git-reflog: add exists command

This is necessary because alternate ref backends might store reflogs
somewhere other than .git/logs.  Code that now directly manipulates
.git/logs should instead go through git-reflog.

Signed-off-by: David Turner <dturner@twopensource.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/git-reflog.txt b/Documentation/git-reflog.txt
index 5e7908e..44c736f 100644 (file)
--- a/Documentation/git-reflog.txt
+++ b/Documentation/git-reflog.txt
@@ -23,6 +23,7 @@ depending on the subcommand:
        [--dry-run] [--verbose] [--all | <refs>...]
 'git reflog delete' [--rewrite] [--updateref]
        [--dry-run] [--verbose] ref@\{specifier\}...
+'git reflog exists' <ref>
 
 Reference logs, or "reflogs", record when the tips of branches and
 other references were updated in the local repository. Reflogs are
@@ -52,6 +53,9 @@ argument must be an _exact_ entry (e.g. "`git reflog delete
 master@{2}`"). This subcommand is also typically not used directly by
 end users.
 
+The "exists" subcommand checks whether a ref has a reflog.  It exits
+with zero status if the reflog exists, and non-zero status if it does
+not.
 
 OPTIONS
 -------

diff --git a/builtin/reflog.c b/builtin/reflog.c
index c2eb8ff..7ed0e85 100644 (file)
--- a/builtin/reflog.c
+++ b/builtin/reflog.c
@@ -13,6 +13,8 @@ static const char reflog_expire_usage[] =
 "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 [--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;
@@ -699,12 +701,38 @@ static int cmd_reflog_delete(int argc, const char **argv, const char *prefix)
        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)
 {
@@ -724,5 +752,8 @@ 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);
 }

diff --git a/t/t1411-reflog-show.sh b/t/t1411-reflog-show.sh
index 6f47c0d..3eb4f10 100755 (executable)
--- a/t/t1411-reflog-show.sh
+++ b/t/t1411-reflog-show.sh
@@ -166,4 +166,9 @@ test_expect_success 'git log -g -p shows diffs vs. parents' '
        test_cmp expect actual
 '
 
+test_expect_success 'reflog exists works' '
+       git reflog exists refs/heads/master &&
+       ! git reflog exists refs/heads/nonexistent
+'
+
 test_done