Date: Thu, 28 Sep 2023 15:52:48 GMT From: Mark Johnston <markj@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 8536447a07fa - main - syslogd: Use pipe to communicate with daemon Message-ID: <202309281552.38SFqm8b022587@gitrepo.freebsd.org>
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The branch main has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=8536447a07fa29073f93af70808db58c760aa6f9 commit 8536447a07fa29073f93af70808db58c760aa6f9 Author: Jake Freeland <jfree@FreeBSD.org> AuthorDate: 2023-09-01 02:51:28 +0000 Commit: Mark Johnston <markj@FreeBSD.org> CommitDate: 2023-09-28 15:51:54 +0000 syslogd: Use pipe to communicate with daemon Previously, syslogd's daemon process would signal that it had finished initialization using SIGALRM. In capability mode, signal delivery is not allowed, so use a pipe to indicate that it is ready to accept messages. Reviewed by: markj MFC after: 3 weeks Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D41459 --- usr.sbin/syslogd/syslogd.c | 100 ++++++++++++++++++++------------------------- 1 file changed, 44 insertions(+), 56 deletions(-) diff --git a/usr.sbin/syslogd/syslogd.c b/usr.sbin/syslogd/syslogd.c index 3f9633ca8c35..8d2f3c3edf14 100644 --- a/usr.sbin/syslogd/syslogd.c +++ b/usr.sbin/syslogd/syslogd.c @@ -135,6 +135,7 @@ static char sccsid[] = "@(#)syslogd.c 8.3 (Berkeley) 4/4/94"; #include <limits.h> #include <netdb.h> #include <paths.h> +#include <poll.h> #include <regex.h> #include <signal.h> #include <stdbool.h> @@ -471,7 +472,6 @@ static bool validate(struct sockaddr *, const char *); static void unmapped(struct sockaddr *); static void wallmsg(struct filed *, struct iovec *, const int iovlen); static int waitdaemon(int); -static void timedout(int); static void increase_rcvbuf(int); static void @@ -599,8 +599,8 @@ main(int argc, char *argv[]) struct sigaction act = { }; struct kevent ev; struct socklist *sl; - pid_t ppid = -1, spid; - int ch, kq, s; + pid_t spid; + int ch, kq, ppipe_w = -1, s; char *p; bool bflag = false, pflag = false, Sflag = false; @@ -813,14 +813,9 @@ main(int argc, char *argv[]) (void)strlcpy(bootfile, getbootfile(), sizeof(bootfile)); - if ((!Foreground) && (!Debug)) { - ppid = waitdaemon(30); - if (ppid < 0) { - warn("could not become daemon"); - pidfile_remove(pfh); - exit(1); - } - } else if (Debug) + if (!Foreground && !Debug) + ppipe_w = waitdaemon(30); + else if (Debug) setlinebuf(stdout); kq = kqueue(); @@ -868,9 +863,14 @@ main(int argc, char *argv[]) for (;;) { if (needdofsync) { dofsync(); - if (ppid != -1) { - kill(ppid, SIGALRM); - ppid = -1; + if (ppipe_w != -1) { + /* + * Close our end of the pipe so our + * parent knows that we have finished + * initialization. + */ + (void)close(ppipe_w); + ppipe_w = -1; } } if (kevent(kq, NULL, 0, &ev, 1, NULL) == -1) { @@ -3237,64 +3237,52 @@ markit(void) /* * fork off and become a daemon, but wait for the child to come online * before returning to the parent, or we get disk thrashing at boot etc. - * Set a timer so we don't hang forever if it wedges. */ static int waitdaemon(int maxwait) { - int status; - pid_t pid, childpid; + struct pollfd pollfd; + int events, pipefd[2], status; + pid_t pid; - switch (childpid = fork()) { - case -1: - return (-1); - case 0: - break; - default: - signal(SIGALRM, timedout); - alarm(maxwait); - while ((pid = wait3(&status, 0, NULL)) != -1) { + if (pipe(pipefd) == -1) { + warn("failed to daemonize, pipe"); + die(0); + } + pid = fork(); + if (pid == -1) { + warn("failed to daemonize, fork"); + die(0); + } else if (pid > 0) { + close(pipefd[1]); + pollfd.fd = pipefd[0]; + pollfd.events = POLLHUP; + events = poll(&pollfd, 1, maxwait * 1000); + if (events == -1) + err(1, "failed to daemonize, poll"); + else if (events == 0) + errx(1, "timed out waiting for child"); + if (waitpid(pid, &status, WNOHANG) > 0) { if (WIFEXITED(status)) errx(1, "child pid %d exited with return code %d", - pid, WEXITSTATUS(status)); + pid, WEXITSTATUS(status)); if (WIFSIGNALED(status)) errx(1, "child pid %d exited on signal %d%s", - pid, WTERMSIG(status), - WCOREDUMP(status) ? " (core dumped)" : - ""); - if (pid == childpid) /* it's gone... */ - break; + pid, WTERMSIG(status), + WCOREDUMP(status) ? " (core dumped)" : ""); } exit(0); } - - if (setsid() == -1) - return (-1); - + close(pipefd[0]); + if (setsid() == -1) { + warn("failed to daemonize, setsid"); + die(0); + } (void)chdir("/"); (void)dup2(nulldesc, STDIN_FILENO); (void)dup2(nulldesc, STDOUT_FILENO); (void)dup2(nulldesc, STDERR_FILENO); - return (getppid()); -} - -/* - * We get a SIGALRM from the child when it's running and finished doing it's - * fsync()'s or O_SYNC writes for all the boot messages. - * - * We also get a signal from the kernel if the timer expires, so check to - * see what happened. - */ -static void -timedout(int sig __unused) -{ - int left; - left = alarm(0); - signal(SIGALRM, SIG_DFL); - if (left == 0) - errx(1, "timed out waiting for child"); - else - _exit(0); + return (pipefd[1]); } /*
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