path: root/src/process
diff options
authorRich Felker <>2013-08-08 23:17:05 -0400
committerRich Felker <>2013-08-08 23:17:05 -0400
commitd4d6d6f322cd13cfca2b179345cdcf67997c3529 (patch)
tree14f41853339c148be7315a2471d7123f3ae3239f /src/process
parent72482f9020e4362b8d35849df6dca49f26d24c54 (diff)
block signals during fork
there are several reasons for this. some of them are related to race conditions that arise since fork is required to be async-signal-safe: if fork or pthread_create is called from a signal handler after the fork syscall has returned but before the subsequent userspace code has finished, inconsistent state could result. also, there seem to be kernel and/or strace bugs related to arrival of signals during fork, at least on some versions, and simply blocking signals eliminates the possibility of such bugs.
Diffstat (limited to 'src/process')
1 files changed, 3 insertions, 0 deletions
diff --git a/src/process/fork.c b/src/process/fork.c
index fb8a430a..1a82f428 100644
--- a/src/process/fork.c
+++ b/src/process/fork.c
@@ -13,7 +13,9 @@ weak_alias(dummy, __fork_handler);
pid_t fork(void)
pid_t ret;
+ sigset_t set;
+ __block_all_sigs(&set);
ret = syscall(SYS_fork);
if (libc.main_thread && !ret) {
pthread_t self = __pthread_self();
@@ -22,6 +24,7 @@ pid_t fork(void)
libc.threads_minus_1 = 0;
libc.main_thread = self;
+ __restore_sigs(&set);
return ret;