If flock is executed from a process which has set SIGCHLD to SIG_IGN, then
flock will eat cpu and hang indefinitely if given a command to execute.
So before we fork(), make sure to set SIGCHLD handling back to the default
so that the later waitpid() doesn't freak out on us.
Signed-off-by: Mike Frysinger <vapier@xxxxxxxxxx>
---
issue can be seen with simple test:
$ cat test.c
#include <signal.h>
#include <unistd.h>
int main(int argc, char *argv[])
{
signal(SIGCHLD, SIG_IGN);
return execv(argv[1], argv+1);
}
$ gcc test.c -o foo
$ ./foo ./flock . -c "ls -d /"
/
<hangs here>
$ strace -p <flock pid>
wait4(7053, 0x7fff5d03fed8, 0, NULL) = -1 ECHILD (No child processes)
wait4(7053, 0x7fff5d03fed8, 0, NULL) = -1 ECHILD (No child processes)
wait4(7053, 0x7fff5d03fed8, 0, NULL) = -1 ECHILD (No child processes)
wait4(7053, 0x7fff5d03fed8, 0, NULL) = -1 ECHILD (No child processes)
....
sys-utils/flock.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/sys-utils/flock.c b/sys-utils/flock.c
index a53f6d3..6a9acb8 100644
--- a/sys-utils/flock.c
+++ b/sys-utils/flock.c
@@ -287,6 +287,8 @@ int main(int argc, char *argv[])
if ( cmd_argv ) {
pid_t w, f;
+ /* Clear any inherited settings */
+ signal(SIGCHLD, SIG_DFL);
f = fork();
if ( f < 0 ) {
--
1.6.5.4
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