Add "--expire <time>" option to 'git prune'

Earlier, 'git prune' would prune all loose unreachable objects.
This could be quite dangerous, as the objects could be used in
an ongoing operation.

This patch adds a mode to expire only loose, unreachable objects
which are older than a certain time.  For example, by

	git prune --expire 14.days

you can prune only those objects which are loose, unreachable
and older than 14 days (and thus probably outdated).

The implementation uses st.st_mtime rather than st.st_ctime,
because it can be tested better, using 'touch -d <time>' (and
omitting the test when the platform does not support that
command line switch).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 20 insertions, 1 deletions

diff --git a/builtin-prune.c b/builtin-prune.c
index 44df59e4a..b5e768421 100644
--- a/builtin-prune.c
+++ b/builtin-prune.c
@@ -7,15 +7,24 @@
 
 static const char prune_usage[] = "git-prune [-n]";
 static int show_only;
+static unsigned long expire;
 
 static int prune_object(char *path, const char *filename, const unsigned char *sha1)
 {
+	const char *fullpath = mkpath("%s/%s", path, filename);
+	if (expire) {
+		struct stat st;
+		if (lstat(fullpath, &st))
+			return error("Could not stat '%s'", fullpath);
+		if (st.st_mtime > expire)
+			return 0;
+	}
 	if (show_only) {
 		enum object_type type = sha1_object_info(sha1, NULL);
 		printf("%s %s\n", sha1_to_hex(sha1),
 		       (type > 0) ? typename(type) : "unknown");
 	} else
-		unlink(mkpath("%s/%s", path, filename));
+		unlink(fullpath);
 	return 0;
 }
 
@@ -85,6 +94,16 @@ int cmd_prune(int argc, const char **argv, const char *prefix)
 			show_only = 1;
 			continue;
 		}
+		if (!strcmp(arg, "--expire")) {
+			if (++i < argc) {
+				expire = approxidate(argv[i]);
+				continue;
+			}
+		}
+		else if (!prefixcmp(arg, "--expire=")) {
+			expire = approxidate(arg + 9);
+			continue;
+		}
 		usage(prune_usage);
 	}