Make git prune remove temporary packs that look like write failures

Write errors when repacking (eg, due to out-of-space conditions)
can leave temporary packs (and possibly other files beginning
with "tmp_") lying around which no existing
codepath removes and which aren't obvious to the casual user.
These can also be multi-megabyte files wasting noticeable space.
Unfortunately there's no way to definitely tell in builtin-prune
that a tmp_ file is not being used by a concurrent process,
such as a fetch. However, it is documented that pruning should
only be done on a quiet repository and --expire is honoured
(using code from Johannes Schindelin, along with a test case
he wrote) so that its safety is the same as that of loose
object pruning.

Since they might be signs of a problem (unlike orphaned loose
objects) the names of any removed files are printed.

Signed-off-by: David Tweed (david.tweed@gmail.com)
Acked-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-prune.c

@@ -83,6 +83,44 @@ static void prune_object_dir(const char *path)
 	}
 }
 
+/*
+ * Write errors (particularly out of space) can result in
+ * failed temporary packs (and more rarely indexes and other
+ * files begining with "tmp_") accumulating in the
+ * object directory.
+ */
+static void remove_temporary_files(void)
+{
+	DIR *dir;
+	struct dirent *de;
+	char* dirname=get_object_directory();
+
+	dir = opendir(dirname);
+	if (!dir) {
+		fprintf(stderr, "Unable to open object directory %s\n",
+			dirname);
+		return;
+	}
+	while ((de = readdir(dir)) != NULL) {
+		if (!prefixcmp(de->d_name, "tmp_")) {
+			char name[PATH_MAX];
+			int c = snprintf(name, PATH_MAX, "%s/%s",
+					 dirname, de->d_name);
+			if (c < 0 || c >= PATH_MAX)
+				continue;
+			if (expire) {
+				struct stat st;
+				if (stat(name, &st) != 0 || st.st_mtime >= expire)
+					continue;
+			}
+			printf("Removing stale temporary file %s\n", name);
+			if (!show_only)
+				unlink(name);
+		}
+	}
+	closedir(dir);
+}
+
 int cmd_prune(int argc, const char **argv, const char *prefix)
 {
 	int i;
@@ -115,5 +153,6 @@ int cmd_prune(int argc, const char **argv, const char *prefix)
 
 	sync();
 	prune_packed_objects(show_only);
+	remove_temporary_files();
 	return 0;
 }

t/t5304-prune.sh

@@ -0,0 +1,32 @@
+#!/bin/sh
+#
+# Copyright (c) 2008 Johannes E. Schindelin
+#
+
+test_description='prune'
+. ./test-lib.sh
+
+test_expect_success setup '
+
+	: > file &&
+	git add file &&
+	test_tick &&
+	git commit -m initial &&
+	git gc
+
+'
+
+test_expect_success 'prune stale packs' '
+
+	orig_pack=$(echo .git/objects/pack/*.pack) &&
+	: > .git/objects/tmp_1.pack &&
+	: > .git/objects/tmp_2.pack &&
+	test-chmtime -86501 .git/objects/tmp_1.pack &&
+	git prune --expire 1.day &&
+	test -f $orig_pack &&
+	test -f .git/objects/tmp_2.pack &&
+	! test -f .git/objects/tmp_1.pack
+
+'
+
+test_done