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supervise-daemon: make logger a child of the supervisor #1103

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749531d
supervise-daemon: pre-close ctty once in main
navi-desu Oct 17, 2026
db1ac50
supervise-daemon: make logger a child of the supervisor
navi-desu Oct 17, 2026
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137 changes: 80 additions & 57 deletions src/supervise-daemon/supervise-daemon.c
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Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,7 @@
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>
#include <spawn.h>

#ifdef HAVE_PAM
#include <security/pam_appl.h>
Expand Down Expand Up @@ -172,9 +173,9 @@ static uid_t uid = 0;
static gid_t gid = 0;
static bool stopgroup = false;
static int devnull_fd = -1;
static int stdin_fd;
static int stdout_fd;
static int stderr_fd;
static int stdin_fds[2], stdout_fds[2], stderr_fds[2];
static int stdout_pid = -1;
static int stderr_pid = -1;
static struct notify notify;
static char *redirect_stdin = NULL;
static char *redirect_stderr = NULL;
Expand Down Expand Up @@ -250,7 +251,7 @@ static void handle_signal(int sig)
while (waitpid((pid_t)(-1), NULL, WNOHANG) > 0) {}
else {
while ((pid = waitpid((pid_t)(-1), NULL, WNOHANG|WNOWAIT)) > 0) {
if (pid == child_pid)
if (pid == child_pid || pid == stdout_pid || pid == stderr_pid)
break;
pid = waitpid(pid, NULL, WNOHANG);
}
Expand Down Expand Up @@ -500,12 +501,6 @@ RC_NORETURN static void child_process(char *exec, char **argv)
}
#endif

/* remove the controlling tty */
#ifdef TIOCNOTTY
ioctl(tty_fd, TIOCNOTTY, 0);
close(tty_fd);
#endif

/* Clean the environment of any RC_ variables */
env_list = rc_stringlist_new();
i = 0;
Expand Down Expand Up @@ -566,49 +561,11 @@ RC_NORETURN static void child_process(char *exec, char **argv)
setenv("PATH", newpath, 1);
}

stdin_fd = devnull_fd;
stdout_fd = devnull_fd;
stderr_fd = devnull_fd;
if (redirect_stdin) {
if ((stdin_fd = xopen_nonblock(redirect_stdin, O_RDONLY, 0)) == -1)
eerrorx("%s: unable to redirect the input file"
" for stdin `%s': %s",
applet, redirect_stdin, strerror(errno));
}
if (redirect_stdout) {
if ((stdout_fd = xopen_nonblock(redirect_stdout,
O_WRONLY | O_CREAT | O_APPEND,
S_IRUSR | S_IWUSR)) == -1)
eerrorx("%s: unable to redirect the logfile"
" for stdout `%s': %s",
applet, redirect_stdout, strerror(errno));
} else if (stdout_process) {
stdout_fd = rc_pipe_command(stdout_process, devnull_fd);
if (stdout_fd == -1)
eerrorx("%s: unable to open the logging process"
" for stdout `%s': %s",
applet, stdout_process, strerror(errno));
}
if (redirect_stderr) {
if ((stderr_fd = xopen_nonblock(redirect_stderr,
O_WRONLY | O_CREAT | O_APPEND,
S_IRUSR | S_IWUSR)) == -1)
eerrorx("%s: unable to redirect the logfile"
" for stderr `%s': %s",
applet, redirect_stderr, strerror(errno));
} else if (stderr_process) {
stderr_fd = rc_pipe_command(stderr_process, devnull_fd);
if (stderr_fd == -1)
eerrorx("%s: unable to open the logging process"
" for stderr `%s': %s",
applet, stderr_process, strerror(errno));
}

dup2(stdin_fd, STDIN_FILENO);
dup2(stdin_fds[1], STDIN_FILENO);
if (redirect_stdout || stdout_process || rc_yesno(getenv("EINFO_QUIET")))
dup2(stdout_fd, STDOUT_FILENO);
dup2(stdout_fds[1], STDOUT_FILENO);
if (redirect_stderr || stderr_process || rc_yesno(getenv("EINFO_QUIET")))
dup2(stderr_fd, STDERR_FILENO);
dup2(stderr_fds[1], STDERR_FILENO);

cloexec_fds_from(3);

Expand Down Expand Up @@ -639,6 +596,43 @@ RC_NORETURN static void child_process(char *exec, char **argv)
eerrorx("%s: failed to exec `%s': %s", applet, exec,strerror(errno));
}

static inline int spawn_logger(const char *process, pid_t *pid, int stdin)
{
const char *command[] = { "sh", "-c", process, NULL };
posix_spawn_file_actions_t fds;
int err = 0;

if ((err = posix_spawn_file_actions_init(&fds)))
goto out;
if ((err = posix_spawn_file_actions_adddup2(&fds, stdin, STDIN_FILENO)))
goto out;
if ((err = posix_spawn_file_actions_adddup2(&fds, devnull_fd, STDOUT_FILENO)))
goto out;
if ((err = posix_spawn_file_actions_adddup2(&fds, devnull_fd, STDERR_FILENO)))
goto out;

err = posix_spawnp(pid, "sh", &fds, NULL, UNCONST(command), environ);
out:
posix_spawn_file_actions_destroy(&fds);
return err;
}

static inline void kill_logger(pid_t pid)
{
sigset_t set;
int sig;

sigemptyset(&set);
sigaddset(&set, SIGCHLD);
sigaddset(&set, SIGALRM);

kill(pid, SIGTERM);
alarm(5);
sigwait(&set, &sig);
if (sig == SIGALRM)
kill(pid, SIGKILL);
}

RC_NORETURN static void supervisor(char *exec, char **argv)
{
FILE *fp;
Expand Down Expand Up @@ -684,12 +678,6 @@ RC_NORETURN static void supervisor(char *exec, char **argv)
rc_service_daemon_set(svcname, exec, (const char * const *) argv,
pidfile, true);

/* remove the controlling tty */
#ifdef TIOCNOTTY
ioctl(tty_fd, TIOCNOTTY, 0);
close(tty_fd);
#endif

/*
* Supervisor main loop
*/
Expand Down Expand Up @@ -753,8 +741,22 @@ RC_NORETURN static void supervisor(char *exec, char **argv)
stopgroup, false, false, true);
if (nkilled > 0)
syslog(LOG_INFO, "killed %d processes", nkilled);

if (stdout_process)
kill_logger(stdout_pid);
if (stderr_process)
kill_logger(stderr_pid);
continue;
}

if (waitpid(stdout_pid, NULL, WNOHANG) == stdout_pid)
if ((errno = spawn_logger(stdout_process, &stdout_pid, stdout_fds[0])))
syslog(LOG_ERR, "failed to respawn logger '%s': %s", stdout_process, strerror(errno));

if (waitpid(stderr_pid, NULL, WNOHANG) == stderr_pid)
if ((errno = spawn_logger(stderr_process, &stderr_pid, stderr_fds[0])))
syslog(LOG_ERR, "failed to respawn logger '%s': %s", stderr_process, strerror(errno));

wait_pid = waitpid(child_pid, &i, WNOHANG);
if (wait_pid == child_pid) {
if (WIFEXITED(i))
Expand Down Expand Up @@ -826,6 +828,21 @@ RC_NORETURN static void supervisor(char *exec, char **argv)
exit(EXIT_SUCCESS);
}

static inline void setup_fd(const char *redirect, const char *process, int fd[2], pid_t *pid) {
int err;

if (redirect) {
if ((fd[1] = xopen_nonblock(redirect, O_WRONLY | O_CREAT | O_APPEND, S_IRUSR | S_IWUSR)) == -1)
eerrorx("%s: unable to redirect the logfile for stdout '%s': %s", applet, redirect, strerror(errno));
} else if (process) {
pipe2(fd, O_CLOEXEC);
if ((err = spawn_logger(process, pid, fd[0])))
eerrorx("%s: unable to open the logging process '%s': %s", applet, process, strerror(err));
} else {
fd[0] = fd[1] = devnull_fd;
}
}

int main(int argc, char **argv)
{
int opt;
Expand Down Expand Up @@ -1280,12 +1297,18 @@ int main(int argc, char **argv)

#ifdef TIOCNOTTY
tty_fd = open("/dev/tty", O_RDWR);
ioctl(tty_fd, TIOCNOTTY, 0);
close(tty_fd);
#endif
devnull_fd = open("/dev/null", O_RDWR);
dup2(devnull_fd, STDIN_FILENO);
dup2(devnull_fd, STDOUT_FILENO);
dup2(devnull_fd, STDERR_FILENO);

setup_fd(redirect_stdin, NULL, stdin_fds, NULL);
setup_fd(redirect_stdout, stdout_process, stdout_fds, &stdout_pid);
setup_fd(redirect_stderr, stderr_process, stderr_fds, &stderr_pid);

if (notify.type == NOTIFY_FD)
close(notify.pipe[0]);

Expand Down
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