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Remove racy optimized file descriptor closing loop in 'spawn'.

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This reverts 9332b63240, thereby
reinstating the performance issue in <https://bugs.gnu.org/59321>.

This optimization was subject to race conditions in multi-threaded code:
new file descriptors could pop up at any time and thus leak in the
child.

* libguile/posix.c (close_inherited_fds): Remove.
(close_inherited_fds_slow): Rename to...
(close_inherited_fds): ... this.
This commit is contained in:
Ludovic Courtès 2023-03-28 23:43:31 +02:00
parent 21ad54b694
commit 7d7067fe15
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GPG key ID: 090B11993D9AEBB5
1 changed files with 1 additions and 29 deletions
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30
libguile/posix.c
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@ -1323,7 +1323,7 @@ SCM_DEFINE (scm_fork, "primitive-fork", 0, 0, 0,
#endif /* HAVE_FORK */ #endif /* HAVE_FORK */
static void static void
close_inherited_fds_slow (posix_spawn_file_actions_t *actions, int max_fd) close_inherited_fds (posix_spawn_file_actions_t *actions, int max_fd)
{ {
while (--max_fd > 2) while (--max_fd > 2)
{ {
@ -1346,34 +1346,6 @@ close_inherited_fds_slow (posix_spawn_file_actions_t *actions, int max_fd)
} }
} }
static void
close_inherited_fds (posix_spawn_file_actions_t *actions, int max_fd)
{
DIR *dirp;
struct dirent *d;
int fd;
/* Try to use the platform-specific list of open file descriptors, so
we don't need to use the brute force approach. */
dirp = opendir ("/proc/self/fd");
if (dirp == NULL)
return close_inherited_fds_slow (actions, max_fd);
while ((d = readdir (dirp)) != NULL)
{
fd = atoi (d->d_name);
/* Skip "." and "..", garbage entries, stdin/stdout/stderr. */
if (fd <= 2)
continue;
posix_spawn_file_actions_addclose (actions, fd);
}
closedir (dirp);
}
static pid_t static pid_t
do_spawn (char *exec_file, char **exec_argv, char **exec_env, do_spawn (char *exec_file, char **exec_argv, char **exec_env,
int in, int out, int err, int spawnp) int in, int out, int err, int spawnp)