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Fix #440: refactor systemd and s6 readiness notifcation

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This patch fixes issue #440 which details how systemd readiness
notification has been broken since its inception in Finit.

In addition to now providing a proper abstract socket, the refactor
also drops the reliance on the Finit client API to fetch a socket.
Now an s6 descriptor is the write end of a pipe() and the systemd
socket is instead created before forking off the service.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
This commit is contained in:
Joachim Wiberg
2025-07-02 16:36:58 +02:00
parent dc497bcd57
commit 76f8a18816
6 changed files with 102 additions and 48 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/api.c
-14
View File
@@ -571,20 +571,6 @@ static void api_cb(uev_t *w, void *arg, int events)
result = do_signal(rq.data, sizeof(rq.data), rq.runlevel);
break;
case INIT_CMD_NOTIFY_SOCKET:
svc = svc_find_by_pid(rq.runlevel);
if (!svc) {
errx(1, "Unknown PID, cannot register notify socket");
result = 1;
break;
}
if (uev_io_init(ctx, &svc->notify_watcher, service_notify_cb, svc, sd, UEV_READ)) {
err(1, "Failed initializing %s readiness notifier", svc_ident(svc, NULL, 0));
break;
}
return; /* Don't close sd, used for notify */
default:
dbg("Unsupported cmd: %d", rq.cmd);
break;
src/client.c
-10
View File
@@ -97,16 +97,6 @@ int client_request(struct init_request *rq, ssize_t len)
return -1;
}
/*
* Exception, only command that don't need to wait for a
* response from Finit. Registers the client socket as a
* readiness notification socket with Finit
*/
if (rq->cmd == INIT_CMD_NOTIFY_SOCKET) {
rq->cmd = INIT_CMD_ACK;
return 0;
}
pfd.fd = sd;
pfd.events = POLLIN | POLLERR | POLLHUP;
if ((rc = poll(&pfd, 1, REQUEST_TIMEOUT)) <= 0) {
src/finit.h
-1
View File
@@ -99,7 +99,6 @@
#define INIT_CMD_SVC_FIND 131
#define INIT_CMD_SVC_FIND_BYC 132
#define INIT_CMD_SIGNAL 133
#define INIT_CMD_NOTIFY_SOCKET 200 /* For readiness notification socket */
#define INIT_CMD_NACK 254
#define INIT_CMD_ACK 255
src/private.h
-1
View File
@@ -46,7 +46,6 @@ int api_exit (void);
void conf_flush_events(void);
void service_monitor (pid_t lost, int status);
void service_notify_cb(uev_t *w, void *arg, int events);
const char *plugin_hook_str (hook_point_t no);
int plugin_exists (hook_point_t no);
src/service.c
+101 -21
View File
@@ -30,6 +30,7 @@
#include <sys/reboot.h>
#include <sys/prctl.h>
#include <sys/resource.h>
#include <sys/un.h>
#include <sys/wait.h>
#include <net/if.h>
#ifdef _LIBITE_LITE
@@ -56,6 +57,9 @@
#include "utmp-api.h"
#include "schedule.h"
#define NOTIFY_PATH "@run/finit/notify/%d"
/*
* run tasks block other tasks/services from starting, we track the
* current run task here. For service_step() and service_start().
@@ -68,6 +72,8 @@ static struct wq work = {
int service_interval = SERVICE_INTERVAL_DEFAULT;
static void svc_set_state(svc_t *svc, svc_state_t new_state);
static void service_notify_cb(uev_t *w, void *arg, int events);
/**
* service_timeout_cb - libuev callback wrapper for service timeouts
@@ -582,6 +588,9 @@ static int service_start(svc_t *svc)
int result = 0, do_progress = 1;
char cmdline[CMD_SIZE] = "";
sigset_t nmask, omask;
int pipefd[2];
int fd = -1;
int sd = -1;
pid_t pid;
size_t i;
@@ -627,6 +636,29 @@ static int service_start(svc_t *svc)
if (svc_is_sysv(svc))
logit(LOG_CONSOLE | LOG_NOTICE, "Calling '%s start' ...", cmdline);
switch (svc->notify) {
case SVC_NOTIFY_S6:
if (pipe(pipefd) == -1) {
err(1, "%s: failed opening pipe for s6 notify", svc_ident(svc, NULL, 0));
svc_missing(svc);
return 1;
}
fd = pipefd[1];
sd = pipefd[0];
break;
case SVC_NOTIFY_SYSTEMD:
sd = socket(AF_UNIX, SOCK_DGRAM | SOCK_NONBLOCK | SOCK_CLOEXEC, 0);
if (sd == -1) {
err(1, "%s: failed opening notify socket", svc_ident(svc, NULL, 0));
svc_missing(svc);
return 1;
}
break;
default:
break;
}
if (!svc->desc[0])
do_progress = 0;
@@ -653,38 +685,72 @@ static int service_start(svc_t *svc)
pid = service_fork(svc);
if (pid < 0) {
if (sd != -1)
close(sd);
if (fd != -1)
close(fd);
result = -1;
goto fail;
}
if (pid > 1) {
struct sockaddr_un sun;
size_t len;
dbg("Starting %s as PID %d", svc_ident(svc, NULL, 0), pid);
svc->pid = pid;
svc->start_time = jiffies();
switch (svc->notify) {
case SVC_NOTIFY_SYSTEMD:
memset(&sun, 0, sizeof(sun));
sun.sun_family = AF_UNIX;
snprintf(sun.sun_path, sizeof(sun.sun_path), NOTIFY_PATH, pid);
len = strlen(sun.sun_path);
sun.sun_path[0] = 0;
result = bind(sd, (struct sockaddr *)&sun, offsetof(struct sockaddr_un, sun_path) + len);
if (result == -1) {
err(1, "%s: failed binding to notify socket", svc_ident(svc, NULL, 0));
close(sd);
break;
}
/* fallthrough */
case SVC_NOTIFY_S6:
close(fd); /* client-end of pipefd for s6 notify */
result = uev_io_init(ctx, &svc->notify_watcher, service_notify_cb, svc, sd, UEV_READ);
if (result < 0) {
err(1, "%s: failed setting up notify callback", svc_ident(svc, NULL, 0));
if (svc->notify == SVC_NOTIFY_S6)
close(fd);
close(sd);
break;
}
default:
break;
}
} else if (pid == 0) {
char str[strlen(NOTIFY_PATH) + 32];
char *args[MAX_NUM_SVC_ARGS + 1];
int status;
if (!svc_is_tty(svc))
redirect(svc);
switch (svc->notify) {
case SVC_NOTIFY_SYSTEMD:
snprintf(str, sizeof(str), NOTIFY_PATH, getpid());
setenv("NOTIFY_SOCKET", str, 1);
/* fallthrough */
case SVC_NOTIFY_S6:
close(sd);
break;
default:
break;
}
if (!svc_is_sysv(svc)) {
wordexp_t we = { 0 };
int rc;
if (svc->notify == SVC_NOTIFY_SYSTEMD || svc->notify == SVC_NOTIFY_S6) {
if (client_command(INIT_CMD_NOTIFY_SOCKET)) {
err(1, "%s: failed creating notify socket", svc_ident(svc, NULL, 0));
client_disconnect();
/* does not change parent, restarting may work. */
svc->notify = SVC_NOTIFY_NONE;
} else {
char val[20];
snprintf(val, sizeof(val), "%d", client_socket());
setenv("NOTIFY_SOCKET", val, 1);
}
}
if ((rc = wordexp(svc->cmd, &we, 0))) {
errx(1, "%s: failed wordexp(%s): %d", svc_ident(svc, NULL, 0), svc->cmd, rc);
nomem:
@@ -701,11 +767,11 @@ static int service_start(svc_t *svc)
if (len == 0)
break;
if (svc->notify == SVC_NOTIFY_SYSTEMD || svc->notify == SVC_NOTIFY_S6) {
if (svc->notify == SVC_NOTIFY_S6) {
char *ptr = strstr(arg, "%n");
if (ptr) {
len = snprintf(str, sizeof(str), "%d", client_socket());
len = snprintf(str, sizeof(str), "%d", fd);
if (len > 0 && len <= 2) {
ptr[0] = ' ';
ptr[1] = ' ';
@@ -2929,14 +2995,15 @@ void service_notify_reconf(void)
* Called when a service sends readiness notification, or when
* the service closes its end of the IPC connection.
*/
void service_notify_cb(uev_t *w, void *arg, int events)
static void service_notify_cb(uev_t *w, void *arg, int events)
{
svc_t *svc = (svc_t *)arg;
int ready = 0;
char buf[32];
ssize_t len;
if (UEV_ERROR == events) {
dbg("Spurious problem with %s notify callback, restarting.", svc_ident(svc, NULL, 0));
dbg("%s: spurious problem with notify callback, restarting.", svc_ident(svc, NULL, 0));
uev_io_start(w);
return;
}
@@ -2946,11 +3013,24 @@ void service_notify_cb(uev_t *w, void *arg, int events)
warn("Failed reading notification from %s", svc_ident(svc, NULL, 0));
return;
}
buf[len] = 0;
/* systemd and s6, respectively. The latter then closes the socket */
if (!strcmp(buf, "READY=1\n") || buf[len - 1] == '\n') {
/* Check for systemd READY=1 or s6 newline termination */
if (svc->notify == SVC_NOTIFY_SYSTEMD) {
char *token = strtok(buf, "\n");
while (token) {
if (!strcmp(token, "READY=1")) {
ready = 1;
break;
}
token = strtok(NULL, "\n");
}
} else if (svc->notify == SVC_NOTIFY_S6 && buf[len - 1] == '\n') {
ready = 1;
}
if (ready) {
/*
* native (pidfile) services are marked as started by
* the pidfile plugin.
src/svc.h
+1 -1
View File
@@ -85,7 +85,7 @@ typedef enum {
SVC_ONCRASH_SCRIPT,
} svc_oncrash_action_t;
/* 0: none, 1: systemd, 2: s6 */
/* 0: none, 1: finit (native), 2: systemd, 3: s6 */
typedef enum {
SVC_NOTIFY_NONE = 0,
SVC_NOTIFY_PID,