commit a3e8dd750e830d79b09f52874c47c4a9f93cdf6a
parent 4a2b8fe4162e2efad7724fba0f5c353abf4c54b5
Author: cowmonk <cowmonk@based.pt>
Date: Tue, 6 Oct 2026 12:17:36 -0700
replace _GNU_SOURCE with _POSIX_C_SOURCE and replace usleep() with nanosleep()
Other notable changes are:
- signal_handler() to save and restore `errno` around its write to the self-pipe.
- supervisor ignores `SIGPIPE`, checking that setting the disposition
suceeds.
- Restored the default `SIGPIPE` dispostion in both the service and
logger child before exec.
among many others to improve portability and quality of the supervisor
Diffstat:
| M | serva.c | | | 157 | +++++++++++++++++++++++++++++++++++++++++++++---------------------------------- |
1 file changed, 90 insertions(+), 67 deletions(-)
diff --git a/serva.c b/serva.c
@@ -1,7 +1,7 @@
/* serva: a simple service supervisor */
-#ifndef _GNU_SOURCE
-#define _GNU_SOURCE /* needed for PATH_MAX */
+#ifndef _XOPEN_SOURCE
+#define _XOPEN_SOURCE 700
#endif
#include "util.h"
@@ -64,16 +64,37 @@ static size_t nsvcs;
static int sigpipe[2];
static volatile sig_atomic_t got_term;
+static void
+cloexec(int fd)
+{
+ int flags;
+
+ flags = fcntl(fd, F_GETFD);
+ if (flags < 0 || fcntl(fd, F_SETFD, flags | FD_CLOEXEC) < 0)
+ eprintf("fcntl FD_CLOEXEC:");
+}
+
+static void
+sleep_briefly(void)
+{
+ struct timespec delay = { 0, 100000000L };
+
+ while (nanosleep(&delay, &delay) < 0 && errno == EINTR)
+ ;
+}
+
/* signal handler: wake self-pipe on SIGCHLD, flag SIGTERM */
static void
signal_handler(int sig)
{
char c;
+ int saved_errno = errno;
if (sig == SIGTERM)
got_term = 1;
c = 0;
write(sigpipe[1], &c, 1);
+ errno = saved_errno;
}
/* parse @-templates: "tty@tty1" -> arg "tty1" */
@@ -336,8 +357,12 @@ start_service(struct Service *s)
/* create logging pipe if needed */
if (s->has_logger && s->pipefd[0] < 0) {
- if (pipe(s->pipefd) < 0)
+ if (pipe(s->pipefd) < 0) {
weprintf("pipe:");
+ return;
+ }
+ cloexec(s->pipefd[0]);
+ cloexec(s->pipefd[1]);
}
s->last_start = time(NULL);
@@ -355,6 +380,7 @@ start_service(struct Service *s)
sigemptyset(&empty);
sigprocmask(SIG_SETMASK, &empty, NULL);
+ signal(SIGPIPE, SIG_DFL);
setsid();
if (chdir(s->dir) < 0)
@@ -393,6 +419,7 @@ start_service(struct Service *s)
sigemptyset(&empty);
sigprocmask(SIG_SETMASK, &empty, NULL);
+ signal(SIGPIPE, SIG_DFL);
if (chdir(s->dir) < 0)
eprintf("chdir %s:", s->dir);
@@ -432,7 +459,7 @@ stop_service(struct Service *s)
break;
if (i == 40)
kill(s->pid, SIGKILL);
- usleep(100000);
+ sleep_briefly();
}
s->pid = 0;
}
@@ -459,7 +486,7 @@ stop_for_dep(struct Service *s)
break;
if (i == 40)
kill(s->pid, SIGKILL);
- usleep(100000);
+ sleep_briefly();
}
s->pid = 0;
}
@@ -642,52 +669,50 @@ status_str(struct Service *s)
return "DOWN";
}
-/* format_status: append one status line for s to resp */
-static size_t
-format_status(struct Service *s, char *resp, size_t size, size_t off)
+/* format_status: write one service's status to the control stream */
+static void
+format_status(struct Service *s, FILE *out)
{
char full[2 * NAME_MAX + 2];
int j;
snprintf(full, sizeof(full), "%s/%s", s->stage, s->name);
- off += snprintf(resp + off, size - off,
- "%-32s %s%s pid=%d runs=%lu uptime=%lds",
+ fprintf(out,
+ "%-32s %s%s pid=%ld runs=%lu uptime=%lds",
full,
status_str(s),
s->noreset ? " (noreset)" : "",
- s->pid,
+ (long)s->pid,
s->nruns,
s->pid > 0 ? (long)(time(NULL) - s->last_start) : 0L);
if (s->last_exit >= 0)
- off += snprintf(resp + off, size - off,
- " exit=%d", s->last_exit);
+ fprintf(out, " exit=%d", s->last_exit);
if (s->last_sig > 0)
- off += snprintf(resp + off, size - off,
- " sig=%d", s->last_sig);
+ fprintf(out, " sig=%d", s->last_sig);
if (s->nneed > 0) {
- off += snprintf(resp + off, size - off, " need=");
+ fprintf(out, " need=");
for (j = 0; j < s->nneed; j++)
- off += snprintf(resp + off, size - off, "%s%s",
+ fprintf(out, "%s%s",
j ? "," : "", s->need[j]);
}
if (s->nafter > 0) {
- off += snprintf(resp + off, size - off, " after=");
+ fprintf(out, " after=");
for (j = 0; j < s->nafter; j++)
- off += snprintf(resp + off, size - off, "%s%s",
+ fprintf(out, "%s%s",
j ? "," : "", s->after[j]);
}
- off += snprintf(resp + off, size - off, "\n");
- return off;
+ fputc('\n', out);
}
/* handle_conn: process one control connection */
static void
handle_conn(int conn)
{
- char buf[4096], resp[8192], cmd, *name, *p;
+ char buf[4096], cmd, *name, *p;
ssize_t n;
- size_t i, off;
+ size_t i;
struct Service *s;
+ FILE *out;
n = read(conn, buf, sizeof(buf) - 1);
if (n <= 0) {
@@ -695,6 +720,12 @@ handle_conn(int conn)
return;
}
buf[n] = '\0';
+ out = fdopen(conn, "w");
+ if (!out) {
+ weprintf("fdopen:");
+ close(conn);
+ return;
+ }
p = strchr(buf, '\n');
if (p)
@@ -712,13 +743,11 @@ handle_conn(int conn)
svcs[i].want_up = 1;
}
check_restarts();
- off = snprintf(resp, sizeof(resp),
- "OK: started all\n");
+ fprintf(out, "OK: started all\n");
} else {
s = find_service(name);
if (!s) {
- off = snprintf(resp, sizeof(resp),
- "ERR: no such service: %s\n", name);
+ fprintf(out, "ERR: no such service: %s\n", name);
break;
}
/* explicit svc -u overrides down and deps */
@@ -727,92 +756,73 @@ handle_conn(int conn)
s->next_restart = 0;
s->backoff = 0;
start_service(s);
- off = snprintf(resp, sizeof(resp),
- "OK: %s up\n", name);
+ fprintf(out, "OK: %s up\n", name);
}
break;
case 'd':
if (strcmp(name, "a") == 0) {
for (i = 0; i < nsvcs; i++)
stop_service(&svcs[i]);
- off = snprintf(resp, sizeof(resp),
- "OK: stopped all\n");
+ fprintf(out, "OK: stopped all\n");
} else {
s = find_service(name);
if (!s) {
- off = snprintf(resp, sizeof(resp),
- "ERR: no such service: %s\n", name);
+ fprintf(out, "ERR: no such service: %s\n", name);
break;
}
stop_service(s);
- off = snprintf(resp, sizeof(resp),
- "OK: %s down\n", name);
+ fprintf(out, "OK: %s down\n", name);
}
stop_cascade();
break;
case 'r':
s = find_service(name);
if (!s) {
- off = snprintf(resp, sizeof(resp),
- "ERR: no such service: %s\n", name);
+ fprintf(out, "ERR: no such service: %s\n", name);
break;
}
restart_service(s);
- off = snprintf(resp, sizeof(resp),
- "OK: %s restarted\n", name);
+ fprintf(out, "OK: %s restarted\n", name);
break;
case 'k':
s = find_service(name);
if (!s) {
- off = snprintf(resp, sizeof(resp),
- "ERR: no such service: %s\n", name);
+ fprintf(out, "ERR: no such service: %s\n", name);
break;
}
if (s->pid > 0)
kill(s->pid, SIGKILL);
- off = snprintf(resp, sizeof(resp),
- "OK: %s killed\n", name);
+ fprintf(out, "OK: %s killed\n", name);
break;
case 't':
s = find_service(name);
if (!s) {
- off = snprintf(resp, sizeof(resp),
- "ERR: no such service: %s\n", name);
+ fprintf(out, "ERR: no such service: %s\n", name);
break;
}
if (s->pid > 0)
kill(s->pid, SIGTERM);
- off = snprintf(resp, sizeof(resp),
- "OK: %s terminated\n", name);
+ fprintf(out, "OK: %s terminated\n", name);
break;
case 's':
- off = 0;
if (name[0]) {
s = find_service(name);
if (!s) {
- off = snprintf(resp, sizeof(resp),
- "ERR: no such service: %s\n", name);
+ fprintf(out, "ERR: no such service: %s\n", name);
break;
}
- off = format_status(s, resp, sizeof(resp), 0);
+ format_status(s, out);
break;
}
- for (i = 0; i < nsvcs; i++) {
- s = &svcs[i];
- if (off + 128 >= sizeof(resp))
- break;
- off = format_status(s, resp, sizeof(resp), off);
- }
+ for (i = 0; i < nsvcs && !ferror(out); i++)
+ format_status(&svcs[i], out);
break;
default:
- off = snprintf(resp, sizeof(resp),
- "ERR: unknown command\n");
+ fprintf(out, "ERR: unknown command\n");
break;
}
- writeall(conn, resp, off);
- shutdown(conn, SHUT_WR);
- close(conn);
+ fshut(out, SOCK_PATH);
}
static void
@@ -832,14 +842,20 @@ main(void)
struct sockaddr_un addr;
struct pollfd pfds[2];
struct sigaction sa;
+ mode_t mask;
char c;
size_t i;
/* self-pipe for signal integration with poll */
if (pipe(sigpipe) < 0)
eprintf("pipe:");
- fcntl(sigpipe[0], F_SETFL, O_NONBLOCK);
- fcntl(sigpipe[1], F_SETFL, O_NONBLOCK);
+ cloexec(sigpipe[0]);
+ cloexec(sigpipe[1]);
+ if (fcntl(sigpipe[0], F_SETFL, O_NONBLOCK) < 0 ||
+ fcntl(sigpipe[1], F_SETFL, O_NONBLOCK) < 0)
+ eprintf("fcntl O_NONBLOCK:");
+ if (signal(SIGPIPE, SIG_IGN) == SIG_ERR)
+ eprintf("signal SIGPIPE:");
/* install signal handlers */
memset(&sa, 0, sizeof(sa));
@@ -855,15 +871,20 @@ main(void)
sock = socket(AF_UNIX, SOCK_STREAM, 0);
if (sock < 0)
eprintf("socket:");
+ cloexec(sock);
memset(&addr, 0, sizeof(addr));
addr.sun_family = AF_UNIX;
- strlcpy(addr.sun_path, SOCK_PATH, sizeof(addr.sun_path));
+ if (strlcpy(addr.sun_path, SOCK_PATH, sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
+ eprintf("socket path too long: %s\n", SOCK_PATH);
unlink(SOCK_PATH);
+ mask = umask(0077);
if (bind(sock, (struct sockaddr *)&addr, sizeof(addr)) < 0)
eprintf("bind %s:", SOCK_PATH);
+ umask(mask);
+ if (chmod(SOCK_PATH, 0600) < 0)
+ eprintf("chmod %s:", SOCK_PATH);
if (listen(sock, 16) < 0)
eprintf("listen:");
- chmod(SOCK_PATH, 0600);
/* mark all non-down services as wanting to be up */
for (i = 0; i < nsvcs; i++) {
@@ -901,8 +922,10 @@ main(void)
if (pfds[0].revents & POLLIN) {
conn = accept(sock, NULL, NULL);
- if (conn >= 0)
+ if (conn >= 0) {
+ cloexec(conn);
handle_conn(conn);
+ }
}
if (pfds[1].revents & POLLIN) {
