Update of /usr/cvsroot/asterisk
In directory mongoose.digium.com:/tmp/cvs-serv6182
Modified Files:
asterisk.c
Log Message:
ensure that ast_safe_system() is thread-safe (issue #4947)
Index: asterisk.c
===================================================================
RCS file: /usr/cvsroot/asterisk/asterisk.c,v
retrieving revision 1.180
retrieving revision 1.181
diff -u -d -r1.180 -r1.181
--- asterisk.c 14 Sep 2005 20:46:49 -0000 1.180
+++ asterisk.c 14 Sep 2005 22:40:54 -0000 1.181
@@ -349,42 +349,62 @@
}
+AST_MUTEX_DEFINE_STATIC(safe_system_lock);
+static unsigned int safe_system_level = 0;
+static void *safe_system_prev_handler;
+
int ast_safe_system(const char *s)
{
- /* XXX This function needs some optimization work XXX */
pid_t pid;
int x;
int res;
struct rusage rusage;
int status;
- void (*prev_handler) = signal(SIGCHLD, null_sig_handler);
+ unsigned int level;
+
+ /* keep track of how many ast_safe_system() functions
+ are running at this moment
+ */
+ ast_mutex_lock(&safe_system_lock);
+ level = safe_system_level++;
+
+ /* only replace the handler if it has not already been done */
+ if (level == 0)
+ safe_system_prev_handler = signal(SIGCHLD, null_sig_handler);
+
+ ast_mutex_unlock(&safe_system_lock);
+
pid = fork();
+
if (pid == 0) {
/* Close file descriptors and launch system command */
- for (x=STDERR_FILENO + 1; x<4096;x++) {
+ for (x = STDERR_FILENO + 1; x < 4096; x++)
close(x);
- }
- res = execl("/bin/sh", "/bin/sh", "-c", s, NULL);
+ execl("/bin/sh", "/bin/sh", "-c", s, NULL);
exit(1);
} else if (pid > 0) {
for(;;) {
res = wait4(pid, &status, 0, &rusage);
if (res > -1) {
- if (WIFEXITED(status))
- res = WEXITSTATUS(status);
- else
- res = -1;
+ res = WIFEXITED(status) ? WEXITSTATUS(status) :
-1;
+ break;
+ } else if (errno != EINTR)
break;
- } else {
- if (errno != EINTR)
- break;
- }
}
} else {
ast_log(LOG_WARNING, "Fork failed: %s\n", strerror(errno));
res = -1;
}
- signal(SIGCHLD, prev_handler);
+
+ ast_mutex_lock(&safe_system_lock);
+ level = --safe_system_level;
+
+ /* only restore the handler if we are the last one */
+ if (level == 0)
+ signal(SIGCHLD, safe_system_prev_handler);
+
+ ast_mutex_unlock(&safe_system_lock);
+
return res;
}
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