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/basic/async.c | 21 +++++---------------- 1 file changed, 5 insertions(+), 16 deletions(-) (limited to 'src/basic/async.c') diff --git a/src/basic/async.c b/src/basic/async.c index c510cbd7f5..21e05d9c2c 100644 --- a/src/basic/async.c +++ b/src/basic/async.c @@ -61,29 +61,18 @@ finish: } int asynchronous_sync(void) { - pid_t pid; + int r; /* This forks off an invocation of fork() as a child process, in order to initiate synchronization to * disk. Note that we implement this as helper process rather than thread as we don't want the sync() to hang our * original process ever, and a thread would do that as the process can't exit with threads hanging in blocking * syscalls. */ - log_debug("Spawning new process for sync"); - - pid = fork(); - if (pid < 0) - return -errno; - - if (pid == 0) { + r = safe_fork("(sd-sync)", FORK_RESET_SIGNALS|FORK_CLOSE_ALL_FDS, NULL); + if (r < 0) + return r; + if (r == 0) { /* Child process */ - - (void) rename_process("(sd-sync)"); - - (void) reset_all_signal_handlers(); - (void) reset_signal_mask(); - - (void) close_all_fds(NULL, 0); - (void) sync(); _exit(EXIT_SUCCESS); } -- cgit v1.2.3