commit.c

/*
 * 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"

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

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

static const char implicit_ident_advice[] =
"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"
"If the identity used for this commit is wrong, you can fix it with:\n"
"\n"
"    git commit --amend --author='Your Name <you@example.com>'\n";

static unsigned char head_sha1[20];

static 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;
static char *edit_message, *use_message;
static char *author_name, *author_email, *author_date;
static int all, edit_flag, also, interactive, only, amend, signoff;
static int quiet, verbose, no_verify, allow_empty, dry_run, renew_authorship;
static int no_post_rewrite;
static char *untracked_files_arg, *force_date;
/*
 * 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_ALL,
} cleanup_mode;
static char *cleanup_arg;

static int use_editor = 1, initial_commit, in_merge, include_status = 1;
static const char *only_include_assumed;
static struct strbuf message;

static int null_termination;
static enum {
	STATUS_FORMAT_LONG,
	STATUS_FORMAT_SHORT,
	STATUS_FORMAT_PORCELAIN,
} status_format = STATUS_FORMAT_LONG;

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

static struct option builtin_commit_options[] = {
	OPT__QUIET(&quiet),
	OPT__VERBOSE(&verbose),

	OPT_GROUP("Commit message options"),
	OPT_FILENAME('F', "file", &logfile, "read log from file"),
	OPT_STRING(0, "author", &force_author, "AUTHOR", "override author for commit"),
	OPT_STRING(0, "date", &force_date, "DATE", "override date for commit"),
	OPT_CALLBACK('m', "message", &message, "MESSAGE", "specify commit message", opt_parse_m),
	OPT_STRING('c', "reedit-message", &edit_message, "COMMIT", "reuse and edit message from specified commit"),
	OPT_STRING('C', "reuse-message", &use_message, "COMMIT", "reuse message from specified commit"),
	OPT_BOOLEAN(0, "reset-author", &renew_authorship, "the commit is authored by me now (used with -C-c/--amend)"),
	OPT_BOOLEAN('s', "signoff", &signoff, "add Signed-off-by:"),
	OPT_FILENAME('t', "template", &template_file, "use specified template file"),
	OPT_BOOLEAN('e', "edit", &edit_flag, "force edit of commit"),
	OPT_STRING(0, "cleanup", &cleanup_arg, "default", "how to strip spaces and #comments from message"),
	OPT_BOOLEAN(0, "status", &include_status, "include status in commit message template"),
	/* end commit message options */

	OPT_GROUP("Commit contents options"),
	OPT_BOOLEAN('a', "all", &all, "commit all changed files"),
	OPT_BOOLEAN('i', "include", &also, "add specified files to index for commit"),
	OPT_BOOLEAN(0, "interactive", &interactive, "interactively add files"),
	OPT_BOOLEAN('o', "only", &only, "commit only specified files"),
	OPT_BOOLEAN('n', "no-verify", &no_verify, "bypass pre-commit hook"),
	OPT_BOOLEAN(0, "dry-run", &dry_run, "show what would be committed"),
	OPT_SET_INT(0, "short", &status_format, "show status concisely",
		    STATUS_FORMAT_SHORT),
	OPT_SET_INT(0, "porcelain", &status_format,
		    "show porcelain output format", STATUS_FORMAT_PORCELAIN),
	OPT_BOOLEAN('z', "null", &null_termination,
		    "terminate entries with NUL"),
	OPT_BOOLEAN(0, "amend", &amend, "amend previous commit"),
	OPT_BOOLEAN(0, "no-post-rewrite", &no_post_rewrite, "bypass post-rewrite hook"),
	{ OPTION_STRING, 'u', "untracked-files", &untracked_files_arg, "mode", "show untracked files, optional modes: all, normal, no. (Default: all)", PARSE_OPT_OPTARG, NULL, (intptr_t)"all" },
	OPT_BOOLEAN(0, "allow-empty", &allow_empty, "ok to record an empty change"),
	/* end commit contents options */

	OPT_END()
};

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 char **pattern)
{
	int i;
	char *m;

	for (i = 0; pattern[i]; i++)
		;
	m = xcalloc(1, i);

	if (with_tree)
		overlay_tree_on_cache(with_tree, prefix);

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

		if (ce->ce_flags & CE_UPDATE)
			continue;
		if (!match_pathspec(pattern, ce->name, ce_namelen(ce), 0, m))
			continue;
		item = string_list_insert(ce->name, list);
		if (ce_skip_worktree(ce))
			item->util = item; /* better a valid pointer than a fake one */
	}

	return report_path_error(m, pattern, prefix ? strlen(prefix) : 0);
}

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(void)
{
	struct tree *tree;
	struct unpack_trees_options opts;
	struct tree_desc t;

	if (initial_commit) {
		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(head_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, int is_status)
{
	int fd;
	struct string_list partial;
	const char **pathspec = NULL;
	int refresh_flags = REFRESH_QUIET;

	if (is_status)
		refresh_flags |= REFRESH_UNMERGED;
	if (interactive) {
		if (interactive_add(argc, argv, prefix) != 0)
			die("interactive add failed");
		if (read_cache_preload(NULL) < 0)
			die("index file corrupt");
		commit_style = COMMIT_AS_IS;
		return get_index_file();
	}

	if (*argv)
		pathspec = get_pathspec(prefix, argv);

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

	/*
	 * 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 && *pathspec)) {
		fd = hold_locked_index(&index_lock, 1);
		add_files_to_cache(also ? prefix : NULL, pathspec, 0);
		refresh_cache_or_die(refresh_flags);
		if (write_cache(fd, active_cache, active_nr) ||
		    close_lock_file(&index_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 (!pathspec || !*pathspec) {
		fd = hold_locked_index(&index_lock, 1);
		refresh_cache_or_die(refresh_flags);
		if (write_cache(fd, active_cache, active_nr) ||
		    commit_locked_index(&index_lock))
			die("unable to write new_index file");
		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 (in_merge)
		die("cannot do a partial commit during a merge.");

	memset(&partial, 0, sizeof(partial));
	partial.strdup_strings = 1;
	if (list_paths(&partial, initial_commit ? NULL : "HEAD", prefix, pathspec))
		exit(1);

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

	fd = hold_locked_index(&index_lock, 1);
	add_remove_files(&partial);
	refresh_cache(REFRESH_QUIET);
	if (write_cache(fd, active_cache, active_nr) ||
	    close_lock_file(&index_lock))
		die("unable to write new_index file");

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

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

	if (write_cache(fd, active_cache, active_nr) ||
	    close_lock_file(&false_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, null_termination);
		break;
	case STATUS_FORMAT_PORCELAIN:
		wt_porcelain_print(s, null_termination);
		break;
	case STATUS_FORMAT_LONG:
		wt_status_print(s);
		break;
	}

	return s->commitable;
}

static int is_a_merge(const unsigned char *sha1)
{
	struct commit *commit = lookup_commit(sha1);
	if (!commit || parse_commit(commit))
		die("could not parse HEAD commit");
	return !!(commit->parents && commit->parents->next);
}

static const char sign_off_header[] = "Signed-off-by: ";

static void determine_author_info(void)
{
	char *name, *email, *date;

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

	if (use_message && !renew_authorship) {
		const char *a, *lb, *rb, *eol;

		a = strstr(use_message_buffer, "\nauthor ");
		if (!a)
			die("invalid commit: %s", use_message);

		lb = strstr(a + 8, " <");
		rb = strstr(a + 8, "> ");
		eol = strchr(a + 8, '\n');
		if (!lb || !rb || !eol)
			die("invalid commit: %s", use_message);

		name = xstrndup(a + 8, lb - (a + 8));
		email = xstrndup(lb + 2, rb - (lb + 2));
		date = xstrndup(rb + 2, eol - (rb + 2));
	}

	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)
		date = force_date;

	author_name = name;
	author_email = email;
	author_date = date;
}

static int ends_rfc2822_footer(struct strbuf *sb)
{
	int ch;
	int hit = 0;
	int i, j, k;
	int len = sb->len;
	int first = 1;
	const char *buf = sb->buf;

	for (i = len - 1; i > 0; i--) {
		if (hit && buf[i] == '\n')
			break;
		hit = (buf[i] == '\n');
	}

	while (i < len - 1 && buf[i] == '\n')
		i++;

	for (; i < len; i = k) {
		for (k = i; k < len && buf[k] != '\n'; k++)
			; /* do nothing */
		k++;

		if ((buf[k] == ' ' || buf[k] == '\t') && !first)
			continue;

		first = 0;

		for (j = 0; i + j < len; j++) {
			ch = buf[i + j];
			if (ch == ':')
				break;
			if (isalnum(ch) ||
			    (ch == '-'))
				continue;
			return 0;
		}
	}
	return 1;
}

static int prepare_to_commit(const char *index_file, const char *prefix,
			     struct wt_status *s)
{
	struct stat statbuf;
	int commitable, saved_color_setting;
	struct strbuf sb = STRBUF_INIT;
	char *buffer;
	FILE *fp;
	const char *hook_arg1 = NULL;
	const char *hook_arg2 = NULL;
	int ident_shown = 0;

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

	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) {
		buffer = strstr(use_message_buffer, "\n\n");
		if (!buffer || buffer[2] == '\0')
			die("commit has empty message");
		strbuf_add(&sb, buffer + 2, strlen(buffer + 2));
		hook_arg1 = "commit";
		hook_arg2 = use_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 && !stat(template_file, &statbuf)) {
		if (strbuf_read_file(&sb, template_file, 0) < 0)
			die_errno("could not read '%s'", template_file);
		hook_arg1 = "template";
	}

	/*
	 * This final case does not modify the template message,
	 * it just sets the argument to the prepare-commit-msg hook.
	 */
	else if (in_merge)
		hook_arg1 = "merge";

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

	if (cleanup_mode != CLEANUP_NONE)
		stripspace(&sb, 0);

	if (signoff) {
		struct strbuf sob = STRBUF_INIT;
		int i;

		strbuf_addstr(&sob, sign_off_header);
		strbuf_addstr(&sob, fmt_name(getenv("GIT_COMMITTER_NAME"),
					     getenv("GIT_COMMITTER_EMAIL")));
		strbuf_addch(&sob, '\n');
		for (i = sb.len - 1; i > 0 && sb.buf[i - 1] != '\n'; i--)
			; /* do nothing */
		if (prefixcmp(sb.buf + i, sob.buf)) {
			if (!i || !ends_rfc2822_footer(&sb))
				strbuf_addch(&sb, '\n');
			strbuf_addbuf(&sb, &sob);
		}
		strbuf_release(&sob);
	}

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

	strbuf_release(&sb);

	determine_author_info();

	/* This checks if committer ident is explicitly given */
	git_committer_info(0);
	if (use_editor && include_status) {
		char *author_ident;
		const char *committer_ident;

		if (in_merge)
			fprintf(fp,
				"#\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",
				git_path("MERGE_HEAD"));

		fprintf(fp,
			"\n"
			"# Please enter the commit message for your changes.");
		if (cleanup_mode == CLEANUP_ALL)
			fprintf(fp,
				" Lines starting\n"
				"# with '#' will be ignored, and an empty"
				" message aborts the commit.\n");
		else /* CLEANUP_SPACE, that is. */
			fprintf(fp,
				" Lines starting\n"
				"# with '#' will be kept; you may remove them"
				" yourself if you want to.\n"
				"# An empty message aborts the commit.\n");
		if (only_include_assumed)
			fprintf(fp, "# %s\n", only_include_assumed);

		author_ident = xstrdup(fmt_name(author_name, author_email));
		committer_ident = fmt_name(getenv("GIT_COMMITTER_NAME"),
					   getenv("GIT_COMMITTER_EMAIL"));
		if (strcmp(author_ident, committer_ident))
			fprintf(fp,
				"%s"
				"# Author:    %s\n",
				ident_shown++ ? "" : "#\n",
				author_ident);
		free(author_ident);

		if (!user_ident_sufficiently_given())
			fprintf(fp,
				"%s"
				"# Committer: %s\n",
				ident_shown++ ? "" : "#\n",
				committer_ident);

		if (ident_shown)
			fprintf(fp, "#\n");

		saved_color_setting = s->use_color;
		s->use_color = 0;
		commitable = run_status(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
			commitable = index_differs_from(parent, 0);
	}

	fclose(fp);

	if (!commitable && !in_merge && !allow_empty &&
	    !(amend && is_a_merge(head_sha1))) {
		run_status(stdout, index_file, prefix, 0, s);
		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 (!active_cache_tree)
		active_cache_tree = cache_tree();
	if (cache_tree_update(active_cache_tree,
			      active_cache, active_nr, 0, 0) < 0) {
		error("Error building trees");
		return 0;
	}

	if (run_hook(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] = { index, NULL };
		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_hook(index_file, "commit-msg", git_path(commit_editmsg), NULL)) {
		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)
{
	struct strbuf tmpl = STRBUF_INIT;
	const char *nl;
	int eol, i, start = 0;

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

	/* See if the template is just a prefix of the message. */
	if (template_file && strbuf_read_file(&tmpl, template_file, 0) > 0) {
		stripspace(&tmpl, cleanup_mode == CLEANUP_ALL);
		if (start + tmpl.len <= sb->len &&
		    memcmp(tmpl.buf, sb->buf + start, tmpl.len) == 0)
			start += tmpl.len;
	}
	strbuf_release(&tmpl);

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

	return 1;
}

static const char *find_author_by_nickname(const char *name)
{
	struct rev_info revs;
	struct commit *commit;
	struct strbuf buf = STRBUF_INIT;
	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);
	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);
		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 int parse_and_validate_options(int argc, const char *argv[],
				      const char * const usage[],
				      const char *prefix,
				      struct wt_status *s)
{
	int f = 0;

	argc = parse_options(argc, argv, prefix, builtin_commit_options, usage,
			     0);

	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 || message.len || use_message)
		use_editor = 0;
	if (edit_flag)
		use_editor = 1;
	if (!use_editor)
		setenv("GIT_EDITOR", ":", 1);

	if (get_sha1("HEAD", head_sha1))
		initial_commit = 1;

	/* Sanity check options */
	if (amend && initial_commit)
		die("You have nothing to amend.");
	if (amend && in_merge)
		die("You are in the middle of a merge -- cannot amend.");

	if (use_message)
		f++;
	if (edit_message)
		f++;
	if (logfile)
		f++;
	if (f > 1)
		die("Only one of -c/-C/-F can be used.");
	if (message.len && f > 0)
		die("Option -m cannot be combined with -c/-C/-F.");
	if (edit_message)
		use_message = edit_message;
	if (amend && !use_message)
		use_message = "HEAD";
	if (!use_message && renew_authorship)
		die("--reset-author can be used only with -C, -c or --amend.");
	if (use_message) {
		unsigned char sha1[20];
		static char utf8[] = "UTF-8";
		const char *out_enc;
		char *enc, *end;
		struct commit *commit;

		if (get_sha1(use_message, sha1))
			die("could not lookup commit %s", use_message);
		commit = lookup_commit_reference(sha1);
		if (!commit || parse_commit(commit))
			die("could not parse commit %s", use_message);

		enc = strstr(commit->buffer, "\nencoding");
		if (enc) {
			end = strchr(enc + 10, '\n');
			enc = xstrndup(enc + 10, end - (enc + 10));
		} else {
			enc = utf8;
		}
		out_enc = git_commit_encoding ? git_commit_encoding : utf8;

		if (strcmp(out_enc, enc))
			use_message_buffer =
				reencode_string(commit->buffer, out_enc, enc);

		/*
		 * If we failed to reencode the buffer, just copy it
		 * byte for byte so the user can try to fix it up.
		 * This also handles the case where input and output
		 * encodings are identical.
		 */
		if (use_message_buffer == NULL)
			use_message_buffer = xstrdup(commit->buffer);
		if (enc != utf8)
			free(enc);
	}

	if (!!also + !!only + !!all + !!interactive > 1)
		die("Only one of --include/--only/--all/--interactive 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 nor -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
		die("Invalid cleanup mode %s", cleanup_arg);

	handle_untracked_files_arg(s);

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

	if (null_termination && status_format == STATUS_FORMAT_LONG)
		status_format = STATUS_FORMAT_PORCELAIN;
	if (status_format != STATUS_FORMAT_LONG)
		dry_run = 1;

	return argc;
}

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

	index_file = prepare_index(argc, argv, prefix, 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, "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 (!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.color") || !strcmp(k, "color.status")) {
		s->use_color = git_config_colorbool(k, v, -1);
		return 0;
	}
	if (!prefixcmp(k, "status.color.") || !prefixcmp(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)
{
	struct wt_status s;
	int fd;
	unsigned char sha1[20];
	static struct option builtin_status_options[] = {
		OPT__VERBOSE(&verbose),
		OPT_SET_INT('s', "short", &status_format,
			    "show status concisely", STATUS_FORMAT_SHORT),
		OPT_SET_INT(0, "porcelain", &status_format,
			    "show porcelain output format",
			    STATUS_FORMAT_PORCELAIN),
		OPT_BOOLEAN('z', "null", &null_termination,
			    "terminate entries with NUL"),
		{ OPTION_STRING, 'u', "untracked-files", &untracked_files_arg,
		  "mode",
		  "show untracked files, optional modes: all, normal, no. (Default: all)",
		  PARSE_OPT_OPTARG, NULL, (intptr_t)"all" },
		OPT_END(),
	};

	if (null_termination && status_format == STATUS_FORMAT_LONG)
		status_format = STATUS_FORMAT_PORCELAIN;

	wt_status_prepare(&s);
	git_config(git_status_config, &s);
	in_merge = file_exists(git_path("MERGE_HEAD"));
	argc = parse_options(argc, argv, prefix,
			     builtin_status_options,
			     builtin_status_usage, 0);
	handle_untracked_files_arg(&s);

	if (*argv)
		s.pathspec = get_pathspec(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) {
		if (!write_cache(fd, active_cache, active_nr))
			commit_locked_index(&index_lock);
		rollback_lock_file(&index_lock);
	}

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

	if (s.relative_paths)
		s.prefix = prefix;
	if (s.use_color == -1)
		s.use_color = git_use_color_default;
	if (diff_use_color_default == -1)
		diff_use_color_default = git_use_color_default;

	switch (status_format) {
	case STATUS_FORMAT_SHORT:
		wt_shortstatus_print(&s, null_termination);
		break;
	case STATUS_FORMAT_PORCELAIN:
		wt_porcelain_print(&s, null_termination);
		break;
	case STATUS_FORMAT_LONG:
		s.verbose = verbose;
		wt_status_print(&s);
		break;
	}
	return 0;
}

static void print_summary(const char *prefix, const unsigned char *sha1)
{
	struct rev_info rev;
	struct commit *commit;
	struct strbuf format = STRBUF_INIT;
	unsigned char junk_sha1[20];
	const char *head = resolve_ref("HEAD", junk_sha1, 0, NULL);
	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 (!commit || 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 (!user_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.abbrev = 0;
	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.rename_limit = 100;
	rev.diffopt.break_opt = 0;
	diff_setup_done(&rev.diffopt);

	printf("[%s%s ",
		!prefixcmp(head, "refs/heads/") ?
			head + 11 :
			!strcmp(head, "HEAD") ?
				"detached HEAD" :
				head,
		initial_commit ? " (root-commit)" : "");

	if (!log_tree_commit(&rev, commit)) {
		struct pretty_print_context ctx = {0};
		struct strbuf buf = STRBUF_INIT;
		ctx.date_mode = DATE_NORMAL;
		format_commit_message(commit, format.buf + 7, &buf, &ctx);
		printf("%s\n", buf.buf);
		strbuf_release(&buf);
	}
	strbuf_release(&format);
}

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

	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;
	}

	return git_status_config(k, v, s);
}

static const char post_rewrite_hook[] = "hooks/post-rewrite";

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;

	if (access(git_path(post_rewrite_hook), X_OK) < 0)
		return 0;

	argv[0] = git_path(post_rewrite_hook);
	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 cmd_commit(int argc, const char **argv, const char *prefix)
{
	struct strbuf sb = STRBUF_INIT;
	const char *index_file, *reflog_msg;
	char *nl, *p;
	unsigned char commit_sha1[20];
	struct ref_lock *ref_lock;
	struct commit_list *parents = NULL, **pptr = &parents;
	struct stat statbuf;
	int allow_fast_forward = 1;
	struct wt_status s;

	wt_status_prepare(&s);
	git_config(git_commit_config, &s);
	in_merge = file_exists(git_path("MERGE_HEAD"));
	s.in_merge = in_merge;

	if (s.use_color == -1)
		s.use_color = git_use_color_default;
	argc = parse_and_validate_options(argc, argv, builtin_commit_usage,
					  prefix, &s);
	if (dry_run) {
		if (diff_use_color_default == -1)
			diff_use_color_default = git_use_color_default;
		return dry_run_commit(argc, argv, prefix, &s);
	}
	index_file = prepare_index(argc, argv, prefix, 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, &s)) {
		rollback_index_files();
		return 1;
	}

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

		reflog_msg = "commit (amend)";
		commit = lookup_commit(head_sha1);
		if (!commit || parse_commit(commit))
			die("could not parse HEAD commit");

		for (c = commit->parents; c; c = c->next)
			pptr = &commit_list_insert(c->item, pptr)->next;
	} else if (in_merge) {
		struct strbuf m = STRBUF_INIT;
		FILE *fp;

		reflog_msg = "commit (merge)";
		pptr = &commit_list_insert(lookup_commit(head_sha1), 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) {
			unsigned char sha1[20];
			if (get_sha1_hex(m.buf, sha1) < 0)
				die("Corrupt MERGE_HEAD file (%s)", m.buf);
			pptr = &commit_list_insert(lookup_commit(sha1), 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 {
		reflog_msg = "commit";
		pptr = &commit_list_insert(lookup_commit(head_sha1), 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));
	}

	/* Truncate the message just before the diff, if any. */
	if (verbose) {
		p = strstr(sb.buf, "\ndiff --git ");
		if (p != NULL)
			strbuf_setlen(&sb, p - sb.buf + 1);
	}

	if (cleanup_mode != CLEANUP_NONE)
		stripspace(&sb, cleanup_mode == CLEANUP_ALL);
	if (message_is_empty(&sb)) {
		rollback_index_files();
		fprintf(stderr, "Aborting commit due to empty commit message.\n");
		exit(1);
	}

	if (commit_tree(sb.buf, active_cache_tree->sha1, parents, commit_sha1,
			fmt_ident(author_name, author_email, author_date,
				IDENT_ERROR_ON_NO_NAME))) {
		rollback_index_files();
		die("failed to write commit object");
	}

	ref_lock = lock_any_ref_for_update("HEAD",
					   initial_commit ? NULL : head_sha1,
					   0);

	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 (!ref_lock) {
		rollback_index_files();
		die("cannot lock HEAD ref");
	}
	if (write_ref_sha1(ref_lock, commit_sha1, sb.buf) < 0) {
		rollback_index_files();
		die("cannot update HEAD ref");
	}

	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_hook(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) {
			copy_note_for_rewrite(cfg, head_sha1, commit_sha1);
			finish_copy_notes_for_rewrite(cfg);
		}
		run_rewrite_hook(head_sha1, commit_sha1);
	}
	if (!quiet)
		print_summary(prefix, commit_sha1);

	return 0;
}