[PATCH v2 1/2] sha1_file: open window into packfiles with CLOEXEC

[larsxschneider@gmail.com]

From: Lars Schneider <larsxschneider@gmail.com>

All processes that the Git main process spawns inherit the open file
descriptors of the main process. These leaked file descriptors can
cause problems.

Use the CLOEXEC flag similar to 05d1ed61 to fix the leaked file
descriptors. Since `git_open_noatime` does not describe the function
properly anymore rename it to `git_open`.

Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
---
 builtin/pack-objects.c |  2 +-
 cache.h                |  2 +-
 pack-bitmap.c          |  2 +-
 sha1_file.c            | 26 ++++++++++++++++----------
 4 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 1e7c2a9..0fd52bd 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -720,7 +720,7 @@ static off_t write_reused_pack(struct sha1file *f)
 	if (!is_pack_valid(reuse_packfile))
 		die("packfile is invalid: %s", reuse_packfile->pack_name);
 
-	fd = git_open_noatime(reuse_packfile->pack_name);
+	fd = git_open(reuse_packfile->pack_name);
 	if (fd < 0)
 		die_errno("unable to open packfile for reuse: %s",
 			  reuse_packfile->pack_name);
diff --git a/cache.h b/cache.h
index b7f34b4..419b7a0 100644
--- a/cache.h
+++ b/cache.h
@@ -1125,7 +1125,7 @@ extern int write_sha1_file(const void *buf, unsigned long len, const char *type,
 extern int hash_sha1_file_literally(const void *buf, unsigned long len, const char *type, unsigned char *sha1, unsigned flags);
 extern int pretend_sha1_file(void *, unsigned long, enum object_type, unsigned char *);
 extern int force_object_loose(const unsigned char *sha1, time_t mtime);
-extern int git_open_noatime(const char *name);
+extern int git_open(const char *name);
 extern void *map_sha1_file(const unsigned char *sha1, unsigned long *size);
 extern int unpack_sha1_header(git_zstream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz);
 extern int parse_sha1_header(const char *hdr, unsigned long *sizep);
diff --git a/pack-bitmap.c b/pack-bitmap.c
index b949e51..39bcc16 100644
--- a/pack-bitmap.c
+++ b/pack-bitmap.c
@@ -266,7 +266,7 @@ static int open_pack_bitmap_1(struct packed_git *packfile)
 		return -1;
 
 	idx_name = pack_bitmap_filename(packfile);
-	fd = git_open_noatime(idx_name);
+	fd = git_open(idx_name);
 	free(idx_name);
 
 	if (fd < 0)
diff --git a/sha1_file.c b/sha1_file.c
index 1e41954..93b836b 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -370,7 +370,7 @@ void read_info_alternates(const char * relative_base, int depth)
 	int fd;
 
 	path = xstrfmt("%s/info/alternates", relative_base);
-	fd = git_open_noatime(path);
+	fd = git_open(path);
 	free(path);
 	if (fd < 0)
 		return;
@@ -663,7 +663,7 @@ static int check_packed_git_idx(const char *path, struct packed_git *p)
 	struct pack_idx_header *hdr;
 	size_t idx_size;
 	uint32_t version, nr, i, *index;
-	int fd = git_open_noatime(path);
+	int fd = git_open(path);
 	struct stat st;
 
 	if (fd < 0)
@@ -1069,7 +1069,7 @@ static int open_packed_git_1(struct packed_git *p)
 	while (pack_max_fds <= pack_open_fds && close_one_pack())
 		; /* nothing */
 
-	p->pack_fd = git_open_noatime(p->pack_name);
+	p->pack_fd = git_open(p->pack_name);
 	if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
 		return -1;
 	pack_open_fds++;
@@ -1586,9 +1586,9 @@ int check_sha1_signature(const unsigned char *sha1, void *map,
 	return hashcmp(sha1, real_sha1) ? -1 : 0;
 }
 
-int git_open_noatime(const char *name)
+int git_open(const char *name)
 {
-	static int sha1_file_open_flag = O_NOATIME;
+	static int sha1_file_open_flag = O_NOATIME | O_CLOEXEC;
 
 	for (;;) {
 		int fd;
@@ -1598,12 +1598,18 @@ int git_open_noatime(const char *name)
 		if (fd >= 0)
 			return fd;
 
-		/* Might the failure be due to O_NOATIME? */
-		if (errno != ENOENT && sha1_file_open_flag) {
-			sha1_file_open_flag = 0;
+		/* Try again w/o O_CLOEXEC: the kernel might not support it */
+		if (O_CLOEXEC && errno == EINVAL &&
+			(sha1_file_open_flag & O_CLOEXEC)) {
+			sha1_file_open_flag &= ~O_CLOEXEC;
 			continue;
 		}
 
+		/* Might the failure be due to O_NOATIME? */
+		if (errno != ENOENT && (sha1_file_open_flag & O_NOATIME)) {
+			sha1_file_open_flag &= ~O_NOATIME;
+			continue;
+		}
 		return -1;
 	}
 }
@@ -1632,7 +1638,7 @@ static int open_sha1_file(const unsigned char *sha1)
 	struct alternate_object_database *alt;
 	int most_interesting_errno;
 
-	fd = git_open_noatime(sha1_file_name(sha1));
+	fd = git_open(sha1_file_name(sha1));
 	if (fd >= 0)
 		return fd;
 	most_interesting_errno = errno;
@@ -1640,7 +1646,7 @@ static int open_sha1_file(const unsigned char *sha1)
 	prepare_alt_odb();
 	for (alt = alt_odb_list; alt; alt = alt->next) {
 		const char *path = alt_sha1_path(alt, sha1);
-		fd = git_open_noatime(path);
+		fd = git_open(path);
 		if (fd >= 0)
 			return fd;
 		if (most_interesting_errno == ENOENT)
-- 
2.10.0