From 45aef547896d1e91b2b2a121566320b5c3a17948 Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Fri, 22 Dec 2017 13:08:14 +0100 Subject: tree-wide: introduce new safe_fork() helper and port everything over MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This adds a new safe_fork() wrapper around fork() and makes use of it everywhere. The new wrapper does a couple of things we previously did manually and separately in a safer, more correct and automatic way: 1. Optionally resets signal handlers/mask in the child 2. Sets a name on all processes we fork off right after forking off (and the patch assigns useful names for all processes we fork off now, following a systematic naming scheme: always enclosed in () – in order to indicate that these are not proper, exec()ed processes, but only forked off children, and if the process is long-running with only our own code, without execve()'ing something else, it gets am "sd-" prefix.) 3. Optionally closes all file descriptors in the child 4. Optionally sets a PR_SET_DEATHSIG to SIGTERM in the child, in a safe way so that the parent dying before this happens being handled safely. 5. Optionally reopens the logs 6. Optionally connects stdin/stdout/stderr to /dev/null 7. Debug logs about the forked off processes. --- src/basic/exec-util.c | 25 +++++++++---------------- 1 file changed, 9 insertions(+), 16 deletions(-) (limited to 'src/basic/exec-util.c') diff --git a/src/basic/exec-util.c b/src/basic/exec-util.c index 718fbf7ee..19ac3686c 100644 --- a/src/basic/exec-util.c +++ b/src/basic/exec-util.c @@ -48,20 +48,19 @@ assert_cc(EAGAIN == EWOULDBLOCK); static int do_spawn(const char *path, char *argv[], int stdout_fd, pid_t *pid) { pid_t _pid; + int r; if (null_or_empty_path(path)) { log_debug("%s is empty (a mask).", path); return 0; } - _pid = fork(); - if (_pid < 0) - return log_error_errno(errno, "Failed to fork: %m"); - if (_pid == 0) { + r = safe_fork("(direxec)", FORK_DEATHSIG, &_pid); + if (r < 0) + return log_error_errno(r, "Failed to fork: %m"); + if (r == 0) { char *_argv[2]; - assert_se(prctl(PR_SET_PDEATHSIG, SIGTERM) == 0); - if (stdout_fd >= 0) { /* If the fd happens to be in the right place, go along with that */ if (stdout_fd != STDOUT_FILENO && @@ -107,11 +106,6 @@ static int do_execute( * If callbacks is nonnull, execution is serial. Otherwise, we default to parallel. */ - (void) reset_all_signal_handlers(); - (void) reset_signal_mask(); - - assert_se(prctl(PR_SET_PDEATHSIG, SIGTERM) == 0); - r = conf_files_list_strv(&paths, NULL, NULL, CONF_FILES_EXECUTABLE, (const char* const*) directories); if (r < 0) return r; @@ -226,11 +220,10 @@ int execute_directories( * them to finish. Optionally a timeout is applied. If a file with the same name * exists in more than one directory, the earliest one wins. */ - executor_pid = fork(); - if (executor_pid < 0) - return log_error_errno(errno, "Failed to fork: %m"); - - if (executor_pid == 0) { + r = safe_fork("(sd-executor)", FORK_RESET_SIGNALS|FORK_DEATHSIG, &executor_pid); + if (r < 0) + return log_error_errno(r, "Failed to fork: %m"); + if (r == 0) { r = do_execute(dirs, timeout, callbacks, callback_args, fd, argv); _exit(r < 0 ? EXIT_FAILURE : EXIT_SUCCESS); } -- cgit v1.2.1