/*
 * Builtin "git commit"
 *
 * Copyright (c) 2007 Kristian Høgsberg <krh@redhat.com>
 * Based on git-commit.sh by Junio C Hamano and Linus Torvalds
 */

#include "cache.h"
#include "cache-tree.h"
#include "color.h"
#include "dir.h"
#include "builtin.h"
#include "diff.h"
#include "diffcore.h"
#include "commit.h"
#include "revision.h"
#include "wt-status.h"
#include "run-command.h"
#include "refs.h"
#include "log-tree.h"
#include "strbuf.h"
#include "utf8.h"
#include "parse-options.h"
#include "string-list.h"
#include "rerere.h"
#include "unpack-trees.h"
#include "quote.h"
#include "submodule.h"
#include "gpg-interface.h"
#include "column.h"
#include "sequencer.h"
#include "notes-utils.h"
#include "mailmap.h"

static const char * const builtin_commit_usage[] = {
        N_("git commit [options] [--] <pathspec>..."),
        NULL
};

static const char * const builtin_status_usage[] = {
        N_("git status [options] [--] <pathspec>..."),
        NULL
};

static const char implicit_ident_advice[] =
N_("Your name and email address were configured automatically based\n"
"on your username and hostname. Please check that they are accurate.\n"
"You can suppress this message by setting them explicitly:\n"
"\n"
"    git config --global user.name \"Your Name\"\n"
"    git config --global user.email you@example.com\n"
"\n"
"After doing this, you may fix the identity used for this commit with:\n"
"\n"
"    git commit --amend --reset-author\n");

static const char empty_amend_advice[] =
N_("You asked to amend the most recent commit, but doing so would make\n"
"it empty. You can repeat your command with --allow-empty, or you can\n"
"remove the commit entirely with \"git reset HEAD^\".\n");

static const char empty_cherry_pick_advice[] =
N_("The previous cherry-pick is now empty, possibly due to conflict resolution.\n"
"If you wish to commit it anyway, use:\n"
"\n"
"    git commit --allow-empty\n"
"\n");

static const char empty_cherry_pick_advice_single[] =
N_("Otherwise, please use 'git reset'\n");

static const char empty_cherry_pick_advice_multi[] =
N_("If you wish to skip this commit, use:\n"
"\n"
"    git reset\n"
"\n"
"Then \"git cherry-pick --continue\" will resume cherry-picking\n"
"the remaining commits.\n");

static const char *use_message_buffer;
static const char commit_editmsg[] = "COMMIT_EDITMSG";
static struct lock_file index_lock; /* real index */
static struct lock_file false_lock; /* used only for partial commits */
static enum {
        COMMIT_AS_IS = 1,
        COMMIT_NORMAL,
        COMMIT_PARTIAL
} commit_style;

static const char *logfile, *force_author;
static const char *template_file;
/*
 * The _message variables are commit names from which to take
 * the commit message and/or authorship.
 */
static const char *author_message, *author_message_buffer;
static char *edit_message, *use_message;
static char *fixup_message, *squash_message;
static int all, also, interactive, patch_interactive, only, amend, signoff;
static int edit_flag = -1; /* unspecified */
static int quiet, verbose, no_verify, allow_empty, dry_run, renew_authorship;
static int no_post_rewrite, allow_empty_message;
static char *untracked_files_arg, *force_date, *ignore_submodule_arg;
static char *sign_commit;

/*
 * The default commit message cleanup mode will remove the lines
 * beginning with # (shell comments) and leading and trailing
 * whitespaces (empty lines or containing only whitespaces)
 * if editor is used, and only the whitespaces if the message
 * is specified explicitly.
 */
static enum {
        CLEANUP_SPACE,
        CLEANUP_NONE,
        CLEANUP_SCISSORS,
        CLEANUP_ALL
} cleanup_mode;
static const char *cleanup_arg;

static enum commit_whence whence;
static int sequencer_in_use;
static int use_editor = 1, include_status = 1;
static int show_ignored_in_status, have_option_m;
static const char *only_include_assumed;
static struct strbuf message = STRBUF_INIT;

static enum status_format {
        STATUS_FORMAT_NONE = 0,
        STATUS_FORMAT_LONG,
        STATUS_FORMAT_SHORT,
        STATUS_FORMAT_PORCELAIN,

        STATUS_FORMAT_UNSPECIFIED
} status_format = STATUS_FORMAT_UNSPECIFIED;

static int opt_parse_m(const struct option *opt, const char *arg, int unset)
{
        struct strbuf *buf = opt->value;
        if (unset) {
                have_option_m = 0;
                strbuf_setlen(buf, 0);
        } else {
                have_option_m = 1;
                if (buf->len)
                        strbuf_addch(buf, '\n');
                strbuf_addstr(buf, arg);
                strbuf_complete_line(buf);
        }
        return 0;
}

static void determine_whence(struct wt_status *s)
{
        if (file_exists(git_path("MERGE_HEAD")))
                whence = FROM_MERGE;
        else if (file_exists(git_path("CHERRY_PICK_HEAD"))) {
                whence = FROM_CHERRY_PICK;
                if (file_exists(git_path("sequencer")))
                        sequencer_in_use = 1;
        }
        else
                whence = FROM_COMMIT;
        if (s)
                s->whence = whence;
}

static void status_init_config(struct wt_status *s, config_fn_t fn)
{
        wt_status_prepare(s);
        gitmodules_config();
        git_config(fn, s);
        determine_whence(s);
        s->hints = advice_status_hints; /* must come after git_config() */
}

static void rollback_index_files(void)
{
        switch (commit_style) {
        case COMMIT_AS_IS:
                break; /* nothing to do */
        case COMMIT_NORMAL:
                rollback_lock_file(&index_lock);
                break;
        case COMMIT_PARTIAL:
                rollback_lock_file(&index_lock);
                rollback_lock_file(&false_lock);
                break;
        }
}

static int commit_index_files(void)
{
        int err = 0;

        switch (commit_style) {
        case COMMIT_AS_IS:
                break; /* nothing to do */
        case COMMIT_NORMAL:
                err = commit_lock_file(&index_lock);
                break;
        case COMMIT_PARTIAL:
                err = commit_lock_file(&index_lock);
                rollback_lock_file(&false_lock);
                break;
        }

        return err;
}

/*
 * Take a union of paths in the index and the named tree (typically, "HEAD"),
 * and return the paths that match the given pattern in list.
 */
static int list_paths(struct string_list *list, const char *with_tree,
                      const char *prefix, const struct pathspec *pattern)
{
        int i;
        char *m;

        if (!pattern->nr)
                return 0;

        m = xcalloc(1, pattern->nr);

        if (with_tree) {
                char *max_prefix = common_prefix(pattern);
                overlay_tree_on_cache(with_tree, max_prefix ? max_prefix : prefix);
                free(max_prefix);
        }

        for (i = 0; i < active_nr; i++) {
                const struct cache_entry *ce = active_cache[i];
                struct string_list_item *item;

                if (ce->ce_flags & CE_UPDATE)
                        continue;
                if (!ce_path_match(ce, pattern, m))
                        continue;
                item = string_list_insert(list, ce->name);
                if (ce_skip_worktree(ce))
                        item->util = item; /* better a valid pointer than a fake one */
        }

        return report_path_error(m, pattern, prefix);
}

static void add_remove_files(struct string_list *list)
{
        int i;
        for (i = 0; i < list->nr; i++) {
                struct stat st;
                struct string_list_item *p = &(list->items[i]);

                /* p->util is skip-worktree */
                if (p->util)
                        continue;

                if (!lstat(p->string, &st)) {
                        if (add_to_cache(p->string, &st, 0))
                                die(_("updating files failed"));
                } else
                        remove_file_from_cache(p->string);
        }
}

static void create_base_index(const struct commit *current_head)
{
        struct tree *tree;
        struct unpack_trees_options opts;
        struct tree_desc t;

        if (!current_head) {
                discard_cache();
                return;
        }

        memset(&opts, 0, sizeof(opts));
        opts.head_idx = 1;
        opts.index_only = 1;
        opts.merge = 1;
        opts.src_index = &the_index;
        opts.dst_index = &the_index;

        opts.fn = oneway_merge;
        tree = parse_tree_indirect(current_head->object.sha1);
        if (!tree)
                die(_("failed to unpack HEAD tree object"));
        parse_tree(tree);
        init_tree_desc(&t, tree->buffer, tree->size);
        if (unpack_trees(1, &t, &opts))
                exit(128); /* We've already reported the error, finish dying */
}

static void refresh_cache_or_die(int refresh_flags)
{
        /*
         * refresh_flags contains REFRESH_QUIET, so the only errors
         * are for unmerged entries.
         */
        if (refresh_cache(refresh_flags | REFRESH_IN_PORCELAIN))
                die_resolve_conflict("commit");
}

static char *prepare_index(int argc, const char **argv, const char *prefix,
                           const struct commit *current_head, int is_status)
{
        struct string_list partial;
        struct pathspec pathspec;
        int refresh_flags = REFRESH_QUIET;

        if (is_status)
                refresh_flags |= REFRESH_UNMERGED;
        parse_pathspec(&pathspec, 0,
                       PATHSPEC_PREFER_FULL,
                       prefix, argv);

        if (read_cache_preload(&pathspec) < 0)
                die(_("index file corrupt"));

        if (interactive) {
                char *old_index_env = NULL;
                hold_locked_index(&index_lock, 1);

                refresh_cache_or_die(refresh_flags);

                if (write_locked_index(&the_index, &index_lock, CLOSE_LOCK))
                        die(_("unable to create temporary index"));

                old_index_env = getenv(INDEX_ENVIRONMENT);
                setenv(INDEX_ENVIRONMENT, index_lock.filename, 1);

                if (interactive_add(argc, argv, prefix, patch_interactive) != 0)
                        die(_("interactive add failed"));

                if (old_index_env && *old_index_env)
                        setenv(INDEX_ENVIRONMENT, old_index_env, 1);
                else
                        unsetenv(INDEX_ENVIRONMENT);

                discard_cache();
                read_cache_from(index_lock.filename);

                commit_style = COMMIT_NORMAL;
                return index_lock.filename;
        }

        /*
         * Non partial, non as-is commit.
         *
         * (1) get the real index;
         * (2) update the_index as necessary;
         * (3) write the_index out to the real index (still locked);
         * (4) return the name of the locked index file.
         *
         * The caller should run hooks on the locked real index, and
         * (A) if all goes well, commit the real index;
         * (B) on failure, rollback the real index.
         */
        if (all || (also && pathspec.nr)) {
                hold_locked_index(&index_lock, 1);
                add_files_to_cache(also ? prefix : NULL, &pathspec, 0);
                refresh_cache_or_die(refresh_flags);
                update_main_cache_tree(WRITE_TREE_SILENT);
                if (write_locked_index(&the_index, &index_lock, CLOSE_LOCK))
                        die(_("unable to write new_index file"));
                commit_style = COMMIT_NORMAL;
                return index_lock.filename;
        }

        /*
         * As-is commit.
         *
         * (1) return the name of the real index file.
         *
         * The caller should run hooks on the real index,
         * and create commit from the_index.
         * We still need to refresh the index here.
         */
        if (!only && !pathspec.nr) {
                hold_locked_index(&index_lock, 1);
                refresh_cache_or_die(refresh_flags);
                if (active_cache_changed) {
                        update_main_cache_tree(WRITE_TREE_SILENT);
                        if (write_locked_index(&the_index, &index_lock,
                                               COMMIT_LOCK))
                                die(_("unable to write new_index file"));
                } else {
                        rollback_lock_file(&index_lock);
                }
                commit_style = COMMIT_AS_IS;
                return get_index_file();
        }

        /*
         * A partial commit.
         *
         * (0) find the set of affected paths;
         * (1) get lock on the real index file;
         * (2) update the_index with the given paths;
         * (3) write the_index out to the real index (still locked);
         * (4) get lock on the false index file;
         * (5) reset the_index from HEAD;
         * (6) update the_index the same way as (2);
         * (7) write the_index out to the false index file;
         * (8) return the name of the false index file (still locked);
         *
         * The caller should run hooks on the locked false index, and
         * create commit from it.  Then
         * (A) if all goes well, commit the real index;
         * (B) on failure, rollback the real index;
         * In either case, rollback the false index.
         */
        commit_style = COMMIT_PARTIAL;

        if (whence != FROM_COMMIT) {
                if (whence == FROM_MERGE)
                        die(_("cannot do a partial commit during a merge."));
                else if (whence == FROM_CHERRY_PICK)
                        die(_("cannot do a partial commit during a cherry-pick."));
        }

        string_list_init(&partial, 1);
        if (list_paths(&partial, !current_head ? NULL : "HEAD", prefix, &pathspec))
                exit(1);

        discard_cache();
        if (read_cache() < 0)
                die(_("cannot read the index"));

        hold_locked_index(&index_lock, 1);
        add_remove_files(&partial);
        refresh_cache(REFRESH_QUIET);
        if (write_locked_index(&the_index, &index_lock, CLOSE_LOCK))
                die(_("unable to write new_index file"));

        hold_lock_file_for_update(&false_lock,
                                  git_path("next-index-%"PRIuMAX,
                                           (uintmax_t) getpid()),
                                  LOCK_DIE_ON_ERROR);

        create_base_index(current_head);
        add_remove_files(&partial);
        refresh_cache(REFRESH_QUIET);

        if (write_locked_index(&the_index, &false_lock, CLOSE_LOCK))
                die(_("unable to write temporary index file"));

        discard_cache();
        read_cache_from(false_lock.filename);

        return false_lock.filename;
}

static int run_status(FILE *fp, const char *index_file, const char *prefix, int nowarn,
                      struct wt_status *s)
{
        unsigned char sha1[20];

        if (s->relative_paths)
                s->prefix = prefix;

        if (amend) {
                s->amend = 1;
                s->reference = "HEAD^1";
        }
        s->verbose = verbose;
        s->index_file = index_file;
        s->fp = fp;
        s->nowarn = nowarn;
        s->is_initial = get_sha1(s->reference, sha1) ? 1 : 0;

        wt_status_collect(s);

        switch (status_format) {
        case STATUS_FORMAT_SHORT:
                wt_shortstatus_print(s);
                break;
        case STATUS_FORMAT_PORCELAIN:
                wt_porcelain_print(s);
                break;
        case STATUS_FORMAT_UNSPECIFIED:
                die("BUG: finalize_deferred_config() should have been called");
                break;
        case STATUS_FORMAT_NONE:
        case STATUS_FORMAT_LONG:
                wt_status_print(s);
                break;
        }

        return s->commitable;
}

static int is_a_merge(const struct commit *current_head)
{
        return !!(current_head->parents && current_head->parents->next);
}

static void export_one(const char *var, const char *s, const char *e, int hack)
{
        struct strbuf buf = STRBUF_INIT;
        if (hack)
                strbuf_addch(&buf, hack);
        strbuf_addf(&buf, "%.*s", (int)(e - s), s);
        setenv(var, buf.buf, 1);
        strbuf_release(&buf);
}

static int sane_ident_split(struct ident_split *person)
{
        if (!person->name_begin || !person->name_end ||
            person->name_begin == person->name_end)
                return 0; /* no human readable name */
        if (!person->mail_begin || !person->mail_end ||
            person->mail_begin == person->mail_end)
                return 0; /* no usable mail */
        if (!person->date_begin || !person->date_end ||
            !person->tz_begin || !person->tz_end)
                return 0;
        return 1;
}

static int parse_force_date(const char *in, char *out, int len)
{
        if (len < 1)
                return -1;
        *out++ = '@';
        len--;

        if (parse_date(in, out, len) < 0) {
                int errors = 0;
                unsigned long t = approxidate_careful(in, &errors);
                if (errors)
                        return -1;
                snprintf(out, len, "%lu", t);
        }

        return 0;
}

static void determine_author_info(struct strbuf *author_ident)
{
        char *name, *email, *date;
        struct ident_split author;
        char date_buf[64];

        name = getenv("GIT_AUTHOR_NAME");
        email = getenv("GIT_AUTHOR_EMAIL");
        date = getenv("GIT_AUTHOR_DATE");

        if (author_message) {
                const char *a, *lb, *rb, *eol;
                size_t len;

                a = strstr(author_message_buffer, "\nauthor ");
                if (!a)
                        die(_("invalid commit: %s"), author_message);

                lb = strchrnul(a + strlen("\nauthor "), '<');
                rb = strchrnul(lb, '>');
                eol = strchrnul(rb, '\n');
                if (!*lb || !*rb || !*eol)
                        die(_("invalid commit: %s"), author_message);

                if (lb == a + strlen("\nauthor "))
                        /* \nauthor <foo@example.com> */
                        name = xcalloc(1, 1);
                else
                        name = xmemdupz(a + strlen("\nauthor "),
                                        (lb - strlen(" ") -
                                         (a + strlen("\nauthor "))));
                email = xmemdupz(lb + strlen("<"), rb - (lb + strlen("<")));
                len = eol - (rb + strlen("> "));
                date = xmalloc(len + 2);
                *date = '@';
                memcpy(date + 1, rb + strlen("> "), len);
                date[len + 1] = '\0';
        }

        if (force_author) {
                const char *lb = strstr(force_author, " <");
                const char *rb = strchr(force_author, '>');

                if (!lb || !rb)
                        die(_("malformed --author parameter"));
                name = xstrndup(force_author, lb - force_author);
                email = xstrndup(lb + 2, rb - (lb + 2));
        }

        if (force_date) {
                if (parse_force_date(force_date, date_buf, sizeof(date_buf)))
                        die(_("invalid date format: %s"), force_date);
                date = date_buf;
        }

        strbuf_addstr(author_ident, fmt_ident(name, email, date, IDENT_STRICT));
        if (!split_ident_line(&author, author_ident->buf, author_ident->len) &&
            sane_ident_split(&author)) {
                export_one("GIT_AUTHOR_NAME", author.name_begin, author.name_end, 0);
                export_one("GIT_AUTHOR_EMAIL", author.mail_begin, author.mail_end, 0);
                export_one("GIT_AUTHOR_DATE", author.date_begin, author.tz_end, '@');
        }
}

static void split_ident_or_die(struct ident_split *id, const struct strbuf *buf)
{
        if (split_ident_line(id, buf->buf, buf->len) ||
            !sane_ident_split(id))
                die(_("Malformed ident string: '%s'"), buf->buf);
}

static int author_date_is_interesting(void)
{
        return author_message || force_date;
}

static void adjust_comment_line_char(const struct strbuf *sb)
{
        char candidates[] = "#;@!$%^&|:";
        char *candidate;
        const char *p;

        comment_line_char = candidates[0];
        if (!memchr(sb->buf, comment_line_char, sb->len))
                return;

        p = sb->buf;
        candidate = strchr(candidates, *p);
        if (candidate)
                *candidate = ' ';
        for (p = sb->buf; *p; p++) {
                if ((p[0] == '\n' || p[0] == '\r') && p[1]) {
                        candidate = strchr(candidates, p[1]);
                        if (candidate)
                                *candidate = ' ';
                }
        }

        for (p = candidates; *p == ' '; p++)
                ;
        if (!*p)
                die(_("unable to select a comment character that is not used\n"
                      "in the current commit message"));
        comment_line_char = *p;
}

static int prepare_to_commit(const char *index_file, const char *prefix,
                             struct commit *current_head,
                             struct wt_status *s,
                             struct strbuf *author_ident)
{
        struct stat statbuf;
        struct strbuf committer_ident = STRBUF_INIT;
        int commitable;
        struct strbuf sb = STRBUF_INIT;
        const char *hook_arg1 = NULL;
        const char *hook_arg2 = NULL;
        int clean_message_contents = (cleanup_mode != CLEANUP_NONE);
        int old_display_comment_prefix;

        /* This checks and barfs if author is badly specified */
        determine_author_info(author_ident);

        if (!no_verify && run_commit_hook(use_editor, index_file, "pre-commit", NULL))
                return 0;

        if (squash_message) {
                /*
                 * Insert the proper subject line before other commit
                 * message options add their content.
                 */
                if (use_message && !strcmp(use_message, squash_message))
                        strbuf_addstr(&sb, "squash! ");
                else {
                        struct pretty_print_context ctx = {0};
                        struct commit *c;
                        c = lookup_commit_reference_by_name(squash_message);
                        if (!c)
                                die(_("could not lookup commit %s"), squash_message);
                        ctx.output_encoding = get_commit_output_encoding();
                        format_commit_message(c, "squash! %s\n\n", &sb,
                                              &ctx);
                }
        }

        if (message.len) {
                strbuf_addbuf(&sb, &message);
                hook_arg1 = "message";
        } else if (logfile && !strcmp(logfile, "-")) {
                if (isatty(0))
                        fprintf(stderr, _("(reading log message from standard input)\n"));
                if (strbuf_read(&sb, 0, 0) < 0)
                        die_errno(_("could not read log from standard input"));
                hook_arg1 = "message";
        } else if (logfile) {
                if (strbuf_read_file(&sb, logfile, 0) < 0)
                        die_errno(_("could not read log file '%s'"),
                                  logfile);
                hook_arg1 = "message";
        } else if (use_message) {
                char *buffer;
                buffer = strstr(use_message_buffer, "\n\n");
                if (buffer)
                        strbuf_addstr(&sb, buffer + 2);
                hook_arg1 = "commit";
                hook_arg2 = use_message;
        } else if (fixup_message) {
                struct pretty_print_context ctx = {0};
                struct commit *commit;
                commit = lookup_commit_reference_by_name(fixup_message);
                if (!commit)
                        die(_("could not lookup commit %s"), fixup_message);
                ctx.output_encoding = get_commit_output_encoding();
                format_commit_message(commit, "fixup! %s\n\n",
                                      &sb, &ctx);
                hook_arg1 = "message";
        } else if (!stat(git_path("MERGE_MSG"), &statbuf)) {
                if (strbuf_read_file(&sb, git_path("MERGE_MSG"), 0) < 0)
                        die_errno(_("could not read MERGE_MSG"));
                hook_arg1 = "merge";
        } else if (!stat(git_path("SQUASH_MSG"), &statbuf)) {
                if (strbuf_read_file(&sb, git_path("SQUASH_MSG"), 0) < 0)
                        die_errno(_("could not read SQUASH_MSG"));
                hook_arg1 = "squash";
        } else if (template_file) {
                if (strbuf_read_file(&sb, template_file, 0) < 0)
                        die_errno(_("could not read '%s'"), template_file);
                hook_arg1 = "template";
                clean_message_contents = 0;
        }

        /*
         * The remaining cases don't modify the template message, but
         * just set the argument(s) to the prepare-commit-msg hook.
         */
        else if (whence == FROM_MERGE)
                hook_arg1 = "merge";
        else if (whence == FROM_CHERRY_PICK) {
                hook_arg1 = "commit";
                hook_arg2 = "CHERRY_PICK_HEAD";
        }

        if (squash_message) {
                /*
                 * If squash_commit was used for the commit subject,
                 * then we're possibly hijacking other commit log options.
                 * Reset the hook args to tell the real story.
                 */
                hook_arg1 = "message";
                hook_arg2 = "";
        }

        s->fp = fopen(git_path(commit_editmsg), "w");
        if (s->fp == NULL)
                die_errno(_("could not open '%s'"), git_path(commit_editmsg));

        /* Ignore status.displayCommentPrefix: we do need comments in COMMIT_EDITMSG. */
        old_display_comment_prefix = s->display_comment_prefix;
        s->display_comment_prefix = 1;

        /*
         * Most hints are counter-productive when the commit has
         * already started.
         */
        s->hints = 0;

        if (clean_message_contents)
                stripspace(&sb, 0);

        if (signoff) {
                /*
                 * See if we have a Conflicts: block at the end. If yes, count
                 * its size, so we can ignore it.
                 */
                int ignore_footer = 0;
                int i, eol, previous = 0;
                const char *nl;

                for (i = 0; i < sb.len; i++) {
                        nl = memchr(sb.buf + i, '\n', sb.len - i);
                        if (nl)
                                eol = nl - sb.buf;
                        else
                                eol = sb.len;
                        if (starts_with(sb.buf + previous, "\nConflicts:\n")) {
                                ignore_footer = sb.len - previous;
                                break;
                        }
                        while (i < eol)
                                i++;
                        previous = eol;
                }

                append_signoff(&sb, ignore_footer, 0);
        }

        if (fwrite(sb.buf, 1, sb.len, s->fp) < sb.len)
                die_errno(_("could not write commit template"));

        if (auto_comment_line_char)
                adjust_comment_line_char(&sb);
        strbuf_release(&sb);

        /* This checks if committer ident is explicitly given */
        strbuf_addstr(&committer_ident, git_committer_info(IDENT_STRICT));
        if (use_editor && include_status) {
                int ident_shown = 0;
                int saved_color_setting;
                struct ident_split ci, ai;

                if (whence != FROM_COMMIT) {
                        if (cleanup_mode == CLEANUP_SCISSORS)
                                wt_status_add_cut_line(s->fp);
                        status_printf_ln(s, GIT_COLOR_NORMAL,
                            whence == FROM_MERGE
                                ? _("\n"
                                        "It looks like you may be committing a merge.\n"
                                        "If this is not correct, please remove the file\n"
                                        "       %s\n"
                                        "and try again.\n")
                                : _("\n"
                                        "It looks like you may be committing a cherry-pick.\n"
                                        "If this is not correct, please remove the file\n"
                                        "       %s\n"
                                        "and try again.\n"),
                                git_path(whence == FROM_MERGE
                                         ? "MERGE_HEAD"
                                         : "CHERRY_PICK_HEAD"));
                }

                fprintf(s->fp, "\n");
                if (cleanup_mode == CLEANUP_ALL)
                        status_printf(s, GIT_COLOR_NORMAL,
                                _("Please enter the commit message for your changes."
                                  " Lines starting\nwith '%c' will be ignored, and an empty"
                                  " message aborts the commit.\n"), comment_line_char);
                else if (cleanup_mode == CLEANUP_SCISSORS && whence == FROM_COMMIT)
                        wt_status_add_cut_line(s->fp);
                else /* CLEANUP_SPACE, that is. */
                        status_printf(s, GIT_COLOR_NORMAL,
                                _("Please enter the commit message for your changes."
                                  " Lines starting\n"
                                  "with '%c' will be kept; you may remove them"
                                  " yourself if you want to.\n"
                                  "An empty message aborts the commit.\n"), comment_line_char);
                if (only_include_assumed)
                        status_printf_ln(s, GIT_COLOR_NORMAL,
                                        "%s", only_include_assumed);

                split_ident_or_die(&ai, author_ident);
                split_ident_or_die(&ci, &committer_ident);

                if (ident_cmp(&ai, &ci))
                        status_printf_ln(s, GIT_COLOR_NORMAL,
                                _("%s"
                                "Author:    %.*s <%.*s>"),
                                ident_shown++ ? "" : "\n",
                                (int)(ai.name_end - ai.name_begin), ai.name_begin,
                                (int)(ai.mail_end - ai.mail_begin), ai.mail_begin);

                if (author_date_is_interesting())
                        status_printf_ln(s, GIT_COLOR_NORMAL,
                                _("%s"
                                "Date:      %s"),
                                ident_shown++ ? "" : "\n",
                                show_ident_date(&ai, DATE_NORMAL));

                if (!committer_ident_sufficiently_given())
                        status_printf_ln(s, GIT_COLOR_NORMAL,
                                _("%s"
                                "Committer: %.*s <%.*s>"),
                                ident_shown++ ? "" : "\n",
                                (int)(ci.name_end - ci.name_begin), ci.name_begin,
                                (int)(ci.mail_end - ci.mail_begin), ci.mail_begin);

                if (ident_shown)
                        status_printf_ln(s, GIT_COLOR_NORMAL, "%s", "");

                saved_color_setting = s->use_color;
                s->use_color = 0;
                commitable = run_status(s->fp, index_file, prefix, 1, s);
                s->use_color = saved_color_setting;
        } else {
                unsigned char sha1[20];
                const char *parent = "HEAD";

                if (!active_nr && read_cache() < 0)
                        die(_("Cannot read index"));

                if (amend)
                        parent = "HEAD^1";

                if (get_sha1(parent, sha1))
                        commitable = !!active_nr;
                else {
                        /*
                         * Unless the user did explicitly request a submodule
                         * ignore mode by passing a command line option we do
                         * not ignore any changed submodule SHA-1s when
                         * comparing index and parent, no matter what is
                         * configured. Otherwise we won't commit any
                         * submodules which were manually staged, which would
                         * be really confusing.
                         */
                        int diff_flags = DIFF_OPT_OVERRIDE_SUBMODULE_CONFIG;
                        if (ignore_submodule_arg &&
                            !strcmp(ignore_submodule_arg, "all"))
                                diff_flags |= DIFF_OPT_IGNORE_SUBMODULES;
                        commitable = index_differs_from(parent, diff_flags);
                }
        }
        strbuf_release(&committer_ident);

        fclose(s->fp);

        /*
         * Reject an attempt to record a non-merge empty commit without
         * explicit --allow-empty. In the cherry-pick case, it may be
         * empty due to conflict resolution, which the user should okay.
         */
        if (!commitable && whence != FROM_MERGE && !allow_empty &&
            !(amend && is_a_merge(current_head))) {
                s->display_comment_prefix = old_display_comment_prefix;
                run_status(stdout, index_file, prefix, 0, s);
                if (amend)
                        fputs(_(empty_amend_advice), stderr);
                else if (whence == FROM_CHERRY_PICK) {
                        fputs(_(empty_cherry_pick_advice), stderr);
                        if (!sequencer_in_use)
                                fputs(_(empty_cherry_pick_advice_single), stderr);
                        else
                                fputs(_(empty_cherry_pick_advice_multi), stderr);
                }
                return 0;
        }

        /*
         * Re-read the index as pre-commit hook could have updated it,
         * and write it out as a tree.  We must do this before we invoke
         * the editor and after we invoke run_status above.
         */
        discard_cache();
        read_cache_from(index_file);
        if (update_main_cache_tree(0)) {
                error(_("Error building trees"));
                return 0;
        }

        if (run_commit_hook(use_editor, index_file, "prepare-commit-msg",
                            git_path(commit_editmsg), hook_arg1, hook_arg2, NULL))
                return 0;

        if (use_editor) {
                char index[PATH_MAX];
                const char *env[2] = { NULL };
                env[0] =  index;
                snprintf(index, sizeof(index), "GIT_INDEX_FILE=%s", index_file);
                if (launch_editor(git_path(commit_editmsg), NULL, env)) {
                        fprintf(stderr,
                        _("Please supply the message using either -m or -F option.\n"));
                        exit(1);
                }
        }

        if (!no_verify &&
            run_commit_hook(use_editor, index_file, "commit-msg", git_path(commit_editmsg), NULL)) {
                return 0;
        }

        return 1;
}

static int rest_is_empty(struct strbuf *sb, int start)
{
        int i, eol;
        const char *nl;

        /* Check if the rest is just whitespace and Signed-of-by's. */
        for (i = start; i < sb->len; i++) {
                nl = memchr(sb->buf + i, '\n', sb->len - i);
                if (nl)
                        eol = nl - sb->buf;
                else
                        eol = sb->len;

                if (strlen(sign_off_header) <= eol - i &&
                    starts_with(sb->buf + i, sign_off_header)) {
                        i = eol;
                        continue;
                }
                while (i < eol)
                        if (!isspace(sb->buf[i++]))
                                return 0;
        }

        return 1;
}

/*
 * Find out if the message in the strbuf contains only whitespace and
 * Signed-off-by lines.
 */
static int message_is_empty(struct strbuf *sb)
{
        if (cleanup_mode == CLEANUP_NONE && sb->len)
                return 0;
        return rest_is_empty(sb, 0);
}

/*
 * See if the user edited the message in the editor or left what
 * was in the template intact
 */
static int template_untouched(struct strbuf *sb)
{
        struct strbuf tmpl = STRBUF_INIT;
        const char *start;

        if (cleanup_mode == CLEANUP_NONE && sb->len)
                return 0;

        if (!template_file || strbuf_read_file(&tmpl, template_file, 0) <= 0)
                return 0;

        stripspace(&tmpl, cleanup_mode == CLEANUP_ALL);
        if (!skip_prefix(sb->buf, tmpl.buf, &start))
                start = sb->buf;
        strbuf_release(&tmpl);
        return rest_is_empty(sb, start - sb->buf);
}

static const char *find_author_by_nickname(const char *name)
{
        struct rev_info revs;
        struct commit *commit;
        struct strbuf buf = STRBUF_INIT;
        struct string_list mailmap = STRING_LIST_INIT_NODUP;
        const char *av[20];
        int ac = 0;

        init_revisions(&revs, NULL);
        strbuf_addf(&buf, "--author=%s", name);
        av[++ac] = "--all";
        av[++ac] = "-i";
        av[++ac] = buf.buf;
        av[++ac] = NULL;
        setup_revisions(ac, av, &revs, NULL);
        revs.mailmap = &mailmap;
        read_mailmap(revs.mailmap, NULL);

        prepare_revision_walk(&revs);
        commit = get_revision(&revs);
        if (commit) {
                struct pretty_print_context ctx = {0};
                ctx.date_mode = DATE_NORMAL;
                strbuf_release(&buf);
                format_commit_message(commit, "%aN <%aE>", &buf, &ctx);
                clear_mailmap(&mailmap);
                return strbuf_detach(&buf, NULL);
        }
        die(_("No existing author found with '%s'"), name);
}


static void handle_untracked_files_arg(struct wt_status *s)
{
        if (!untracked_files_arg)
                ; /* default already initialized */
        else if (!strcmp(untracked_files_arg, "no"))
                s->show_untracked_files = SHOW_NO_UNTRACKED_FILES;
        else if (!strcmp(untracked_files_arg, "normal"))
                s->show_untracked_files = SHOW_NORMAL_UNTRACKED_FILES;
        else if (!strcmp(untracked_files_arg, "all"))
                s->show_untracked_files = SHOW_ALL_UNTRACKED_FILES;
        else
                die(_("Invalid untracked files mode '%s'"), untracked_files_arg);
}

static const char *read_commit_message(const char *name)
{
        const char *out_enc;
        struct commit *commit;

        commit = lookup_commit_reference_by_name(name);
        if (!commit)
                die(_("could not lookup commit %s"), name);
        out_enc = get_commit_output_encoding();
        return logmsg_reencode(commit, NULL, out_enc);
}

/*
 * Enumerate what needs to be propagated when --porcelain
 * is not in effect here.
 */
static struct status_deferred_config {
        enum status_format status_format;
        int show_branch;
} status_deferred_config = {
        STATUS_FORMAT_UNSPECIFIED,
        -1 /* unspecified */
};

static void finalize_deferred_config(struct wt_status *s)
{
        int use_deferred_config = (status_format != STATUS_FORMAT_PORCELAIN &&
                                   !s->null_termination);

        if (s->null_termination) {
                if (status_format == STATUS_FORMAT_NONE ||
                    status_format == STATUS_FORMAT_UNSPECIFIED)
                        status_format = STATUS_FORMAT_PORCELAIN;
                else if (status_format == STATUS_FORMAT_LONG)
                        die(_("--long and -z are incompatible"));
        }

        if (use_deferred_config && status_format == STATUS_FORMAT_UNSPECIFIED)
                status_format = status_deferred_config.status_format;
        if (status_format == STATUS_FORMAT_UNSPECIFIED)
                status_format = STATUS_FORMAT_NONE;

        if (use_deferred_config && s->show_branch < 0)
                s->show_branch = status_deferred_config.show_branch;
        if (s->show_branch < 0)
                s->show_branch = 0;
}

static int parse_and_validate_options(int argc, const char *argv[],
                                      const struct option *options,
                                      const char * const usage[],
                                      const char *prefix,
                                      struct commit *current_head,
                                      struct wt_status *s)
{
        int f = 0;

        argc = parse_options(argc, argv, prefix, options, usage, 0);
        finalize_deferred_config(s);

        if (force_author && !strchr(force_author, '>'))
                force_author = find_author_by_nickname(force_author);

        if (force_author && renew_authorship)
                die(_("Using both --reset-author and --author does not make sense"));

        if (logfile || have_option_m || use_message || fixup_message)
                use_editor = 0;
        if (0 <= edit_flag)
                use_editor = edit_flag;

        /* Sanity check options */
        if (amend && !current_head)
                die(_("You have nothing to amend."));
        if (amend && whence != FROM_COMMIT) {
                if (whence == FROM_MERGE)
                        die(_("You are in the middle of a merge -- cannot amend."));
                else if (whence == FROM_CHERRY_PICK)
                        die(_("You are in the middle of a cherry-pick -- cannot amend."));
        }
        if (fixup_message && squash_message)
                die(_("Options --squash and --fixup cannot be used together"));
        if (use_message)
                f++;
        if (edit_message)
                f++;
        if (fixup_message)
                f++;
        if (logfile)
                f++;
        if (f > 1)
                die(_("Only one of -c/-C/-F/--fixup can be used."));
        if (message.len && f > 0)
                die((_("Option -m cannot be combined with -c/-C/-F/--fixup.")));
        if (f || message.len)
                template_file = NULL;
        if (edit_message)
                use_message = edit_message;
        if (amend && !use_message && !fixup_message)
                use_message = "HEAD";
        if (!use_message && whence != FROM_CHERRY_PICK && renew_authorship)
                die(_("--reset-author can be used only with -C, -c or --amend."));
        if (use_message) {
                use_message_buffer = read_commit_message(use_message);
                if (!renew_authorship) {
                        author_message = use_message;
                        author_message_buffer = use_message_buffer;
                }
        }
        if (whence == FROM_CHERRY_PICK && !renew_authorship) {
                author_message = "CHERRY_PICK_HEAD";
                author_message_buffer = read_commit_message(author_message);
        }

        if (patch_interactive)
                interactive = 1;

        if (also + only + all + interactive > 1)
                die(_("Only one of --include/--only/--all/--interactive/--patch can be used."));
        if (argc == 0 && (also || (only && !amend)))
                die(_("No paths with --include/--only does not make sense."));
        if (argc == 0 && only && amend)
                only_include_assumed = _("Clever... amending the last one with dirty index.");
        if (argc > 0 && !also && !only)
                only_include_assumed = _("Explicit paths specified without -i or -o; assuming --only paths...");
        if (!cleanup_arg || !strcmp(cleanup_arg, "default"))
                cleanup_mode = use_editor ? CLEANUP_ALL : CLEANUP_SPACE;
        else if (!strcmp(cleanup_arg, "verbatim"))
                cleanup_mode = CLEANUP_NONE;
        else if (!strcmp(cleanup_arg, "whitespace"))
                cleanup_mode = CLEANUP_SPACE;
        else if (!strcmp(cleanup_arg, "strip"))
                cleanup_mode = CLEANUP_ALL;
        else if (!strcmp(cleanup_arg, "scissors"))
                cleanup_mode = use_editor ? CLEANUP_SCISSORS : CLEANUP_SPACE;
        else
                die(_("Invalid cleanup mode %s"), cleanup_arg);

        handle_untracked_files_arg(s);

        if (all && argc > 0)
                die(_("Paths with -a does not make sense."));

        if (status_format != STATUS_FORMAT_NONE)
                dry_run = 1;

        return argc;
}

static int dry_run_commit(int argc, const char **argv, const char *prefix,
                          const struct commit *current_head, struct wt_status *s)
{
        int commitable;
        const char *index_file;

        index_file = prepare_index(argc, argv, prefix, current_head, 1);
        commitable = run_status(stdout, index_file, prefix, 0, s);
        rollback_index_files();

        return commitable ? 0 : 1;
}

static int parse_status_slot(const char *var, int offset)
{
        if (!strcasecmp(var+offset, "header"))
                return WT_STATUS_HEADER;
        if (!strcasecmp(var+offset, "branch"))
                return WT_STATUS_ONBRANCH;
        if (!strcasecmp(var+offset, "updated")
                || !strcasecmp(var+offset, "added"))
                return WT_STATUS_UPDATED;
        if (!strcasecmp(var+offset, "changed"))
                return WT_STATUS_CHANGED;
        if (!strcasecmp(var+offset, "untracked"))
                return WT_STATUS_UNTRACKED;
        if (!strcasecmp(var+offset, "nobranch"))
                return WT_STATUS_NOBRANCH;
        if (!strcasecmp(var+offset, "unmerged"))
                return WT_STATUS_UNMERGED;
        return -1;
}

static int git_status_config(const char *k, const char *v, void *cb)
{
        struct wt_status *s = cb;

        if (starts_with(k, "column."))
                return git_column_config(k, v, "status", &s->colopts);
        if (!strcmp(k, "status.submodulesummary")) {
                int is_bool;
                s->submodule_summary = git_config_bool_or_int(k, v, &is_bool);
                if (is_bool && s->submodule_summary)
                        s->submodule_summary = -1;
                return 0;
        }
        if (!strcmp(k, "status.short")) {
                if (git_config_bool(k, v))
                        status_deferred_config.status_format = STATUS_FORMAT_SHORT;
                else
                        status_deferred_config.status_format = STATUS_FORMAT_NONE;
                return 0;
        }
        if (!strcmp(k, "status.branch")) {
                status_deferred_config.show_branch = git_config_bool(k, v);
                return 0;
        }
        if (!strcmp(k, "status.color") || !strcmp(k, "color.status")) {
                s->use_color = git_config_colorbool(k, v);
                return 0;
        }
        if (!strcmp(k, "status.displaycommentprefix")) {
                s->display_comment_prefix = git_config_bool(k, v);
                return 0;
        }
        if (starts_with(k, "status.color.") || starts_with(k, "color.status.")) {
                int slot = parse_status_slot(k, 13);
                if (slot < 0)
                        return 0;
                if (!v)
                        return config_error_nonbool(k);
                color_parse(v, k, s->color_palette[slot]);
                return 0;
        }
        if (!strcmp(k, "status.relativepaths")) {
                s->relative_paths = git_config_bool(k, v);
                return 0;
        }
        if (!strcmp(k, "status.showuntrackedfiles")) {
                if (!v)
                        return config_error_nonbool(k);
                else if (!strcmp(v, "no"))
                        s->show_untracked_files = SHOW_NO_UNTRACKED_FILES;
                else if (!strcmp(v, "normal"))
                        s->show_untracked_files = SHOW_NORMAL_UNTRACKED_FILES;
                else if (!strcmp(v, "all"))
                        s->show_untracked_files = SHOW_ALL_UNTRACKED_FILES;
                else
                        return error(_("Invalid untracked files mode '%s'"), v);
                return 0;
        }
        return git_diff_ui_config(k, v, NULL);
}

int cmd_status(int argc, const char **argv, const char *prefix)
{
        static struct wt_status s;
        int fd;
        unsigned char sha1[20];
        static struct option builtin_status_options[] = {
                OPT__VERBOSE(&verbose, N_("be verbose")),
                OPT_SET_INT('s', "short", &status_format,
                            N_("show status concisely"), STATUS_FORMAT_SHORT),
                OPT_BOOL('b', "branch", &s.show_branch,
                         N_("show branch information")),
                OPT_SET_INT(0, "porcelain", &status_format,
                            N_("machine-readable output"),
                            STATUS_FORMAT_PORCELAIN),
                OPT_SET_INT(0, "long", &status_format,
                            N_("show status in long format (default)"),
                            STATUS_FORMAT_LONG),
                OPT_BOOL('z', "null", &s.null_termination,
                         N_("terminate entries with NUL")),
                { OPTION_STRING, 'u', "untracked-files", &untracked_files_arg,
                  N_("mode"),
                  N_("show untracked files, optional modes: all, normal, no. (Default: all)"),
                  PARSE_OPT_OPTARG, NULL, (intptr_t)"all" },
                OPT_BOOL(0, "ignored", &show_ignored_in_status,
                         N_("show ignored files")),
                { OPTION_STRING, 0, "ignore-submodules", &ignore_submodule_arg, N_("when"),
                  N_("ignore changes to submodules, optional when: all, dirty, untracked. (Default: all)"),
                  PARSE_OPT_OPTARG, NULL, (intptr_t)"all" },
                OPT_COLUMN(0, "column", &s.colopts, N_("list untracked files in columns")),
                OPT_END(),
        };

        if (argc == 2 && !strcmp(argv[1], "-h"))
                usage_with_options(builtin_status_usage, builtin_status_options);

        status_init_config(&s, git_status_config);
        argc = parse_options(argc, argv, prefix,
                             builtin_status_options,
                             builtin_status_usage, 0);
        finalize_colopts(&s.colopts, -1);
        finalize_deferred_config(&s);

        handle_untracked_files_arg(&s);
        if (show_ignored_in_status)
                s.show_ignored_files = 1;
        parse_pathspec(&s.pathspec, 0,
                       PATHSPEC_PREFER_FULL,
                       prefix, argv);

        read_cache_preload(&s.pathspec);
        refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED, &s.pathspec, NULL, NULL);

        fd = hold_locked_index(&index_lock, 0);
        if (0 <= fd)
                update_index_if_able(&the_index, &index_lock);

        s.is_initial = get_sha1(s.reference, sha1) ? 1 : 0;
        s.ignore_submodule_arg = ignore_submodule_arg;
        wt_status_collect(&s);

        if (s.relative_paths)
                s.prefix = prefix;

        switch (status_format) {
        case STATUS_FORMAT_SHORT:
                wt_shortstatus_print(&s);
                break;
        case STATUS_FORMAT_PORCELAIN:
                wt_porcelain_print(&s);
                break;
        case STATUS_FORMAT_UNSPECIFIED:
                die("BUG: finalize_deferred_config() should have been called");
                break;
        case STATUS_FORMAT_NONE:
        case STATUS_FORMAT_LONG:
                s.verbose = verbose;
                s.ignore_submodule_arg = ignore_submodule_arg;
                wt_status_print(&s);
                break;
        }
        return 0;
}

static void print_summary(const char *prefix, const unsigned char *sha1,
                          int initial_commit)
{
        struct rev_info rev;
        struct commit *commit;
        struct strbuf format = STRBUF_INIT;
        unsigned char junk_sha1[20];
        const char *head;
        struct pretty_print_context pctx = {0};
        struct strbuf author_ident = STRBUF_INIT;
        struct strbuf committer_ident = STRBUF_INIT;

        commit = lookup_commit(sha1);
        if (!commit)
                die(_("couldn't look up newly created commit"));
        if (parse_commit(commit))
                die(_("could not parse newly created commit"));

        strbuf_addstr(&format, "format:%h] %s");

        format_commit_message(commit, "%an <%ae>", &author_ident, &pctx);
        format_commit_message(commit, "%cn <%ce>", &committer_ident, &pctx);
        if (strbuf_cmp(&author_ident, &committer_ident)) {
                strbuf_addstr(&format, "\n Author: ");
                strbuf_addbuf_percentquote(&format, &author_ident);
        }
        if (author_date_is_interesting()) {
                struct strbuf date = STRBUF_INIT;
                format_commit_message(commit, "%ad", &date, &pctx);
                strbuf_addstr(&format, "\n Date: ");
                strbuf_addbuf_percentquote(&format, &date);
                strbuf_release(&date);
        }
        if (!committer_ident_sufficiently_given()) {
                strbuf_addstr(&format, "\n Committer: ");
                strbuf_addbuf_percentquote(&format, &committer_ident);
                if (advice_implicit_identity) {
                        strbuf_addch(&format, '\n');
                        strbuf_addstr(&format, _(implicit_ident_advice));
                }
        }
        strbuf_release(&author_ident);
        strbuf_release(&committer_ident);

        init_revisions(&rev, prefix);
        setup_revisions(0, NULL, &rev, NULL);

        rev.diff = 1;
        rev.diffopt.output_format =
                DIFF_FORMAT_SHORTSTAT | DIFF_FORMAT_SUMMARY;

        rev.verbose_header = 1;
        rev.show_root_diff = 1;
        get_commit_format(format.buf, &rev);
        rev.always_show_header = 0;
        rev.diffopt.detect_rename = 1;
        rev.diffopt.break_opt = 0;
        diff_setup_done(&rev.diffopt);

        head = resolve_ref_unsafe("HEAD", junk_sha1, 0, NULL);
        printf("[%s%s ",
                starts_with(head, "refs/heads/") ?
                        head + 11 :
                        !strcmp(head, "HEAD") ?
                                _("detached HEAD") :
                                head,
                initial_commit ? _(" (root-commit)") : "");

        if (!log_tree_commit(&rev, commit)) {
                rev.always_show_header = 1;
                rev.use_terminator = 1;
                log_tree_commit(&rev, commit);
        }

        strbuf_release(&format);
}

static int git_commit_config(const char *k, const char *v, void *cb)
{
        struct wt_status *s = cb;
        int status;

        if (!strcmp(k, "commit.template"))
                return git_config_pathname(&template_file, k, v);
        if (!strcmp(k, "commit.status")) {
                include_status = git_config_bool(k, v);
                return 0;
        }
        if (!strcmp(k, "commit.cleanup"))
                return git_config_string(&cleanup_arg, k, v);
        if (!strcmp(k, "commit.gpgsign")) {
                sign_commit = git_config_bool(k, v) ? "" : NULL;
                return 0;
        }

        status = git_gpg_config(k, v, NULL);
        if (status)
                return status;
        return git_status_config(k, v, s);
}

static int run_rewrite_hook(const unsigned char *oldsha1,
                            const unsigned char *newsha1)
{
        /* oldsha1 SP newsha1 LF NUL */
        static char buf[2*40 + 3];
        struct child_process proc;
        const char *argv[3];
        int code;
        size_t n;

        argv[0] = find_hook("post-rewrite");
        if (!argv[0])
                return 0;

        argv[1] = "amend";
        argv[2] = NULL;

        memset(&proc, 0, sizeof(proc));
        proc.argv = argv;
        proc.in = -1;
        proc.stdout_to_stderr = 1;

        code = start_command(&proc);
        if (code)
                return code;
        n = snprintf(buf, sizeof(buf), "%s %s\n",
                     sha1_to_hex(oldsha1), sha1_to_hex(newsha1));
        write_in_full(proc.in, buf, n);
        close(proc.in);
        return finish_command(&proc);
}

int run_commit_hook(int editor_is_used, const char *index_file, const char *name, ...)
{
        const char *hook_env[3] =  { NULL };
        char index[PATH_MAX];
        va_list args;
        int ret;

        snprintf(index, sizeof(index), "GIT_INDEX_FILE=%s", index_file);
        hook_env[0] = index;

        /*
         * Let the hook know that no editor will be launched.
         */
        if (!editor_is_used)
                hook_env[1] = "GIT_EDITOR=:";

        va_start(args, name);
        ret = run_hook_ve(hook_env, name, args);
        va_end(args);

        return ret;
}

int cmd_commit(int argc, const char **argv, const char *prefix)
{
        static struct wt_status s;
        static struct option builtin_commit_options[] = {
                OPT__QUIET(&quiet, N_("suppress summary after successful commit")),
                OPT__VERBOSE(&verbose, N_("show diff in commit message template")),

                OPT_GROUP(N_("Commit message options")),
                OPT_FILENAME('F', "file", &logfile, N_("read message from file")),
                OPT_STRING(0, "author", &force_author, N_("author"), N_("override author for commit")),
                OPT_STRING(0, "date", &force_date, N_("date"), N_("override date for commit")),
                OPT_CALLBACK('m', "message", &message, N_("message"), N_("commit message"), opt_parse_m),
                OPT_STRING('c', "reedit-message", &edit_message, N_("commit"), N_("reuse and edit message from specified commit")),
                OPT_STRING('C', "reuse-message", &use_message, N_("commit"), N_("reuse message from specified commit")),
                OPT_STRING(0, "fixup", &fixup_message, N_("commit"), N_("use autosquash formatted message to fixup specified commit")),
                OPT_STRING(0, "squash", &squash_message, N_("commit"), N_("use autosquash formatted message to squash specified commit")),
                OPT_BOOL(0, "reset-author", &renew_authorship, N_("the commit is authored by me now (used with -C/-c/--amend)")),
                OPT_BOOL('s', "signoff", &signoff, N_("add Signed-off-by:")),
                OPT_FILENAME('t', "template", &template_file, N_("use specified template file")),
                OPT_BOOL('e', "edit", &edit_flag, N_("force edit of commit")),
                OPT_STRING(0, "cleanup", &cleanup_arg, N_("default"), N_("how to strip spaces and #comments from message")),
                OPT_BOOL(0, "status", &include_status, N_("include status in commit message template")),
                { OPTION_STRING, 'S', "gpg-sign", &sign_commit, N_("key-id"),
                  N_("GPG sign commit"), PARSE_OPT_OPTARG, NULL, (intptr_t) "" },
                /* end commit message options */

                OPT_GROUP(N_("Commit contents options")),
                OPT_BOOL('a', "all", &all, N_("commit all changed files")),
                OPT_BOOL('i', "include", &also, N_("add specified files to index for commit")),
                OPT_BOOL(0, "interactive", &interactive, N_("interactively add files")),
                OPT_BOOL('p', "patch", &patch_interactive, N_("interactively add changes")),
                OPT_BOOL('o', "only", &only, N_("commit only specified files")),
                OPT_BOOL('n', "no-verify", &no_verify, N_("bypass pre-commit hook")),
                OPT_BOOL(0, "dry-run", &dry_run, N_("show what would be committed")),
                OPT_SET_INT(0, "short", &status_format, N_("show status concisely"),
                            STATUS_FORMAT_SHORT),
                OPT_BOOL(0, "branch", &s.show_branch, N_("show branch information")),
                OPT_SET_INT(0, "porcelain", &status_format,
                            N_("machine-readable output"), STATUS_FORMAT_PORCELAIN),
                OPT_SET_INT(0, "long", &status_format,
                            N_("show status in long format (default)"),
                            STATUS_FORMAT_LONG),
                OPT_BOOL('z', "null", &s.null_termination,
                         N_("terminate entries with NUL")),
                OPT_BOOL(0, "amend", &amend, N_("amend previous commit")),
                OPT_BOOL(0, "no-post-rewrite", &no_post_rewrite, N_("bypass post-rewrite hook")),
                { OPTION_STRING, 'u', "untracked-files", &untracked_files_arg, N_("mode"), N_("show untracked files, optional modes: all, normal, no. (Default: all)"), PARSE_OPT_OPTARG, NULL, (intptr_t)"all" },
                /* end commit contents options */

                OPT_HIDDEN_BOOL(0, "allow-empty", &allow_empty,
                                N_("ok to record an empty change")),
                OPT_HIDDEN_BOOL(0, "allow-empty-message", &allow_empty_message,
                                N_("ok to record a change with an empty message")),

                OPT_END()
        };

        struct strbuf sb = STRBUF_INIT;
        struct strbuf author_ident = STRBUF_INIT;
        const char *index_file, *reflog_msg;
        char *nl;
        unsigned char sha1[20];
        struct ref_lock *ref_lock;
        struct commit_list *parents = NULL, **pptr = &parents;
        struct stat statbuf;
        struct commit *current_head = NULL;
        struct commit_extra_header *extra = NULL;

        if (argc == 2 && !strcmp(argv[1], "-h"))
                usage_with_options(builtin_commit_usage, builtin_commit_options);

        status_init_config(&s, git_commit_config);
        status_format = STATUS_FORMAT_NONE; /* Ignore status.short */
        s.colopts = 0;

        if (get_sha1("HEAD", sha1))
                current_head = NULL;
        else {
                current_head = lookup_commit_or_die(sha1, "HEAD");
                if (parse_commit(current_head))
                        die(_("could not parse HEAD commit"));
        }
        argc = parse_and_validate_options(argc, argv, builtin_commit_options,
                                          builtin_commit_usage,
                                          prefix, current_head, &s);
        if (dry_run)
                return dry_run_commit(argc, argv, prefix, current_head, &s);
        index_file = prepare_index(argc, argv, prefix, current_head, 0);

        /* Set up everything for writing the commit object.  This includes
           running hooks, writing the trees, and interacting with the user.  */
        if (!prepare_to_commit(index_file, prefix,
                               current_head, &s, &author_ident)) {
                rollback_index_files();
                return 1;
        }

        /* Determine parents */
        reflog_msg = getenv("GIT_REFLOG_ACTION");
        if (!current_head) {
                if (!reflog_msg)
                        reflog_msg = "commit (initial)";
        } else if (amend) {
                struct commit_list *c;

                if (!reflog_msg)
                        reflog_msg = "commit (amend)";
                for (c = current_head->parents; c; c = c->next)
                        pptr = &commit_list_insert(c->item, pptr)->next;
        } else if (whence == FROM_MERGE) {
                struct strbuf m = STRBUF_INIT;
                FILE *fp;
                int allow_fast_forward = 1;

                if (!reflog_msg)
                        reflog_msg = "commit (merge)";
                pptr = &commit_list_insert(current_head, pptr)->next;
                fp = fopen(git_path("MERGE_HEAD"), "r");
                if (fp == NULL)
                        die_errno(_("could not open '%s' for reading"),
                                  git_path("MERGE_HEAD"));
                while (strbuf_getline(&m, fp, '\n') != EOF) {
                        struct commit *parent;

                        parent = get_merge_parent(m.buf);
                        if (!parent)
                                die(_("Corrupt MERGE_HEAD file (%s)"), m.buf);
                        pptr = &commit_list_insert(parent, pptr)->next;
                }
                fclose(fp);
                strbuf_release(&m);
                if (!stat(git_path("MERGE_MODE"), &statbuf)) {
                        if (strbuf_read_file(&sb, git_path("MERGE_MODE"), 0) < 0)
                                die_errno(_("could not read MERGE_MODE"));
                        if (!strcmp(sb.buf, "no-ff"))
                                allow_fast_forward = 0;
                }
                if (allow_fast_forward)
                        parents = reduce_heads(parents);
        } else {
                if (!reflog_msg)
                        reflog_msg = (whence == FROM_CHERRY_PICK)
                                        ? "commit (cherry-pick)"
                                        : "commit";
                pptr = &commit_list_insert(current_head, pptr)->next;
        }

        /* Finally, get the commit message */
        strbuf_reset(&sb);
        if (strbuf_read_file(&sb, git_path(commit_editmsg), 0) < 0) {
                int saved_errno = errno;
                rollback_index_files();
                die(_("could not read commit message: %s"), strerror(saved_errno));
        }

        if (verbose || /* Truncate the message just before the diff, if any. */
            cleanup_mode == CLEANUP_SCISSORS)
                wt_status_truncate_message_at_cut_line(&sb);

        if (cleanup_mode != CLEANUP_NONE)
                stripspace(&sb, cleanup_mode == CLEANUP_ALL);
        if (template_untouched(&sb) && !allow_empty_message) {
                rollback_index_files();
                fprintf(stderr, _("Aborting commit; you did not edit the message.\n"));
                exit(1);
        }
        if (message_is_empty(&sb) && !allow_empty_message) {
                rollback_index_files();
                fprintf(stderr, _("Aborting commit due to empty commit message.\n"));
                exit(1);
        }

        if (amend) {
                const char *exclude_gpgsig[2] = { "gpgsig", NULL };
                extra = read_commit_extra_headers(current_head, exclude_gpgsig);
        } else {
                struct commit_extra_header **tail = &extra;
                append_merge_tag_headers(parents, &tail);
        }

        if (commit_tree_extended(sb.buf, sb.len, active_cache_tree->sha1,
                         parents, sha1, author_ident.buf, sign_commit, extra)) {
                rollback_index_files();
                die(_("failed to write commit object"));
        }
        strbuf_release(&author_ident);
        free_commit_extra_headers(extra);

        ref_lock = lock_any_ref_for_update("HEAD",
                                           !current_head
                                           ? NULL
                                           : current_head->object.sha1,
                                           0, NULL);
        if (!ref_lock) {
                rollback_index_files();
                die(_("cannot lock HEAD ref"));
        }

        nl = strchr(sb.buf, '\n');
        if (nl)
                strbuf_setlen(&sb, nl + 1 - sb.buf);
        else
                strbuf_addch(&sb, '\n');
        strbuf_insert(&sb, 0, reflog_msg, strlen(reflog_msg));
        strbuf_insert(&sb, strlen(reflog_msg), ": ", 2);

        if (write_ref_sha1(ref_lock, sha1, sb.buf) < 0) {
                rollback_index_files();
                die(_("cannot update HEAD ref"));
        }

        unlink(git_path("CHERRY_PICK_HEAD"));
        unlink(git_path("REVERT_HEAD"));
        unlink(git_path("MERGE_HEAD"));
        unlink(git_path("MERGE_MSG"));
        unlink(git_path("MERGE_MODE"));
        unlink(git_path("SQUASH_MSG"));

        if (commit_index_files())
                die (_("Repository has been updated, but unable to write\n"
                     "new_index file. Check that disk is not full or quota is\n"
                     "not exceeded, and then \"git reset HEAD\" to recover."));

        rerere(0);
        run_commit_hook(use_editor, get_index_file(), "post-commit", NULL);
        if (amend && !no_post_rewrite) {
                struct notes_rewrite_cfg *cfg;
                cfg = init_copy_notes_for_rewrite("amend");
                if (cfg) {
                        /* we are amending, so current_head is not NULL */
                        copy_note_for_rewrite(cfg, current_head->object.sha1, sha1);
                        finish_copy_notes_for_rewrite(cfg, "Notes added by 'git commit --amend'");
                }
                run_rewrite_hook(current_head->object.sha1, sha1);
        }
        if (!quiet)
                print_summary(prefix, sha1, !current_head);

        return 0;
}