Merge branch 'ss/clone-depth-single-doc' into maint
[gitweb.git] / builtin / reflog.c
index 177e0acd2003995064fd9c83803a43c5336ef143..f39960e5e480abcd08898b2f04aa444c1d7bec17 100644 (file)
@@ -1,5 +1,5 @@
-#include "cache.h"
 #include "builtin.h"
+#include "lockfile.h"
 #include "commit.h"
 #include "refs.h"
 #include "dir.h"
@@ -8,32 +8,26 @@
 #include "revision.h"
 #include "reachable.h"
 
-/*
- * reflog expire
- */
-
+/* NEEDSWORK: switch to using parse_options */
 static const char reflog_expire_usage[] =
-"git reflog expire [--verbose] [--dry-run] [--stale-fix] [--expire=<time>] [--expire-unreachable=<time>] [--all] <refs>...";
+"git reflog expire [--expire=<time>] [--expire-unreachable=<time>] [--rewrite] [--updateref] [--stale-fix] [--dry-run | -n] [--verbose] [--all] <refs>...";
 static const char reflog_delete_usage[] =
-"git reflog delete [--verbose] [--dry-run] [--rewrite] [--updateref] <refs>...";
+"git reflog delete [--rewrite] [--updateref] [--dry-run | -n] [--verbose] <refs>...";
+static const char reflog_exists_usage[] =
+"git reflog exists <ref>";
 
 static unsigned long default_reflog_expire;
 static unsigned long default_reflog_expire_unreachable;
 
 struct cmd_reflog_expire_cb {
        struct rev_info revs;
-       int dry_run;
        int stalefix;
-       int rewrite;
-       int updateref;
-       int verbose;
        unsigned long expire_total;
        unsigned long expire_unreachable;
        int recno;
 };
 
-struct expire_reflog_cb {
-       FILE *newlog;
+struct expire_reflog_policy_cb {
        enum {
                UE_NORMAL,
                UE_ALWAYS,
@@ -41,14 +35,16 @@ struct expire_reflog_cb {
        } unreachable_expire_kind;
        struct commit_list *mark_list;
        unsigned long mark_limit;
-       struct cmd_reflog_expire_cb *cmd;
-       unsigned char last_kept_sha1[20];
+       struct cmd_reflog_expire_cb cmd;
+       struct commit *tip_commit;
+       struct commit_list *tips;
 };
 
 struct collected_reflog {
        unsigned char sha1[20];
        char reflog[FLEX_ARRAY];
 };
+
 struct collect_reflog_cb {
        struct collected_reflog **e;
        int alloc;
@@ -94,8 +90,7 @@ static int tree_is_complete(const unsigned char *sha1)
                        complete = 0;
                }
        }
-       free(tree->buffer);
-       tree->buffer = NULL;
+       free_tree_buffer(tree);
 
        if (complete)
                tree->object.flags |= SEEN;
@@ -131,7 +126,7 @@ static int commit_is_complete(struct commit *commit)
                struct commit_list *parent;
 
                c = (struct commit *)study.objects[--study.nr].item;
-               if (!c->object.parsed && !parse_object(c->object.sha1))
+               if (!c->object.parsed && !parse_object(c->object.oid.hash))
                        c->object.flags |= INCOMPLETE;
 
                if (c->object.flags & INCOMPLETE) {
@@ -157,7 +152,7 @@ static int commit_is_complete(struct commit *commit)
                for (i = 0; i < found.nr; i++) {
                        struct commit *c =
                                (struct commit *)found.objects[i].item;
-                       if (!tree_is_complete(c->tree->object.sha1)) {
+                       if (!tree_is_complete(c->tree->object.oid.hash)) {
                                is_incomplete = 1;
                                c->object.flags |= INCOMPLETE;
                        }
@@ -221,9 +216,8 @@ static int keep_entry(struct commit **it, unsigned char *sha1)
  * 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_cb *cb)
+static void mark_reachable(struct expire_reflog_policy_cb *cb)
 {
-       struct commit *commit;
        struct commit_list *pending;
        unsigned long expire_limit = cb->mark_limit;
        struct commit_list *leftover = NULL;
@@ -233,11 +227,8 @@ static void mark_reachable(struct expire_reflog_cb *cb)
 
        pending = cb->mark_list;
        while (pending) {
-               struct commit_list *entry = pending;
                struct commit_list *parent;
-               pending = entry->next;
-               commit = entry->item;
-               free(entry);
+               struct commit *commit = pop_commit(&pending);
                if (commit->object.flags & REACHABLE)
                        continue;
                if (parse_commit(commit))
@@ -260,7 +251,7 @@ static void mark_reachable(struct expire_reflog_cb *cb)
        cb->mark_list = leftover;
 }
 
-static int unreachable(struct expire_reflog_cb *cb, struct commit *commit, unsigned char *sha1)
+static int unreachable(struct expire_reflog_policy_cb *cb, struct commit *commit, unsigned char *sha1)
 {
        /*
         * We may or may not have the commit yet - if not, look it
@@ -289,175 +280,112 @@ static int unreachable(struct expire_reflog_cb *cb, struct commit *commit, unsig
        return !(commit->object.flags & REACHABLE);
 }
 
-static int expire_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
-               const char *email, unsigned long timestamp, int tz,
-               const char *message, void *cb_data)
+/*
+ * Return true iff the specified reflog entry should be expired.
+ */
+static int should_expire_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
+                                   const char *email, unsigned long timestamp, int tz,
+                                   const char *message, void *cb_data)
 {
-       struct expire_reflog_cb *cb = cb_data;
+       struct expire_reflog_policy_cb *cb = cb_data;
        struct commit *old, *new;
 
-       if (timestamp < cb->cmd->expire_total)
-               goto prune;
-
-       if (cb->cmd->rewrite)
-               osha1 = cb->last_kept_sha1;
+       if (timestamp < cb->cmd.expire_total)
+               return 1;
 
        old = new = NULL;
-       if (cb->cmd->stalefix &&
+       if (cb->cmd.stalefix &&
            (!keep_entry(&old, osha1) || !keep_entry(&new, nsha1)))
-               goto prune;
+               return 1;
 
-       if (timestamp < cb->cmd->expire_unreachable) {
+       if (timestamp < cb->cmd.expire_unreachable) {
                if (cb->unreachable_expire_kind == UE_ALWAYS)
-                       goto prune;
+                       return 1;
                if (unreachable(cb, old, osha1) || unreachable(cb, new, nsha1))
-                       goto prune;
+                       return 1;
        }
 
-       if (cb->cmd->recno && --(cb->cmd->recno) == 0)
-               goto prune;
-
-       if (cb->newlog) {
-               char sign = (tz < 0) ? '-' : '+';
-               int zone = (tz < 0) ? (-tz) : tz;
-               fprintf(cb->newlog, "%s %s %s %lu %c%04d\t%s",
-                       sha1_to_hex(osha1), sha1_to_hex(nsha1),
-                       email, timestamp, sign, zone,
-                       message);
-               hashcpy(cb->last_kept_sha1, nsha1);
-       }
-       if (cb->cmd->verbose)
-               printf("keep %s", message);
-       return 0;
- prune:
-       if (!cb->newlog)
-               printf("would prune %s", message);
-       else if (cb->cmd->verbose)
-               printf("prune %s", message);
+       if (cb->cmd.recno && --(cb->cmd.recno) == 0)
+               return 1;
+
        return 0;
 }
 
-static int push_tip_to_list(const char *refname, const unsigned char *sha1, int flags, void *cb_data)
+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(sha1, 1);
+       tip_commit = lookup_commit_reference_gently(oid->hash, 1);
        if (!tip_commit)
                return 0;
        commit_list_insert(tip_commit, list);
        return 0;
 }
 
-static int expire_reflog(const char *ref, const unsigned char *sha1, int unused, void *cb_data)
+static void reflog_expiry_prepare(const char *refname,
+                                 const unsigned char *sha1,
+                                 void *cb_data)
 {
-       struct cmd_reflog_expire_cb *cmd = cb_data;
-       struct expire_reflog_cb cb;
-       struct ref_lock *lock;
-       char *log_file, *newlog_path = NULL;
-       struct commit *tip_commit;
-       struct commit_list *tips;
-       int status = 0;
-
-       memset(&cb, 0, sizeof(cb));
-
-       /*
-        * we take the lock for the ref itself to prevent it from
-        * getting updated.
-        */
-       lock = lock_any_ref_for_update(ref, sha1, 0);
-       if (!lock)
-               return error("cannot lock ref '%s'", ref);
-       log_file = git_pathdup("logs/%s", ref);
-       if (!file_exists(log_file))
-               goto finish;
-       if (!cmd->dry_run) {
-               newlog_path = git_pathdup("logs/%s.lock", ref);
-               cb.newlog = fopen(newlog_path, "w");
-       }
+       struct expire_reflog_policy_cb *cb = cb_data;
 
-       cb.cmd = cmd;
-
-       if (!cmd->expire_unreachable || !strcmp(ref, "HEAD")) {
-               tip_commit = NULL;
-               cb.unreachable_expire_kind = UE_HEAD;
+       if (!cb->cmd.expire_unreachable || !strcmp(refname, "HEAD")) {
+               cb->tip_commit = NULL;
+               cb->unreachable_expire_kind = UE_HEAD;
        } else {
-               tip_commit = lookup_commit_reference_gently(sha1, 1);
-               if (!tip_commit)
-                       cb.unreachable_expire_kind = UE_ALWAYS;
+               cb->tip_commit = lookup_commit_reference_gently(sha1, 1);
+               if (!cb->tip_commit)
+                       cb->unreachable_expire_kind = UE_ALWAYS;
                else
-                       cb.unreachable_expire_kind = UE_NORMAL;
+                       cb->unreachable_expire_kind = UE_NORMAL;
        }
 
-       if (cmd->expire_unreachable <= cmd->expire_total)
-               cb.unreachable_expire_kind = UE_ALWAYS;
+       if (cb->cmd.expire_unreachable <= cb->cmd.expire_total)
+               cb->unreachable_expire_kind = UE_ALWAYS;
 
-       cb.mark_list = NULL;
-       tips = NULL;
-       if (cb.unreachable_expire_kind != UE_ALWAYS) {
-               if (cb.unreachable_expire_kind == UE_HEAD) {
+       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, &tips);
-                       for (elem = tips; elem; elem = elem->next)
-                               commit_list_insert(elem->item, &cb.mark_list);
+
+                       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(tip_commit, &cb.mark_list);
+                       commit_list_insert(cb->tip_commit, &cb->mark_list);
                }
-               cb.mark_limit = cmd->expire_total;
-               mark_reachable(&cb);
+               cb->mark_limit = cb->cmd.expire_total;
+               mark_reachable(cb);
        }
+}
 
-       for_each_reflog_ent(ref, expire_reflog_ent, &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) {
+       if (cb->unreachable_expire_kind != UE_ALWAYS) {
+               if (cb->unreachable_expire_kind == UE_HEAD) {
                        struct commit_list *elem;
-                       for (elem = tips; elem; elem = elem->next)
-                               clear_commit_marks(tip_commit, REACHABLE);
-                       free_commit_list(tips);
+                       for (elem = cb->tips; elem; elem = elem->next)
+                               clear_commit_marks(elem->item, REACHABLE);
+                       free_commit_list(cb->tips);
                } else {
-                       clear_commit_marks(tip_commit, REACHABLE);
+                       clear_commit_marks(cb->tip_commit, REACHABLE);
                }
        }
- finish:
-       if (cb.newlog) {
-               if (fclose(cb.newlog)) {
-                       status |= error("%s: %s", strerror(errno),
-                                       newlog_path);
-                       unlink(newlog_path);
-               } else if (cmd->updateref &&
-                       (write_in_full(lock->lock_fd,
-                               sha1_to_hex(cb.last_kept_sha1), 40) != 40 ||
-                        write_str_in_full(lock->lock_fd, "\n") != 1 ||
-                        close_ref(lock) < 0)) {
-                       status |= error("Couldn't write %s",
-                               lock->lk->filename);
-                       unlink(newlog_path);
-               } else if (rename(newlog_path, log_file)) {
-                       status |= error("cannot rename %s to %s",
-                                       newlog_path, log_file);
-                       unlink(newlog_path);
-               } else if (cmd->updateref && commit_ref(lock)) {
-                       status |= error("Couldn't set %s", lock->ref_name);
-               } else {
-                       adjust_shared_perm(log_file);
-               }
-       }
-       free(newlog_path);
-       free(log_file);
-       unlock_ref(lock);
-       return status;
 }
 
-static int collect_reflog(const char *ref, const unsigned char *sha1, int unused, void *cb_data)
+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;
        size_t namelen = strlen(ref);
 
        e = xmalloc(sizeof(*e) + namelen + 1);
-       hashcpy(e->sha1, sha1);
+       hashcpy(e->sha1, oid->hash);
        memcpy(e->reflog, ref, namelen + 1);
        ALLOC_GROW(cb->e, cb->nr + 1, cb->alloc);
        cb->e[cb->nr++] = e;
@@ -508,26 +436,27 @@ static int parse_expire_cfg_value(const char *var, const char *value, unsigned l
 
 static int reflog_expire_config(const char *var, const char *value, void *cb)
 {
-       const char *lastdot = strrchr(var, '.');
+       const char *pattern, *key;
+       int pattern_len;
        unsigned long expire;
        int slot;
        struct reflog_expire_cfg *ent;
 
-       if (!lastdot || prefixcmp(var, "gc."))
+       if (parse_config_key(var, "gc", &pattern, &pattern_len, &key) < 0)
                return git_default_config(var, value, cb);
 
-       if (!strcmp(lastdot, ".reflogexpire")) {
+       if (!strcmp(key, "reflogexpire")) {
                slot = EXPIRE_TOTAL;
                if (parse_expire_cfg_value(var, value, &expire))
                        return -1;
-       } else if (!strcmp(lastdot, ".reflogexpireunreachable")) {
+       } else if (!strcmp(key, "reflogexpireunreachable")) {
                slot = EXPIRE_UNREACH;
                if (parse_expire_cfg_value(var, value, &expire))
                        return -1;
        } else
                return git_default_config(var, value, cb);
 
-       if (lastdot == var + 2) {
+       if (!pattern) {
                switch (slot) {
                case EXPIRE_TOTAL:
                        default_reflog_expire = expire;
@@ -539,7 +468,7 @@ static int reflog_expire_config(const char *var, const char *value, void *cb)
                return 0;
        }
 
-       ent = find_cfg_ent(var + 3, lastdot - (var+3));
+       ent = find_cfg_ent(pattern, pattern_len);
        if (!ent)
                return -1;
        switch (slot) {
@@ -561,7 +490,7 @@ static void set_reflog_expiry_param(struct cmd_reflog_expire_cb *cb, int slot, c
                return; /* both given explicitly -- nothing to tweak */
 
        for (ent = reflog_expire_cfg; ent; ent = ent->next) {
-               if (!fnmatch(ent->pattern, ref, 0)) {
+               if (!wildmatch(ent->pattern, ref, 0, NULL)) {
                        if (!(slot & EXPIRE_TOTAL))
                                cb->expire_total = ent->expire_total;
                        if (!(slot & EXPIRE_UNREACH))
@@ -590,10 +519,11 @@ static void set_reflog_expiry_param(struct cmd_reflog_expire_cb *cb, int slot, c
 
 static int cmd_reflog_expire(int argc, const char **argv, const char *prefix)
 {
-       struct cmd_reflog_expire_cb cb;
+       struct expire_reflog_policy_cb cb;
        unsigned long now = time(NULL);
        int i, status, do_all;
        int explicit_expiry = 0;
+       unsigned int flags = 0;
 
        default_reflog_expire_unreachable = now - 30 * 24 * 3600;
        default_reflog_expire = now - 90 * 24 * 3600;
@@ -603,33 +533,33 @@ static int cmd_reflog_expire(int argc, const char **argv, const char *prefix)
        do_all = status = 0;
        memset(&cb, 0, sizeof(cb));
 
-       cb.expire_total = default_reflog_expire;
-       cb.expire_unreachable = default_reflog_expire_unreachable;
+       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"))
-                       cb.dry_run = 1;
-               else if (!prefixcmp(arg, "--expire=")) {
-                       if (parse_expiry_date(arg + 9, &cb.expire_total))
+                       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 (!prefixcmp(arg, "--expire-unreachable=")) {
-                       if (parse_expiry_date(arg + 21, &cb.expire_unreachable))
+               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.stalefix = 1;
+                       cb.cmd.stalefix = 1;
                else if (!strcmp(arg, "--rewrite"))
-                       cb.rewrite = 1;
+                       flags |= EXPIRE_REFLOGS_REWRITE;
                else if (!strcmp(arg, "--updateref"))
-                       cb.updateref = 1;
+                       flags |= EXPIRE_REFLOGS_UPDATE_REF;
                else if (!strcmp(arg, "--all"))
                        do_all = 1;
                else if (!strcmp(arg, "--verbose"))
-                       cb.verbose = 1;
+                       flags |= EXPIRE_REFLOGS_VERBOSE;
                else if (!strcmp(arg, "--")) {
                        i++;
                        break;
@@ -645,12 +575,12 @@ static int cmd_reflog_expire(int argc, const char **argv, const char *prefix)
         * even in older repository.  We cannot trust what's reachable
         * from reflog if the repository was pruned with older git.
         */
-       if (cb.stalefix) {
-               init_revisions(&cb.revs, prefix);
-               if (cb.verbose)
+       if (cb.cmd.stalefix) {
+               init_revisions(&cb.cmd.revs, prefix);
+               if (flags & EXPIRE_REFLOGS_VERBOSE)
                        printf("Marking reachable objects...");
-               mark_reachable_objects(&cb.revs, 0, NULL);
-               if (cb.verbose)
+               mark_reachable_objects(&cb.cmd.revs, 0, 0, NULL);
+               if (flags & EXPIRE_REFLOGS_VERBOSE)
                        putchar('\n');
        }
 
@@ -662,8 +592,12 @@ static int cmd_reflog_expire(int argc, const char **argv, const char *prefix)
                for_each_reflog(collect_reflog, &collected);
                for (i = 0; i < collected.nr; i++) {
                        struct collected_reflog *e = collected.e[i];
-                       set_reflog_expiry_param(&cb, explicit_expiry, e->reflog);
-                       status |= expire_reflog(e->reflog, e->sha1, 0, &cb);
+                       set_reflog_expiry_param(&cb.cmd, explicit_expiry, e->reflog);
+                       status |= reflog_expire(e->reflog, e->sha1, flags,
+                                               reflog_expiry_prepare,
+                                               should_expire_reflog_ent,
+                                               reflog_expiry_cleanup,
+                                               &cb);
                        free(e);
                }
                free(collected.e);
@@ -676,8 +610,12 @@ static int cmd_reflog_expire(int argc, const char **argv, const char *prefix)
                        status |= error("%s points nowhere!", argv[i]);
                        continue;
                }
-               set_reflog_expiry_param(&cb, explicit_expiry, ref);
-               status |= expire_reflog(ref, sha1, 0, &cb);
+               set_reflog_expiry_param(&cb.cmd, explicit_expiry, ref);
+               status |= reflog_expire(ref, sha1, flags,
+                                       reflog_expiry_prepare,
+                                       should_expire_reflog_ent,
+                                       reflog_expiry_cleanup,
+                                       &cb);
        }
        return status;
 }
@@ -686,29 +624,30 @@ static int count_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
                const char *email, unsigned long timestamp, int tz,
                const char *message, void *cb_data)
 {
-       struct cmd_reflog_expire_cb *cb = cb_data;
-       if (!cb->expire_total || timestamp < cb->expire_total)
-               cb->recno++;
+       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 cmd_reflog_expire_cb cb;
+       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"))
-                       cb.dry_run = 1;
+                       flags |= EXPIRE_REFLOGS_DRY_RUN;
                else if (!strcmp(arg, "--rewrite"))
-                       cb.rewrite = 1;
+                       flags |= EXPIRE_REFLOGS_REWRITE;
                else if (!strcmp(arg, "--updateref"))
-                       cb.updateref = 1;
+                       flags |= EXPIRE_REFLOGS_UPDATE_REF;
                else if (!strcmp(arg, "--verbose"))
-                       cb.verbose = 1;
+                       flags |= EXPIRE_REFLOGS_VERBOSE;
                else if (!strcmp(arg, "--")) {
                        i++;
                        break;
@@ -740,26 +679,56 @@ static int cmd_reflog_delete(int argc, const char **argv, const char *prefix)
 
                recno = strtoul(spec + 2, &ep, 10);
                if (*ep == '}') {
-                       cb.recno = -recno;
+                       cb.cmd.recno = -recno;
                        for_each_reflog_ent(ref, count_reflog_ent, &cb);
                } else {
-                       cb.expire_total = approxidate(spec + 2);
+                       cb.cmd.expire_total = approxidate(spec + 2);
                        for_each_reflog_ent(ref, count_reflog_ent, &cb);
-                       cb.expire_total = 0;
+                       cb.cmd.expire_total = 0;
                }
 
-               status |= expire_reflog(ref, sha1, 0, &cb);
+               status |= reflog_expire(ref, sha1, 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[] =
-"git reflog [ show | expire | delete ]";
+"git reflog [ show | expire | delete | exists ]";
 
 int cmd_reflog(int argc, const char **argv, const char *prefix)
 {
@@ -779,5 +748,8 @@ int cmd_reflog(int argc, const char **argv, const char *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);
 }