From 4c253ed1cae8b4df72ce1353ee826a4fae399e25 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/activate/activate.c | 31 ++++++++----------------------- 1 file changed, 8 insertions(+), 23 deletions(-) (limited to 'src/activate') diff --git a/src/activate/activate.c b/src/activate/activate.c index 83807efdcf..67067a8f32 100644 --- a/src/activate/activate.c +++ b/src/activate/activate.c @@ -267,38 +267,23 @@ static int exec_process(const char* name, char **argv, char **env, int start_fd, static int fork_and_exec_process(const char* child, char** argv, char **env, int fd) { _cleanup_free_ char *joined = NULL; - pid_t parent_pid, child_pid; + pid_t child_pid; + int r; joined = strv_join(argv, " "); if (!joined) return log_oom(); - parent_pid = getpid_cached(); - - child_pid = fork(); - if (child_pid < 0) - return log_error_errno(errno, "Failed to fork: %m"); - - /* In the child */ - if (child_pid == 0) { - - (void) reset_all_signal_handlers(); - (void) reset_signal_mask(); - - /* Make sure the child goes away when the parent dies */ - if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0) - _exit(EXIT_FAILURE); - - /* Check whether our parent died before we were able - * to set the death signal */ - if (getppid() != parent_pid) - _exit(EXIT_SUCCESS); - + r = safe_fork("(activate)", FORK_RESET_SIGNALS|FORK_DEATHSIG, &child_pid); + if (r < 0) + return log_error_errno(r, "Failed to fork: %m"); + if (r == 0) { + /* In the child */ exec_process(child, argv, env, fd, 1); _exit(EXIT_FAILURE); } - log_info("Spawned %s (%s) as PID %d", child, joined, child_pid); + log_info("Spawned %s (%s) as PID " PID_FMT ".", child, joined, child_pid); return 0; } -- cgit v1.2.1