From 1e3001a8e2386a1433d1769a5a78007596bbc04d Mon Sep 17 00:00:00 2001 From: Junio C Hamano Date: Mon, 31 Oct 2016 10:41:41 -0700 Subject: [PATCH] git_open_cloexec(): use fcntl(2) w/ FD_CLOEXEC fallback 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 Signed-off-by: Junio C Hamano --- sha1_file.c | 24 +++++++++++++++++++----- 1 file changed, 19 insertions(+), 5 deletions(-) diff --git a/sha1_file.c b/sha1_file.c index dfbf398183..64e1a21fc6 100644 --- a/sha1_file.c +++ b/sha1_file.c @@ -1561,14 +1561,28 @@ int check_sha1_signature(const unsigned char *sha1, void *map, int git_open_cloexec(const char *name, int flags) { - static int cloexec = O_CLOEXEC; - int fd = open(name, flags | cloexec); + int fd; + 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 */ - cloexec &= ~O_CLOEXEC; - fd = open(name, flags | cloexec); + o_cloexec &= ~O_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; }