
 }
 
-static int is_index_unchanged(void)
+static int is_index_unchanged(struct repository *r)
 {
        struct object_id head_oid, *cache_tree_oid;
        struct commit *head_commit;
+       struct index_state *istate = r->index;
 
        if (!resolve_ref_unsafe("HEAD", RESOLVE_REF_READING, &head_oid, NULL))
                return error(_("could not resolve HEAD commit"));
 
-       head_commit = lookup_commit(&head_oid);
+       head_commit = lookup_commit(r, &head_oid);
 
        /*
         * If head_commit is NULL, check_commit, called from
@@ -604,10 +623,10 @@ static int is_index_unchanged(void)
        if (parse_commit(head_commit))
                return -1;
 
-       if (!(cache_tree_oid = get_cache_tree_oid()))
+       if (!(cache_tree_oid = get_cache_tree_oid(istate)))
                return -1;
 
-       return !oidcmp(cache_tree_oid, get_commit_tree_oid(head_commit));
+       return oideq(cache_tree_oid, get_commit_tree_oid(head_commit));
 }
 
 static int write_author_script(const char *message)
@@ -636,7 +655,7 @@ static int write_author_script(const char *message)
                else if (*message != '\'')
                        strbuf_addch(&buf, *(message++));
                else
-                       strbuf_addf(&buf, "'\\\\%c'", *(message++));
+                       strbuf_addf(&buf, "'\\%c'", *(message++));
        strbuf_addstr(&buf, "'\nGIT_AUTHOR_EMAIL='");
        while (*message && *message != '\n' && *message != '\r')
                if (skip_prefix(message, "> ", &message))
@@ -644,45 +663,144 @@ static int write_author_script(const char *message)
                else if (*message != '\'')
                        strbuf_addch(&buf, *(message++));
                else
-                       strbuf_addf(&buf, "'\\\\%c'", *(message++));
+                       strbuf_addf(&buf, "'\\%c'", *(message++));
        strbuf_addstr(&buf, "'\nGIT_AUTHOR_DATE='@");
        while (*message && *message != '\n' && *message != '\r')
                if (*message != '\'')
                        strbuf_addch(&buf, *(message++));
                else
-                       strbuf_addf(&buf, "'\\\\%c'", *(message++));
+                       strbuf_addf(&buf, "'\\%c'", *(message++));
+       strbuf_addch(&buf, '\'');
        res = write_message(buf.buf, buf.len, rebase_path_author_script(), 1);
        strbuf_release(&buf);
        return res;
 }
 
+/**
+ * Take a series of KEY='VALUE' lines where VALUE part is
+ * sq-quoted, and append <KEY, VALUE> at the end of the string list
+ */
+static int parse_key_value_squoted(char *buf, struct string_list *list)
+{
+       while (*buf) {
+               struct string_list_item *item;
+               char *np;
+               char *cp = strchr(buf, '=');
+               if (!cp) {
+                       np = strchrnul(buf, '\n');
+                       return error(_("no key present in '%.*s'"),
+                                    (int) (np - buf), buf);
+               }
+               np = strchrnul(cp, '\n');
+               *cp++ = '\0';
+               item = string_list_append(list, buf);
+
+               buf = np + (*np == '\n');
+               *np = '\0';
+               cp = sq_dequote(cp);
+               if (!cp)
+                       return error(_("unable to dequote value of '%s'"),
+                                    item->string);
+               item->util = xstrdup(cp);
+       }
+       return 0;
+}
+
+/**
+ * Reads and parses the state directory's "author-script" file, and sets name,
+ * email and date accordingly.
+ * Returns 0 on success, -1 if the file could not be parsed.
+ *
+ * The author script is of the format:
+ *
+ *     GIT_AUTHOR_NAME='$author_name'
+ *     GIT_AUTHOR_EMAIL='$author_email'
+ *     GIT_AUTHOR_DATE='$author_date'
+ *
+ * where $author_name, $author_email and $author_date are quoted. We are strict
+ * with our parsing, as the file was meant to be eval'd in the old
+ * git-am.sh/git-rebase--interactive.sh scripts, and thus if the file differs
+ * from what this function expects, it is better to bail out than to do
+ * something that the user does not expect.
+ */
+int read_author_script(const char *path, char **name, char **email, char **date,
+                      int allow_missing)
+{
+       struct strbuf buf = STRBUF_INIT;
+       struct string_list kv = STRING_LIST_INIT_DUP;
+       int retval = -1; /* assume failure */
+       int i, name_i = -2, email_i = -2, date_i = -2, err = 0;
+
+       if (strbuf_read_file(&buf, path, 256) <= 0) {
+               strbuf_release(&buf);
+               if (errno == ENOENT && allow_missing)
+                       return 0;
+               else
+                       return error_errno(_("could not open '%s' for reading"),
+                                          path);
+       }
+
+       if (parse_key_value_squoted(buf.buf, &kv))
+               goto finish;
+
+       for (i = 0; i < kv.nr; i++) {
+               if (!strcmp(kv.items[i].string, "GIT_AUTHOR_NAME")) {
+                       if (name_i != -2)
+                               name_i = error(_("'GIT_AUTHOR_NAME' already given"));
+                       else
+                               name_i = i;
+               } else if (!strcmp(kv.items[i].string, "GIT_AUTHOR_EMAIL")) {
+                       if (email_i != -2)
+                               email_i = error(_("'GIT_AUTHOR_EMAIL' already given"));
+                       else
+                               email_i = i;
+               } else if (!strcmp(kv.items[i].string, "GIT_AUTHOR_DATE")) {
+                       if (date_i != -2)
+                               date_i = error(_("'GIT_AUTHOR_DATE' already given"));
+                       else
+                               date_i = i;
+               } else {
+                       err = error(_("unknown variable '%s'"),
+                                   kv.items[i].string);
+               }
+       }
+       if (name_i == -2)
+               error(_("missing 'GIT_AUTHOR_NAME'"));
+       if (email_i == -2)
+               error(_("missing 'GIT_AUTHOR_EMAIL'"));
+       if (date_i == -2)
+               error(_("missing 'GIT_AUTHOR_DATE'"));
+       if (date_i < 0 || email_i < 0 || date_i < 0 || err)
+               goto finish;
+       *name = kv.items[name_i].util;
+       *email = kv.items[email_i].util;
+       *date = kv.items[date_i].util;
+       retval = 0;
+finish:
+       string_list_clear(&kv, !!retval);
+       strbuf_release(&buf);
+       return retval;
+}
+
 /*
- * Read a list of environment variable assignments (such as the author-script
- * file) into an environment block. Returns -1 on error, 0 otherwise.
+ * Read a GIT_AUTHOR_NAME, GIT_AUTHOR_EMAIL AND GIT_AUTHOR_DATE from a
+ * file with shell quoting into struct argv_array. Returns -1 on
+ * error, 0 otherwise.
  */
 static int read_env_script(struct argv_array *env)
 {
-       struct strbuf script = STRBUF_INIT;
-       int i, count = 0;
-       char *p, *p2;
+       char *name, *email, *date;
 
-       if (strbuf_read_file(&script, rebase_path_author_script(), 256) <= 0)
+       if (read_author_script(rebase_path_author_script(),
+                              &name, &email, &date, 0))
                return -1;
 
-       for (p = script.buf; *p; p++)
-               if (skip_prefix(p, "'\\\\''", (const char **)&p2))
-                       strbuf_splice(&script, p - script.buf, p2 - p, "'", 1);
-               else if (*p == '\'')
-                       strbuf_splice(&script, p-- - script.buf, 1, "", 0);
-               else if (*p == '\n') {
-                       *p = '\0';
-                       count++;
-               }
-
-       for (i = 0, p = script.buf; i < count; i++) {
-               argv_array_push(env, p);
-               p += strlen(p) + 1;
-       }
+       argv_array_pushf(env, "GIT_AUTHOR_NAME=%s", name);
+       argv_array_pushf(env, "GIT_AUTHOR_EMAIL=%s", email);
+       argv_array_pushf(env, "GIT_AUTHOR_DATE=%s", date);
+       free(name);
+       free(email);
+       free(date);
 
        return 0;
 }
@@ -702,46 +820,28 @@ static char *get_author(const char *message)
 /* Read author-script and return an ident line (author <email> timestamp) */
 static const char *read_author_ident(struct strbuf *buf)
 {
-       const char *keys[] = {
-               "GIT_AUTHOR_NAME=", "GIT_AUTHOR_EMAIL=", "GIT_AUTHOR_DATE="
-       };
-       char *in, *out, *eol;
-       int i = 0, len;
+       struct strbuf out = STRBUF_INIT;
+       char *name, *email, *date;
 
-       if (strbuf_read_file(buf, rebase_path_author_script(), 256) <= 0)
+       if (read_author_script(rebase_path_author_script(),
+                              &name, &email, &date, 0))
                return NULL;
 
-       /* dequote values and construct ident line in-place */
-       for (in = out = buf->buf; i < 3 && in - buf->buf < buf->len; i++) {
-               if (!skip_prefix(in, keys[i], (const char **)&in)) {
-                       warning("could not parse '%s' (looking for '%s'",
-                               rebase_path_author_script(), keys[i]);
-                       return NULL;
-               }
-
-               eol = strchrnul(in, '\n');
-               *eol = '\0';
-               sq_dequote(in);
-               len = strlen(in);
-
-               if (i > 0) /* separate values by spaces */
-                       *(out++) = ' ';
-               if (i == 1) /* email needs to be surrounded by <...> */
-                       *(out++) = '<';
-               memmove(out, in, len);
-               out += len;
-               if (i == 1) /* email needs to be surrounded by <...> */
-                       *(out++) = '>';
-               in = eol + 1;
-       }
-
-       if (i < 3) {
-               warning("could not parse '%s' (looking for '%s')",
-                       rebase_path_author_script(), keys[i]);
+       /* validate date since fmt_ident() will die() on bad value */
+       if (parse_date(date, &out)){
+               warning(_("invalid date format '%s' in '%s'"),
+                       date, rebase_path_author_script());
+               strbuf_release(&out);
                return NULL;
        }
 
-       buf->len = out - buf->buf;
+       strbuf_reset(&out);
+       strbuf_addstr(&out, fmt_ident(name, email, WANT_AUTHOR_IDENT, date, 0));
+       strbuf_swap(buf, &out);
+       strbuf_release(&out);
+       free(name);
+       free(email);
+       free(date);
        return buf->buf;
 }
 
@@ -766,6 +866,23 @@ N_("you have staged changes in your working tree\n"
 #define VERIFY_MSG  (1<<4)
 #define CREATE_ROOT_COMMIT (1<<5)
 
+static int run_command_silent_on_success(struct child_process *cmd)
+{
+       struct strbuf buf = STRBUF_INIT;
+       int rc;
+
+       cmd->stdout_to_stderr = 1;
+       rc = pipe_command(cmd,
+                         NULL, 0,
+                         NULL, 0,
+                         &buf, 0);
+
+       if (rc)
+               fputs(buf.buf, stderr);
+       strbuf_release(&buf);
+       return rc;
+}
+
 /*
  * If we are cherry-pick, and if the merge did not result in
  * hand-editing, we will hit this commit and inherit the original
@@ -778,7 +895,9 @@ N_("you have staged changes in your working tree\n"
  * interactive rebase: in that case, we will want to retain the
  * author metadata.
  */
-static int run_git_commit(const char *defmsg, struct replay_opts *opts,
+static int run_git_commit(struct repository *r,
+                         const char *defmsg,
+                         struct replay_opts *opts,
                          unsigned int flags)
 {
        struct child_process cmd = CHILD_PROCESS_INIT;
@@ -786,15 +905,22 @@ static int run_git_commit(const char *defmsg, struct replay_opts *opts,
 
        if ((flags & CREATE_ROOT_COMMIT) && !(flags & AMEND_MSG)) {
                struct strbuf msg = STRBUF_INIT, script = STRBUF_INIT;
-               const char *author = is_rebase_i(opts) ?
-                       read_author_ident(&script) : NULL;
+               const char *author = NULL;
                struct object_id root_commit, *cache_tree_oid;
                int res = 0;
 
+               if (is_rebase_i(opts)) {
+                       author = read_author_ident(&script);
+                       if (!author) {
+                               strbuf_release(&script);
+                               return -1;
+                       }
+               }
+
                if (!defmsg)
                        BUG("root commit without message");
 
-               if (!(cache_tree_oid = get_cache_tree_oid()))
+               if (!(cache_tree_oid = get_cache_tree_oid(r->index)))
                        res = -1;
 
                if (!res)
@@ -820,18 +946,11 @@ static int run_git_commit(const char *defmsg, struct replay_opts *opts,
 
        cmd.git_cmd = 1;
 
-       if (is_rebase_i(opts)) {
-               if (!(flags & EDIT_MSG)) {
-                       cmd.stdout_to_stderr = 1;
-                       cmd.err = -1;
-               }
-
-               if (read_env_script(&cmd.env_array)) {
-                       const char *gpg_opt = gpg_sign_opt_quoted(opts);
+       if (is_rebase_i(opts) && read_env_script(&cmd.env_array)) {
+               const char *gpg_opt = gpg_sign_opt_quoted(opts);
 
-                       return error(_(staged_changes_advice),
-                                    gpg_opt, gpg_opt);
-               }
+               return error(_(staged_changes_advice),
+                            gpg_opt, gpg_opt);
        }
 
        argv_array_push(&cmd.args, "commit");
@@ -858,24 +977,13 @@ static int run_git_commit(const char *defmsg, struct replay_opts *opts,
        if ((flags & ALLOW_EMPTY))
                argv_array_push(&cmd.args, "--allow-empty");
 
-       if (opts->allow_empty_message)
+       if (!(flags & EDIT_MSG))
                argv_array_push(&cmd.args, "--allow-empty-message");
 
-       if (cmd.err == -1) {
-               /* hide stderr on success */
-               struct strbuf buf = STRBUF_INIT;
-               int rc = pipe_command(&cmd,
-                                     NULL, 0,
-                                     /* stdout is already redirected */
-                                     NULL, 0,
-                                     &buf, 0);
-               if (rc)
-                       fputs(buf.buf, stderr);
-               strbuf_release(&buf);
-               return rc;
-       }
-
-       return run_command(&cmd);
+       if (is_rebase_i(opts) && !(flags & EDIT_MSG))
+               return run_command_silent_on_success(&cmd);
+       else
+               return run_command(&cmd);
 }
 
 static int rest_is_empty(const struct strbuf *sb, int start)
@@ -994,6 +1102,7 @@ static int run_rewrite_hook(const struct object_id *oldoid,
        proc.argv = argv;
        proc.in = -1;
        proc.stdout_to_stderr = 1;
+       proc.trace2_hook_name = "post-rewrite";
 
        code = start_command(&proc);
        if (code)
@@ -1007,7 +1116,8 @@ static int run_rewrite_hook(const struct object_id *oldoid,
        return finish_command(&proc);
 }
 
-void commit_post_rewrite(const struct commit *old_head,
+void commit_post_rewrite(struct repository *r,
+                        const struct commit *old_head,
                         const struct object_id *new_head)
 {
        struct notes_rewrite_cfg *cfg;
@@ -1016,12 +1126,14 @@ void commit_post_rewrite(const struct commit *old_head,
        if (cfg) {
                /* we are amending, so old_head is not NULL */
                copy_note_for_rewrite(cfg, &old_head->object.oid, new_head);
-               finish_copy_notes_for_rewrite(cfg, "Notes added by 'git commit --amend'");
+               finish_copy_notes_for_rewrite(r, cfg, "Notes added by 'git commit --amend'");
        }
        run_rewrite_hook(&old_head->object.oid, new_head);
 }
 
-static int run_prepare_commit_msg_hook(struct strbuf *msg, const char *commit)
+static int run_prepare_commit_msg_hook(struct repository *r,
+                                      struct strbuf *msg,
+                                      const char *commit)
 {
        struct argv_array hook_env = ARGV_ARRAY_INIT;
        int ret;
@@ -1031,7 +1143,7 @@ static int run_prepare_commit_msg_hook(struct strbuf *msg, const char *commit)
        if (write_message(msg->buf, msg->len, name, 0))
                return -1;
 
-       argv_array_pushf(&hook_env, "GIT_INDEX_FILE=%s", get_index_file());
+       argv_array_pushf(&hook_env, "GIT_INDEX_FILE=%s", r->index_file);
        argv_array_push(&hook_env, "GIT_EDITOR=:");
        if (commit)
                ret = run_hook_le(hook_env.argv, "prepare-commit-msg", name,
@@ -1087,7 +1199,9 @@ static const char *implicit_ident_advice(void)
 
 }
 
-void print_commit_summary(const char *prefix, const struct object_id *oid,
+void print_commit_summary(struct repository *r,
+                         const char *prefix,
+                         const struct object_id *oid,
                          unsigned int flags)
 {
        struct rev_info rev;
@@ -1098,7 +1212,7 @@ void print_commit_summary(const char *prefix, const struct object_id *oid,
        struct strbuf author_ident = STRBUF_INIT;
        struct strbuf committer_ident = STRBUF_INIT;
 
-       commit = lookup_commit(oid);
+       commit = lookup_commit(r, oid);
        if (!commit)
                die(_("couldn't look up newly created commit"));
        if (parse_commit(commit))
@@ -1131,7 +1245,7 @@ void print_commit_summary(const char *prefix, const struct object_id *oid,
        strbuf_release(&author_ident);
        strbuf_release(&committer_ident);
 
-       init_revisions(&rev, prefix);
+       repo_init_revisions(r, &rev, prefix);
        setup_revisions(0, NULL, &rev, NULL);
 
        rev.diff = 1;
@@ -1165,7 +1279,7 @@ void print_commit_summary(const char *prefix, const struct object_id *oid,
        strbuf_release(&format);
 }
 
-static int parse_head(struct commit **head)
+static int parse_head(struct repository *r, struct commit **head)
 {
        struct commit *current_head;
        struct object_id oid;
@@ -1173,10 +1287,10 @@ static int parse_head(struct commit **head)
        if (get_oid("HEAD", &oid)) {
                current_head = NULL;
        } else {
-               current_head = lookup_commit_reference(&oid);
+               current_head = lookup_commit_reference(r, &oid);
                if (!current_head)
                        return error(_("could not parse HEAD"));
-               if (oidcmp(&oid, &current_head->object.oid)) {
+               if (!oideq(&oid, &current_head->object.oid)) {
                        warning(_("HEAD %s is not a commit!"),
                                oid_to_hex(&oid));
                }
@@ -1197,7 +1311,8 @@ static int parse_head(struct commit **head)
  *   0 - success
  *   1 - run 'git commit'
  */
-static int try_to_commit(struct strbuf *msg, const char *author,
+static int try_to_commit(struct repository *r,
+                        struct strbuf *msg, const char *author,
                         struct replay_opts *opts, unsigned int flags,
                         struct object_id *oid)
 {
@@ -1212,7 +1327,7 @@ static int try_to_commit(struct strbuf *msg, const char *author,
        enum commit_msg_cleanup_mode cleanup;
        int res = 0;
 
-       if (parse_head(&current_head))
+       if (parse_head(r, &current_head))
                return -1;
 
        if (flags & AMEND_MSG) {
@@ -1241,20 +1356,20 @@ static int try_to_commit(struct strbuf *msg, const char *author,
                commit_list_insert(current_head, &parents);
        }
 
-       if (write_cache_as_tree(&tree, 0, NULL)) {
+       if (write_index_as_tree(&tree, r->index, r->index_file, 0, NULL)) {
                res = error(_("git write-tree failed to write a tree"));
                goto out;
        }
 
-       if (!(flags & ALLOW_EMPTY) && !oidcmp(current_head ?
-                                             get_commit_tree_oid(current_head) :
-                                             the_hash_algo->empty_tree, &tree)) {
+       if (!(flags & ALLOW_EMPTY) && oideq(current_head ?
+                                           get_commit_tree_oid(current_head) :
+                                           the_hash_algo->empty_tree, &tree)) {
                res = 1; /* run 'git commit' to display error message */
                goto out;
        }
 
        if (find_hook("prepare-commit-msg")) {
-               res = run_prepare_commit_msg_hook(msg, hook_commit);
+               res = run_prepare_commit_msg_hook(r, msg, hook_commit);
                if (res)
                        goto out;
                if (strbuf_read_file(&commit_msg, git_path_commit_editmsg(),
@@ -1272,7 +1387,7 @@ static int try_to_commit(struct strbuf *msg, const char *author,
 
        if (cleanup != COMMIT_MSG_CLEANUP_NONE)
                strbuf_stripspace(msg, cleanup == COMMIT_MSG_CLEANUP_ALL);
-       if (!opts->allow_empty_message && message_is_empty(msg, cleanup)) {
+       if ((flags & EDIT_MSG) && message_is_empty(msg, cleanup)) {
                res = 1; /* run 'git commit' to display error message */
                goto out;
        }
@@ -1292,7 +1407,7 @@ static int try_to_commit(struct strbuf *msg, const char *author,
        }
 
        if (flags & AMEND_MSG)
-               commit_post_rewrite(current_head, oid);
+               commit_post_rewrite(r, current_head, oid);
 
 out:
        free_commit_extra_headers(extra);
@@ -1303,7 +1418,8 @@ static int try_to_commit(struct strbuf *msg, const char *author,
        return res;
 }
 
-static int do_commit(const char *msg_file, const char *author,
+static int do_commit(struct repository *r,
+                    const char *msg_file, const char *author,
                     struct replay_opts *opts, unsigned int flags)
 {
        int res = 1;
@@ -1318,20 +1434,20 @@ static int do_commit(const char *msg_file, const char *author,
                                             "from '%s'"),
                                           msg_file);
 
-               res = try_to_commit(msg_file ? &sb : NULL, author, opts, flags,
-                                   &oid);
+               res = try_to_commit(r, msg_file ? &sb : NULL,
+                                   author, opts, flags, &oid);
                strbuf_release(&sb);
                if (!res) {
-                       unlink(git_path_cherry_pick_head());
-                       unlink(git_path_merge_msg());
+                       unlink(git_path_cherry_pick_head(r));
+                       unlink(git_path_merge_msg(r));
                        if (!is_rebase_i(opts))
-                               print_commit_summary(NULL, &oid,
+                               print_commit_summary(r, NULL, &oid,
                                                SUMMARY_SHOW_AUTHOR_DATE);
                        return res;
                }
        }
        if (res == 1)
-               return run_git_commit(msg_file, opts, flags);
+               return run_git_commit(r, msg_file, opts, flags);
 
        return res;
 }
@@ -1353,13 +1469,15 @@ static int is_original_commit_empty(struct commit *commit)
                ptree_oid = the_hash_algo->empty_tree; /* commit is root */
        }
 
-       return !oidcmp(ptree_oid, get_commit_tree_oid(commit));
+       return oideq(ptree_oid, get_commit_tree_oid(commit));
 }
 
 /*
  * Do we run "git commit" with "--allow-empty"?
  */
-static int allow_empty(struct replay_opts *opts, struct commit *commit)
+static int allow_empty(struct repository *r,
+                      struct replay_opts *opts,
+                      struct commit *commit)
 {
        int index_unchanged, empty_commit;
 
@@ -1376,7 +1494,7 @@ static int allow_empty(struct replay_opts *opts, struct commit *commit)
        if (!opts->allow_empty)
                return 0; /* let "git commit" barf as necessary */
 
-       index_unchanged = is_index_unchanged();
+       index_unchanged = is_index_unchanged(r);
        if (index_unchanged < 0)
                return index_unchanged;
        if (!index_unchanged)
@@ -1394,31 +1512,6 @@ static int allow_empty(struct replay_opts *opts, struct commit *commit)
                return 1;
 }
 
-/*
- * Note that ordering matters in this enum. Not only must it match the mapping
- * below, it is also divided into several sections that matter.  When adding
- * new commands, make sure you add it in the right section.
- */
-enum todo_command {
-       /* commands that handle commits */
-       TODO_PICK = 0,
-       TODO_REVERT,
-       TODO_EDIT,
-       TODO_REWORD,
-       TODO_FIXUP,
-       TODO_SQUASH,
-       /* commands that do something else than handling a single commit */
-       TODO_EXEC,
-       TODO_LABEL,
-       TODO_RESET,
-       TODO_MERGE,
-       /* commands that do nothing but are counted for reporting progress */
-       TODO_NOOP,
-       TODO_DROP,
-       /* comments (not counted for reporting progress) */
-       TODO_COMMENT
-};
-
 static struct {
        char c;
        const char *str;
@@ -1430,6 +1523,7 @@ static struct {
        { 'f', "fixup" },
        { 's', "squash" },
        { 'x', "exec" },
+       { 'b', "break" },
        { 'l', "label" },
        { 't', "reset" },
        { 'm', "merge" },
@@ -1442,7 +1536,7 @@ static const char *command_to_string(const enum todo_command command)
 {
        if (command < TODO_COMMENT)
                return todo_command_info[command].str;
-       die("Unknown command: %d", command);
+       die(_("unknown command: %d"), command);
 }
 
 static char command_to_char(const enum todo_command command)
@@ -1478,8 +1572,10 @@ static int is_pick_or_similar(enum todo_command command)
        }
 }
 
-static int update_squash_messages(enum todo_command command,
-               struct commit *commit, struct replay_opts *opts)
+static int update_squash_messages(struct repository *r,
+                                 enum todo_command command,
+                                 struct commit *commit,
+                                 struct replay_opts *opts)
 {
        struct strbuf buf = STRBUF_INIT;
        int res;
@@ -1508,7 +1604,7 @@ static int update_squash_messages(enum todo_command command,
 
                if (get_oid("HEAD", &head))
                        return error(_("need a HEAD to fixup"));
-               if (!(head_commit = lookup_commit_reference(&head)))
+               if (!(head_commit = lookup_commit_reference(r, &head)))
                        return error(_("could not read HEAD"));
                if (!(head_message = get_commit_buffer(head_commit, NULL)))
                        return error(_("could not read HEAD's commit message"));
@@ -1540,13 +1636,13 @@ static int update_squash_messages(enum todo_command command,
                unlink(rebase_path_fixup_msg());
                strbuf_addf(&buf, "\n%c ", comment_line_char);
                strbuf_addf(&buf, _("This is the commit message #%d:"),
-                           ++opts->current_fixup_count);
+                           ++opts->current_fixup_count + 1);
                strbuf_addstr(&buf, "\n\n");
                strbuf_addstr(&buf, body);
        } else if (command == TODO_FIXUP) {
                strbuf_addf(&buf, "\n%c ", comment_line_char);
                strbuf_addf(&buf, _("The commit message #%d will be skipped:"),
-                           ++opts->current_fixup_count);
+                           ++opts->current_fixup_count + 1);
                strbuf_addstr(&buf, "\n\n");
                strbuf_add_commented_lines(&buf, body, strlen(body));
        } else
@@ -1569,7 +1665,8 @@ static int update_squash_messages(enum todo_command command,
        return res;
 }
 
-static void flush_rewritten_pending(void) {
+static void flush_rewritten_pending(void)
+{
        struct strbuf buf = STRBUF_INIT;
        struct object_id newoid;
        FILE *out;
@@ -1594,7 +1691,8 @@ static void flush_rewritten_pending(void) {
 }
 
 static void record_in_rewritten(struct object_id *oid,
-               enum todo_command next_command) {
+               enum todo_command next_command)
+{
        FILE *out = fopen_or_warn(rebase_path_rewritten_pending(), "a");
 
        if (!out)
@@ -1607,11 +1705,14 @@ static void record_in_rewritten(struct object_id *oid,
                flush_rewritten_pending();
 }
 
-static int do_pick_commit(enum todo_command command, struct commit *commit,
-               struct replay_opts *opts, int final_fixup)
+static int do_pick_commit(struct repository *r,
+                         enum todo_command command,
+                         struct commit *commit,
+                         struct replay_opts *opts,
+                         int final_fixup)
 {
        unsigned int flags = opts->edit ? EDIT_MSG : 0;
-       const char *msg_file = opts->edit ? NULL : git_path_merge_msg();
+       const char *msg_file = opts->edit ? NULL : git_path_merge_msg(r);
        struct object_id head;
        struct commit *base, *next, *parent;
        const char *base_label, *next_label;
@@ -1627,24 +1728,24 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
                 * that represents the "current" state for merge-recursive
                 * to work on.
                 */
-               if (write_cache_as_tree(&head, 0, NULL))
+               if (write_index_as_tree(&head, r->index, r->index_file, 0, NULL))
                        return error(_("your index file is unmerged."));
        } else {
                unborn = get_oid("HEAD", &head);
                /* Do we want to generate a root commit? */
                if (is_pick_or_similar(command) && opts->have_squash_onto &&
-                   !oidcmp(&head, &opts->squash_onto)) {
+                   oideq(&head, &opts->squash_onto)) {
                        if (is_fixup(command))
                                return error(_("cannot fixup root commit"));
                        flags |= CREATE_ROOT_COMMIT;
                        unborn = 1;
                } else if (unborn)
                        oidcpy(&head, the_hash_algo->empty_tree);
-               if (index_differs_from(unborn ? empty_tree_oid_hex() : "HEAD",
+               if (index_differs_from(r, unborn ? empty_tree_oid_hex() : "HEAD",
                                       NULL, 0))
-                       return error_dirty_index(opts);
+                       return error_dirty_index(r, opts);
        }
-       discard_cache();
+       discard_index(r->index);
 
        if (!commit->parents)
                parent = NULL;
@@ -1665,9 +1766,13 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
                        return error(_("commit %s does not have parent %d"),
                                oid_to_hex(&commit->object.oid), opts->mainline);
                parent = p->item;
-       } else if (0 < opts->mainline)
-               return error(_("mainline was specified but commit %s is not a merge."),
-                       oid_to_hex(&commit->object.oid));
+       } else if (1 < opts->mainline)
+               /*
+                *  Non-first parent explicitly specified as mainline for
+                *  non-merge commit
+                */
+               return error(_("commit %s does not have parent %d"),
+                            oid_to_hex(&commit->object.oid), opts->mainline);
        else
                parent = commit->parents->item;
 
@@ -1676,11 +1781,11 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
                        oid_to_hex(&commit->object.oid));
 
        if (opts->allow_ff && !is_fixup(command) &&
-           ((parent && !oidcmp(&parent->object.oid, &head)) ||
+           ((parent && oideq(&parent->object.oid, &head)) ||
             (!parent && unborn))) {
                if (is_rebase_i(opts))
                        write_author_script(msg.message);
-               res = fast_forward_to(&commit->object.oid, &head, unborn,
+               res = fast_forward_to(r, &commit->object.oid, &head, unborn,
                        opts);
                if (res || command != TODO_REWORD)
                        goto leave;
@@ -1744,7 +1849,7 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
        if (command == TODO_REWORD)
                flags |= EDIT_MSG | VERIFY_MSG;
        else if (is_fixup(command)) {
-               if (update_squash_messages(command, commit, opts))
+               if (update_squash_messages(r, command, commit, opts))
                        return -1;
                flags |= AMEND_MSG;
                if (!final_fixup)
@@ -1753,12 +1858,12 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
                        flags |= CLEANUP_MSG;
                        msg_file = rebase_path_fixup_msg();
                } else {
-                       const char *dest = git_path_squash_msg();
+                       const char *dest = git_path_squash_msg(r);
                        unlink(dest);
                        if (copy_file(dest, rebase_path_squash_msg(), 0666))
                                return error(_("could not rename '%s' to '%s'"),
                                             rebase_path_squash_msg(), dest);
-                       unlink(git_path_merge_msg());
+                       unlink(git_path_merge_msg(r));
                        msg_file = dest;
                        flags |= EDIT_MSG;
                }
@@ -1770,22 +1875,23 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
        if (is_rebase_i(opts) && write_author_script(msg.message) < 0)
                res = -1;
        else if (!opts->strategy || !strcmp(opts->strategy, "recursive") || command == TODO_REVERT) {
-               res = do_recursive_merge(base, next, base_label, next_label,
+               res = do_recursive_merge(r, base, next, base_label, next_label,
                                         &head, &msgbuf, opts);
                if (res < 0)
-                       return res;
+                       goto leave;
+
                res |= write_message(msgbuf.buf, msgbuf.len,
-                                    git_path_merge_msg(), 0);
+                                    git_path_merge_msg(r), 0);
        } else {
                struct commit_list *common = NULL;
                struct commit_list *remotes = NULL;
 
                res = write_message(msgbuf.buf, msgbuf.len,
-                                   git_path_merge_msg(), 0);
+                                   git_path_merge_msg(r), 0);
 
                commit_list_insert(base, &common);
                commit_list_insert(next, &remotes);
-               res |= try_merge_command(opts->strategy,
+               res |= try_merge_command(r, opts->strategy,
                                         opts->xopts_nr, (const char **)opts->xopts,
                                        common, oid_to_hex(&head), remotes);
                free_commit_list(common);
@@ -1813,12 +1919,12 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
                      ? _("could not revert %s... %s")
                      : _("could not apply %s... %s"),
                      short_commit_name(commit), msg.subject);
-               print_advice(res == 1, opts);
-               rerere(opts->allow_rerere_auto);
+               print_advice(r, res == 1, opts);
+               repo_rerere(r, opts->allow_rerere_auto);
                goto leave;
        }
 
-       allow = allow_empty(opts, commit);
+       allow = allow_empty(r, opts, commit);
        if (allow < 0) {
                res = allow;
                goto leave;
@@ -1827,7 +1933,7 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
        if (!opts->no_commit) {
 fast_forward_edit:
                if (author || command == TODO_REVERT || (flags & AMEND_MSG))
-                       res = do_commit(msg_file, author, opts, flags);
+                       res = do_commit(r, msg_file, author, opts, flags);
                else
                        res = error(_("unable to parse commit author"));
        }
@@ -1860,23 +1966,22 @@ static int prepare_revs(struct replay_opts *opts)
        if (prepare_revision_walk(opts->revs))
                return error(_("revision walk setup failed"));
 
-       if (!opts->revs->commits)
-               return error(_("empty commit set passed"));
        return 0;
 }
 
-static int read_and_refresh_cache(struct replay_opts *opts)
+static int read_and_refresh_cache(struct repository *r,
+                                 struct replay_opts *opts)
 {
        struct lock_file index_lock = LOCK_INIT;
-       int index_fd = hold_locked_index(&index_lock, 0);
-       if (read_index_preload(&the_index, NULL) < 0) {
+       int index_fd = repo_hold_locked_index(r, &index_lock, 0);
+       if (repo_read_index(r) < 0) {
                rollback_lock_file(&index_lock);
                return error(_("git %s: failed to read the index"),
                        _(action_name(opts)));
        }
-       refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED, NULL, NULL, NULL);
+       refresh_index(r->index, REFRESH_QUIET|REFRESH_UNMERGED, NULL, NULL, NULL);
        if (index_fd >= 0) {
-               if (write_locked_index(&the_index, &index_lock,
+               if (write_locked_index(r->index, &index_lock,
                                       COMMIT_LOCK | SKIP_IF_UNCHANGED)) {
                        return error(_("git %s: failed to refresh the index"),
                                _(action_name(opts)));
@@ -1889,26 +1994,7 @@ enum todo_item_flags {
        TODO_EDIT_MERGE_MSG = 1
 };
 
-struct todo_item {
-       enum todo_command command;
-       struct commit *commit;
-       unsigned int flags;
-       const char *arg;
-       int arg_len;
-       size_t offset_in_buf;
-};
-
-struct todo_list {
-       struct strbuf buf;
-       struct todo_item *items;
-       int nr, alloc, current;
-       int done_nr, total_nr;
-       struct stat_data stat;
-};
-
-#define TODO_LIST_INIT { STRBUF_INIT }
-
-static void todo_list_release(struct todo_list *todo_list)
+void todo_list_release(struct todo_list *todo_list)
 {
        strbuf_release(&todo_list->buf);
        FREE_AND_NULL(todo_list->items);
@@ -1921,7 +2007,14 @@ static struct todo_item *append_new_todo(struct todo_list *todo_list)
        return todo_list->items + todo_list->nr++;
 }
 
-static int parse_insn_line(struct todo_item *item, const char *bol, char *eol)
+const char *todo_item_get_arg(struct todo_list *todo_list,
+                             struct todo_item *item)
+{
+       return todo_list->buf.buf + item->arg_offset;
+}
+
+static int parse_insn_line(struct repository *r, struct todo_item *item,
+                          const char *buf, const char *bol, char *eol)
 {
        struct object_id commit_oid;
        char *end_of_object_name;
@@ -1935,7 +2028,7 @@ static int parse_insn_line(struct todo_item *item, const char *bol, char *eol)
        if (bol == eol || *bol == '\r' || *bol == comment_line_char) {
                item->command = TODO_COMMENT;
                item->commit = NULL;
-               item->arg = bol;
+               item->arg_offset = bol - buf;
                item->arg_len = eol - bol;
                return 0;
        }
@@ -1944,7 +2037,8 @@ static int parse_insn_line(struct todo_item *item, const char *bol, char *eol)
                if (skip_prefix(bol, todo_command_info[i].str, &bol)) {
                        item->command = i;
                        break;
-               } else if (bol[1] == ' ' && *bol == todo_command_info[i].c) {
+               } else if ((bol + 1 == eol || bol[1] == ' ') &&
+                          *bol == todo_command_info[i].c) {
                        bol++;
                        item->command = i;
                        break;
@@ -1956,12 +2050,12 @@ static int parse_insn_line(struct todo_item *item, const char *bol, char *eol)
        padding = strspn(bol, " \t");
        bol += padding;
 
-       if (item->command == TODO_NOOP) {
+       if (item->command == TODO_NOOP || item->command == TODO_BREAK) {
                if (bol != eol)
                        return error(_("%s does not accept arguments: '%s'"),
                                     command_to_string(item->command), bol);
                item->commit = NULL;
-               item->arg = bol;
+               item->arg_offset = bol - buf;
                item->arg_len = eol - bol;
                return 0;
        }
@@ -1973,7 +2067,7 @@ static int parse_insn_line(struct todo_item *item, const char *bol, char *eol)
        if (item->command == TODO_EXEC || item->command == TODO_LABEL ||
            item->command == TODO_RESET) {
                item->commit = NULL;
-               item->arg = bol;
+               item->arg_offset = bol - buf;
                item->arg_len = (int)(eol - bol);
                return 0;
        }
@@ -1987,7 +2081,7 @@ static int parse_insn_line(struct todo_item *item, const char *bol, char *eol)
                } else {
                        item->flags |= TODO_EDIT_MERGE_MSG;
                        item->commit = NULL;
-                       item->arg = bol;
+                       item->arg_offset = bol - buf;
                        item->arg_len = (int)(eol - bol);
                        return 0;
                }
@@ -1999,22 +2093,27 @@ static int parse_insn_line(struct todo_item *item, const char *bol, char *eol)
        status = get_oid(bol, &commit_oid);
        *end_of_object_name = saved;
 
-       item->arg = end_of_object_name + strspn(end_of_object_name, " \t");
-       item->arg_len = (int)(eol - item->arg);
+       bol = end_of_object_name + strspn(end_of_object_name, " \t");
+       item->arg_offset = bol - buf;
+       item->arg_len = (int)(eol - bol);
 
        if (status < 0)
-               return -1;
+               return error(_("could not parse '%.*s'"),
+                            (int)(end_of_object_name - bol), bol);
 
-       item->commit = lookup_commit_reference(&commit_oid);
+       item->commit = lookup_commit_reference(r, &commit_oid);
        return !item->commit;
 }
 
-static int parse_insn_buffer(char *buf, struct todo_list *todo_list)
+int todo_list_parse_insn_buffer(struct repository *r, char *buf,
+                               struct todo_list *todo_list)
 {
        struct todo_item *item;
        char *p = buf, *next_p;
        int i, res = 0, fixup_okay = file_exists(rebase_path_done());
 
+       todo_list->current = todo_list->nr = 0;
+
        for (i = 1; *p; i++, p = next_p) {
                char *eol = strchrnul(p, '\n');
 
@@ -2025,10 +2124,13 @@ static int parse_insn_buffer(char *buf, struct todo_list *todo_list)
 
                item = append_new_todo(todo_list);
                item->offset_in_buf = p - todo_list->buf.buf;
-               if (parse_insn_line(item, p, eol)) {
+               if (parse_insn_line(r, item, buf, p, eol)) {
                        res = error(_("invalid line %d: %.*s"),
                                i, (int)(eol - p), p);
-                       item->command = TODO_NOOP;
+                       item->command = TODO_COMMENT + 1;
+                       item->arg_offset = p - buf;
+                       item->arg_len = (int)(eol - p);
+                       item->commit = NULL;
                }
 
                if (fixup_okay)
@@ -2086,8 +2188,9 @@ static ssize_t strbuf_read_file_or_whine(struct strbuf *sb, const char *path)
        return len;
 }
 
-static int read_populate_todo(struct todo_list *todo_list,
-                       struct replay_opts *opts)
+static int read_populate_todo(struct repository *r,
+                             struct todo_list *todo_list,
+                             struct replay_opts *opts)
 {
        struct stat st;
        const char *todo_file = get_todo_path(opts);
@@ -2102,7 +2205,7 @@ static int read_populate_todo(struct todo_list *todo_list,
                return error(_("could not stat '%s'"), todo_file);
        fill_stat_data(&todo_list->stat, &st);
 
-       res = parse_insn_buffer(todo_list->buf.buf, todo_list);
+       res = todo_list_parse_insn_buffer(r, todo_list->buf.buf, todo_list);
        if (res) {
                if (is_rebase_i(opts))
                        return error(_("please fix this using "
@@ -2133,7 +2236,7 @@ static int read_populate_todo(struct todo_list *todo_list,
                FILE *f = fopen_or_warn(rebase_path_msgtotal(), "w");
 
                if (strbuf_read_file(&done.buf, rebase_path_done(), 0) > 0 &&
-                               !parse_insn_buffer(done.buf.buf, &done))
+                   !todo_list_parse_insn_buffer(r, done.buf.buf, &done))
                        todo_list->done_nr = count_commands(&done);
                else
                        todo_list->done_nr = 0;
@@ -2172,6 +2275,15 @@ static int populate_opts_cb(const char *key, const char *value, void *data)
                opts->no_commit = git_config_bool_or_int(key, value, &error_flag);
        else if (!strcmp(key, "options.edit"))
                opts->edit = git_config_bool_or_int(key, value, &error_flag);
+       else if (!strcmp(key, "options.allow-empty"))
+               opts->allow_empty =
+                       git_config_bool_or_int(key, value, &error_flag);
+       else if (!strcmp(key, "options.allow-empty-message"))
+               opts->allow_empty_message =
+                       git_config_bool_or_int(key, value, &error_flag);
+       else if (!strcmp(key, "options.keep-redundant-commits"))
+               opts->keep_redundant_commits =
+                       git_config_bool_or_int(key, value, &error_flag);
        else if (!strcmp(key, "options.signoff"))
                opts->signoff = git_config_bool_or_int(key, value, &error_flag);
        else if (!strcmp(key, "options.record-origin"))
@@ -2200,18 +2312,16 @@ static int populate_opts_cb(const char *key, const char *value, void *data)
        return 0;
 }
 
-static void read_strategy_opts(struct replay_opts *opts, struct strbuf *buf)
+void parse_strategy_opts(struct replay_opts *opts, char *raw_opts)
 {
        int i;
+       char *strategy_opts_string = raw_opts;
 
-       strbuf_reset(buf);
-       if (!read_oneliner(buf, rebase_path_strategy(), 0))
-               return;
-       opts->strategy = strbuf_detach(buf, NULL);
-       if (!read_oneliner(buf, rebase_path_strategy_opts(), 0))
-               return;
+       if (*strategy_opts_string == ' ')
+               strategy_opts_string++;
 
-       opts->xopts_nr = split_cmdline(buf->buf, (const char ***)&opts->xopts);
+       opts->xopts_nr = split_cmdline(strategy_opts_string,
+                                      (const char ***)&opts->xopts);
        for (i = 0; i < opts->xopts_nr; i++) {
                const char *arg = opts->xopts[i];
 
@@ -2220,6 +2330,18 @@ static void read_strategy_opts(struct replay_opts *opts, struct strbuf *buf)
        }
 }
 
+static void read_strategy_opts(struct replay_opts *opts, struct strbuf *buf)
+{
+       strbuf_reset(buf);
+       if (!read_oneliner(buf, rebase_path_strategy(), 0))
+               return;
+       opts->strategy = strbuf_detach(buf, NULL);
+       if (!read_oneliner(buf, rebase_path_strategy_opts(), 0))
+               return;
+
+       parse_strategy_opts(opts, buf->buf);
+}
+
 static int read_populate_opts(struct replay_opts *opts)
 {
        if (is_rebase_i(opts)) {
@@ -2246,11 +2368,17 @@ static int read_populate_opts(struct replay_opts *opts)
                if (file_exists(rebase_path_verbose()))
                        opts->verbose = 1;
 
+               if (file_exists(rebase_path_quiet()))
+                       opts->quiet = 1;
+
                if (file_exists(rebase_path_signoff())) {
                        opts->allow_ff = 0;
                        opts->signoff = 1;
                }
 
+               if (file_exists(rebase_path_reschedule_failed_exec()))
+                       opts->reschedule_failed_exec = 1;
+
                read_strategy_opts(opts, &buf);
                strbuf_release(&buf);
 
@@ -2287,6 +2415,54 @@ static int read_populate_opts(struct replay_opts *opts)
        return 0;
 }
 
+static void write_strategy_opts(struct replay_opts *opts)
+{
+       int i;
+       struct strbuf buf = STRBUF_INIT;
+
+       for (i = 0; i < opts->xopts_nr; ++i)
+               strbuf_addf(&buf, " --%s", opts->xopts[i]);
+
+       write_file(rebase_path_strategy_opts(), "%s\n", buf.buf);
+       strbuf_release(&buf);
+}
+
+int write_basic_state(struct replay_opts *opts, const char *head_name,
+                     const char *onto, const char *orig_head)
+{
+       const char *quiet = getenv("GIT_QUIET");
+
+       if (head_name)
+               write_file(rebase_path_head_name(), "%s\n", head_name);
+       if (onto)
+               write_file(rebase_path_onto(), "%s\n", onto);
+       if (orig_head)
+               write_file(rebase_path_orig_head(), "%s\n", orig_head);
+
+       if (quiet)
+               write_file(rebase_path_quiet(), "%s\n", quiet);
+       if (opts->verbose)
+               write_file(rebase_path_verbose(), "%s", "");
+       if (opts->strategy)
+               write_file(rebase_path_strategy(), "%s\n", opts->strategy);
+       if (opts->xopts_nr > 0)
+               write_strategy_opts(opts);
+
+       if (opts->allow_rerere_auto == RERERE_AUTOUPDATE)
+               write_file(rebase_path_allow_rerere_autoupdate(), "--rerere-autoupdate\n");
+       else if (opts->allow_rerere_auto == RERERE_NOAUTOUPDATE)
+               write_file(rebase_path_allow_rerere_autoupdate(), "--no-rerere-autoupdate\n");
+
+       if (opts->gpg_sign)
+               write_file(rebase_path_gpg_sign_opt(), "-S%s\n", opts->gpg_sign);
+       if (opts->signoff)
+               write_file(rebase_path_signoff(), "--signoff\n");
+       if (opts->reschedule_failed_exec)
+               write_file(rebase_path_reschedule_failed_exec(), "%s", "");
+
+       return 0;
+}
+
 static int walk_revs_populate_todo(struct todo_list *todo_list,
                                struct replay_opts *opts)
 {
@@ -2306,7 +2482,7 @@ static int walk_revs_populate_todo(struct todo_list *todo_list,
 
                item->command = command;
                item->commit = commit;
-               item->arg = NULL;
+               item->arg_offset = 0;
                item->arg_len = 0;
                item->offset_in_buf = todo_list->buf.len;
                subject_len = find_commit_subject(commit_buffer, &subject);
@@ -2314,6 +2490,10 @@ static int walk_revs_populate_todo(struct todo_list *todo_list,
                        short_commit_name(commit), subject_len, subject);
                unuse_commit_buffer(commit, commit_buffer);
        }
+
+       if (!todo_list->nr)
+               return error(_("empty commit set passed"));
+
        return 0;
 }
 
@@ -2373,7 +2553,7 @@ static int rollback_is_safe(void)
        if (get_oid("HEAD", &actual_head))
                oidclr(&actual_head);
 
-       return !oidcmp(&actual_head, &expected_head);
+       return oideq(&actual_head, &expected_head);
 }
 
 static int reset_for_rollback(const struct object_id *oid)
@@ -2387,12 +2567,12 @@ static int reset_for_rollback(const struct object_id *oid)
        return run_command_v_opt(argv, RUN_GIT_CMD);
 }
 
-static int rollback_single_pick(void)
+static int rollback_single_pick(struct repository *r)
 {
        struct object_id head_oid;
 
-       if (!file_exists(git_path_cherry_pick_head()) &&
-           !file_exists(git_path_revert_head()))
+       if (!file_exists(git_path_cherry_pick_head(r)) &&
+           !file_exists(git_path_revert_head(r)))
                return error(_("no cherry-pick or revert in progress"));
        if (read_ref_full("HEAD", 0, &head_oid, NULL))
                return error(_("cannot resolve HEAD"));
@@ -2401,7 +2581,7 @@ static int rollback_single_pick(void)
        return reset_for_rollback(&head_oid);
 }
 
-int sequencer_rollback(struct replay_opts *opts)
+int sequencer_rollback(struct repository *r, struct replay_opts *opts)
 {
        FILE *f;
        struct object_id oid;
@@ -2415,7 +2595,7 @@ int sequencer_rollback(struct replay_opts *opts)
                 * If CHERRY_PICK_HEAD or REVERT_HEAD indicates
                 * a single-cherry-pick in progress, abort that.
                 */
-               return rollback_single_pick();
+               return rollback_single_pick(r);
        }
        if (!f)
                return error_errno(_("cannot open '%s'"), git_path_head_file());
@@ -2497,40 +2677,60 @@ static int save_opts(struct replay_opts *opts)
        int res = 0;
 
        if (opts->no_commit)
-               res |= git_config_set_in_file_gently(opts_file, "options.no-commit", "true");
+               res |= git_config_set_in_file_gently(opts_file,
+                                       "options.no-commit", "true");
        if (opts->edit)
-               res |= git_config_set_in_file_gently(opts_file, "options.edit", "true");
+               res |= git_config_set_in_file_gently(opts_file,
+                                       "options.edit", "true");
+       if (opts->allow_empty)
+               res |= git_config_set_in_file_gently(opts_file,
+                                       "options.allow-empty", "true");
+       if (opts->allow_empty_message)
+               res |= git_config_set_in_file_gently(opts_file,
+                               "options.allow-empty-message", "true");
+       if (opts->keep_redundant_commits)
+               res |= git_config_set_in_file_gently(opts_file,
+                               "options.keep-redundant-commits", "true");
        if (opts->signoff)
-               res |= git_config_set_in_file_gently(opts_file, "options.signoff", "true");
+               res |= git_config_set_in_file_gently(opts_file,
+                                       "options.signoff", "true");
        if (opts->record_origin)
-               res |= git_config_set_in_file_gently(opts_file, "options.record-origin", "true");
+               res |= git_config_set_in_file_gently(opts_file,
+                                       "options.record-origin", "true");
        if (opts->allow_ff)
-               res |= git_config_set_in_file_gently(opts_file, "options.allow-ff", "true");
+               res |= git_config_set_in_file_gently(opts_file,
+                                       "options.allow-ff", "true");
        if (opts->mainline) {
                struct strbuf buf = STRBUF_INIT;
                strbuf_addf(&buf, "%d", opts->mainline);
-               res |= git_config_set_in_file_gently(opts_file, "options.mainline", buf.buf);
+               res |= git_config_set_in_file_gently(opts_file,
+                                       "options.mainline", buf.buf);
                strbuf_release(&buf);
        }
        if (opts->strategy)
-               res |= git_config_set_in_file_gently(opts_file, "options.strategy", opts->strategy);
+               res |= git_config_set_in_file_gently(opts_file,
+                                       "options.strategy", opts->strategy);
        if (opts->gpg_sign)
-               res |= git_config_set_in_file_gently(opts_file, "options.gpg-sign", opts->gpg_sign);
+               res |= git_config_set_in_file_gently(opts_file,
+                                       "options.gpg-sign", opts->gpg_sign);
        if (opts->xopts) {
                int i;
                for (i = 0; i < opts->xopts_nr; i++)
                        res |= git_config_set_multivar_in_file_gently(opts_file,
-                                                       "options.strategy-option",
-                                                       opts->xopts[i], "^$", 0);
+                                       "options.strategy-option",
+                                       opts->xopts[i], "^$", 0);
        }
        if (opts->allow_rerere_auto)
-               res |= git_config_set_in_file_gently(opts_file, "options.allow-rerere-auto",
-                                                    opts->allow_rerere_auto == RERERE_AUTOUPDATE ?
-                                                    "true" : "false");
+               res |= git_config_set_in_file_gently(opts_file,
+                               "options.allow-rerere-auto",
+                               opts->allow_rerere_auto == RERERE_AUTOUPDATE ?
+                               "true" : "false");
        return res;
 }
 
-static int make_patch(struct commit *commit, struct replay_opts *opts)
+static int make_patch(struct repository *r,
+                     struct commit *commit,
+                     struct replay_opts *opts)
 {
        struct strbuf buf = STRBUF_INIT;
        struct rev_info log_tree_opt;
@@ -2546,7 +2746,7 @@ static int make_patch(struct commit *commit, struct replay_opts *opts)
 
        strbuf_addf(&buf, "%s/patch", get_dir(opts));
        memset(&log_tree_opt, 0, sizeof(log_tree_opt));
-       init_revisions(&log_tree_opt, NULL);
+       repo_init_revisions(r, &log_tree_opt, NULL);
        log_tree_opt.abbrev = 0;
        log_tree_opt.diff = 1;
        log_tree_opt.diffopt.output_format = DIFF_FORMAT_PATCH;
@@ -2586,45 +2786,67 @@ static int intend_to_amend(void)
        return write_message(p, strlen(p), rebase_path_amend(), 1);
 }
 
-static int error_with_patch(struct commit *commit,
-       const char *subject, int subject_len,
-       struct replay_opts *opts, int exit_code, int to_amend)
+static int error_with_patch(struct repository *r,
+                           struct commit *commit,
+                           const char *subject, int subject_len,
+                           struct replay_opts *opts,
+                           int exit_code, int to_amend)
 {
-       if (make_patch(commit, opts))
-               return -1;
+       if (commit) {
+               if (make_patch(r, commit, opts))
+                       return -1;
+       } else if (copy_file(rebase_path_message(),
+                            git_path_merge_msg(r), 0666))
+               return error(_("unable to copy '%s' to '%s'"),
+                            git_path_merge_msg(r), rebase_path_message());
 
        if (to_amend) {
                if (intend_to_amend())
                        return -1;
 
-               fprintf(stderr, "You can amend the commit now, with\n"
-                       "\n"
-                       "  git commit --amend %s\n"
-                       "\n"
-                       "Once you are satisfied with your changes, run\n"
-                       "\n"
-                       "  git rebase --continue\n", gpg_sign_opt_quoted(opts));
-       } else if (exit_code)
-               fprintf(stderr, "Could not apply %s... %.*s\n",
-                       short_commit_name(commit), subject_len, subject);
+               fprintf(stderr,
+                       _("You can amend the commit now, with\n"
+                         "\n"
+                         "  git commit --amend %s\n"
+                         "\n"
+                         "Once you are satisfied with your changes, run\n"
+                         "\n"
+                         "  git rebase --continue\n"),
+                       gpg_sign_opt_quoted(opts));
+       } else if (exit_code) {
+               if (commit)
+                       fprintf_ln(stderr, _("Could not apply %s... %.*s"),
+                                  short_commit_name(commit), subject_len, subject);
+               else
+                       /*
+                        * We don't have the hash of the parent so
+                        * just print the line from the todo file.
+                        */
+                       fprintf_ln(stderr, _("Could not merge %.*s"),
+                                  subject_len, subject);
+       }
 
        return exit_code;
 }
 
-static int error_failed_squash(struct commit *commit,
-       struct replay_opts *opts, int subject_len, const char *subject)
+static int error_failed_squash(struct repository *r,
+                              struct commit *commit,
+                              struct replay_opts *opts,
+                              int subject_len,
+                              const char *subject)
 {
        if (copy_file(rebase_path_message(), rebase_path_squash_msg(), 0666))
                return error(_("could not copy '%s' to '%s'"),
                        rebase_path_squash_msg(), rebase_path_message());
-       unlink(git_path_merge_msg());
-       if (copy_file(git_path_merge_msg(), rebase_path_message(), 0666))
+       unlink(git_path_merge_msg(r));
+       if (copy_file(git_path_merge_msg(r), rebase_path_message(), 0666))
                return error(_("could not copy '%s' to '%s'"),
-                            rebase_path_message(), git_path_merge_msg());
-       return error_with_patch(commit, subject, subject_len, opts, 1, 0);
+                            rebase_path_message(),
+                            git_path_merge_msg(r));
+       return error_with_patch(r, commit, subject, subject_len, opts, 1, 0);
 }
 
-static int do_exec(const char *command_line)
+static int do_exec(struct repository *r, const char *command_line)
 {
        struct argv_array child_env = ARGV_ARRAY_INIT;
        const char *child_argv[] = { NULL, NULL };
@@ -2633,14 +2855,16 @@ static int do_exec(const char *command_line)
        fprintf(stderr, "Executing: %s\n", command_line);
        child_argv[0] = command_line;
        argv_array_pushf(&child_env, "GIT_DIR=%s", absolute_path(get_git_dir()));
+       argv_array_pushf(&child_env, "GIT_WORK_TREE=%s",
+                        absolute_path(get_git_work_tree()));
        status = run_command_v_opt_cd_env(child_argv, RUN_USING_SHELL, NULL,
                                          child_env.argv);
 
        /* force re-reading of the cache */
-       if (discard_cache() < 0 || read_cache() < 0)
+       if (discard_index(r->index) < 0 || repo_read_index(r) < 0)
                return error(_("could not read index"));
 
-       dirty = require_clean_work_tree("rebase", NULL, 1, 1);
+       dirty = require_clean_work_tree(r, "rebase", NULL, 1, 1);
 
        if (status) {
                warning(_("execution failed: %s\n%s"
@@ -2706,9 +2930,9 @@ static int safe_append(const char *filename, const char *fmt, ...)
        return 0;
 }
 
-static int do_label(const char *name, int len)
+static int do_label(struct repository *r, const char *name, int len)
 {
-       struct ref_store *refs = get_main_ref_store(the_repository);
+       struct ref_store *refs = get_main_ref_store(r);
        struct ref_transaction *transaction;
        struct strbuf ref_name = STRBUF_INIT, err = STRBUF_INIT;
        struct strbuf msg = STRBUF_INIT;
@@ -2716,7 +2940,7 @@ static int do_label(const char *name, int len)
        struct object_id head_oid;
 
        if (len == 1 && *name == '#')
-               return error("Illegal label name: '%.*s'", len, name);
+               return error(_("illegal label name: '%.*s'"), len, name);
 
        strbuf_addf(&ref_name, "refs/rewritten/%.*s", len, name);
        strbuf_addf(&msg, "rebase -i (label) '%.*s'", len, name);
@@ -2749,7 +2973,9 @@ static int do_label(const char *name, int len)
 static const char *reflog_message(struct replay_opts *opts,
        const char *sub_action, const char *fmt, ...);
 
-static int do_reset(const char *name, int len, struct replay_opts *opts)
+static int do_reset(struct repository *r,
+                   const char *name, int len,
+                   struct replay_opts *opts)
 {
        struct strbuf ref_name = STRBUF_INIT;
        struct object_id oid;
@@ -2757,9 +2983,9 @@ static int do_reset(const char *name, int len, struct replay_opts *opts)
        struct tree_desc desc;
        struct tree *tree;
        struct unpack_trees_options unpack_tree_opts;
-       int ret = 0, i;
+       int ret = 0;
 
-       if (hold_locked_index(&lock, LOCK_REPORT_ON_ERROR) < 0)
+       if (repo_hold_locked_index(r, &lock, LOCK_REPORT_ON_ERROR) < 0)
                return -1;
 
        if (len == 10 && !strncmp("[new root]", name, len)) {
@@ -2777,10 +3003,13 @@ static int do_reset(const char *name, int len, struct replay_opts *opts)
                }
                oidcpy(&oid, &opts->squash_onto);
        } else {
+               int i;
+
                /* Determine the length of the label */
                for (i = 0; i < len; i++)
                        if (isspace(name[i]))
-                               len = i;
+                               break;
+               len = i;
 
                strbuf_addf(&ref_name, "refs/rewritten/%.*s", len, name);
                if (get_oid(ref_name.buf, &oid) &&
@@ -2795,13 +3024,13 @@ static int do_reset(const char *name, int len, struct replay_opts *opts)
        memset(&unpack_tree_opts, 0, sizeof(unpack_tree_opts));
        setup_unpack_trees_porcelain(&unpack_tree_opts, "reset");
        unpack_tree_opts.head_idx = 1;
-       unpack_tree_opts.src_index = &the_index;
-       unpack_tree_opts.dst_index = &the_index;
+       unpack_tree_opts.src_index = r->index;
+       unpack_tree_opts.dst_index = r->index;
        unpack_tree_opts.fn = oneway_merge;
        unpack_tree_opts.merge = 1;
        unpack_tree_opts.update = 1;
 
-       if (read_cache_unmerged()) {
+       if (repo_read_index_unmerged(r)) {
                rollback_lock_file(&lock);
                strbuf_release(&ref_name);
                return error_resolve_conflict(_(action_name(opts)));
@@ -2823,9 +3052,9 @@ static int do_reset(const char *name, int len, struct replay_opts *opts)
        }
 
        tree = parse_tree_indirect(&oid);
-       prime_cache_tree(&the_index, tree);
+       prime_cache_tree(r, r->index, tree);
 
-       if (write_locked_index(&the_index, &lock, COMMIT_LOCK) < 0)
+       if (write_locked_index(r->index, &lock, COMMIT_LOCK) < 0)
                ret = error(_("could not write index"));
        free((void *)desc.buffer);
 
@@ -2838,7 +3067,29 @@ static int do_reset(const char *name, int len, struct replay_opts *opts)
        return ret;
 }
 
-static int do_merge(struct commit *commit, const char *arg, int arg_len,
+static struct commit *lookup_label(const char *label, int len,
+                                  struct strbuf *buf)
+{
+       struct commit *commit;
+
+       strbuf_reset(buf);
+       strbuf_addf(buf, "refs/rewritten/%.*s", len, label);
+       commit = lookup_commit_reference_by_name(buf->buf);
+       if (!commit) {
+               /* fall back to non-rewritten ref or commit */
+               strbuf_splice(buf, 0, strlen("refs/rewritten/"), "", 0);
+               commit = lookup_commit_reference_by_name(buf->buf);
+       }
+
+       if (!commit)
+               error(_("could not resolve '%s'"), buf->buf);
+
+       return commit;
+}
+
+static int do_merge(struct repository *r,
+                   struct commit *commit,
+                   const char *arg, int arg_len,
                    int flags, struct replay_opts *opts)
 {
        int run_commit_flags = (flags & TODO_EDIT_MERGE_MSG) ?
@@ -2846,12 +3097,13 @@ static int do_merge(struct commit *commit, const char *arg, int arg_len,
        struct strbuf ref_name = STRBUF_INIT;
        struct commit *head_commit, *merge_commit, *i;
        struct commit_list *bases, *j, *reversed = NULL;
+       struct commit_list *to_merge = NULL, **tail = &to_merge;
        struct merge_options o;
-       int merge_arg_len, oneline_offset, can_fast_forward, ret;
+       int merge_arg_len, oneline_offset, can_fast_forward, ret, k;
        static struct lock_file lock;
        const char *p;
 
-       if (hold_locked_index(&lock, LOCK_REPORT_ON_ERROR) < 0) {
+       if (repo_hold_locked_index(r, &lock, LOCK_REPORT_ON_ERROR) < 0) {
                ret = -1;
                goto leave_merge;
        }
@@ -2862,38 +3114,51 @@ static int do_merge(struct commit *commit, const char *arg, int arg_len,
                goto leave_merge;
        }
 
-       oneline_offset = arg_len;
-       merge_arg_len = strcspn(arg, " \t\n");
-       p = arg + merge_arg_len;
-       p += strspn(p, " \t\n");
-       if (*p == '#' && (!p[1] || isspace(p[1]))) {
-               p += 1 + strspn(p + 1, " \t\n");
-               oneline_offset = p - arg;
-       } else if (p - arg < arg_len)
-               BUG("octopus merges are not supported yet: '%s'", p);
-
-       strbuf_addf(&ref_name, "refs/rewritten/%.*s", merge_arg_len, arg);
-       merge_commit = lookup_commit_reference_by_name(ref_name.buf);
-       if (!merge_commit) {
-               /* fall back to non-rewritten ref or commit */
-               strbuf_splice(&ref_name, 0, strlen("refs/rewritten/"), "", 0);
-               merge_commit = lookup_commit_reference_by_name(ref_name.buf);
+       /*
+        * For octopus merges, the arg starts with the list of revisions to be
+        * merged. The list is optionally followed by '#' and the oneline.
+        */
+       merge_arg_len = oneline_offset = arg_len;
+       for (p = arg; p - arg < arg_len; p += strspn(p, " \t\n")) {
+               if (!*p)
+                       break;
+               if (*p == '#' && (!p[1] || isspace(p[1]))) {
+                       p += 1 + strspn(p + 1, " \t\n");
+                       oneline_offset = p - arg;
+                       break;
+               }
+               k = strcspn(p, " \t\n");
+               if (!k)
+                       continue;
+               merge_commit = lookup_label(p, k, &ref_name);
+               if (!merge_commit) {
+                       ret = error(_("unable to parse '%.*s'"), k, p);
+                       goto leave_merge;
+               }
+               tail = &commit_list_insert(merge_commit, tail)->next;
+               p += k;
+               merge_arg_len = p - arg;
        }
 
-       if (!merge_commit) {
-               ret = error(_("could not resolve '%s'"), ref_name.buf);
+       if (!to_merge) {
+               ret = error(_("nothing to merge: '%.*s'"), arg_len, arg);
                goto leave_merge;
        }
 
        if (opts->have_squash_onto &&
-           !oidcmp(&head_commit->object.oid, &opts->squash_onto)) {
+           oideq(&head_commit->object.oid, &opts->squash_onto)) {
                /*
                 * When the user tells us to "merge" something into a
                 * "[new root]", let's simply fast-forward to the merge head.
                 */
                rollback_lock_file(&lock);
-               ret = fast_forward_to(&merge_commit->object.oid,
-                                      &head_commit->object.oid, 0, opts);
+               if (to_merge->next)
+                       ret = error(_("octopus merge cannot be executed on "
+                                     "top of a [new root]"));
+               else
+                       ret = fast_forward_to(r, &to_merge->item->object.oid,
+                                             &head_commit->object.oid, 0,
+                                             opts);
                goto leave_merge;
        }
 
@@ -2910,11 +3175,11 @@ static int do_merge(struct commit *commit, const char *arg, int arg_len,
                write_author_script(message);
                find_commit_subject(message, &body);
                len = strlen(body);
-               ret = write_message(body, len, git_path_merge_msg(), 0);
+               ret = write_message(body, len, git_path_merge_msg(r), 0);
                unuse_commit_buffer(commit, message);
                if (ret) {
                        error_errno(_("could not write '%s'"),
-                                   git_path_merge_msg());
+                                   git_path_merge_msg(r));
                        goto leave_merge;
                }
        } else {
@@ -2929,17 +3194,18 @@ static int do_merge(struct commit *commit, const char *arg, int arg_len,
                        p = arg + oneline_offset;
                        len = arg_len - oneline_offset;
                } else {
-                       strbuf_addf(&buf, "Merge branch '%.*s'",
+                       strbuf_addf(&buf, "Merge %s '%.*s'",
+                                   to_merge->next ? "branches" : "branch",
                                    merge_arg_len, arg);
                        p = buf.buf;
                        len = buf.len;
                }
 
-               ret = write_message(p, len, git_path_merge_msg(), 0);
+               ret = write_message(p, len, git_path_merge_msg(r), 0);
                strbuf_release(&buf);
                if (ret) {
                        error_errno(_("could not write '%s'"),
-                                   git_path_merge_msg());
+                                   git_path_merge_msg(r));
                        goto leave_merge;
                }
        }
@@ -2949,50 +3215,99 @@ static int do_merge(struct commit *commit, const char *arg, int arg_len,
         * commit, we cannot fast-forward.
         */
        can_fast_forward = opts->allow_ff && commit && commit->parents &&
-               !oidcmp(&commit->parents->item->object.oid,
-                       &head_commit->object.oid);
+               oideq(&commit->parents->item->object.oid,
+                     &head_commit->object.oid);
 
        /*
-        * If the merge head is different from the original one, we cannot
+        * If any merge head is different from the original one, we cannot
         * fast-forward.
         */
        if (can_fast_forward) {
-               struct commit_list *second_parent = commit->parents->next;
+               struct commit_list *p = commit->parents->next;
 
-               if (second_parent && !second_parent->next &&
-                   oidcmp(&merge_commit->object.oid,
-                          &second_parent->item->object.oid))
+               for (j = to_merge; j && p; j = j->next, p = p->next)
+                       if (!oideq(&j->item->object.oid,
+                                  &p->item->object.oid)) {
+                               can_fast_forward = 0;
+                               break;
+                       }
+               /*
+                * If the number of merge heads differs from the original merge
+                * commit, we cannot fast-forward.
+                */
+               if (j || p)
                        can_fast_forward = 0;
        }
 
-       if (can_fast_forward && commit->parents->next &&
-           !commit->parents->next->next &&
-           !oidcmp(&commit->parents->next->item->object.oid,
-                   &merge_commit->object.oid)) {
+       if (can_fast_forward) {
                rollback_lock_file(&lock);
-               ret = fast_forward_to(&commit->object.oid,
+               ret = fast_forward_to(r, &commit->object.oid,
                                      &head_commit->object.oid, 0, opts);
                goto leave_merge;
        }
 
-       write_message(oid_to_hex(&merge_commit->object.oid), GIT_SHA1_HEXSZ,
-                     git_path_merge_head(), 0);
-       write_message("no-ff", 5, git_path_merge_mode(), 0);
+       if (to_merge->next) {
+               /* Octopus merge */
+               struct child_process cmd = CHILD_PROCESS_INIT;
+
+               if (read_env_script(&cmd.env_array)) {
+                       const char *gpg_opt = gpg_sign_opt_quoted(opts);
+
+                       ret = error(_(staged_changes_advice), gpg_opt, gpg_opt);
+                       goto leave_merge;
+               }
+
+               cmd.git_cmd = 1;
+               argv_array_push(&cmd.args, "merge");
+               argv_array_push(&cmd.args, "-s");
+               argv_array_push(&cmd.args, "octopus");
+               argv_array_push(&cmd.args, "--no-edit");
+               argv_array_push(&cmd.args, "--no-ff");
+               argv_array_push(&cmd.args, "--no-log");
+               argv_array_push(&cmd.args, "--no-stat");
+               argv_array_push(&cmd.args, "-F");
+               argv_array_push(&cmd.args, git_path_merge_msg(r));
+               if (opts->gpg_sign)
+                       argv_array_push(&cmd.args, opts->gpg_sign);
+
+               /* Add the tips to be merged */
+               for (j = to_merge; j; j = j->next)
+                       argv_array_push(&cmd.args,
+                                       oid_to_hex(&j->item->object.oid));
+
+               strbuf_release(&ref_name);
+               unlink(git_path_cherry_pick_head(r));
+               rollback_lock_file(&lock);
+
+               rollback_lock_file(&lock);
+               ret = run_command(&cmd);
 
+               /* force re-reading of the cache */
+               if (!ret && (discard_index(r->index) < 0 ||
+                            repo_read_index(r) < 0))
+                       ret = error(_("could not read index"));
+               goto leave_merge;
+       }
+
+       merge_commit = to_merge->item;
        bases = get_merge_bases(head_commit, merge_commit);
-       if (bases && !oidcmp(&merge_commit->object.oid,
-                            &bases->item->object.oid)) {
+       if (bases && oideq(&merge_commit->object.oid,
+                          &bases->item->object.oid)) {
                ret = 0;
                /* skip merging an ancestor of HEAD */
                goto leave_merge;
        }
 
+       write_message(oid_to_hex(&merge_commit->object.oid), GIT_SHA1_HEXSZ,
+                     git_path_merge_head(r), 0);
+       write_message("no-ff", 5, git_path_merge_mode(r), 0);
+
        for (j = bases; j; j = j->next)
                commit_list_insert(j->item, &reversed);
        free_commit_list(bases);
 
-       read_cache();
-       init_merge_options(&o);
+       repo_read_index(r);
+       init_merge_options(&o, r);
        o.branch1 = "HEAD";
        o.branch2 = ref_name.buf;
        o.buffer_output = 2;
@@ -3016,27 +3331,28 @@ static int do_merge(struct commit *commit, const char *arg, int arg_len,
         */
        ret = !ret;
 
-       if (active_cache_changed &&
-           write_locked_index(&the_index, &lock, COMMIT_LOCK)) {
+       if (r->index->cache_changed &&
+           write_locked_index(r->index, &lock, COMMIT_LOCK)) {
                ret = error(_("merge: Unable to write new index file"));
                goto leave_merge;
        }
 
        rollback_lock_file(&lock);
        if (ret)
-               rerere(opts->allow_rerere_auto);
+               repo_rerere(r, opts->allow_rerere_auto);
        else
                /*
                 * In case of problems, we now want to return a positive
                 * value (a negative one would indicate that the `merge`
                 * command needs to be rescheduled).
                 */
-               ret = !!run_git_commit(git_path_merge_msg(), opts,
-                                    run_commit_flags);
+               ret = !!run_git_commit(r, git_path_merge_msg(r), opts,
+                                      run_commit_flags);
 
 leave_merge:
        strbuf_release(&ref_name);
        rollback_lock_file(&lock);
+       free_commit_list(to_merge);
        return ret;
 }
 
@@ -3130,6 +3446,73 @@ static const char *reflog_message(struct replay_opts *opts,
        return buf.buf;
 }
 
+static int run_git_checkout(struct replay_opts *opts, const char *commit,
+                           const char *action)
+{
+       struct child_process cmd = CHILD_PROCESS_INIT;
+
+       cmd.git_cmd = 1;
+
+       argv_array_push(&cmd.args, "checkout");
+       argv_array_push(&cmd.args, commit);
+       argv_array_pushf(&cmd.env_array, GIT_REFLOG_ACTION "=%s", action);
+
+       if (opts->verbose)
+               return run_command(&cmd);
+       else
+               return run_command_silent_on_success(&cmd);
+}
+
+int prepare_branch_to_be_rebased(struct replay_opts *opts, const char *commit)
+{
+       const char *action;
+
+       if (commit && *commit) {
+               action = reflog_message(opts, "start", "checkout %s", commit);
+               if (run_git_checkout(opts, commit, action))
+                       return error(_("could not checkout %s"), commit);
+       }
+
+       return 0;
+}
+
+static int checkout_onto(struct replay_opts *opts,
+                        const char *onto_name, const char *onto,
+                        const char *orig_head)
+{
+       struct object_id oid;
+       const char *action = reflog_message(opts, "start", "checkout %s", onto_name);
+
+       if (get_oid(orig_head, &oid))
+               return error(_("%s: not a valid OID"), orig_head);
+
+       if (run_git_checkout(opts, onto, action)) {
+               apply_autostash(opts);
+               sequencer_remove_state(opts);
+               return error(_("could not detach HEAD"));
+       }
+
+       return update_ref(NULL, "ORIG_HEAD", &oid, NULL, 0, UPDATE_REFS_MSG_ON_ERR);
+}
+
+static int stopped_at_head(struct repository *r)
+{
+       struct object_id head;
+       struct commit *commit;
+       struct commit_message message;
+
+       if (get_oid("HEAD", &head) ||
+           !(commit = lookup_commit(r, &head)) ||
+           parse_commit(commit) || get_message(commit, &message))
+               fprintf(stderr, _("Stopped at HEAD\n"));
+       else {
+               fprintf(stderr, _("Stopped at %s\n"), message.label);
+               free_message(commit, &message);
+       }
+       return 0;
+
+}
+
 static const char rescheduled_advice[] =
 N_("Could not execute the todo command\n"
 "\n"
@@ -3141,7 +3524,9 @@ N_("Could not execute the todo command\n"
 "    git rebase --edit-todo\n"
 "    git rebase --continue\n");
 
-static int pick_commits(struct todo_list *todo_list, struct replay_opts *opts)
+static int pick_commits(struct repository *r,
+                       struct todo_list *todo_list,
+                       struct replay_opts *opts)
 {
        int res = 0, reschedule = 0;
 
@@ -3149,11 +3534,13 @@ static int pick_commits(struct todo_list *todo_list, struct replay_opts *opts)
        if (opts->allow_ff)
                assert(!(opts->signoff || opts->no_commit ||
                                opts->record_origin || opts->edit));
-       if (read_and_refresh_cache(opts))
+       if (read_and_refresh_cache(r, opts))
                return -1;
 
        while (todo_list->current < todo_list->nr) {
                struct todo_item *item = todo_list->items + todo_list->current;
+               const char *arg = todo_item_get_arg(todo_list, item);
+
                if (save_todo(todo_list, opts))
                        return -1;
                if (is_rebase_i(opts)) {
@@ -3166,23 +3553,28 @@ static int pick_commits(struct todo_list *todo_list, struct replay_opts *opts)
                                        fprintf(f, "%d\n", todo_list->done_nr);
                                        fclose(f);
                                }
-                               fprintf(stderr, "Rebasing (%d/%d)%s",
-                                       todo_list->done_nr,
-                                       todo_list->total_nr,
-                                       opts->verbose ? "\n" : "\r");
+                               if (!opts->quiet)
+                                       fprintf(stderr, "Rebasing (%d/%d)%s",
+                                               todo_list->done_nr,
+                                               todo_list->total_nr,
+                                               opts->verbose ? "\n" : "\r");
                        }
                        unlink(rebase_path_message());
                        unlink(rebase_path_author_script());
                        unlink(rebase_path_stopped_sha());
                        unlink(rebase_path_amend());
+                       unlink(git_path_merge_head(the_repository));
                        delete_ref(NULL, "REBASE_HEAD", NULL, REF_NO_DEREF);
+
+                       if (item->command == TODO_BREAK)
+                               return stopped_at_head(r);
                }
                if (item->command <= TODO_SQUASH) {
                        if (is_rebase_i(opts))
                                setenv("GIT_REFLOG_ACTION", reflog_message(opts,
                                        command_to_string(item->command), NULL),
                                        1);
-                       res = do_pick_commit(item->command, item->commit,
+                       res = do_pick_commit(r, item->command, item->commit,
                                        opts, is_final_fixup(todo_list));
                        if (is_rebase_i(opts) && res < 0) {
                                /* Reschedule */
@@ -3201,10 +3593,9 @@ static int pick_commits(struct todo_list *todo_list, struct replay_opts *opts)
                                        fprintf(stderr,
                                                _("Stopped at %s...  %.*s\n"),
                                                short_commit_name(commit),
-                                               item->arg_len, item->arg);
-                               return error_with_patch(commit,
-                                       item->arg, item->arg_len, opts, res,
-                                       !res);
+                                               item->arg_len, arg);
+                               return error_with_patch(r, commit,
+                                       arg, item->arg_len, opts, res, !res);
                        }
                        if (is_rebase_i(opts) && !res)
                                record_in_rewritten(&item->commit->object.oid,
@@ -3212,43 +3603,61 @@ static int pick_commits(struct todo_list *todo_list, struct replay_opts *opts)
                        if (res && is_fixup(item->command)) {
                                if (res == 1)
                                        intend_to_amend();
-                               return error_failed_squash(item->commit, opts,
-                                       item->arg_len, item->arg);
-                       } else if (res && is_rebase_i(opts) && item->commit)
-                               return res | error_with_patch(item->commit,
-                                       item->arg, item->arg_len, opts, res,
-                                       item->command == TODO_REWORD);
+                               return error_failed_squash(r, item->commit, opts,
+                                       item->arg_len, arg);
+                       } else if (res && is_rebase_i(opts) && item->commit) {
+                               int to_amend = 0;
+                               struct object_id oid;
+
+                               /*
+                                * If we are rewording and have either
+                                * fast-forwarded already, or are about to
+                                * create a new root commit, we want to amend,
+                                * otherwise we do not.
+                                */
+                               if (item->command == TODO_REWORD &&
+                                   !get_oid("HEAD", &oid) &&
+                                   (oideq(&item->commit->object.oid, &oid) ||
+                                    (opts->have_squash_onto &&
+                                     oideq(&opts->squash_onto, &oid))))
+                                       to_amend = 1;
+
+                               return res | error_with_patch(r, item->commit,
+                                               arg, item->arg_len, opts,
+                                               res, to_amend);
+                       }
                } else if (item->command == TODO_EXEC) {
-                       char *end_of_arg = (char *)(item->arg + item->arg_len);
+                       char *end_of_arg = (char *)(arg + item->arg_len);
                        int saved = *end_of_arg;
                        struct stat st;
 
                        *end_of_arg = '\0';
-                       res = do_exec(item->arg);
+                       res = do_exec(r, arg);
                        *end_of_arg = saved;
 
-                       /* Reread the todo file if it has changed. */
-                       if (res)
-                               ; /* fall through */
-                       else if (stat(get_todo_path(opts), &st))
+                       if (res) {
+                               if (opts->reschedule_failed_exec)
+                                       reschedule = 1;
+                       else if (stat(get_todo_path(opts), &st))
                                res = error_errno(_("could not stat '%s'"),
                                                  get_todo_path(opts));
                        else if (match_stat_data(&todo_list->stat, &st)) {
+                               /* Reread the todo file if it has changed. */
                                todo_list_release(todo_list);
-                               if (read_populate_todo(todo_list, opts))
+                               if (read_populate_todo(r, todo_list, opts))
                                        res = -1; /* message was printed */
                                /* `current` will be incremented below */
                                todo_list->current = -1;
                        }
                } else if (item->command == TODO_LABEL) {
-                       if ((res = do_label(item->arg, item->arg_len)))
+                       if ((res = do_label(r, arg, item->arg_len)))
                                reschedule = 1;
                } else if (item->command == TODO_RESET) {
-                       if ((res = do_reset(item->arg, item->arg_len, opts)))
+                       if ((res = do_reset(r, arg, item->arg_len, opts)))
                                reschedule = 1;
                } else if (item->command == TODO_MERGE) {
-                       if ((res = do_merge(item->commit,
-                                           item->arg, item->arg_len,
+                       if ((res = do_merge(r, item->commit,
+                                           arg, item->arg_len,
                                            item->flags, opts)) < 0)
                                reschedule = 1;
                        else if (item->commit)
@@ -3256,10 +3665,9 @@ static int pick_commits(struct todo_list *todo_list, struct replay_opts *opts)
                                                    peek_command(todo_list, 1));
                        if (res > 0)
                                /* failed with merge conflicts */
-                               return error_with_patch(item->commit,
-                                                       item->arg,
-                                                       item->arg_len, opts,
-                                                       res, 0);
+                               return error_with_patch(r, item->commit,
+                                                       arg, item->arg_len,
+                                                       opts, res, 0);
                } else if (!is_noop(item->command))
                        return error(_("unknown command %d"), item->command);
 
@@ -3272,10 +3680,10 @@ static int pick_commits(struct todo_list *todo_list, struct replay_opts *opts)
                        if (save_todo(todo_list, opts))
                                return -1;
                        if (item->commit)
-                               return error_with_patch(item->commit,
-                                                       item->arg,
-                                                       item->arg_len, opts,
-                                                       res, 0);
+                               return error_with_patch(r,
+                                                       item->commit,
+                                                       arg, item->arg_len,
+                                                       opts, res, 0);
                }
 
                todo_list->current++;
@@ -3337,7 +3745,7 @@ static int pick_commits(struct todo_list *todo_list, struct replay_opts *opts)
                        struct object_id orig, head;
 
                        memset(&log_tree_opt, 0, sizeof(log_tree_opt));
-                       init_revisions(&log_tree_opt, NULL);
+                       repo_init_revisions(r, &log_tree_opt, NULL);
                        log_tree_opt.diff = 1;
                        log_tree_opt.diffopt.output_format =
                                DIFF_FORMAT_DIFFSTAT;
@@ -3372,6 +3780,7 @@ static int pick_commits(struct todo_list *todo_list, struct replay_opts *opts)
                                hook.in = open(rebase_path_rewritten_list(),
                                        O_RDONLY);
                                hook.stdout_to_stderr = 1;
+                               hook.trace2_hook_name = "post-rewrite";
                                argv_array_push(&hook.args, post_rewrite_hook);
                                argv_array_push(&hook.args, "rebase");
                                /* we don't care if this hook failed */
@@ -3380,8 +3789,10 @@ static int pick_commits(struct todo_list *todo_list, struct replay_opts *opts)
                }
                apply_autostash(opts);
 
-               fprintf(stderr, "Successfully rebased and updated %s.\n",
-                       head_ref.buf);
+               if (!opts->quiet)
+                       fprintf(stderr,
+                               "Successfully rebased and updated %s.\n",
+                               head_ref.buf);
 
                strbuf_release(&buf);
                strbuf_release(&head_ref);
@@ -3394,26 +3805,27 @@ static int pick_commits(struct todo_list *todo_list, struct replay_opts *opts)
        return sequencer_remove_state(opts);
 }
 
-static int continue_single_pick(void)
+static int continue_single_pick(struct repository *r)
 {
        const char *argv[] = { "commit", NULL };
 
-       if (!file_exists(git_path_cherry_pick_head()) &&
-           !file_exists(git_path_revert_head()))
+       if (!file_exists(git_path_cherry_pick_head(r)) &&
+           !file_exists(git_path_revert_head(r)))
                return error(_("no cherry-pick or revert in progress"));
        return run_command_v_opt(argv, RUN_GIT_CMD);
 }
 
-static int commit_staged_changes(struct replay_opts *opts,
+static int commit_staged_changes(struct repository *r,
+                                struct replay_opts *opts,
                                 struct todo_list *todo_list)
 {
        unsigned int flags = ALLOW_EMPTY | EDIT_MSG;
        unsigned int final_fixup = 0, is_clean;
 
-       if (has_unstaged_changes(1))
+       if (has_unstaged_changes(r, 1))
                return error(_("cannot rebase: You have unstaged changes."));
 
-       is_clean = !has_uncommitted_changes(0);
+       is_clean = !has_uncommitted_changes(r, 0);
 
        if (file_exists(rebase_path_amend())) {
                struct strbuf rev = STRBUF_INIT;
@@ -3426,7 +3838,7 @@ static int commit_staged_changes(struct replay_opts *opts,
                if (get_oid_hex(rev.buf, &to_amend))
                        return error(_("invalid contents: '%s'"),
                                rebase_path_amend());
-               if (!is_clean && oidcmp(&head, &to_amend))
+               if (!is_clean && !oideq(&head, &to_amend))
                        return error(_("\nYou have uncommitted changes in your "
                                       "working tree. Please, commit them\n"
                                       "first and then run 'git rebase "
@@ -3438,9 +3850,20 @@ static int commit_staged_changes(struct replay_opts *opts,
                 * the commit message and if there was a squash, let the user
                 * edit it.
                 */
-               if (is_clean && !oidcmp(&head, &to_amend) &&
-                   opts->current_fixup_count > 0 &&
-                   file_exists(rebase_path_stopped_sha())) {
+               if (!is_clean || !opts->current_fixup_count)
+                       ; /* this is not the final fixup */
+               else if (!oideq(&head, &to_amend) ||
+                        !file_exists(rebase_path_stopped_sha())) {
+                       /* was a final fixup or squash done manually? */
+                       if (!is_fixup(peek_command(todo_list, 0))) {
+                               unlink(rebase_path_fixup_msg());
+                               unlink(rebase_path_squash_msg());
+                               unlink(rebase_path_current_fixups());
+                               strbuf_reset(&opts->current_fixups);
+                               opts->current_fixup_count = 0;
+                       }
+               } else {
+                       /* we are in a fixup/squash chain */
                        const char *p = opts->current_fixups.buf;
                        int len = opts->current_fixups.len;
 
@@ -3486,7 +3909,7 @@ static int commit_staged_changes(struct replay_opts *opts,
                                struct commit *commit;
                                const char *path = rebase_path_squash_msg();
 
-                               if (parse_head(&commit) ||
+                               if (parse_head(r, &commit) ||
                                    !(p = get_commit_buffer(commit, NULL)) ||
                                    write_message(p, strlen(p), path, 0)) {
                                        unuse_commit_buffer(commit, p);
@@ -3502,7 +3925,7 @@ static int commit_staged_changes(struct replay_opts *opts,
        }
 
        if (is_clean) {
-               const char *cherry_pick_head = git_path_cherry_pick_head();
+               const char *cherry_pick_head = git_path_cherry_pick_head(r);
 
                if (file_exists(cherry_pick_head) && unlink(cherry_pick_head))
                        return error(_("could not remove CHERRY_PICK_HEAD"));
@@ -3510,10 +3933,11 @@ static int commit_staged_changes(struct replay_opts *opts,
                        return 0;
        }
 
-       if (run_git_commit(final_fixup ? NULL : rebase_path_message(),
+       if (run_git_commit(r, final_fixup ? NULL : rebase_path_message(),
                           opts, flags))
                return error(_("could not commit staged changes."));
        unlink(rebase_path_amend());
+       unlink(git_path_merge_head(the_repository));
        if (final_fixup) {
                unlink(rebase_path_fixup_msg());
                unlink(rebase_path_squash_msg());
@@ -3530,36 +3954,36 @@ static int commit_staged_changes(struct replay_opts *opts,
        return 0;
 }
 
-int sequencer_continue(struct replay_opts *opts)
+int sequencer_continue(struct repository *r, struct replay_opts *opts)
 {
        struct todo_list todo_list = TODO_LIST_INIT;
        int res;
 
-       if (read_and_refresh_cache(opts))
+       if (read_and_refresh_cache(r, opts))
                return -1;
 
        if (read_populate_opts(opts))
                return -1;
        if (is_rebase_i(opts)) {
-               if ((res = read_populate_todo(&todo_list, opts)))
+               if ((res = read_populate_todo(r, &todo_list, opts)))
                        goto release_todo_list;
-               if (commit_staged_changes(opts, &todo_list))
+               if (commit_staged_changes(r, opts, &todo_list))
                        return -1;
        } else if (!file_exists(get_todo_path(opts)))
-               return continue_single_pick();
-       else if ((res = read_populate_todo(&todo_list, opts)))
+               return continue_single_pick(r);
+       else if ((res = read_populate_todo(r, &todo_list, opts)))
                goto release_todo_list;
 
        if (!is_rebase_i(opts)) {
                /* Verify that the conflict has been resolved */
-               if (file_exists(git_path_cherry_pick_head()) ||
-                   file_exists(git_path_revert_head())) {
-                       res = continue_single_pick();
+               if (file_exists(git_path_cherry_pick_head(r)) ||
+                   file_exists(git_path_revert_head(r))) {
+                       res = continue_single_pick(r);
                        if (res)
                                goto release_todo_list;
                }
-               if (index_differs_from("HEAD", NULL, 0)) {
-                       res = error_dirty_index(opts);
+               if (index_differs_from(r, "HEAD", NULL, 0)) {
+                       res = error_dirty_index(r, opts);
                        goto release_todo_list;
                }
                todo_list.current++;
@@ -3573,27 +3997,30 @@ int sequencer_continue(struct replay_opts *opts)
                strbuf_release(&buf);
        }
 
-       res = pick_commits(&todo_list, opts);
+       res = pick_commits(r, &todo_list, opts);
 release_todo_list:
        todo_list_release(&todo_list);
        return res;
 }
 
-static int single_pick(struct commit *cmit, struct replay_opts *opts)
+static int single_pick(struct repository *r,
+                      struct commit *cmit,
+                      struct replay_opts *opts)
 {
        setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
-       return do_pick_commit(opts->action == REPLAY_PICK ?
+       return do_pick_commit(r, opts->action == REPLAY_PICK ?
                TODO_PICK : TODO_REVERT, cmit, opts, 0);
 }
 
-int sequencer_pick_revisions(struct replay_opts *opts)
+int sequencer_pick_revisions(struct repository *r,
+                            struct replay_opts *opts)
 {
        struct todo_list todo_list = TODO_LIST_INIT;
        struct object_id oid;
        int i, res;
 
        assert(opts->revs);
-       if (read_and_refresh_cache(opts))
+       if (read_and_refresh_cache(r, opts))
                return -1;
 
        for (i = 0; i < opts->revs->pending.nr; i++) {
@@ -3605,8 +4032,8 @@ int sequencer_pick_revisions(struct replay_opts *opts)
                        continue;
 
                if (!get_oid(name, &oid)) {
-                       if (!lookup_commit_reference_gently(&oid, 1)) {
-                               enum object_type type = oid_object_info(the_repository,
+                       if (!lookup_commit_reference_gently(r, &oid, 1)) {
+                               enum object_type type = oid_object_info(r,
                                                                        &oid,
                                                                        NULL);
                                return error(_("%s: can't cherry-pick a %s"),
@@ -3631,9 +4058,11 @@ int sequencer_pick_revisions(struct replay_opts *opts)
                if (prepare_revision_walk(opts->revs))
                        return error(_("revision walk setup failed"));
                cmit = get_revision(opts->revs);
-               if (!cmit || get_revision(opts->revs))
-                       return error("BUG: expected exactly one commit from walk");
-               return single_pick(cmit, opts);
+               if (!cmit)
+                       return error(_("empty commit set passed"));
+               if (get_revision(opts->revs))
+                       BUG("unexpected extra commit from walk");
+               return single_pick(r, cmit, opts);
        }
 
        /*
@@ -3652,20 +4081,19 @@ int sequencer_pick_revisions(struct replay_opts *opts)
        if (save_opts(opts))
                return -1;
        update_abort_safety_file();
-       res = pick_commits(&todo_list, opts);
+       res = pick_commits(r, &todo_list, opts);
        todo_list_release(&todo_list);
        return res;
 }
 
-void append_signoff(struct strbuf *msgbuf, int ignore_footer, unsigned flag)
+void append_signoff(struct strbuf *msgbuf, size_t ignore_footer, unsigned flag)
 {
        unsigned no_dup_sob = flag & APPEND_SIGNOFF_DEDUP;
        struct strbuf sob = STRBUF_INIT;
        int has_footer;
 
        strbuf_addstr(&sob, sign_off_header);
-       strbuf_addstr(&sob, fmt_name(getenv("GIT_COMMITTER_NAME"),
-                               getenv("GIT_COMMITTER_EMAIL")));
+       strbuf_addstr(&sob, fmt_name(WANT_COMMITTER_IDENT));
        strbuf_addch(&sob, '\n');
 
        if (!ignore_footer)
@@ -3832,7 +4260,7 @@ static const char *label_oid(struct object_id *oid, const char *label,
 }
 
 static int make_script_with_merges(struct pretty_print_context *pp,
-                                  struct rev_info *revs, FILE *out,
+                                  struct rev_info *revs, struct strbuf *out,
                                   unsigned flags)
 {
        int keep_empty = flags & TODO_LIST_KEEP_EMPTY;
@@ -3874,7 +4302,6 @@ static int make_script_with_merges(struct pretty_print_context *pp,
         */
        while ((commit = get_revision(revs))) {
                struct commit_list *to_merge;
-               int is_octopus;
                const char *p1, *p2;
                struct object_id *oid;
                int is_empty;
@@ -3906,11 +4333,6 @@ static int make_script_with_merges(struct pretty_print_context *pp,
                        continue;
                }
 
-               is_octopus = to_merge && to_merge->next;
-
-               if (is_octopus)
-                       BUG("Octopus merges not yet supported");
-
                /* Create a label */
                strbuf_reset(&label);
                if (skip_prefix(oneline.buf, "Merge ", &p1) &&
@@ -3932,13 +4354,17 @@ static int make_script_with_merges(struct pretty_print_context *pp,
                strbuf_addf(&buf, "%s -C %s",
                            cmd_merge, oid_to_hex(&commit->object.oid));
 
-               /* label the tip of merged branch */
-               oid = &to_merge->item->object.oid;
-               strbuf_addch(&buf, ' ');
+               /* label the tips of merged branches */
+               for (; to_merge; to_merge = to_merge->next) {
+                       oid = &to_merge->item->object.oid;
+                       strbuf_addch(&buf, ' ');
+
+                       if (!oidset_contains(&interesting, oid)) {
+                               strbuf_addstr(&buf, label_oid(oid, NULL,
+                                                             &state));
+                               continue;
+                       }
 
-               if (!oidset_contains(&interesting, oid))
-                       strbuf_addstr(&buf, label_oid(oid, NULL, &state));
-               else {
                        tips_tail = &commit_list_insert(to_merge->item,
                                                        tips_tail)->next;
 
@@ -3962,9 +4388,7 @@ static int make_script_with_merges(struct pretty_print_context *pp,
                        struct object_id *oid = &parent->item->object.oid;
                        if (!oidset_contains(&interesting, oid))
                                continue;
-                       if (!oidset_contains(&child_seen, oid))
-                               oidset_insert(&child_seen, oid);
-                       else
+                       if (oidset_insert(&child_seen, oid))
                                label_oid(oid, "branch-point", &state);
                }
 
@@ -3981,7 +4405,7 @@ static int make_script_with_merges(struct pretty_print_context *pp,
         * gathering commits not yet shown, reversing the list on the fly,
         * then outputting that list (labeling revisions as needed).
         */
-       fprintf(out, "%s onto\n", cmd_label);
+       strbuf_addf(out, "%s onto\n", cmd_label);
        for (iter = tips; iter; iter = iter->next) {
                struct commit_list *list = NULL, *iter2;
 
@@ -3991,9 +4415,9 @@ static int make_script_with_merges(struct pretty_print_context *pp,
                entry = oidmap_get(&state.commit2label, &commit->object.oid);
 
                if (entry)
-                       fprintf(out, "\n# Branch %s\n", entry->string);
+                       strbuf_addf(out, "\n%c Branch %s\n", comment_line_char, entry->string);
                else
-                       fprintf(out, "\n");
+                       strbuf_addch(out, '\n');
 
                while (oidset_contains(&interesting, &commit->object.oid) &&
                       !oidset_contains(&shown, &commit->object.oid)) {
@@ -4006,8 +4430,8 @@ static int make_script_with_merges(struct pretty_print_context *pp,
                }
 
                if (!commit)
-                       fprintf(out, "%s %s\n", cmd_reset,
-                               rebase_cousins ? "onto" : "[new root]");
+                       strbuf_addf(out, "%s %s\n", cmd_reset,
+                                   rebase_cousins ? "onto" : "[new root]");
                else {
                        const char *to = NULL;
 
@@ -4020,12 +4444,12 @@ static int make_script_with_merges(struct pretty_print_context *pp,
                                               &state);
 
                        if (!to || !strcmp(to, "onto"))
-                               fprintf(out, "%s onto\n", cmd_reset);
+                               strbuf_addf(out, "%s onto\n", cmd_reset);
                        else {
                                strbuf_reset(&oneline);
                                pretty_print_commit(pp, commit, &oneline);
-                               fprintf(out, "%s %s # %s\n",
-                                       cmd_reset, to, oneline.buf);
+                               strbuf_addf(out, "%s %s # %s\n",
+                                           cmd_reset, to, oneline.buf);
                        }
                }
 
@@ -4034,11 +4458,11 @@ static int make_script_with_merges(struct pretty_print_context *pp,
                        entry = oidmap_get(&commit2todo, oid);
                        /* only show if not already upstream */
                        if (entry)
-                               fprintf(out, "%s\n", entry->string);
+                               strbuf_addf(out, "%s\n", entry->string);
                        entry = oidmap_get(&state.commit2label, oid);
                        if (entry)
-                               fprintf(out, "%s %s\n",
-                                       cmd_label, entry->string);
+                               strbuf_addf(out, "%s %s\n",
+                                           cmd_label, entry->string);
                        oidset_insert(&shown, oid);
                }
 
@@ -4060,19 +4484,18 @@ static int make_script_with_merges(struct pretty_print_context *pp,
        return 0;
 }
 
-int sequencer_make_script(FILE *out, int argc, const char **argv,
-                         unsigned flags)
+int sequencer_make_script(struct repository *r, struct strbuf *out, int argc,
+                         const char **argv, unsigned flags)
 {
        char *format = NULL;
        struct pretty_print_context pp = {0};
-       struct strbuf buf = STRBUF_INIT;
        struct rev_info revs;
        struct commit *commit;
        int keep_empty = flags & TODO_LIST_KEEP_EMPTY;
        const char *insn = flags & TODO_LIST_ABBREVIATE_CMDS ? "p" : "pick";
        int rebase_merges = flags & TODO_LIST_REBASE_MERGES;
 
-       init_revisions(&revs, NULL);
+       repo_init_revisions(r, &revs, NULL);
        revs.verbose_header = 1;
        if (!rebase_merges)
                revs.max_parents = 1;
@@ -4108,16 +4531,13 @@ int sequencer_make_script(FILE *out, int argc, const char **argv,
 
                if (!is_empty && (commit->object.flags & PATCHSAME))
                        continue;
-               strbuf_reset(&buf);
                if (!keep_empty && is_empty)
-                       strbuf_addf(&buf, "%c ", comment_line_char);
-               strbuf_addf(&buf, "%s %s ", insn,
+                       strbuf_addf(out, "%c ", comment_line_char);
+               strbuf_addf(out, "%s %s ", insn,
                            oid_to_hex(&commit->object.oid));
-               pretty_print_commit(&pp, commit, &buf);
-               strbuf_addch(&buf, '\n');
-               fputs(buf.buf, out);
+               pretty_print_commit(&pp, commit, out);
+               strbuf_addch(out, '\n');
        }
-       strbuf_release(&buf);
        return 0;
 }
 
@@ -4125,70 +4545,95 @@ int sequencer_make_script(FILE *out, int argc, const char **argv,
  * Add commands after pick and (series of) squash/fixup commands
  * in the todo list.
  */
-int sequencer_add_exec_commands(const char *commands)
+void todo_list_add_exec_commands(struct todo_list *todo_list,
+                                struct string_list *commands)
 {
-       const char *todo_file = rebase_path_todo();
-       struct todo_list todo_list = TODO_LIST_INIT;
-       struct todo_item *item;
-       struct strbuf *buf = &todo_list.buf;
-       size_t offset = 0, commands_len = strlen(commands);
-       int i, first;
+       struct strbuf *buf = &todo_list->buf;
+       size_t base_offset = buf->len;
+       int i, insert, nr = 0, alloc = 0;
+       struct todo_item *items = NULL, *base_items = NULL;
+
+       base_items = xcalloc(commands->nr, sizeof(struct todo_item));
+       for (i = 0; i < commands->nr; i++) {
+               size_t command_len = strlen(commands->items[i].string);
+
+               strbuf_addstr(buf, commands->items[i].string);
+               strbuf_addch(buf, '\n');
 
-       if (strbuf_read_file(&todo_list.buf, todo_file, 0) < 0)
-               return error(_("could not read '%s'."), todo_file);
+               base_items[i].command = TODO_EXEC;
+               base_items[i].offset_in_buf = base_offset;
+               base_items[i].arg_offset = base_offset + strlen("exec ");
+               base_items[i].arg_len = command_len - strlen("exec ");
 
-       if (parse_insn_buffer(todo_list.buf.buf, &todo_list)) {
-               todo_list_release(&todo_list);
-               return error(_("unusable todo list: '%s'"), todo_file);
+               base_offset += command_len + 1;
        }
 
-       first = 1;
-       /* insert <commands> before every pick except the first one */
-       for (item = todo_list.items, i = 0; i < todo_list.nr; i++, item++) {
-               if (item->command == TODO_PICK && !first) {
-                       strbuf_insert(buf, item->offset_in_buf + offset,
-                                     commands, commands_len);
-                       offset += commands_len;
+       /*
+        * Insert <commands> after every pick. Here, fixup/squash chains
+        * are considered part of the pick, so we insert the commands *after*
+        * those chains if there are any.
+        *
+        * As we insert the exec commands immediatly after rearranging
+        * any fixups and before the user edits the list, a fixup chain
+        * can never contain comments (any comments are empty picks that
+        * have been commented out because the user did not specify
+        * --keep-empty).  So, it is safe to insert an exec command
+        * without looking at the command following a comment.
+        */
+       insert = 0;
+       for (i = 0; i < todo_list->nr; i++) {
+               enum todo_command command = todo_list->items[i].command;
+               if (insert && !is_fixup(command)) {
+                       ALLOC_GROW(items, nr + commands->nr, alloc);
+                       COPY_ARRAY(items + nr, base_items, commands->nr);
+                       nr += commands->nr;
+
+                       insert = 0;
                }
-               first = 0;
+
+               ALLOC_GROW(items, nr + 1, alloc);
+               items[nr++] = todo_list->items[i];
+
+               if (command == TODO_PICK || command == TODO_MERGE)
+                       insert = 1;
        }
 
-       /* append final <commands> */
-       strbuf_add(buf, commands, commands_len);
+       /* insert or append final <commands> */
+       if (insert || nr == todo_list->nr) {
+               ALLOC_GROW(items, nr + commands->nr, alloc);
+               COPY_ARRAY(items + nr, base_items, commands->nr);
+               nr += commands->nr;
+       }
 
-       i = write_message(buf->buf, buf->len, todo_file, 0);
-       todo_list_release(&todo_list);
-       return i;
+       free(base_items);
+       FREE_AND_NULL(todo_list->items);
+       todo_list->items = items;
+       todo_list->nr = nr;
+       todo_list->alloc = alloc;
 }
 
-int transform_todos(unsigned flags)
+static void todo_list_to_strbuf(struct repository *r, struct todo_list *todo_list,
+                               struct strbuf *buf, int num, unsigned flags)
 {
-       const char *todo_file = rebase_path_todo();
-       struct todo_list todo_list = TODO_LIST_INIT;
-       struct strbuf buf = STRBUF_INIT;
        struct todo_item *item;
-       int i;
-
-       if (strbuf_read_file(&todo_list.buf, todo_file, 0) < 0)
-               return error(_("could not read '%s'."), todo_file);
+       int i, max = todo_list->nr;
 
-       if (parse_insn_buffer(todo_list.buf.buf, &todo_list)) {
-               todo_list_release(&todo_list);
-               return error(_("unusable todo list: '%s'"), todo_file);
-       }
+       if (num > 0 && num < max)
+               max = num;
 
-       for (item = todo_list.items, i = 0; i < todo_list.nr; i++, item++) {
+       for (item = todo_list->items, i = 0; i < max; i++, item++) {
                /* if the item is not a command write it and continue */
                if (item->command >= TODO_COMMENT) {
-                       strbuf_addf(&buf, "%.*s\n", item->arg_len, item->arg);
+                       strbuf_addf(buf, "%.*s\n", item->arg_len,
+                                   todo_item_get_arg(todo_list, item));
                        continue;
                }
 
                /* add command to the buffer */
                if (flags & TODO_LIST_ABBREVIATE_CMDS)
-                       strbuf_addch(&buf, command_to_char(item->command));
+                       strbuf_addch(buf, command_to_char(item->command));
                else
-                       strbuf_addstr(&buf, command_to_string(item->command));
+                       strbuf_addstr(buf, command_to_string(item->command));
 
                /* add commit id */
                if (item->commit) {
@@ -4198,180 +4643,92 @@ int transform_todos(unsigned flags)
 
                        if (item->command == TODO_MERGE) {
                                if (item->flags & TODO_EDIT_MERGE_MSG)
-                                       strbuf_addstr(&buf, " -c");
+                                       strbuf_addstr(buf, " -c");
                                else
-                                       strbuf_addstr(&buf, " -C");
+                                       strbuf_addstr(buf, " -C");
                        }
 
-                       strbuf_addf(&buf, " %s", oid);
+                       strbuf_addf(buf, " %s", oid);
                }
 
                /* add all the rest */
                if (!item->arg_len)
-                       strbuf_addch(&buf, '\n');
+                       strbuf_addch(buf, '\n');
                else
-                       strbuf_addf(&buf, " %.*s\n", item->arg_len, item->arg);
+                       strbuf_addf(buf, " %.*s\n", item->arg_len,
+                                   todo_item_get_arg(todo_list, item));
        }
-
-       i = write_message(buf.buf, buf.len, todo_file, 0);
-       todo_list_release(&todo_list);
-       return i;
 }
 
-enum check_level {
-       CHECK_IGNORE = 0, CHECK_WARN, CHECK_ERROR
-};
-
-static enum check_level get_missing_commit_check_level(void)
+int todo_list_write_to_file(struct repository *r, struct todo_list *todo_list,
+                           const char *file, const char *shortrevisions,
+                           const char *shortonto, int num, unsigned flags)
 {
-       const char *value;
+       int res;
+       struct strbuf buf = STRBUF_INIT;
+
+       todo_list_to_strbuf(r, todo_list, &buf, num, flags);
+       if (flags & TODO_LIST_APPEND_TODO_HELP)
+               append_todo_help(flags & TODO_LIST_KEEP_EMPTY, count_commands(todo_list),
+                                shortrevisions, shortonto, &buf);
 
-       if (git_config_get_value("rebase.missingcommitscheck", &value) ||
-                       !strcasecmp("ignore", value))
-               return CHECK_IGNORE;
-       if (!strcasecmp("warn", value))
-               return CHECK_WARN;
-       if (!strcasecmp("error", value))
-               return CHECK_ERROR;
-       warning(_("unrecognized setting %s for option "
-                 "rebase.missingCommitsCheck. Ignoring."), value);
-       return CHECK_IGNORE;
+       res = write_message(buf.buf, buf.len, file, 0);
+       strbuf_release(&buf);
+
+       return res;
 }
 
-/*
- * Check if the user dropped some commits by mistake
- * Behaviour determined by rebase.missingCommitsCheck.
- * Check if there is an unrecognized command or a
- * bad SHA-1 in a command.
- */
-int check_todo_list(void)
+static const char edit_todo_list_advice[] =
+N_("You can fix this with 'git rebase --edit-todo' "
+"and then run 'git rebase --continue'.\n"
+"Or you can abort the rebase with 'git rebase"
+" --abort'.\n");
+
+int check_todo_list_from_file(struct repository *r)
 {
-       enum check_level check_level = get_missing_commit_check_level();
-       struct strbuf todo_file = STRBUF_INIT;
-       struct todo_list todo_list = TODO_LIST_INIT;
-       struct strbuf missing = STRBUF_INIT;
-       int advise_to_edit_todo = 0, res = 0, i;
+       struct todo_list old_todo = TODO_LIST_INIT, new_todo = TODO_LIST_INIT;
+       int res = 0;
 
-       strbuf_addstr(&todo_file, rebase_path_todo());
-       if (strbuf_read_file_or_whine(&todo_list.buf, todo_file.buf) < 0) {
+       if (strbuf_read_file_or_whine(&new_todo.buf, rebase_path_todo()) < 0) {
                res = -1;
-               goto leave_check;
-       }
-       advise_to_edit_todo = res =
-               parse_insn_buffer(todo_list.buf.buf, &todo_list);
-
-       if (res || check_level == CHECK_IGNORE)
-               goto leave_check;
-
-       /* Mark the commits in git-rebase-todo as seen */
-       for (i = 0; i < todo_list.nr; i++) {
-               struct commit *commit = todo_list.items[i].commit;
-               if (commit)
-                       commit->util = (void *)1;
+               goto out;
        }
 
-       todo_list_release(&todo_list);
-       strbuf_addstr(&todo_file, ".backup");
-       if (strbuf_read_file_or_whine(&todo_list.buf, todo_file.buf) < 0) {
+       if (strbuf_read_file_or_whine(&old_todo.buf, rebase_path_todo_backup()) < 0) {
                res = -1;
-               goto leave_check;
-       }
-       strbuf_release(&todo_file);
-       res = !!parse_insn_buffer(todo_list.buf.buf, &todo_list);
-
-       /* Find commits in git-rebase-todo.backup yet unseen */
-       for (i = todo_list.nr - 1; i >= 0; i--) {
-               struct todo_item *item = todo_list.items + i;
-               struct commit *commit = item->commit;
-               if (commit && !commit->util) {
-                       strbuf_addf(&missing, " - %s %.*s\n",
-                                   short_commit_name(commit),
-                                   item->arg_len, item->arg);
-                       commit->util = (void *)1;
-               }
+               goto out;
        }
 
-       /* Warn about missing commits */
-       if (!missing.len)
-               goto leave_check;
-
-       if (check_level == CHECK_ERROR)
-               advise_to_edit_todo = res = 1;
-
-       fprintf(stderr,
-               _("Warning: some commits may have been dropped accidentally.\n"
-               "Dropped commits (newer to older):\n"));
-
-       /* Make the list user-friendly and display */
-       fputs(missing.buf, stderr);
-       strbuf_release(&missing);
-
-       fprintf(stderr, _("To avoid this message, use \"drop\" to "
-               "explicitly remove a commit.\n\n"
-               "Use 'git config rebase.missingCommitsCheck' to change "
-               "the level of warnings.\n"
-               "The possible behaviours are: ignore, warn, error.\n\n"));
-
-leave_check:
-       strbuf_release(&todo_file);
-       todo_list_release(&todo_list);
-
-       if (advise_to_edit_todo)
-               fprintf(stderr,
-                       _("You can fix this with 'git rebase --edit-todo' "
-                         "and then run 'git rebase --continue'.\n"
-                         "Or you can abort the rebase with 'git rebase"
-                         " --abort'.\n"));
+       res = todo_list_parse_insn_buffer(r, old_todo.buf.buf, &old_todo);
+       if (!res)
+               res = todo_list_parse_insn_buffer(r, new_todo.buf.buf, &new_todo);
+       if (!res)
+               res = todo_list_check(&old_todo, &new_todo);
+       if (res)
+               fprintf(stderr, _(edit_todo_list_advice));
+out:
+       todo_list_release(&old_todo);
+       todo_list_release(&new_todo);
 
        return res;
 }
 
-static int rewrite_file(const char *path, const char *buf, size_t len)
-{
-       int rc = 0;
-       int fd = open(path, O_WRONLY | O_TRUNC);
-       if (fd < 0)
-               return error_errno(_("could not open '%s' for writing"), path);
-       if (write_in_full(fd, buf, len) < 0)
-               rc = error_errno(_("could not write to '%s'"), path);
-       if (close(fd) && !rc)
-               rc = error_errno(_("could not close '%s'"), path);
-       return rc;
-}
-
 /* skip picking commits whose parents are unchanged */
-int skip_unnecessary_picks(void)
+static int skip_unnecessary_picks(struct repository *r,
+                                 struct todo_list *todo_list,
+                                 struct object_id *base_oid)
 {
-       const char *todo_file = rebase_path_todo();
-       struct strbuf buf = STRBUF_INIT;
-       struct todo_list todo_list = TODO_LIST_INIT;
-       struct object_id onto_oid, *oid = &onto_oid, *parent_oid;
-       int fd, i;
-
-       if (!read_oneliner(&buf, rebase_path_onto(), 0))
-               return error(_("could not read 'onto'"));
-       if (get_oid(buf.buf, &onto_oid)) {
-               strbuf_release(&buf);
-               return error(_("need a HEAD to fixup"));
-       }
-       strbuf_release(&buf);
-
-       if (strbuf_read_file_or_whine(&todo_list.buf, todo_file) < 0)
-               return -1;
-       if (parse_insn_buffer(todo_list.buf.buf, &todo_list) < 0) {
-               todo_list_release(&todo_list);
-               return -1;
-       }
+       struct object_id *parent_oid;
+       int i;
 
-       for (i = 0; i < todo_list.nr; i++) {
-               struct todo_item *item = todo_list.items + i;
+       for (i = 0; i < todo_list->nr; i++) {
+               struct todo_item *item = todo_list->items + i;
 
                if (item->command >= TODO_NOOP)
                        continue;
                if (item->command != TODO_PICK)
                        break;
                if (parse_commit(item->commit)) {
-                       todo_list_release(&todo_list);
                        return error(_("could not parse commit '%s'"),
                                oid_to_hex(&item->commit->object.oid));
                }
@@ -4380,46 +4737,111 @@ int skip_unnecessary_picks(void)
                if (item->commit->parents->next)
                        break; /* merge commit */
                parent_oid = &item->commit->parents->item->object.oid;
-               if (hashcmp(parent_oid->hash, oid->hash))
+               if (!oideq(parent_oid, base_oid))
                        break;
-               oid = &item->commit->object.oid;
+               oidcpy(base_oid, &item->commit->object.oid);
        }
        if (i > 0) {
-               int offset = get_item_line_offset(&todo_list, i);
                const char *done_path = rebase_path_done();
 
-               fd = open(done_path, O_CREAT | O_WRONLY | O_APPEND, 0666);
-               if (fd < 0) {
-                       error_errno(_("could not open '%s' for writing"),
-                                   done_path);
-                       todo_list_release(&todo_list);
-                       return -1;
-               }
-               if (write_in_full(fd, todo_list.buf.buf, offset) < 0) {
+               if (todo_list_write_to_file(r, todo_list, done_path, NULL, NULL, i, 0)) {
                        error_errno(_("could not write to '%s'"), done_path);
-                       todo_list_release(&todo_list);
-                       close(fd);
                        return -1;
                }
-               close(fd);
 
-               if (rewrite_file(rebase_path_todo(), todo_list.buf.buf + offset,
-                                todo_list.buf.len - offset) < 0) {
-                       todo_list_release(&todo_list);
-                       return -1;
-               }
+               MOVE_ARRAY(todo_list->items, todo_list->items + i, todo_list->nr - i);
+               todo_list->nr -= i;
+               todo_list->current = 0;
 
-               todo_list.current = i;
-               if (is_fixup(peek_command(&todo_list, 0)))
-                       record_in_rewritten(oid, peek_command(&todo_list, 0));
+               if (is_fixup(peek_command(todo_list, 0)))
+                       record_in_rewritten(base_oid, peek_command(todo_list, 0));
        }
 
-       todo_list_release(&todo_list);
-       printf("%s\n", oid_to_hex(oid));
-
        return 0;
 }
 
+int complete_action(struct repository *r, struct replay_opts *opts, unsigned flags,
+                   const char *shortrevisions, const char *onto_name,
+                   const char *onto, const char *orig_head, struct string_list *commands,
+                   unsigned autosquash, struct todo_list *todo_list)
+{
+       const char *shortonto, *todo_file = rebase_path_todo();
+       struct todo_list new_todo = TODO_LIST_INIT;
+       struct strbuf *buf = &todo_list->buf;
+       struct object_id oid;
+       int res;
+
+       get_oid(onto, &oid);
+       shortonto = find_unique_abbrev(&oid, DEFAULT_ABBREV);
+
+       if (buf->len == 0) {
+               struct todo_item *item = append_new_todo(todo_list);
+               item->command = TODO_NOOP;
+               item->commit = NULL;
+               item->arg_len = item->arg_offset = item->flags = item->offset_in_buf = 0;
+       }
+
+       if (autosquash && todo_list_rearrange_squash(todo_list))
+               return -1;
+
+       if (commands->nr)
+               todo_list_add_exec_commands(todo_list, commands);
+
+       if (count_commands(todo_list) == 0) {
+               apply_autostash(opts);
+               sequencer_remove_state(opts);
+
+               return error(_("nothing to do"));
+       }
+
+       res = edit_todo_list(r, todo_list, &new_todo, shortrevisions,
+                            shortonto, flags);
+       if (res == -1)
+               return -1;
+       else if (res == -2) {
+               apply_autostash(opts);
+               sequencer_remove_state(opts);
+
+               return -1;
+       } else if (res == -3) {
+               apply_autostash(opts);
+               sequencer_remove_state(opts);
+               todo_list_release(&new_todo);
+
+               return error(_("nothing to do"));
+       }
+
+       if (todo_list_parse_insn_buffer(r, new_todo.buf.buf, &new_todo) ||
+           todo_list_check(todo_list, &new_todo)) {
+               fprintf(stderr, _(edit_todo_list_advice));
+               checkout_onto(opts, onto_name, onto, orig_head);
+               todo_list_release(&new_todo);
+
+               return -1;
+       }
+
+       if (opts->allow_ff && skip_unnecessary_picks(r, &new_todo, &oid)) {
+               todo_list_release(&new_todo);
+               return error(_("could not skip unnecessary pick commands"));
+       }
+
+       if (todo_list_write_to_file(r, &new_todo, todo_file, NULL, NULL, -1,
+                                   flags & ~(TODO_LIST_SHORTEN_IDS))) {
+               todo_list_release(&new_todo);
+               return error_errno(_("could not write '%s'"), todo_file);
+       }
+
+       todo_list_release(&new_todo);
+
+       if (checkout_onto(opts, onto_name, oid_to_hex(&oid), orig_head))
+               return -1;
+
+       if (require_clean_work_tree(r, "rebase", "", 1, 1))
+               return -1;
+
+       return sequencer_continue(r, opts);
+}
+
 struct subject2item_entry {
        struct hashmap_entry entry;
        int i;
@@ -4433,6 +4855,8 @@ static int subject2item_cmp(const void *fndata,
        return key ? strcmp(a->subject, key) : strcmp(a->subject, b->subject);
 }
 
+define_commit_slab(commit_todo_item, struct todo_item *);
+
 /*
  * Rearrange the todo list that has both "pick commit-id msg" and "pick
  * commit-id fixup!/squash! msg" in it so that the latter is put immediately
@@ -4442,21 +4866,15 @@ static int subject2item_cmp(const void *fndata,
  * message will have to be retrieved from the commit (as the oneline in the
  * script cannot be trusted) in order to normalize the autosquash arrangement.
  */
-int rearrange_squash(void)
+int todo_list_rearrange_squash(struct todo_list *todo_list)
 {
-       const char *todo_file = rebase_path_todo();
-       struct todo_list todo_list = TODO_LIST_INIT;
        struct hashmap subject2item;
-       int res = 0, rearranged = 0, *next, *tail, i;
+       int rearranged = 0, *next, *tail, i, nr = 0, alloc = 0;
        char **subjects;
+       struct commit_todo_item commit_todo;
+       struct todo_item *items = NULL;
 
-       if (strbuf_read_file_or_whine(&todo_list.buf, todo_file) < 0)
-               return -1;
-       if (parse_insn_buffer(todo_list.buf.buf, &todo_list) < 0) {
-               todo_list_release(&todo_list);
-               return -1;
-       }
-
+       init_commit_todo_item(&commit_todo);
        /*
         * The hashmap maps onelines to the respective todo list index.
         *
@@ -4467,13 +4885,13 @@ int rearrange_squash(void)
         * be moved to appear after the i'th.
         */
        hashmap_init(&subject2item, (hashmap_cmp_fn) subject2item_cmp,
-                    NULL, todo_list.nr);
-       ALLOC_ARRAY(next, todo_list.nr);
-       ALLOC_ARRAY(tail, todo_list.nr);
-       ALLOC_ARRAY(subjects, todo_list.nr);
-       for (i = 0; i < todo_list.nr; i++) {
+                    NULL, todo_list->nr);
+       ALLOC_ARRAY(next, todo_list->nr);
+       ALLOC_ARRAY(tail, todo_list->nr);
+       ALLOC_ARRAY(subjects, todo_list->nr);
+       for (i = 0; i < todo_list->nr; i++) {
                struct strbuf buf = STRBUF_INIT;
-               struct todo_item *item = todo_list.items + i;
+               struct todo_item *item = todo_list->items + i;
                const char *commit_buffer, *subject, *p;
                size_t subject_len;
                int i2 = -1;
@@ -4486,11 +4904,11 @@ int rearrange_squash(void)
                }
 
                if (is_fixup(item->command)) {
-                       todo_list_release(&todo_list);
+                       clear_commit_todo_item(&commit_todo);
                        return error(_("the script was already rearranged."));
                }
 
-               item->commit->util = item;
+               *commit_todo_item_at(&commit_todo, item->commit) = item;
 
                parse_commit(item->commit);
                commit_buffer = get_commit_buffer(item->commit, NULL);
@@ -4517,10 +4935,10 @@ int rearrange_squash(void)
                        else if (!strchr(p, ' ') &&
                                 (commit2 =
                                  lookup_commit_reference_by_name(p)) &&
-                                commit2->util)
+                                *commit_todo_item_at(&commit_todo, commit2))
                                /* found by commit name */
-                               i2 = (struct todo_item *)commit2->util
-                                       - todo_list.items;
+                               i2 = *commit_todo_item_at(&commit_todo, commit2)
+                                       - todo_list->items;
                        else {
                                /* copy can be a prefix of the commit subject */
                                for (i2 = 0; i2 < i; i2++)
@@ -4533,7 +4951,7 @@ int rearrange_squash(void)
                }
                if (i2 >= 0) {
                        rearranged = 1;
-                       todo_list.items[i].command =
+                       todo_list->items[i].command =
                                starts_with(subject, "fixup!") ?
                                TODO_FIXUP : TODO_SQUASH;
                        if (next[i2] < 0)
@@ -4551,10 +4969,8 @@ int rearrange_squash(void)
        }
 
        if (rearranged) {
-               struct strbuf buf = STRBUF_INIT;
-
-               for (i = 0; i < todo_list.nr; i++) {
-                       enum todo_command command = todo_list.items[i].command;
+               for (i = 0; i < todo_list->nr; i++) {
+                       enum todo_command command = todo_list->items[i].command;
                        int cur = i;
 
                        /*
@@ -4565,36 +4981,26 @@ int rearrange_squash(void)
                                continue;
 
                        while (cur >= 0) {
-                               const char *bol =
-                                       get_item_line(&todo_list, cur);
-                               const char *eol =
-                                       get_item_line(&todo_list, cur + 1);
-
-                               /* replace 'pick', by 'fixup' or 'squash' */
-                               command = todo_list.items[cur].command;
-                               if (is_fixup(command)) {
-                                       strbuf_addstr(&buf,
-                                               todo_command_info[command].str);
-                                       bol += strcspn(bol, " \t");
-                               }
-
-                               strbuf_add(&buf, bol, eol - bol);
-
+                               ALLOC_GROW(items, nr + 1, alloc);
+                               items[nr++] = todo_list->items[cur];
                                cur = next[cur];
                        }
                }
 
-               res = rewrite_file(todo_file, buf.buf, buf.len);
-               strbuf_release(&buf);
+               FREE_AND_NULL(todo_list->items);
+               todo_list->items = items;
+               todo_list->nr = nr;
+               todo_list->alloc = alloc;
        }
 
        free(next);
        free(tail);
-       for (i = 0; i < todo_list.nr; i++)
+       for (i = 0; i < todo_list->nr; i++)
                free(subjects[i]);
        free(subjects);
        hashmap_free(&subject2item, 1);
-       todo_list_release(&todo_list);
 
-       return res;
+       clear_commit_todo_item(&commit_todo);
+
+       return 0;
 }