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implement readiness notification #767

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Merged
navi-desu merged 1 commit into from
Feb 22, 2025
Merged

implement readiness notification #767

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40 changes: 40 additions & 0 deletions src/shared/misc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -532,6 +532,46 @@ pid_t get_pid(const char *applet,const char *pidfile)
return pid;
}

struct ready ready_parse(const char *applet, const char *ready_string)
{
struct ready ready = {0};
if (sscanf(ready_string, "fd:%d", &ready.fd) != 1)
eerrorx("%s: invalid ready '%s'.", applet, optarg);

ready.type = READY_FD;

if (pipe(ready.pipe) == -1)
eerrorx("%s: pipe failed: %s", applet, strerror(errno));

return ready;
}

bool ready_wait(const char *applet, struct ready ready)
{
if (ready.type == READY_NONE)
return true;

close(ready.pipe[1]);
ready.fd = ready.pipe[0];

for (;;) {
char buf[BUFSIZ];
ssize_t bytes = read(ready.fd, buf, BUFSIZ);
if (bytes == -1) {
if (errno != EINTR) {
eerror("%s: read failed '%s'\n", applet, strerror(errno));
return false;
}
continue;
}

if (memchr(buf, '\n', bytes))
break;
}

return true;
}

#ifndef HAVE_CLOSE_RANGE
static inline int close_range(int first RC_UNUSED,
int last RC_UNUSED,
Expand Down
13 changes: 13 additions & 0 deletions src/shared/misc.h
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Original file line number Diff line number Diff line change
Expand Up @@ -66,4 +66,17 @@ pid_t get_pid(const char *applet, const char *pidfile);

void cloexec_fds_from(int);

struct ready {
enum {
READY_NONE = 0,
READY_FD,
} type;

int pipe[2];
int fd;
};

struct ready ready_parse(const char *applet, const char *ready_string);
bool ready_wait(const char *applet, struct ready ready);

#endif
20 changes: 18 additions & 2 deletions src/start-stop-daemon/start-stop-daemon.c
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Expand Up @@ -89,6 +89,7 @@ enum {
LONGOPT_SCHEDULER,
LONGOPT_SCHEDULER_PRIO,
LONGOPT_SECBITS,
LONGOPT_READY,
};

const char *applet = NULL;
Expand Down Expand Up @@ -130,6 +131,7 @@ const struct option longopts[] = {
{ "progress", 0, NULL, 'P'},
{ "scheduler", 1, NULL, LONGOPT_SCHEDULER},
{ "scheduler-priority", 1, NULL, LONGOPT_SCHEDULER_PRIO},
{ "ready", 1, NULL, LONGOPT_READY},
longopts_COMMON
};
const char * const longopts_help[] = {
Expand Down Expand Up @@ -353,6 +355,8 @@ int main(int argc, char **argv)
int pipefd[2];
char readbuf[1];
ssize_t ss;
struct ready ready;
int ret = EXIT_SUCCESS;

applet = basename_c(argv[0]);
atexit(cleanup);
Expand Down Expand Up @@ -621,6 +625,10 @@ int main(int argc, char **argv)
sscanf(optarg, "%d", &sched_prio);
break;

case LONGOPT_READY:
ready = ready_parse(applet, optarg);
break;

case_RC_COMMON_GETOPT
}

Expand Down Expand Up @@ -1103,6 +1111,11 @@ int main(int argc, char **argv)

cloexec_fds_from(3);

if (ready.type == READY_FD) {
close(ready.pipe[0]);
dup2(ready.pipe[1], ready.fd);
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@N-R-K N-R-K Feb 22, 2025

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This should be checked.

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@navi-desu navi-desu Feb 22, 2025

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those don't really matter at this point. if they fail, the daemon can't write the \n, so the supervisor will already be waiting on ready until openrc-run times out and kill it

the best we can do is check and log, if we exit same thing happens, supervisor will start waiting until timeout and s-s-d won't be doing healthchecks

i'd argue for s-s-d it's better to let the exec go through, since then we have a chance of the daemon writing it's pid file so the timeout can kill it cleanly. for s-d that doesn't matter

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@N-R-K N-R-K Feb 22, 2025

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if they fail, the daemon can't write the \n

Not necessarily. Let's say the ready fd is supposed to be 3 and the dup2 fails. And in the daemon there's code like this:

somefd = open("somefile", ...); // this gets fd 3 since it's available
// ...
write(3, "ready\n", 6); // this now writes into "somefile"

Now you end up with the deamon potentially writing nonsense elsewhere.

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@navi-desu navi-desu Feb 22, 2025

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good point, i'll add the checks then

}

if (scheduler != NULL) {
int scheduler_index;
struct sched_param sched = {.sched_priority = sched_prio};
Expand Down Expand Up @@ -1187,7 +1200,10 @@ int main(int argc, char **argv)
start_wait = 0;
}

if (start_wait > 0) {
if (ready.type != READY_NONE) {
if (!ready_wait(applet, ready))
ret = EXIT_FAILURE;
} else if (start_wait > 0) {
struct timespec ts;
bool alive = false;

Expand Down Expand Up @@ -1227,6 +1243,6 @@ int main(int argc, char **argv)
rc_service_daemon_set(svcname, exec,
(const char *const *)margv, pidfile, true);

exit(EXIT_SUCCESS);
exit(ret);
/* NOTREACHED */
}
20 changes: 18 additions & 2 deletions src/supervise-daemon/supervise-daemon.c
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Expand Up @@ -82,6 +82,7 @@ enum {
LONGOPT_SECBITS,
LONGOPT_STDERR_LOGGER,
LONGOPT_STDOUT_LOGGER,
LONGOPT_READY,
};

const char *applet = NULL;
Expand Down Expand Up @@ -116,6 +117,7 @@ const struct option longopts[] = {
{ "stdout-logger",1, NULL, LONGOPT_STDOUT_LOGGER},
{ "stderr-logger",1, NULL, LONGOPT_STDERR_LOGGER},
{ "reexec", 0, NULL, '3'},
{ "ready", 1, NULL, LONGOPT_READY},
longopts_COMMON
};
const char * const longopts_help[] = {
Expand Down Expand Up @@ -165,6 +167,7 @@ static int devnull_fd = -1;
static int stdin_fd;
static int stdout_fd;
static int stderr_fd;
static struct ready ready;
static char *redirect_stderr = NULL;
static char *redirect_stdout = NULL;
static char *stderr_process = NULL;
Expand Down Expand Up @@ -588,6 +591,9 @@ RC_NORETURN static void child_process(char *exec, char **argv)

cloexec_fds_from(3);

if (ready.type == READY_FD)
dup2(ready.pipe[1], ready.fd);
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@N-R-K N-R-K Feb 22, 2025

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Same here.


cmdline = make_cmdline(argv);
syslog(LOG_INFO, "Child command line: %s", cmdline);
free(cmdline);
Expand Down Expand Up @@ -1070,6 +1076,10 @@ int main(int argc, char **argv)
stderr_process = optarg;
break;

case LONGOPT_READY:
ready = ready_parse(applet, optarg);
break;

case_RC_COMMON_GETOPT
}

Expand Down Expand Up @@ -1207,19 +1217,25 @@ int main(int argc, char **argv)
if (child_pid == -1)
eerrorx("%s: fork: %s", applet, strerror(errno));
if (child_pid != 0)
/* first parent process, do nothing. */
exit(EXIT_SUCCESS);
exit(ready_wait(applet, ready) ? EXIT_SUCCESS : EXIT_FAILURE);

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

if (ready.type == READY_FD)
close(ready.pipe[0]);

child_pid = fork();
if (child_pid == -1)
eerrorx("%s: fork: %s", applet, strerror(errno));
else if (child_pid != 0) {
if (ready.type == READY_FD)
close(ready.pipe[1]);
c = argv;
x = 0;
while (c && *c) {
Expand Down