Squashed 'third_party/git/' content from commit cb71568594

git-subtree-dir: third_party/git
git-subtree-split: cb715685942260375e1eb8153b0768a376e4ece7

1 files changed, 788 insertions, 0 deletions

diff --git a/builtin/reflog.c b/builtin/reflog.c
new file mode 100644
index 000000000000..4d3430900d06
--- /dev/null
+++ b/builtin/reflog.c
@@ -0,0 +1,788 @@
+#include "builtin.h"
+#include "config.h"
+#include "lockfile.h"
+#include "object-store.h"
+#include "repository.h"
+#include "commit.h"
+#include "refs.h"
+#include "dir.h"
+#include "tree-walk.h"
+#include "diff.h"
+#include "revision.h"
+#include "reachable.h"
+#include "worktree.h"
+
+/* NEEDSWORK: switch to using parse_options */
+static const char reflog_expire_usage[] =
+N_("git reflog expire [--expire=<time>] "
+   "[--expire-unreachable=<time>] "
+   "[--rewrite] [--updateref] [--stale-fix] [--dry-run | -n] "
+   "[--verbose] [--all] <refs>...");
+static const char reflog_delete_usage[] =
+N_("git reflog delete [--rewrite] [--updateref] "
+   "[--dry-run | -n] [--verbose] <refs>...");
+static const char reflog_exists_usage[] =
+N_("git reflog exists <ref>");
+
+static timestamp_t default_reflog_expire;
+static timestamp_t default_reflog_expire_unreachable;
+
+struct cmd_reflog_expire_cb {
+	struct rev_info revs;
+	int stalefix;
+	timestamp_t expire_total;
+	timestamp_t expire_unreachable;
+	int recno;
+};
+
+struct expire_reflog_policy_cb {
+	enum {
+		UE_NORMAL,
+		UE_ALWAYS,
+		UE_HEAD
+	} unreachable_expire_kind;
+	struct commit_list *mark_list;
+	unsigned long mark_limit;
+	struct cmd_reflog_expire_cb cmd;
+	struct commit *tip_commit;
+	struct commit_list *tips;
+};
+
+struct collected_reflog {
+	struct object_id oid;
+	char reflog[FLEX_ARRAY];
+};
+
+struct collect_reflog_cb {
+	struct collected_reflog **e;
+	int alloc;
+	int nr;
+	struct worktree *wt;
+};
+
+/* Remember to update object flag allocation in object.h */
+#define INCOMPLETE	(1u<<10)
+#define STUDYING	(1u<<11)
+#define REACHABLE	(1u<<12)
+
+static int tree_is_complete(const struct object_id *oid)
+{
+	struct tree_desc desc;
+	struct name_entry entry;
+	int complete;
+	struct tree *tree;
+
+	tree = lookup_tree(the_repository, oid);
+	if (!tree)
+		return 0;
+	if (tree->object.flags & SEEN)
+		return 1;
+	if (tree->object.flags & INCOMPLETE)
+		return 0;
+
+	if (!tree->buffer) {
+		enum object_type type;
+		unsigned long size;
+		void *data = read_object_file(oid, &type, &size);
+		if (!data) {
+			tree->object.flags |= INCOMPLETE;
+			return 0;
+		}
+		tree->buffer = data;
+		tree->size = size;
+	}
+	init_tree_desc(&desc, tree->buffer, tree->size);
+	complete = 1;
+	while (tree_entry(&desc, &entry)) {
+		if (!has_object_file(&entry.oid) ||
+		    (S_ISDIR(entry.mode) && !tree_is_complete(&entry.oid))) {
+			tree->object.flags |= INCOMPLETE;
+			complete = 0;
+		}
+	}
+	free_tree_buffer(tree);
+
+	if (complete)
+		tree->object.flags |= SEEN;
+	return complete;
+}
+
+static int commit_is_complete(struct commit *commit)
+{
+	struct object_array study;
+	struct object_array found;
+	int is_incomplete = 0;
+	int i;
+
+	/* early return */
+	if (commit->object.flags & SEEN)
+		return 1;
+	if (commit->object.flags & INCOMPLETE)
+		return 0;
+	/*
+	 * Find all commits that are reachable and are not marked as
+	 * SEEN.  Then make sure the trees and blobs contained are
+	 * complete.  After that, mark these commits also as SEEN.
+	 * If some of the objects that are needed to complete this
+	 * commit are missing, mark this commit as INCOMPLETE.
+	 */
+	memset(&study, 0, sizeof(study));
+	memset(&found, 0, sizeof(found));
+	add_object_array(&commit->object, NULL, &study);
+	add_object_array(&commit->object, NULL, &found);
+	commit->object.flags |= STUDYING;
+	while (study.nr) {
+		struct commit *c;
+		struct commit_list *parent;
+
+		c = (struct commit *)object_array_pop(&study);
+		if (!c->object.parsed && !parse_object(the_repository, &c->object.oid))
+			c->object.flags |= INCOMPLETE;
+
+		if (c->object.flags & INCOMPLETE) {
+			is_incomplete = 1;
+			break;
+		}
+		else if (c->object.flags & SEEN)
+			continue;
+		for (parent = c->parents; parent; parent = parent->next) {
+			struct commit *p = parent->item;
+			if (p->object.flags & STUDYING)
+				continue;
+			p->object.flags |= STUDYING;
+			add_object_array(&p->object, NULL, &study);
+			add_object_array(&p->object, NULL, &found);
+		}
+	}
+	if (!is_incomplete) {
+		/*
+		 * make sure all commits in "found" array have all the
+		 * necessary objects.
+		 */
+		for (i = 0; i < found.nr; i++) {
+			struct commit *c =
+				(struct commit *)found.objects[i].item;
+			if (!tree_is_complete(get_commit_tree_oid(c))) {
+				is_incomplete = 1;
+				c->object.flags |= INCOMPLETE;
+			}
+		}
+		if (!is_incomplete) {
+			/* mark all found commits as complete, iow SEEN */
+			for (i = 0; i < found.nr; i++)
+				found.objects[i].item->flags |= SEEN;
+		}
+	}
+	/* clear flags from the objects we traversed */
+	for (i = 0; i < found.nr; i++)
+		found.objects[i].item->flags &= ~STUDYING;
+	if (is_incomplete)
+		commit->object.flags |= INCOMPLETE;
+	else {
+		/*
+		 * If we come here, we have (1) traversed the ancestry chain
+		 * from the "commit" until we reach SEEN commits (which are
+		 * known to be complete), and (2) made sure that the commits
+		 * encountered during the above traversal refer to trees that
+		 * are complete.  Which means that we know *all* the commits
+		 * we have seen during this process are complete.
+		 */
+		for (i = 0; i < found.nr; i++)
+			found.objects[i].item->flags |= SEEN;
+	}
+	/* free object arrays */
+	object_array_clear(&study);
+	object_array_clear(&found);
+	return !is_incomplete;
+}
+
+static int keep_entry(struct commit **it, struct object_id *oid)
+{
+	struct commit *commit;
+
+	if (is_null_oid(oid))
+		return 1;
+	commit = lookup_commit_reference_gently(the_repository, oid, 1);
+	if (!commit)
+		return 0;
+
+	/*
+	 * Make sure everything in this commit exists.
+	 *
+	 * We have walked all the objects reachable from the refs
+	 * and cache earlier.  The commits reachable by this commit
+	 * must meet SEEN commits -- and then we should mark them as
+	 * SEEN as well.
+	 */
+	if (!commit_is_complete(commit))
+		return 0;
+	*it = commit;
+	return 1;
+}
+
+/*
+ * Starting from commits in the cb->mark_list, mark commits that are
+ * reachable from them.  Stop the traversal at commits older than
+ * the expire_limit and queue them back, so that the caller can call
+ * us again to restart the traversal with longer expire_limit.
+ */
+static void mark_reachable(struct expire_reflog_policy_cb *cb)
+{
+	struct commit_list *pending;
+	timestamp_t expire_limit = cb->mark_limit;
+	struct commit_list *leftover = NULL;
+
+	for (pending = cb->mark_list; pending; pending = pending->next)
+		pending->item->object.flags &= ~REACHABLE;
+
+	pending = cb->mark_list;
+	while (pending) {
+		struct commit_list *parent;
+		struct commit *commit = pop_commit(&pending);
+		if (commit->object.flags & REACHABLE)
+			continue;
+		if (parse_commit(commit))
+			continue;
+		commit->object.flags |= REACHABLE;
+		if (commit->date < expire_limit) {
+			commit_list_insert(commit, &leftover);
+			continue;
+		}
+		commit->object.flags |= REACHABLE;
+		parent = commit->parents;
+		while (parent) {
+			commit = parent->item;
+			parent = parent->next;
+			if (commit->object.flags & REACHABLE)
+				continue;
+			commit_list_insert(commit, &pending);
+		}
+	}
+	cb->mark_list = leftover;
+}
+
+static int unreachable(struct expire_reflog_policy_cb *cb, struct commit *commit, struct object_id *oid)
+{
+	/*
+	 * We may or may not have the commit yet - if not, look it
+	 * up using the supplied sha1.
+	 */
+	if (!commit) {
+		if (is_null_oid(oid))
+			return 0;
+
+		commit = lookup_commit_reference_gently(the_repository, oid,
+							1);
+
+		/* Not a commit -- keep it */
+		if (!commit)
+			return 0;
+	}
+
+	/* Reachable from the current ref?  Don't prune. */
+	if (commit->object.flags & REACHABLE)
+		return 0;
+
+	if (cb->mark_list && cb->mark_limit) {
+		cb->mark_limit = 0; /* dig down to the root */
+		mark_reachable(cb);
+	}
+
+	return !(commit->object.flags & REACHABLE);
+}
+
+/*
+ * Return true iff the specified reflog entry should be expired.
+ */
+static int should_expire_reflog_ent(struct object_id *ooid, struct object_id *noid,
+				    const char *email, timestamp_t timestamp, int tz,
+				    const char *message, void *cb_data)
+{
+	struct expire_reflog_policy_cb *cb = cb_data;
+	struct commit *old_commit, *new_commit;
+
+	if (timestamp < cb->cmd.expire_total)
+		return 1;
+
+	old_commit = new_commit = NULL;
+	if (cb->cmd.stalefix &&
+	    (!keep_entry(&old_commit, ooid) || !keep_entry(&new_commit, noid)))
+		return 1;
+
+	if (timestamp < cb->cmd.expire_unreachable) {
+		if (cb->unreachable_expire_kind == UE_ALWAYS)
+			return 1;
+		if (unreachable(cb, old_commit, ooid) || unreachable(cb, new_commit, noid))
+			return 1;
+	}
+
+	if (cb->cmd.recno && --(cb->cmd.recno) == 0)
+		return 1;
+
+	return 0;
+}
+
+static int push_tip_to_list(const char *refname, const struct object_id *oid,
+			    int flags, void *cb_data)
+{
+	struct commit_list **list = cb_data;
+	struct commit *tip_commit;
+	if (flags & REF_ISSYMREF)
+		return 0;
+	tip_commit = lookup_commit_reference_gently(the_repository, oid, 1);
+	if (!tip_commit)
+		return 0;
+	commit_list_insert(tip_commit, list);
+	return 0;
+}
+
+static int is_head(const char *refname)
+{
+	switch (ref_type(refname)) {
+	case REF_TYPE_OTHER_PSEUDOREF:
+	case REF_TYPE_MAIN_PSEUDOREF:
+		if (parse_worktree_ref(refname, NULL, NULL, &refname))
+			BUG("not a worktree ref: %s", refname);
+		break;
+	default:
+		break;
+	}
+	return !strcmp(refname, "HEAD");
+}
+
+static void reflog_expiry_prepare(const char *refname,
+				  const struct object_id *oid,
+				  void *cb_data)
+{
+	struct expire_reflog_policy_cb *cb = cb_data;
+
+	if (!cb->cmd.expire_unreachable || is_head(refname)) {
+		cb->tip_commit = NULL;
+		cb->unreachable_expire_kind = UE_HEAD;
+	} else {
+		cb->tip_commit = lookup_commit_reference_gently(the_repository,
+								oid, 1);
+		if (!cb->tip_commit)
+			cb->unreachable_expire_kind = UE_ALWAYS;
+		else
+			cb->unreachable_expire_kind = UE_NORMAL;
+	}
+
+	if (cb->cmd.expire_unreachable <= cb->cmd.expire_total)
+		cb->unreachable_expire_kind = UE_ALWAYS;
+
+	cb->mark_list = NULL;
+	cb->tips = NULL;
+	if (cb->unreachable_expire_kind != UE_ALWAYS) {
+		if (cb->unreachable_expire_kind == UE_HEAD) {
+			struct commit_list *elem;
+
+			for_each_ref(push_tip_to_list, &cb->tips);
+			for (elem = cb->tips; elem; elem = elem->next)
+				commit_list_insert(elem->item, &cb->mark_list);
+		} else {
+			commit_list_insert(cb->tip_commit, &cb->mark_list);
+		}
+		cb->mark_limit = cb->cmd.expire_total;
+		mark_reachable(cb);
+	}
+}
+
+static void reflog_expiry_cleanup(void *cb_data)
+{
+	struct expire_reflog_policy_cb *cb = cb_data;
+
+	if (cb->unreachable_expire_kind != UE_ALWAYS) {
+		if (cb->unreachable_expire_kind == UE_HEAD) {
+			struct commit_list *elem;
+			for (elem = cb->tips; elem; elem = elem->next)
+				clear_commit_marks(elem->item, REACHABLE);
+			free_commit_list(cb->tips);
+		} else {
+			clear_commit_marks(cb->tip_commit, REACHABLE);
+		}
+	}
+}
+
+static int collect_reflog(const char *ref, const struct object_id *oid, int unused, void *cb_data)
+{
+	struct collected_reflog *e;
+	struct collect_reflog_cb *cb = cb_data;
+	struct strbuf newref = STRBUF_INIT;
+
+	/*
+	 * Avoid collecting the same shared ref multiple times because
+	 * they are available via all worktrees.
+	 */
+	if (!cb->wt->is_current && ref_type(ref) == REF_TYPE_NORMAL)
+		return 0;
+
+	strbuf_worktree_ref(cb->wt, &newref, ref);
+	FLEX_ALLOC_STR(e, reflog, newref.buf);
+	strbuf_release(&newref);
+
+	oidcpy(&e->oid, oid);
+	ALLOC_GROW(cb->e, cb->nr + 1, cb->alloc);
+	cb->e[cb->nr++] = e;
+	return 0;
+}
+
+static struct reflog_expire_cfg {
+	struct reflog_expire_cfg *next;
+	timestamp_t expire_total;
+	timestamp_t expire_unreachable;
+	char pattern[FLEX_ARRAY];
+} *reflog_expire_cfg, **reflog_expire_cfg_tail;
+
+static struct reflog_expire_cfg *find_cfg_ent(const char *pattern, size_t len)
+{
+	struct reflog_expire_cfg *ent;
+
+	if (!reflog_expire_cfg_tail)
+		reflog_expire_cfg_tail = &reflog_expire_cfg;
+
+	for (ent = reflog_expire_cfg; ent; ent = ent->next)
+		if (!strncmp(ent->pattern, pattern, len) &&
+		    ent->pattern[len] == '\0')
+			return ent;
+
+	FLEX_ALLOC_MEM(ent, pattern, pattern, len);
+	*reflog_expire_cfg_tail = ent;
+	reflog_expire_cfg_tail = &(ent->next);
+	return ent;
+}
+
+/* expiry timer slot */
+#define EXPIRE_TOTAL   01
+#define EXPIRE_UNREACH 02
+
+static int reflog_expire_config(const char *var, const char *value, void *cb)
+{
+	const char *pattern, *key;
+	int pattern_len;
+	timestamp_t expire;
+	int slot;
+	struct reflog_expire_cfg *ent;
+
+	if (parse_config_key(var, "gc", &pattern, &pattern_len, &key) < 0)
+		return git_default_config(var, value, cb);
+
+	if (!strcmp(key, "reflogexpire")) {
+		slot = EXPIRE_TOTAL;
+		if (git_config_expiry_date(&expire, var, value))
+			return -1;
+	} else if (!strcmp(key, "reflogexpireunreachable")) {
+		slot = EXPIRE_UNREACH;
+		if (git_config_expiry_date(&expire, var, value))
+			return -1;
+	} else
+		return git_default_config(var, value, cb);
+
+	if (!pattern) {
+		switch (slot) {
+		case EXPIRE_TOTAL:
+			default_reflog_expire = expire;
+			break;
+		case EXPIRE_UNREACH:
+			default_reflog_expire_unreachable = expire;
+			break;
+		}
+		return 0;
+	}
+
+	ent = find_cfg_ent(pattern, pattern_len);
+	if (!ent)
+		return -1;
+	switch (slot) {
+	case EXPIRE_TOTAL:
+		ent->expire_total = expire;
+		break;
+	case EXPIRE_UNREACH:
+		ent->expire_unreachable = expire;
+		break;
+	}
+	return 0;
+}
+
+static void set_reflog_expiry_param(struct cmd_reflog_expire_cb *cb, int slot, const char *ref)
+{
+	struct reflog_expire_cfg *ent;
+
+	if (slot == (EXPIRE_TOTAL|EXPIRE_UNREACH))
+		return; /* both given explicitly -- nothing to tweak */
+
+	for (ent = reflog_expire_cfg; ent; ent = ent->next) {
+		if (!wildmatch(ent->pattern, ref, 0)) {
+			if (!(slot & EXPIRE_TOTAL))
+				cb->expire_total = ent->expire_total;
+			if (!(slot & EXPIRE_UNREACH))
+				cb->expire_unreachable = ent->expire_unreachable;
+			return;
+		}
+	}
+
+	/*
+	 * If unconfigured, make stash never expire
+	 */
+	if (!strcmp(ref, "refs/stash")) {
+		if (!(slot & EXPIRE_TOTAL))
+			cb->expire_total = 0;
+		if (!(slot & EXPIRE_UNREACH))
+			cb->expire_unreachable = 0;
+		return;
+	}
+
+	/* Nothing matched -- use the default value */
+	if (!(slot & EXPIRE_TOTAL))
+		cb->expire_total = default_reflog_expire;
+	if (!(slot & EXPIRE_UNREACH))
+		cb->expire_unreachable = default_reflog_expire_unreachable;
+}
+
+static int cmd_reflog_expire(int argc, const char **argv, const char *prefix)
+{
+	struct expire_reflog_policy_cb cb;
+	timestamp_t now = time(NULL);
+	int i, status, do_all, all_worktrees = 1;
+	int explicit_expiry = 0;
+	unsigned int flags = 0;
+
+	default_reflog_expire_unreachable = now - 30 * 24 * 3600;
+	default_reflog_expire = now - 90 * 24 * 3600;
+	git_config(reflog_expire_config, NULL);
+
+	save_commit_buffer = 0;
+	do_all = status = 0;
+	memset(&cb, 0, sizeof(cb));
+
+	cb.cmd.expire_total = default_reflog_expire;
+	cb.cmd.expire_unreachable = default_reflog_expire_unreachable;
+
+	for (i = 1; i < argc; i++) {
+		const char *arg = argv[i];
+		if (!strcmp(arg, "--dry-run") || !strcmp(arg, "-n"))
+			flags |= EXPIRE_REFLOGS_DRY_RUN;
+		else if (starts_with(arg, "--expire=")) {
+			if (parse_expiry_date(arg + 9, &cb.cmd.expire_total))
+				die(_("'%s' is not a valid timestamp"), arg);
+			explicit_expiry |= EXPIRE_TOTAL;
+		}
+		else if (starts_with(arg, "--expire-unreachable=")) {
+			if (parse_expiry_date(arg + 21, &cb.cmd.expire_unreachable))
+				die(_("'%s' is not a valid timestamp"), arg);
+			explicit_expiry |= EXPIRE_UNREACH;
+		}
+		else if (!strcmp(arg, "--stale-fix"))
+			cb.cmd.stalefix = 1;
+		else if (!strcmp(arg, "--rewrite"))
+			flags |= EXPIRE_REFLOGS_REWRITE;
+		else if (!strcmp(arg, "--updateref"))
+			flags |= EXPIRE_REFLOGS_UPDATE_REF;
+		else if (!strcmp(arg, "--all"))
+			do_all = 1;
+		else if (!strcmp(arg, "--single-worktree"))
+			all_worktrees = 0;
+		else if (!strcmp(arg, "--verbose"))
+			flags |= EXPIRE_REFLOGS_VERBOSE;
+		else if (!strcmp(arg, "--")) {
+			i++;
+			break;
+		}
+		else if (arg[0] == '-')
+			usage(_(reflog_expire_usage));
+		else
+			break;
+	}
+
+	/*
+	 * We can trust the commits and objects reachable from refs
+	 * even in older repository.  We cannot trust what's reachable
+	 * from reflog if the repository was pruned with older git.
+	 */
+	if (cb.cmd.stalefix) {
+		repo_init_revisions(the_repository, &cb.cmd.revs, prefix);
+		if (flags & EXPIRE_REFLOGS_VERBOSE)
+			printf(_("Marking reachable objects..."));
+		mark_reachable_objects(&cb.cmd.revs, 0, 0, NULL);
+		if (flags & EXPIRE_REFLOGS_VERBOSE)
+			putchar('\n');
+	}
+
+	if (do_all) {
+		struct collect_reflog_cb collected;
+		struct worktree **worktrees, **p;
+		int i;
+
+		memset(&collected, 0, sizeof(collected));
+		worktrees = get_worktrees(0);
+		for (p = worktrees; *p; p++) {
+			if (!all_worktrees && !(*p)->is_current)
+				continue;
+			collected.wt = *p;
+			refs_for_each_reflog(get_worktree_ref_store(*p),
+					     collect_reflog, &collected);
+		}
+		free_worktrees(worktrees);
+		for (i = 0; i < collected.nr; i++) {
+			struct collected_reflog *e = collected.e[i];
+			set_reflog_expiry_param(&cb.cmd, explicit_expiry, e->reflog);
+			status |= reflog_expire(e->reflog, &e->oid, flags,
+						reflog_expiry_prepare,
+						should_expire_reflog_ent,
+						reflog_expiry_cleanup,
+						&cb);
+			free(e);
+		}
+		free(collected.e);
+	}
+
+	for (; i < argc; i++) {
+		char *ref;
+		struct object_id oid;
+		if (!dwim_log(argv[i], strlen(argv[i]), &oid, &ref)) {
+			status |= error(_("%s points nowhere!"), argv[i]);
+			continue;
+		}
+		set_reflog_expiry_param(&cb.cmd, explicit_expiry, ref);
+		status |= reflog_expire(ref, &oid, flags,
+					reflog_expiry_prepare,
+					should_expire_reflog_ent,
+					reflog_expiry_cleanup,
+					&cb);
+	}
+	return status;
+}
+
+static int count_reflog_ent(struct object_id *ooid, struct object_id *noid,
+		const char *email, timestamp_t timestamp, int tz,
+		const char *message, void *cb_data)
+{
+	struct expire_reflog_policy_cb *cb = cb_data;
+	if (!cb->cmd.expire_total || timestamp < cb->cmd.expire_total)
+		cb->cmd.recno++;
+	return 0;
+}
+
+static int cmd_reflog_delete(int argc, const char **argv, const char *prefix)
+{
+	struct expire_reflog_policy_cb cb;
+	int i, status = 0;
+	unsigned int flags = 0;
+
+	memset(&cb, 0, sizeof(cb));
+
+	for (i = 1; i < argc; i++) {
+		const char *arg = argv[i];
+		if (!strcmp(arg, "--dry-run") || !strcmp(arg, "-n"))
+			flags |= EXPIRE_REFLOGS_DRY_RUN;
+		else if (!strcmp(arg, "--rewrite"))
+			flags |= EXPIRE_REFLOGS_REWRITE;
+		else if (!strcmp(arg, "--updateref"))
+			flags |= EXPIRE_REFLOGS_UPDATE_REF;
+		else if (!strcmp(arg, "--verbose"))
+			flags |= EXPIRE_REFLOGS_VERBOSE;
+		else if (!strcmp(arg, "--")) {
+			i++;
+			break;
+		}
+		else if (arg[0] == '-')
+			usage(_(reflog_delete_usage));
+		else
+			break;
+	}
+
+	if (argc - i < 1)
+		return error(_("no reflog specified to delete"));
+
+	for ( ; i < argc; i++) {
+		const char *spec = strstr(argv[i], "@{");
+		struct object_id oid;
+		char *ep, *ref;
+		int recno;
+
+		if (!spec) {
+			status |= error(_("not a reflog: %s"), argv[i]);
+			continue;
+		}
+
+		if (!dwim_log(argv[i], spec - argv[i], &oid, &ref)) {
+			status |= error(_("no reflog for '%s'"), argv[i]);
+			continue;
+		}
+
+		recno = strtoul(spec + 2, &ep, 10);
+		if (*ep == '}') {
+			cb.cmd.recno = -recno;
+			for_each_reflog_ent(ref, count_reflog_ent, &cb);
+		} else {
+			cb.cmd.expire_total = approxidate(spec + 2);
+			for_each_reflog_ent(ref, count_reflog_ent, &cb);
+			cb.cmd.expire_total = 0;
+		}
+
+		status |= reflog_expire(ref, &oid, flags,
+					reflog_expiry_prepare,
+					should_expire_reflog_ent,
+					reflog_expiry_cleanup,
+					&cb);
+		free(ref);
+	}
+	return status;
+}
+
+static int cmd_reflog_exists(int argc, const char **argv, const char *prefix)
+{
+	int i, start = 0;
+
+	for (i = 1; i < argc; i++) {
+		const char *arg = argv[i];
+		if (!strcmp(arg, "--")) {
+			i++;
+			break;
+		}
+		else if (arg[0] == '-')
+			usage(_(reflog_exists_usage));
+		else
+			break;
+	}
+
+	start = i;
+
+	if (argc - start != 1)
+		usage(_(reflog_exists_usage));
+
+	if (check_refname_format(argv[start], REFNAME_ALLOW_ONELEVEL))
+		die(_("invalid ref format: %s"), argv[start]);
+	return !reflog_exists(argv[start]);
+}
+
+/*
+ * main "reflog"
+ */
+
+static const char reflog_usage[] =
+N_("git reflog [ show | expire | delete | exists ]");
+
+int cmd_reflog(int argc, const char **argv, const char *prefix)
+{
+	if (argc > 1 && !strcmp(argv[1], "-h"))
+		usage(_(reflog_usage));
+
+	/* With no command, we default to showing it. */
+	if (argc < 2 || *argv[1] == '-')
+		return cmd_log_reflog(argc, argv, prefix);
+
+	if (!strcmp(argv[1], "show"))
+		return cmd_log_reflog(argc - 1, argv + 1, prefix);
+
+	if (!strcmp(argv[1], "expire"))
+		return cmd_reflog_expire(argc - 1, argv + 1, prefix);
+
+	if (!strcmp(argv[1], "delete"))
+		return cmd_reflog_delete(argc - 1, argv + 1, prefix);
+
+	if (!strcmp(argv[1], "exists"))
+		return cmd_reflog_exists(argc - 1, argv + 1, prefix);
+
+	return cmd_log_reflog(argc, argv, prefix);
+}