Merge branch 'ms/core-icase-doc'
[gitweb.git] / sequencer.c
index 2eb5ec7227300316f5a192f54edf7818af87f827..03c47405fbf2c1896d4a1d38ef9f204518d7e92d 100644 (file)
@@ -2,12 +2,13 @@
 #include "config.h"
 #include "lockfile.h"
 #include "dir.h"
+#include "object-store.h"
 #include "object.h"
 #include "commit.h"
 #include "sequencer.h"
 #include "tag.h"
 #include "run-command.h"
-#include "exec_cmd.h"
+#include "exec-cmd.h"
 #include "utf8.h"
 #include "cache-tree.h"
 #include "diff.h"
 #include "hashmap.h"
 #include "notes-utils.h"
 #include "sigchain.h"
+#include "unpack-trees.h"
+#include "worktree.h"
+#include "oidmap.h"
+#include "oidset.h"
+#include "commit-slab.h"
+#include "alias.h"
 
 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
 
@@ -118,6 +125,19 @@ static GIT_PATH_FUNC(rebase_path_stopped_sha, "rebase-merge/stopped-sha")
 static GIT_PATH_FUNC(rebase_path_rewritten_list, "rebase-merge/rewritten-list")
 static GIT_PATH_FUNC(rebase_path_rewritten_pending,
        "rebase-merge/rewritten-pending")
+
+/*
+ * The path of the file containig the OID of the "squash onto" commit, i.e.
+ * the dummy commit used for `reset [new root]`.
+ */
+static GIT_PATH_FUNC(rebase_path_squash_onto, "rebase-merge/squash-onto")
+
+/*
+ * The path of the file listing refs that need to be deleted after the rebase
+ * finishes. This is used by the `label` command to record the need for cleanup.
+ */
+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).
@@ -125,6 +145,7 @@ static GIT_PATH_FUNC(rebase_path_rewritten_pending,
 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_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")
 static GIT_PATH_FUNC(rebase_path_autostash, "rebase-merge/autostash")
@@ -156,6 +177,7 @@ 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;
        }
 
@@ -242,9 +264,24 @@ static const char *gpg_sign_opt_quoted(struct replay_opts *opts)
 
 int sequencer_remove_state(struct replay_opts *opts)
 {
-       struct strbuf dir = STRBUF_INIT;
+       struct strbuf buf = STRBUF_INIT;
        int i;
 
+       if (is_rebase_i(opts) &&
+           strbuf_read_file(&buf, rebase_path_refs_to_delete(), 0) > 0) {
+               char *p = buf.buf;
+               while (*p) {
+                       char *eol = strchr(p, '\n');
+                       if (eol)
+                               *eol = '\0';
+                       if (delete_ref("(rebase -i) cleanup", p, NULL, 0) < 0)
+                               warning(_("could not delete '%s'"), p);
+                       if (!eol)
+                               break;
+                       p = eol + 1;
+               }
+       }
+
        free(opts->gpg_sign);
        free(opts->strategy);
        for (i = 0; i < opts->xopts_nr; i++)
@@ -252,9 +289,10 @@ int sequencer_remove_state(struct replay_opts *opts)
        free(opts->xopts);
        strbuf_release(&opts->current_fixups);
 
-       strbuf_addstr(&dir, get_dir(opts));
-       remove_dir_recursively(&dir, 0);
-       strbuf_release(&dir);
+       strbuf_reset(&buf);
+       strbuf_addstr(&buf, get_dir(opts));
+       remove_dir_recursively(&buf, 0);
+       strbuf_release(&buf);
 
        return 0;
 }
@@ -281,7 +319,7 @@ struct commit_message {
 
 static const char *short_commit_name(struct commit *commit)
 {
-       return find_unique_abbrev(commit->object.oid.hash, DEFAULT_ABBREV);
+       return find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV);
 }
 
 static int get_message(struct commit *commit, struct commit_message *out)
@@ -320,7 +358,7 @@ 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(the_repository));
                return;
        }
 
@@ -344,12 +382,14 @@ static int write_message(const void *buf, size_t len, const char *filename,
        if (msg_fd < 0)
                return error_errno(_("could not lock '%s'"), filename);
        if (write_in_full(msg_fd, buf, len) < 0) {
+               error_errno(_("could not write to '%s'"), filename);
                rollback_lock_file(&msg_file);
-               return error_errno(_("could not write to '%s'"), filename);
+               return -1;
        }
        if (append_eol && write(msg_fd, "\n", 1) < 0) {
+               error_errno(_("could not write eol to '%s'"), filename);
                rollback_lock_file(&msg_file);
-               return error_errno(_("could not write eol to '%s'"), filename);
+               return -1;
        }
        if (commit_lock_file(&msg_file) < 0)
                return error(_("failed to finalize '%s'"), filename);
@@ -439,7 +479,8 @@ static int fast_forward_to(const struct object_id *to, const struct object_id *f
        transaction = ref_transaction_begin(&err);
        if (!transaction ||
            ref_transaction_update(transaction, "HEAD",
-                                  to, unborn ? &null_oid : from,
+                                  to, unborn && !is_rebase_i(opts) ?
+                                  &null_oid : from,
                                   0, sb.buf, &err) ||
            ref_transaction_commit(transaction, &err)) {
                ref_transaction_free(transaction);
@@ -498,8 +539,8 @@ 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 ? next->tree : empty_tree();
-       base_tree = base ? base->tree : empty_tree();
+       next_tree = next ? get_commit_tree(next) : empty_tree();
+       base_tree = base ? get_commit_tree(base) : empty_tree();
 
        for (xopt = opts->xopts; xopt != opts->xopts + opts->xopts_nr; xopt++)
                parse_merge_opt(&o, *xopt);
@@ -531,9 +572,23 @@ static int do_recursive_merge(struct commit *base, struct commit *next,
        return !clean;
 }
 
+static struct object_id *get_cache_tree_oid(void)
+{
+       if (!active_cache_tree)
+               active_cache_tree = cache_tree();
+
+       if (!cache_tree_fully_valid(active_cache_tree))
+               if (cache_tree_update(&the_index, 0)) {
+                       error(_("unable to update cache tree"));
+                       return NULL;
+               }
+
+       return &active_cache_tree->oid;
+}
+
 static int is_index_unchanged(void)
 {
-       struct object_id head_oid;
+       struct object_id head_oid, *cache_tree_oid;
        struct commit *head_commit;
 
        if (!resolve_ref_unsafe("HEAD", RESOLVE_REF_READING, &head_oid, NULL))
@@ -552,15 +607,10 @@ static int is_index_unchanged(void)
        if (parse_commit(head_commit))
                return -1;
 
-       if (!active_cache_tree)
-               active_cache_tree = cache_tree();
-
-       if (!cache_tree_fully_valid(active_cache_tree))
-               if (cache_tree_update(&the_index, 0))
-                       return error(_("unable to update cache tree"));
+       if (!(cache_tree_oid = get_cache_tree_oid()))
+               return -1;
 
-       return !oidcmp(&active_cache_tree->oid,
-                      &head_commit->tree->object.oid);
+       return !oidcmp(cache_tree_oid, get_commit_tree_oid(head_commit));
 }
 
 static int write_author_script(const char *message)
@@ -652,6 +702,52 @@ static char *get_author(const char *message)
        return NULL;
 }
 
+/* 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;
+
+       if (strbuf_read_file(buf, rebase_path_author_script(), 256) <= 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]);
+               return NULL;
+       }
+
+       buf->len = out - buf->buf;
+       return buf->buf;
+}
+
 static const char staged_changes_advice[] =
 N_("you have staged changes in your working tree\n"
 "If these changes are meant to be squashed into the previous commit, run:\n"
@@ -671,6 +767,7 @@ N_("you have staged changes in your working tree\n"
 #define AMEND_MSG   (1<<2)
 #define CLEANUP_MSG (1<<3)
 #define VERIFY_MSG  (1<<4)
+#define CREATE_ROOT_COMMIT (1<<5)
 
 /*
  * If we are cherry-pick, and if the merge did not result in
@@ -690,6 +787,40 @@ static int run_git_commit(const char *defmsg, struct replay_opts *opts,
        struct child_process cmd = CHILD_PROCESS_INIT;
        const char *value;
 
+       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;
+               struct object_id root_commit, *cache_tree_oid;
+               int res = 0;
+
+               if (!defmsg)
+                       BUG("root commit without message");
+
+               if (!(cache_tree_oid = get_cache_tree_oid()))
+                       res = -1;
+
+               if (!res)
+                       res = strbuf_read_file(&msg, defmsg, 0);
+
+               if (res <= 0)
+                       res = error_errno(_("could not read '%s'"), defmsg);
+               else
+                       res = commit_tree(msg.buf, msg.len, cache_tree_oid,
+                                         NULL, &root_commit, author,
+                                         opts->gpg_sign);
+
+               strbuf_release(&msg);
+               strbuf_release(&script);
+               if (!res) {
+                       update_ref(NULL, "CHERRY_PICK_HEAD", &root_commit, NULL,
+                                  REF_NO_DEREF, UPDATE_REFS_MSG_ON_ERR);
+                       res = update_ref(NULL, "HEAD", &root_commit, NULL, 0,
+                                        UPDATE_REFS_MSG_ON_ERR);
+               }
+               return res < 0 ? error(_("writing root commit")) : 0;
+       }
+
        cmd.git_cmd = 1;
 
        if (is_rebase_i(opts)) {
@@ -1113,14 +1244,14 @@ static int try_to_commit(struct strbuf *msg, const char *author,
                commit_list_insert(current_head, &parents);
        }
 
-       if (write_cache_as_tree(tree.hash, 0, NULL)) {
+       if (write_cache_as_tree(&tree, 0, NULL)) {
                res = error(_("git write-tree failed to write a tree"));
                goto out;
        }
 
        if (!(flags & ALLOW_EMPTY) && !oidcmp(current_head ?
-                                             &current_head->tree->object.oid :
-                                             &empty_tree_oid, &tree)) {
+                                             get_commit_tree_oid(current_head) :
+                                             the_hash_algo->empty_tree, &tree)) {
                res = 1; /* run 'git commit' to display error message */
                goto out;
        }
@@ -1149,6 +1280,8 @@ static int try_to_commit(struct strbuf *msg, const char *author,
                goto out;
        }
 
+       reset_ident_date();
+
        if (commit_tree_extended(msg->buf, msg->len, &tree, parents,
                                 oid, author, opts->gpg_sign, extra)) {
                res = error(_("failed to write commit object"));
@@ -1178,7 +1311,8 @@ static int do_commit(const char *msg_file, const char *author,
 {
        int res = 1;
 
-       if (!(flags & EDIT_MSG) && !(flags & VERIFY_MSG)) {
+       if (!(flags & EDIT_MSG) && !(flags & VERIFY_MSG) &&
+           !(flags & CREATE_ROOT_COMMIT)) {
                struct object_id oid;
                struct strbuf sb = STRBUF_INIT;
 
@@ -1191,8 +1325,8 @@ static int do_commit(const char *msg_file, const char *author,
                                    &oid);
                strbuf_release(&sb);
                if (!res) {
-                       unlink(git_path_cherry_pick_head());
-                       unlink(git_path_merge_msg());
+                       unlink(git_path_cherry_pick_head(the_repository));
+                       unlink(git_path_merge_msg(the_repository));
                        if (!is_rebase_i(opts))
                                print_commit_summary(NULL, &oid,
                                                SUMMARY_SHOW_AUTHOR_DATE);
@@ -1217,12 +1351,12 @@ static int is_original_commit_empty(struct commit *commit)
                if (parse_commit(parent))
                        return error(_("could not parse parent commit %s"),
                                oid_to_hex(&parent->object.oid));
-               ptree_oid = &parent->tree->object.oid;
+               ptree_oid = get_commit_tree_oid(parent);
        } else {
                ptree_oid = the_hash_algo->empty_tree; /* commit is root */
        }
 
-       return !oidcmp(ptree_oid, &commit->tree->object.oid);
+       return !oidcmp(ptree_oid, get_commit_tree_oid(commit));
 }
 
 /*
@@ -1278,6 +1412,9 @@ enum todo_command {
        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,
@@ -1296,6 +1433,9 @@ static struct {
        { 'f', "fixup" },
        { 's', "squash" },
        { 'x', "exec" },
+       { 'l', "label" },
+       { 't', "reset" },
+       { 'm', "merge" },
        { 0,   "noop" },
        { 'd', "drop" },
        { 0,   NULL }
@@ -1325,6 +1465,22 @@ static int is_fixup(enum todo_command command)
        return command == TODO_FIXUP || command == TODO_SQUASH;
 }
 
+/* Does this command create a (non-merge) commit? */
+static int is_pick_or_similar(enum todo_command command)
+{
+       switch (command) {
+       case TODO_PICK:
+       case TODO_REVERT:
+       case TODO_EDIT:
+       case TODO_REWORD:
+       case TODO_FIXUP:
+       case TODO_SQUASH:
+               return 1;
+       default:
+               return 0;
+       }
+}
+
 static int update_squash_messages(enum todo_command command,
                struct commit *commit, struct replay_opts *opts)
 {
@@ -1458,7 +1614,7 @@ static int do_pick_commit(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(the_repository);
        struct object_id head;
        struct commit *base, *next, *parent;
        const char *base_label, *next_label;
@@ -1474,13 +1630,20 @@ 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.hash, 0, NULL))
+               if (write_cache_as_tree(&head, 0, NULL))
                        return error(_("your index file is unmerged."));
        } else {
                unborn = get_oid("HEAD", &head);
-               if (unborn)
+               /* Do we want to generate a root commit? */
+               if (is_pick_or_similar(command) && opts->have_squash_onto &&
+                   !oidcmp(&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_SHA1_HEX : "HEAD",
+               if (index_differs_from(unborn ? empty_tree_oid_hex() : "HEAD",
                                       NULL, 0))
                        return error_dirty_index(opts);
        }
@@ -1593,18 +1756,18 @@ 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(the_repository);
                        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(the_repository));
                        msg_file = dest;
                        flags |= EDIT_MSG;
                }
        }
 
-       if (opts->signoff)
+       if (opts->signoff && !is_fixup(command))
                append_signoff(&msgbuf, 0, 0);
 
        if (is_rebase_i(opts) && write_author_script(msg.message) < 0)
@@ -1613,15 +1776,16 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
                res = do_recursive_merge(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(the_repository), 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(the_repository), 0);
 
                commit_list_insert(base, &common);
                commit_list_insert(next, &remotes);
@@ -1725,9 +1889,14 @@ static int read_and_refresh_cache(struct replay_opts *opts)
        return 0;
 }
 
+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;
@@ -1762,6 +1931,8 @@ static int parse_insn_line(struct todo_item *item, const char *bol, char *eol)
        char *end_of_object_name;
        int i, saved, status, padding;
 
+       item->flags = 0;
+
        /* left-trim */
        bol += strspn(bol, " \t");
 
@@ -1803,13 +1974,29 @@ static int parse_insn_line(struct todo_item *item, const char *bol, char *eol)
                return error(_("missing arguments for %s"),
                             command_to_string(item->command));
 
-       if (item->command == TODO_EXEC) {
+       if (item->command == TODO_EXEC || item->command == TODO_LABEL ||
+           item->command == TODO_RESET) {
                item->commit = NULL;
                item->arg = bol;
                item->arg_len = (int)(eol - bol);
                return 0;
        }
 
+       if (item->command == TODO_MERGE) {
+               if (skip_prefix(bol, "-C", &bol))
+                       bol += strspn(bol, " \t");
+               else if (skip_prefix(bol, "-c", &bol)) {
+                       bol += strspn(bol, " \t");
+                       item->flags |= TODO_EDIT_MERGE_MSG;
+               } else {
+                       item->flags |= TODO_EDIT_MERGE_MSG;
+                       item->commit = NULL;
+                       item->arg = bol;
+                       item->arg_len = (int)(eol - bol);
+                       return 0;
+               }
+       }
+
        end_of_object_name = (char *) bol + strcspn(bol, " \t\n");
        saved = *end_of_object_name;
        *end_of_object_name = '\0';
@@ -1871,6 +2058,23 @@ static int count_commands(struct todo_list *todo_list)
        return count;
 }
 
+static int get_item_line_offset(struct todo_list *todo_list, int index)
+{
+       return index < todo_list->nr ?
+               todo_list->items[index].offset_in_buf : todo_list->buf.len;
+}
+
+static const char *get_item_line(struct todo_list *todo_list, int index)
+{
+       return todo_list->buf.buf + get_item_line_offset(todo_list, index);
+}
+
+static int get_item_line_length(struct todo_list *todo_list, int index)
+{
+       return get_item_line_offset(todo_list, index + 1)
+               -  get_item_line_offset(todo_list, index);
+}
+
 static ssize_t strbuf_read_file_or_whine(struct strbuf *sb, const char *path)
 {
        int fd;
@@ -2003,6 +2207,7 @@ static int populate_opts_cb(const char *key, const char *value, void *data)
 static void read_strategy_opts(struct replay_opts *opts, struct strbuf *buf)
 {
        int i;
+       char *strategy_opts_string;
 
        strbuf_reset(buf);
        if (!read_oneliner(buf, rebase_path_strategy(), 0))
@@ -2011,7 +2216,11 @@ static void read_strategy_opts(struct replay_opts *opts, struct strbuf *buf)
        if (!read_oneliner(buf, rebase_path_strategy_opts(), 0))
                return;
 
-       opts->xopts_nr = split_cmdline(buf->buf, (const char ***)&opts->xopts);
+       strategy_opts_string = buf->buf;
+       if (*strategy_opts_string == ' ')
+               strategy_opts_string++;
+       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];
 
@@ -2046,6 +2255,11 @@ static int read_populate_opts(struct replay_opts *opts)
                if (file_exists(rebase_path_verbose()))
                        opts->verbose = 1;
 
+               if (file_exists(rebase_path_signoff())) {
+                       opts->allow_ff = 0;
+                       opts->signoff = 1;
+               }
+
                read_strategy_opts(opts, &buf);
                strbuf_release(&buf);
 
@@ -2059,6 +2273,12 @@ static int read_populate_opts(struct replay_opts *opts)
                        }
                }
 
+               if (read_oneliner(&buf, rebase_path_squash_onto(), 0)) {
+                       if (get_oid_hex(buf.buf, &opts->squash_onto) < 0)
+                               return error(_("unusable squash-onto"));
+                       opts->have_squash_onto = 1;
+               }
+
                return 0;
        }
 
@@ -2132,9 +2352,9 @@ static int save_head(const char *head)
        written = write_in_full(fd, buf.buf, buf.len);
        strbuf_release(&buf);
        if (written < 0) {
+               error_errno(_("could not write to '%s'"), git_path_head_file());
                rollback_lock_file(&head_lock);
-               return error_errno(_("could not write to '%s'"),
-                                  git_path_head_file());
+               return -1;
        }
        if (commit_lock_file(&head_lock) < 0)
                return error(_("failed to finalize '%s'"), git_path_head_file());
@@ -2180,8 +2400,8 @@ static int rollback_single_pick(void)
 {
        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(the_repository)) &&
+           !file_exists(git_path_revert_head(the_repository)))
                return error(_("no cherry-pick or revert in progress"));
        if (read_ref_full("HEAD", 0, &head_oid, NULL))
                return error(_("cannot resolve HEAD"));
@@ -2255,29 +2475,27 @@ static int save_todo(struct todo_list *todo_list, struct replay_opts *opts)
        fd = hold_lock_file_for_update(&todo_lock, todo_path, 0);
        if (fd < 0)
                return error_errno(_("could not lock '%s'"), todo_path);
-       offset = next < todo_list->nr ?
-               todo_list->items[next].offset_in_buf : todo_list->buf.len;
+       offset = get_item_line_offset(todo_list, next);
        if (write_in_full(fd, todo_list->buf.buf + offset,
                        todo_list->buf.len - offset) < 0)
                return error_errno(_("could not write to '%s'"), todo_path);
        if (commit_lock_file(&todo_lock) < 0)
                return error(_("failed to finalize '%s'"), todo_path);
 
-       if (is_rebase_i(opts)) {
-               const char *done_path = rebase_path_done();
-               int fd = open(done_path, O_CREAT | O_WRONLY | O_APPEND, 0666);
-               int prev_offset = !next ? 0 :
-                       todo_list->items[next - 1].offset_in_buf;
+       if (is_rebase_i(opts) && next > 0) {
+               const char *done = rebase_path_done();
+               int fd = open(done, O_CREAT | O_WRONLY | O_APPEND, 0666);
+               int ret = 0;
 
-               if (fd >= 0 && offset > prev_offset &&
-                   write_in_full(fd, todo_list->buf.buf + prev_offset,
-                                 offset - prev_offset) < 0) {
-                       close(fd);
-                       return error_errno(_("could not write to '%s'"),
-                                          done_path);
-               }
-               if (fd >= 0)
-                       close(fd);
+               if (fd < 0)
+                       return 0;
+               if (write_in_full(fd, get_item_line(todo_list, next - 1),
+                                 get_item_line_length(todo_list, next - 1))
+                   < 0)
+                       ret = error_errno(_("could not write to '%s'"), done);
+               if (close(fd) < 0)
+                       ret = error_errno(_("failed to finalize '%s'"), done);
+               return ret;
        }
        return 0;
 }
@@ -2408,10 +2626,11 @@ static int error_failed_squash(struct commit *commit,
        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(the_repository));
+       if (copy_file(git_path_merge_msg(the_repository), rebase_path_message(), 0666))
                return error(_("could not copy '%s' to '%s'"),
-                            rebase_path_message(), git_path_merge_msg());
+                            rebase_path_message(),
+                            git_path_merge_msg(the_repository));
        return error_with_patch(commit, subject, subject_len, opts, 1, 0);
 }
 
@@ -2460,6 +2679,377 @@ static int do_exec(const char *command_line)
        return status;
 }
 
+static int safe_append(const char *filename, const char *fmt, ...)
+{
+       va_list ap;
+       struct lock_file lock = LOCK_INIT;
+       int fd = hold_lock_file_for_update(&lock, filename,
+                                          LOCK_REPORT_ON_ERROR);
+       struct strbuf buf = STRBUF_INIT;
+
+       if (fd < 0)
+               return -1;
+
+       if (strbuf_read_file(&buf, filename, 0) < 0 && errno != ENOENT) {
+               error_errno(_("could not read '%s'"), filename);
+               rollback_lock_file(&lock);
+               return -1;
+       }
+       strbuf_complete(&buf, '\n');
+       va_start(ap, fmt);
+       strbuf_vaddf(&buf, fmt, ap);
+       va_end(ap);
+
+       if (write_in_full(fd, buf.buf, buf.len) < 0) {
+               error_errno(_("could not write to '%s'"), filename);
+               strbuf_release(&buf);
+               rollback_lock_file(&lock);
+               return -1;
+       }
+       if (commit_lock_file(&lock) < 0) {
+               strbuf_release(&buf);
+               rollback_lock_file(&lock);
+               return error(_("failed to finalize '%s'"), filename);
+       }
+
+       strbuf_release(&buf);
+       return 0;
+}
+
+static int do_label(const char *name, int len)
+{
+       struct ref_store *refs = get_main_ref_store(the_repository);
+       struct ref_transaction *transaction;
+       struct strbuf ref_name = STRBUF_INIT, err = STRBUF_INIT;
+       struct strbuf msg = STRBUF_INIT;
+       int ret = 0;
+       struct object_id head_oid;
+
+       if (len == 1 && *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);
+
+       transaction = ref_store_transaction_begin(refs, &err);
+       if (!transaction) {
+               error("%s", err.buf);
+               ret = -1;
+       } else if (get_oid("HEAD", &head_oid)) {
+               error(_("could not read HEAD"));
+               ret = -1;
+       } else if (ref_transaction_update(transaction, ref_name.buf, &head_oid,
+                                         NULL, 0, msg.buf, &err) < 0 ||
+                  ref_transaction_commit(transaction, &err)) {
+               error("%s", err.buf);
+               ret = -1;
+       }
+       ref_transaction_free(transaction);
+       strbuf_release(&err);
+       strbuf_release(&msg);
+
+       if (!ret)
+               ret = safe_append(rebase_path_refs_to_delete(),
+                                 "%s\n", ref_name.buf);
+       strbuf_release(&ref_name);
+
+       return ret;
+}
+
+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)
+{
+       struct strbuf ref_name = STRBUF_INIT;
+       struct object_id oid;
+       struct lock_file lock = LOCK_INIT;
+       struct tree_desc desc;
+       struct tree *tree;
+       struct unpack_trees_options unpack_tree_opts;
+       int ret = 0, i;
+
+       if (hold_locked_index(&lock, LOCK_REPORT_ON_ERROR) < 0)
+               return -1;
+
+       if (len == 10 && !strncmp("[new root]", name, len)) {
+               if (!opts->have_squash_onto) {
+                       const char *hex;
+                       if (commit_tree("", 0, the_hash_algo->empty_tree,
+                                       NULL, &opts->squash_onto,
+                                       NULL, NULL))
+                               return error(_("writing fake root commit"));
+                       opts->have_squash_onto = 1;
+                       hex = oid_to_hex(&opts->squash_onto);
+                       if (write_message(hex, strlen(hex),
+                                         rebase_path_squash_onto(), 0))
+                               return error(_("writing squash-onto"));
+               }
+               oidcpy(&oid, &opts->squash_onto);
+       } else {
+               /* Determine the length of the label */
+               for (i = 0; i < len; i++)
+                       if (isspace(name[i]))
+                               len = i;
+
+               strbuf_addf(&ref_name, "refs/rewritten/%.*s", len, name);
+               if (get_oid(ref_name.buf, &oid) &&
+                   get_oid(ref_name.buf + strlen("refs/rewritten/"), &oid)) {
+                       error(_("could not read '%s'"), ref_name.buf);
+                       rollback_lock_file(&lock);
+                       strbuf_release(&ref_name);
+                       return -1;
+               }
+       }
+
+       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.fn = oneway_merge;
+       unpack_tree_opts.merge = 1;
+       unpack_tree_opts.update = 1;
+
+       if (read_cache_unmerged()) {
+               rollback_lock_file(&lock);
+               strbuf_release(&ref_name);
+               return error_resolve_conflict(_(action_name(opts)));
+       }
+
+       if (!fill_tree_descriptor(&desc, &oid)) {
+               error(_("failed to find tree of %s"), oid_to_hex(&oid));
+               rollback_lock_file(&lock);
+               free((void *)desc.buffer);
+               strbuf_release(&ref_name);
+               return -1;
+       }
+
+       if (unpack_trees(1, &desc, &unpack_tree_opts)) {
+               rollback_lock_file(&lock);
+               free((void *)desc.buffer);
+               strbuf_release(&ref_name);
+               return -1;
+       }
+
+       tree = parse_tree_indirect(&oid);
+       prime_cache_tree(&the_index, tree);
+
+       if (write_locked_index(&the_index, &lock, COMMIT_LOCK) < 0)
+               ret = error(_("could not write index"));
+       free((void *)desc.buffer);
+
+       if (!ret)
+               ret = update_ref(reflog_message(opts, "reset", "'%.*s'",
+                                               len, name), "HEAD", &oid,
+                                NULL, 0, UPDATE_REFS_MSG_ON_ERR);
+
+       strbuf_release(&ref_name);
+       return ret;
+}
+
+static int do_merge(struct commit *commit, const char *arg, int arg_len,
+                   int flags, struct replay_opts *opts)
+{
+       int run_commit_flags = (flags & TODO_EDIT_MERGE_MSG) ?
+               EDIT_MSG | VERIFY_MSG : 0;
+       struct strbuf ref_name = STRBUF_INIT;
+       struct commit *head_commit, *merge_commit, *i;
+       struct commit_list *bases, *j, *reversed = NULL;
+       struct merge_options o;
+       int merge_arg_len, oneline_offset, can_fast_forward, ret;
+       static struct lock_file lock;
+       const char *p;
+
+       if (hold_locked_index(&lock, LOCK_REPORT_ON_ERROR) < 0) {
+               ret = -1;
+               goto leave_merge;
+       }
+
+       head_commit = lookup_commit_reference_by_name("HEAD");
+       if (!head_commit) {
+               ret = error(_("cannot merge without a current revision"));
+               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);
+       }
+
+       if (!merge_commit) {
+               ret = error(_("could not resolve '%s'"), ref_name.buf);
+               goto leave_merge;
+       }
+
+       if (opts->have_squash_onto &&
+           !oidcmp(&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);
+               goto leave_merge;
+       }
+
+       if (commit) {
+               const char *message = get_commit_buffer(commit, NULL);
+               const char *body;
+               int len;
+
+               if (!message) {
+                       ret = error(_("could not get commit message of '%s'"),
+                                   oid_to_hex(&commit->object.oid));
+                       goto leave_merge;
+               }
+               write_author_script(message);
+               find_commit_subject(message, &body);
+               len = strlen(body);
+               ret = write_message(body, len, git_path_merge_msg(the_repository), 0);
+               unuse_commit_buffer(commit, message);
+               if (ret) {
+                       error_errno(_("could not write '%s'"),
+                                   git_path_merge_msg(the_repository));
+                       goto leave_merge;
+               }
+       } else {
+               struct strbuf buf = STRBUF_INIT;
+               int len;
+
+               strbuf_addf(&buf, "author %s", git_author_info(0));
+               write_author_script(buf.buf);
+               strbuf_reset(&buf);
+
+               if (oneline_offset < arg_len) {
+                       p = arg + oneline_offset;
+                       len = arg_len - oneline_offset;
+               } else {
+                       strbuf_addf(&buf, "Merge branch '%.*s'",
+                                   merge_arg_len, arg);
+                       p = buf.buf;
+                       len = buf.len;
+               }
+
+               ret = write_message(p, len, git_path_merge_msg(the_repository), 0);
+               strbuf_release(&buf);
+               if (ret) {
+                       error_errno(_("could not write '%s'"),
+                                   git_path_merge_msg(the_repository));
+                       goto leave_merge;
+               }
+       }
+
+       /*
+        * If HEAD is not identical to the first parent of the original merge
+        * commit, we cannot fast-forward.
+        */
+       can_fast_forward = opts->allow_ff && commit && commit->parents &&
+               !oidcmp(&commit->parents->item->object.oid,
+                       &head_commit->object.oid);
+
+       /*
+        * If the merge head is different from the original one, we cannot
+        * fast-forward.
+        */
+       if (can_fast_forward) {
+               struct commit_list *second_parent = commit->parents->next;
+
+               if (second_parent && !second_parent->next &&
+                   oidcmp(&merge_commit->object.oid,
+                          &second_parent->item->object.oid))
+                       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)) {
+               rollback_lock_file(&lock);
+               ret = fast_forward_to(&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(the_repository), 0);
+       write_message("no-ff", 5, git_path_merge_mode(the_repository), 0);
+
+       bases = get_merge_bases(head_commit, merge_commit);
+       if (bases && !oidcmp(&merge_commit->object.oid,
+                            &bases->item->object.oid)) {
+               ret = 0;
+               /* skip merging an ancestor of HEAD */
+               goto leave_merge;
+       }
+
+       for (j = bases; j; j = j->next)
+               commit_list_insert(j->item, &reversed);
+       free_commit_list(bases);
+
+       read_cache();
+       init_merge_options(&o);
+       o.branch1 = "HEAD";
+       o.branch2 = ref_name.buf;
+       o.buffer_output = 2;
+
+       ret = merge_recursive(&o, head_commit, merge_commit, reversed, &i);
+       if (ret <= 0)
+               fputs(o.obuf.buf, stdout);
+       strbuf_release(&o.obuf);
+       if (ret < 0) {
+               error(_("could not even attempt to merge '%.*s'"),
+                     merge_arg_len, arg);
+               goto leave_merge;
+       }
+       /*
+        * The return value of merge_recursive() is 1 on clean, and 0 on
+        * unclean merge.
+        *
+        * Let's reverse that, so that do_merge() returns 0 upon success and
+        * 1 upon failed merge (keeping the return value -1 for the cases where
+        * we will want to reschedule the `merge` command).
+        */
+       ret = !ret;
+
+       if (active_cache_changed &&
+           write_locked_index(&the_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);
+       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(the_repository), opts,
+                                    run_commit_flags);
+
+leave_merge:
+       strbuf_release(&ref_name);
+       rollback_lock_file(&lock);
+       return ret;
+}
+
 static int is_final_fixup(struct todo_list *todo_list)
 {
        int i = todo_list->current;
@@ -2550,9 +3140,20 @@ static const char *reflog_message(struct replay_opts *opts,
        return buf.buf;
 }
 
+static const char rescheduled_advice[] =
+N_("Could not execute the todo command\n"
+"\n"
+"    %.*s"
+"\n"
+"It has been rescheduled; To edit the command before continuing, please\n"
+"edit the todo list first:\n"
+"\n"
+"    git rebase --edit-todo\n"
+"    git rebase --continue\n");
+
 static int pick_commits(struct todo_list *todo_list, struct replay_opts *opts)
 {
-       int res = 0;
+       int res = 0, reschedule = 0;
 
        setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
        if (opts->allow_ff)
@@ -2595,6 +3196,11 @@ static int pick_commits(struct todo_list *todo_list, struct replay_opts *opts)
                                        opts, is_final_fixup(todo_list));
                        if (is_rebase_i(opts) && res < 0) {
                                /* Reschedule */
+                               advise(_(rescheduled_advice),
+                                      get_item_line_length(todo_list,
+                                                           todo_list->current),
+                                      get_item_line(todo_list,
+                                                    todo_list->current));
                                todo_list->current--;
                                if (save_todo(todo_list, opts))
                                        return -1;
@@ -2618,10 +3224,27 @@ static int pick_commits(struct todo_list *todo_list, struct replay_opts *opts)
                                        intend_to_amend();
                                return error_failed_squash(item->commit, opts,
                                        item->arg_len, item->arg);
-                       } else if (res && is_rebase_i(opts))
+                       } 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) &&
+                                   (!oidcmp(&item->commit->object.oid, &oid) ||
+                                    (opts->have_squash_onto &&
+                                     !oidcmp(&opts->squash_onto, &oid))))
+                                       to_amend = 1;
+
                                return res | error_with_patch(item->commit,
-                                       item->arg, item->arg_len, opts, res,
-                                       item->command == TODO_REWORD);
+                                               item->arg, item->arg_len, opts,
+                                               res, to_amend);
+                       }
                } else if (item->command == TODO_EXEC) {
                        char *end_of_arg = (char *)(item->arg + item->arg_len);
                        int saved = *end_of_arg;
@@ -2644,9 +3267,44 @@ static int pick_commits(struct todo_list *todo_list, struct replay_opts *opts)
                                /* `current` will be incremented below */
                                todo_list->current = -1;
                        }
+               } else if (item->command == TODO_LABEL) {
+                       if ((res = do_label(item->arg, item->arg_len)))
+                               reschedule = 1;
+               } else if (item->command == TODO_RESET) {
+                       if ((res = do_reset(item->arg, item->arg_len, opts)))
+                               reschedule = 1;
+               } else if (item->command == TODO_MERGE) {
+                       if ((res = do_merge(item->commit,
+                                           item->arg, item->arg_len,
+                                           item->flags, opts)) < 0)
+                               reschedule = 1;
+                       else if (item->commit)
+                               record_in_rewritten(&item->commit->object.oid,
+                                                   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);
                } else if (!is_noop(item->command))
                        return error(_("unknown command %d"), item->command);
 
+               if (reschedule) {
+                       advise(_(rescheduled_advice),
+                              get_item_line_length(todo_list,
+                                                   todo_list->current),
+                              get_item_line(todo_list, todo_list->current));
+                       todo_list->current--;
+                       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);
+               }
+
                todo_list->current++;
                if (res)
                        return res;
@@ -2767,8 +3425,8 @@ static int continue_single_pick(void)
 {
        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(the_repository)) &&
+           !file_exists(git_path_revert_head(the_repository)))
                return error(_("no cherry-pick or revert in progress"));
        return run_command_v_opt(argv, RUN_GIT_CMD);
 }
@@ -2871,7 +3529,7 @@ 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(the_repository);
 
                if (file_exists(cherry_pick_head) && unlink(cherry_pick_head))
                        return error(_("could not remove CHERRY_PICK_HEAD"));
@@ -2921,8 +3579,8 @@ int sequencer_continue(struct replay_opts *opts)
 
        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())) {
+               if (file_exists(git_path_cherry_pick_head(the_repository)) ||
+                   file_exists(git_path_revert_head(the_repository))) {
                        res = continue_single_pick();
                        if (res)
                                goto release_todo_list;
@@ -2975,7 +3633,9 @@ int sequencer_pick_revisions(struct replay_opts *opts)
 
                if (!get_oid(name, &oid)) {
                        if (!lookup_commit_reference_gently(&oid, 1)) {
-                               enum object_type type = sha1_object_info(oid.hash, NULL);
+                               enum object_type type = oid_object_info(the_repository,
+                                                                       &oid,
+                                                                       NULL);
                                return error(_("%s: can't cherry-pick a %s"),
                                        name, type_name(type));
                        }
@@ -3085,6 +3745,348 @@ void append_signoff(struct strbuf *msgbuf, int ignore_footer, unsigned flag)
        strbuf_release(&sob);
 }
 
+struct labels_entry {
+       struct hashmap_entry entry;
+       char label[FLEX_ARRAY];
+};
+
+static int labels_cmp(const void *fndata, const struct labels_entry *a,
+                     const struct labels_entry *b, const void *key)
+{
+       return key ? strcmp(a->label, key) : strcmp(a->label, b->label);
+}
+
+struct string_entry {
+       struct oidmap_entry entry;
+       char string[FLEX_ARRAY];
+};
+
+struct label_state {
+       struct oidmap commit2label;
+       struct hashmap labels;
+       struct strbuf buf;
+};
+
+static const char *label_oid(struct object_id *oid, const char *label,
+                            struct label_state *state)
+{
+       struct labels_entry *labels_entry;
+       struct string_entry *string_entry;
+       struct object_id dummy;
+       size_t len;
+       int i;
+
+       string_entry = oidmap_get(&state->commit2label, oid);
+       if (string_entry)
+               return string_entry->string;
+
+       /*
+        * For "uninteresting" commits, i.e. commits that are not to be
+        * rebased, and which can therefore not be labeled, we use a unique
+        * abbreviation of the commit name. This is slightly more complicated
+        * than calling find_unique_abbrev() because we also need to make
+        * sure that the abbreviation does not conflict with any other
+        * label.
+        *
+        * We disallow "interesting" commits to be labeled by a string that
+        * is a valid full-length hash, to ensure that we always can find an
+        * abbreviation for any uninteresting commit's names that does not
+        * clash with any other label.
+        */
+       if (!label) {
+               char *p;
+
+               strbuf_reset(&state->buf);
+               strbuf_grow(&state->buf, GIT_SHA1_HEXSZ);
+               label = p = state->buf.buf;
+
+               find_unique_abbrev_r(p, oid, default_abbrev);
+
+               /*
+                * We may need to extend the abbreviated hash so that there is
+                * no conflicting label.
+                */
+               if (hashmap_get_from_hash(&state->labels, strihash(p), p)) {
+                       size_t i = strlen(p) + 1;
+
+                       oid_to_hex_r(p, oid);
+                       for (; i < GIT_SHA1_HEXSZ; i++) {
+                               char save = p[i];
+                               p[i] = '\0';
+                               if (!hashmap_get_from_hash(&state->labels,
+                                                          strihash(p), p))
+                                       break;
+                               p[i] = save;
+                       }
+               }
+       } else if (((len = strlen(label)) == the_hash_algo->hexsz &&
+                   !get_oid_hex(label, &dummy)) ||
+                  (len == 1 && *label == '#') ||
+                  hashmap_get_from_hash(&state->labels,
+                                        strihash(label), label)) {
+               /*
+                * If the label already exists, or if the label is a valid full
+                * OID, or the label is a '#' (which we use as a separator
+                * between merge heads and oneline), we append a dash and a
+                * number to make it unique.
+                */
+               struct strbuf *buf = &state->buf;
+
+               strbuf_reset(buf);
+               strbuf_add(buf, label, len);
+
+               for (i = 2; ; i++) {
+                       strbuf_setlen(buf, len);
+                       strbuf_addf(buf, "-%d", i);
+                       if (!hashmap_get_from_hash(&state->labels,
+                                                  strihash(buf->buf),
+                                                  buf->buf))
+                               break;
+               }
+
+               label = buf->buf;
+       }
+
+       FLEX_ALLOC_STR(labels_entry, label, label);
+       hashmap_entry_init(labels_entry, strihash(label));
+       hashmap_add(&state->labels, labels_entry);
+
+       FLEX_ALLOC_STR(string_entry, string, label);
+       oidcpy(&string_entry->entry.oid, oid);
+       oidmap_put(&state->commit2label, string_entry);
+
+       return string_entry->string;
+}
+
+static int make_script_with_merges(struct pretty_print_context *pp,
+                                  struct rev_info *revs, FILE *out,
+                                  unsigned flags)
+{
+       int keep_empty = flags & TODO_LIST_KEEP_EMPTY;
+       int rebase_cousins = flags & TODO_LIST_REBASE_COUSINS;
+       struct strbuf buf = STRBUF_INIT, oneline = STRBUF_INIT;
+       struct strbuf label = STRBUF_INIT;
+       struct commit_list *commits = NULL, **tail = &commits, *iter;
+       struct commit_list *tips = NULL, **tips_tail = &tips;
+       struct commit *commit;
+       struct oidmap commit2todo = OIDMAP_INIT;
+       struct string_entry *entry;
+       struct oidset interesting = OIDSET_INIT, child_seen = OIDSET_INIT,
+               shown = OIDSET_INIT;
+       struct label_state state = { OIDMAP_INIT, { NULL }, STRBUF_INIT };
+
+       int abbr = flags & TODO_LIST_ABBREVIATE_CMDS;
+       const char *cmd_pick = abbr ? "p" : "pick",
+               *cmd_label = abbr ? "l" : "label",
+               *cmd_reset = abbr ? "t" : "reset",
+               *cmd_merge = abbr ? "m" : "merge";
+
+       oidmap_init(&commit2todo, 0);
+       oidmap_init(&state.commit2label, 0);
+       hashmap_init(&state.labels, (hashmap_cmp_fn) labels_cmp, NULL, 0);
+       strbuf_init(&state.buf, 32);
+
+       if (revs->cmdline.nr && (revs->cmdline.rev[0].flags & BOTTOM)) {
+               struct object_id *oid = &revs->cmdline.rev[0].item->oid;
+               FLEX_ALLOC_STR(entry, string, "onto");
+               oidcpy(&entry->entry.oid, oid);
+               oidmap_put(&state.commit2label, entry);
+       }
+
+       /*
+        * First phase:
+        * - get onelines for all commits
+        * - gather all branch tips (i.e. 2nd or later parents of merges)
+        * - label all branch tips
+        */
+       while ((commit = get_revision(revs))) {
+               struct commit_list *to_merge;
+               int is_octopus;
+               const char *p1, *p2;
+               struct object_id *oid;
+               int is_empty;
+
+               tail = &commit_list_insert(commit, tail)->next;
+               oidset_insert(&interesting, &commit->object.oid);
+
+               is_empty = is_original_commit_empty(commit);
+               if (!is_empty && (commit->object.flags & PATCHSAME))
+                       continue;
+
+               strbuf_reset(&oneline);
+               pretty_print_commit(pp, commit, &oneline);
+
+               to_merge = commit->parents ? commit->parents->next : NULL;
+               if (!to_merge) {
+                       /* non-merge commit: easy case */
+                       strbuf_reset(&buf);
+                       if (!keep_empty && is_empty)
+                               strbuf_addf(&buf, "%c ", comment_line_char);
+                       strbuf_addf(&buf, "%s %s %s", cmd_pick,
+                                   oid_to_hex(&commit->object.oid),
+                                   oneline.buf);
+
+                       FLEX_ALLOC_STR(entry, string, buf.buf);
+                       oidcpy(&entry->entry.oid, &commit->object.oid);
+                       oidmap_put(&commit2todo, entry);
+
+                       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) &&
+                   (p1 = strchr(p1, '\'')) &&
+                   (p2 = strchr(++p1, '\'')))
+                       strbuf_add(&label, p1, p2 - p1);
+               else if (skip_prefix(oneline.buf, "Merge pull request ",
+                                    &p1) &&
+                        (p1 = strstr(p1, " from ")))
+                       strbuf_addstr(&label, p1 + strlen(" from "));
+               else
+                       strbuf_addbuf(&label, &oneline);
+
+               for (p1 = label.buf; *p1; p1++)
+                       if (isspace(*p1))
+                               *(char *)p1 = '-';
+
+               strbuf_reset(&buf);
+               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, ' ');
+
+               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;
+
+                       strbuf_addstr(&buf, label_oid(oid, label.buf, &state));
+               }
+               strbuf_addf(&buf, " # %s", oneline.buf);
+
+               FLEX_ALLOC_STR(entry, string, buf.buf);
+               oidcpy(&entry->entry.oid, &commit->object.oid);
+               oidmap_put(&commit2todo, entry);
+       }
+
+       /*
+        * Second phase:
+        * - label branch points
+        * - add HEAD to the branch tips
+        */
+       for (iter = commits; iter; iter = iter->next) {
+               struct commit_list *parent = iter->item->parents;
+               for (; parent; parent = parent->next) {
+                       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
+                               label_oid(oid, "branch-point", &state);
+               }
+
+               /* Add HEAD as implict "tip of branch" */
+               if (!iter->next)
+                       tips_tail = &commit_list_insert(iter->item,
+                                                       tips_tail)->next;
+       }
+
+       /*
+        * Third phase: output the todo list. This is a bit tricky, as we
+        * want to avoid jumping back and forth between revisions. To
+        * accomplish that goal, we walk backwards from the branch tips,
+        * 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);
+       for (iter = tips; iter; iter = iter->next) {
+               struct commit_list *list = NULL, *iter2;
+
+               commit = iter->item;
+               if (oidset_contains(&shown, &commit->object.oid))
+                       continue;
+               entry = oidmap_get(&state.commit2label, &commit->object.oid);
+
+               if (entry)
+                       fprintf(out, "\n# Branch %s\n", entry->string);
+               else
+                       fprintf(out, "\n");
+
+               while (oidset_contains(&interesting, &commit->object.oid) &&
+                      !oidset_contains(&shown, &commit->object.oid)) {
+                       commit_list_insert(commit, &list);
+                       if (!commit->parents) {
+                               commit = NULL;
+                               break;
+                       }
+                       commit = commit->parents->item;
+               }
+
+               if (!commit)
+                       fprintf(out, "%s %s\n", cmd_reset,
+                               rebase_cousins ? "onto" : "[new root]");
+               else {
+                       const char *to = NULL;
+
+                       entry = oidmap_get(&state.commit2label,
+                                          &commit->object.oid);
+                       if (entry)
+                               to = entry->string;
+                       else if (!rebase_cousins)
+                               to = label_oid(&commit->object.oid, NULL,
+                                              &state);
+
+                       if (!to || !strcmp(to, "onto"))
+                               fprintf(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);
+                       }
+               }
+
+               for (iter2 = list; iter2; iter2 = iter2->next) {
+                       struct object_id *oid = &iter2->item->object.oid;
+                       entry = oidmap_get(&commit2todo, oid);
+                       /* only show if not already upstream */
+                       if (entry)
+                               fprintf(out, "%s\n", entry->string);
+                       entry = oidmap_get(&state.commit2label, oid);
+                       if (entry)
+                               fprintf(out, "%s %s\n",
+                                       cmd_label, entry->string);
+                       oidset_insert(&shown, oid);
+               }
+
+               free_commit_list(list);
+       }
+
+       free_commit_list(commits);
+       free_commit_list(tips);
+
+       strbuf_release(&label);
+       strbuf_release(&oneline);
+       strbuf_release(&buf);
+
+       oidmap_free(&commit2todo, 1);
+       oidmap_free(&state.commit2label, 1);
+       hashmap_free(&state.labels, 1);
+       strbuf_release(&state.buf);
+
+       return 0;
+}
+
 int sequencer_make_script(FILE *out, int argc, const char **argv,
                          unsigned flags)
 {
@@ -3095,11 +4097,13 @@ int sequencer_make_script(FILE *out, int argc, const char **argv,
        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);
        revs.verbose_header = 1;
-       revs.max_parents = 1;
-       revs.cherry_pick = 1;
+       if (!rebase_merges)
+               revs.max_parents = 1;
+       revs.cherry_mark = 1;
        revs.limited = 1;
        revs.reverse = 1;
        revs.right_only = 1;
@@ -3123,9 +4127,16 @@ int sequencer_make_script(FILE *out, int argc, const char **argv,
        if (prepare_revision_walk(&revs) < 0)
                return error(_("make_script: error preparing revisions"));
 
+       if (rebase_merges)
+               return make_script_with_merges(&pp, &revs, out, flags);
+
        while ((commit = get_revision(&revs))) {
+               int is_empty  = is_original_commit_empty(commit);
+
+               if (!is_empty && (commit->object.flags & PATCHSAME))
+                       continue;
                strbuf_reset(&buf);
-               if (!keep_empty && is_original_commit_empty(commit))
+               if (!keep_empty && is_empty)
                        strbuf_addf(&buf, "%c ", comment_line_char);
                strbuf_addf(&buf, "%s %s ", insn,
                            oid_to_hex(&commit->object.oid));
@@ -3212,8 +4223,16 @@ int transform_todos(unsigned flags)
                                          short_commit_name(item->commit) :
                                          oid_to_hex(&item->commit->object.oid);
 
+                       if (item->command == TODO_MERGE) {
+                               if (item->flags & TODO_EDIT_MERGE_MSG)
+                                       strbuf_addstr(&buf, " -c");
+                               else
+                                       strbuf_addstr(&buf, " -C");
+                       }
+
                        strbuf_addf(&buf, " %s", oid);
                }
+
                /* add all the rest */
                if (!item->arg_len)
                        strbuf_addch(&buf, '\n');
@@ -3246,6 +4265,7 @@ static enum check_level get_missing_commit_check_level(void)
        return CHECK_IGNORE;
 }
 
+define_commit_slab(commit_seen, unsigned char);
 /*
  * Check if the user dropped some commits by mistake
  * Behaviour determined by rebase.missingCommitsCheck.
@@ -3259,6 +4279,9 @@ int check_todo_list(void)
        struct todo_list todo_list = TODO_LIST_INIT;
        struct strbuf missing = STRBUF_INIT;
        int advise_to_edit_todo = 0, res = 0, i;
+       struct commit_seen commit_seen;
+
+       init_commit_seen(&commit_seen);
 
        strbuf_addstr(&todo_file, rebase_path_todo());
        if (strbuf_read_file_or_whine(&todo_list.buf, todo_file.buf) < 0) {
@@ -3275,7 +4298,7 @@ int check_todo_list(void)
        for (i = 0; i < todo_list.nr; i++) {
                struct commit *commit = todo_list.items[i].commit;
                if (commit)
-                       commit->util = (void *)1;
+                       *commit_seen_at(&commit_seen, commit) = 1;
        }
 
        todo_list_release(&todo_list);
@@ -3291,11 +4314,11 @@ int check_todo_list(void)
        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) {
+               if (commit && !*commit_seen_at(&commit_seen, commit)) {
                        strbuf_addf(&missing, " - %s %.*s\n",
                                    short_commit_name(commit),
                                    item->arg_len, item->arg);
-                       commit->util = (void *)1;
+                       *commit_seen_at(&commit_seen, commit) = 1;
                }
        }
 
@@ -3321,6 +4344,7 @@ int check_todo_list(void)
                "The possible behaviours are: ignore, warn, error.\n\n"));
 
 leave_check:
+       clear_commit_seen(&commit_seen);
        strbuf_release(&todo_file);
        todo_list_release(&todo_list);
 
@@ -3393,8 +4417,7 @@ int skip_unnecessary_picks(void)
                oid = &item->commit->object.oid;
        }
        if (i > 0) {
-               int offset = i < todo_list.nr ?
-                       todo_list.items[i].offset_in_buf : todo_list.buf.len;
+               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);
@@ -3442,6 +4465,8 @@ 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
@@ -3458,6 +4483,7 @@ int rearrange_squash(void)
        struct hashmap subject2item;
        int res = 0, rearranged = 0, *next, *tail, i;
        char **subjects;
+       struct commit_todo_item commit_todo;
 
        if (strbuf_read_file_or_whine(&todo_list.buf, todo_file) < 0)
                return -1;
@@ -3466,6 +4492,7 @@ int rearrange_squash(void)
                return -1;
        }
 
+       init_commit_todo_item(&commit_todo);
        /*
         * The hashmap maps onelines to the respective todo list index.
         *
@@ -3489,17 +4516,18 @@ int rearrange_squash(void)
                struct subject2item_entry *entry;
 
                next[i] = tail[i] = -1;
-               if (item->command >= TODO_EXEC) {
+               if (!item->commit || item->command == TODO_DROP) {
                        subjects[i] = NULL;
                        continue;
                }
 
                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);
@@ -3526,9 +4554,9 @@ 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
+                               i2 = *commit_todo_item_at(&commit_todo, commit2)
                                        - todo_list.items;
                        else {
                                /* copy can be a prefix of the commit subject */
@@ -3574,12 +4602,10 @@ int rearrange_squash(void)
                                continue;
 
                        while (cur >= 0) {
-                               int offset = todo_list.items[cur].offset_in_buf;
-                               int end_offset = cur + 1 < todo_list.nr ?
-                                       todo_list.items[cur + 1].offset_in_buf :
-                                       todo_list.buf.len;
-                               char *bol = todo_list.buf.buf + offset;
-                               char *eol = todo_list.buf.buf + end_offset;
+                               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;
@@ -3607,5 +4633,6 @@ int rearrange_squash(void)
        hashmap_free(&subject2item, 1);
        todo_list_release(&todo_list);
 
+       clear_commit_todo_item(&commit_todo);
        return res;
 }