ensure that ast_safe_system() is thread-safe (issue #4947)
git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@6603 65c4cc65-6c06-0410-ace0-fbb531ad65f3
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asterisk.c
48
asterisk.c
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@ -349,42 +349,62 @@ static void null_sig_handler(int signal)
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}
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AST_MUTEX_DEFINE_STATIC(safe_system_lock);
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static unsigned int safe_system_level = 0;
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static void *safe_system_prev_handler;
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int ast_safe_system(const char *s)
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{
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/* XXX This function needs some optimization work XXX */
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pid_t pid;
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int x;
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int res;
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struct rusage rusage;
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int status;
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void (*prev_handler) = signal(SIGCHLD, null_sig_handler);
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unsigned int level;
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/* keep track of how many ast_safe_system() functions
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are running at this moment
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*/
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ast_mutex_lock(&safe_system_lock);
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level = safe_system_level++;
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/* only replace the handler if it has not already been done */
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if (level == 0)
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safe_system_prev_handler = signal(SIGCHLD, null_sig_handler);
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ast_mutex_unlock(&safe_system_lock);
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pid = fork();
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if (pid == 0) {
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/* Close file descriptors and launch system command */
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for (x=STDERR_FILENO + 1; x<4096;x++) {
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for (x = STDERR_FILENO + 1; x < 4096; x++)
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close(x);
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}
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res = execl("/bin/sh", "/bin/sh", "-c", s, NULL);
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execl("/bin/sh", "/bin/sh", "-c", s, NULL);
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exit(1);
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} else if (pid > 0) {
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for(;;) {
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res = wait4(pid, &status, 0, &rusage);
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if (res > -1) {
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if (WIFEXITED(status))
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res = WEXITSTATUS(status);
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else
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res = -1;
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res = WIFEXITED(status) ? WEXITSTATUS(status) : -1;
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break;
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} else if (errno != EINTR)
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break;
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} else {
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if (errno != EINTR)
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break;
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}
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}
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} else {
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ast_log(LOG_WARNING, "Fork failed: %s\n", strerror(errno));
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res = -1;
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}
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signal(SIGCHLD, prev_handler);
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ast_mutex_lock(&safe_system_lock);
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level = --safe_system_level;
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/* only restore the handler if we are the last one */
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if (level == 0)
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signal(SIGCHLD, safe_system_prev_handler);
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ast_mutex_unlock(&safe_system_lock);
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return res;
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}
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