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core: Fix possible deadlock due to get_max_fds.

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* src/posix-io.c (get_max_fds): Do not use the Linux optimization.
--

Signed-off-by: Werner Koch <wk@gnupg.org>
This commit is contained in:
Werner Koch 2017-02-03 13:13:22 +01:00
parent afc308598d
commit 93a59070c6
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GPG Key ID: E3FDFF218E45B72B
1 changed files with 36 additions and 30 deletions
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66
src/posix-io.c
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@ -287,37 +287,43 @@ get_max_fds (void)
int rc;
/* Under Linux we can figure out the highest used file descriptor by
* reading /proc/self/fd. This is in the common cases much fast than
* for example doing 4096 close calls where almost all of them will
* fail. */
#ifdef __linux__
{
DIR *dir = NULL;
struct dirent *dir_entry;
const char *s;
int x;
* reading /proc/self/fd. This is in the common cases much faster
* than for example doing 4096 close calls where almost all of them
* will fail.
*
* Unfortunately we can't call opendir between fork and exec in a
* multi-threaded process because opendir uses malloc and thus a
* mutex which may deadlock with a malloc in another thread. Thus
* the code is not used until we can have a opendir variant which
* does not use malloc. */
/* #ifdef __linux__ */
/* { */
/* DIR *dir = NULL; */
/* struct dirent *dir_entry; */
/* const char *s; */
/* int x; */
dir = opendir ("/proc/self/fd");
if (dir)
{
while ((dir_entry = readdir (dir)))
{
s = dir_entry->d_name;
if ( *s < '0' || *s > '9')
continue;
x = atoi (s);
if (x > fds)
fds = x;
}
closedir (dir);
}
if (fds != -1)
{
fds++;
source = "/proc";
}
}
#endif /* __linux__ */
/* dir = opendir ("/proc/self/fd"); */
/* if (dir) */
/* { */
/* while ((dir_entry = readdir (dir))) */
/* { */
/* s = dir_entry->d_name; */
/* if ( *s < '0' || *s > '9') */
/* continue; */
/* x = atoi (s); */
/* if (x > fds) */
/* fds = x; */
/* } */
/* closedir (dir); */
/* } */
/* if (fds != -1) */
/* { */
/* fds++; */
/* source = "/proc"; */
/* } */
/* } */
/* #endif /\* __linux__ *\/ */
#ifdef RLIMIT_NOFILE
if (fds == -1)