diff options
| -rwxr-xr-x | asterisk.c | 48 |
1 files changed, 34 insertions, 14 deletions
diff --git a/asterisk.c b/asterisk.c index d251f666b..7c74e67f1 100755 --- a/asterisk.c +++ b/asterisk.c @@ -349,42 +349,62 @@ static void null_sig_handler(int signal) } +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; } |