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git_open_cloexec(): use fcntl(2) w/ FD_CLOEXEC fallback

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A platform might not support open(2) with O_CLOEXEC but may support
telling the same with fcntl(2) to flip FD_CLOEXEC bit on on an open
file descriptor.  It is a fallback that is inherently racy and this
may not be worth doing, though.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Junio C Hamano
2016-10-31 10:41:41 -07:00
parent 1b8ac5ead5
commit 1e3001a8e2
1 changed files with 19 additions and 5 deletions
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24
sha1_file.c
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@ -1561,14 +1561,28 @@ int check_sha1_signature(const unsigned char *sha1, void *map,
int git_open_cloexec(const char *name, int flags) int git_open_cloexec(const char *name, int flags)
{ {
static int cloexec = O_CLOEXEC; int fd;
int fd = open(name, flags | cloexec); static int o_cloexec = O_CLOEXEC;
if ((cloexec & O_CLOEXEC) && fd < 0 && errno == EINVAL) { fd = open(name, flags | o_cloexec);
if ((o_cloexec & O_CLOEXEC) && fd < 0 && errno == EINVAL) {
/* Try again w/o O_CLOEXEC: the kernel might not support it */ /* Try again w/o O_CLOEXEC: the kernel might not support it */
cloexec &= ~O_CLOEXEC; o_cloexec &= ~O_CLOEXEC;
fd = open(name, flags | cloexec); fd = open(name, flags | o_cloexec);
} }
#if defined(F_GETFL) && defined(F_SETFL) && defined(FD_CLOEXEC)
{
static int fd_cloexec = FD_CLOEXEC;
if (!o_cloexec && 0 <= fd && fd_cloexec) {
/* Opened w/o O_CLOEXEC? try with fcntl(2) to add it */
int flags = fcntl(fd, F_GETFL);
if (fcntl(fd, F_SETFL, flags | fd_cloexec))
fd_cloexec = 0;
}
}
#endif
return fd; return fd;
} }