[PATCH v2.5] Make git prune remove temporary packs that look like write failures

[David Steven Tweed <d.s.tweed@reading.ac.uk>]

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)
---

This version incorporates all the agreed with changes from the
previous version, and includes Johannes Schindelin's
modifications and also his test. If you want to change the attribution
lines to be him that's fine.

(BTW, I won't be reading mail until after the weekend now.)

 builtin-prune.c  |   39 +++++++++++++++++++++++++++++++++++++++
 t/t5304-prune.sh |   32 ++++++++++++++++++++++++++++++++
 2 files changed, 71 insertions(+), 0 deletions(-)
 create mode 100644 t/t5304-prune.sh

diff --git a/builtin-prune.c b/builtin-prune.c
index b5e7684..f25ddb6 100644
--- a/builtin-prune.c
+++ b/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;
 }
diff --git a/t/t5304-prune.sh b/t/t5304-prune.sh
new file mode 100644
index 0000000..6560af7
--- /dev/null
+++ b/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