catsit/service.c

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/* Copyright (C) 2020 C. McEnroe <june@causal.agency>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
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#include <assert.h>
#include <err.h>
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#include <fcntl.h>
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#include <limits.h>
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#include <paths.h>
#include <signal.h>
#include <stdint.h>
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#include <stdio.h>
#include <stdlib.h>
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#include <string.h>
#include <sys/time.h>
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#include <sys/wait.h>
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#include <syslog.h>
#include <time.h>
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#include <unistd.h>
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#include "daemon.h"
const char *serviceDir = "/";
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uid_t serviceUID;
gid_t serviceGID;
char *serviceEnviron[EnvironLen] = {
[SHELL] = "SHELL=" _PATH_BSHELL,
[PATH] = "PATH=" _PATH_DEFPATH,
};
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struct Prepend prepend;
struct Services services;
static void serviceFree(struct Service *service) {
free(service->name);
free(service->command);
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if (service->outPipe[0] >= 0) {
close(service->outPipe[0]);
close(service->outPipe[1]);
}
if (service->errPipe[0] >= 0) {
close(service->errPipe[0]);
close(service->errPipe[1]);
}
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}
int serviceAdd(const char *name, const char *command) {
struct Service *service = NULL;
for (size_t i = 0; i < services.len; ++i) {
if (!strcmp(services.ptr[i].name, name)) {
service = &services.ptr[i];
break;
}
}
if (service) {
char *dup = strdup(command);
if (!dup) return -1;
free(service->command);
service->command = dup;
return 0;
}
if (services.len == services.cap) {
size_t cap = (services.cap ? services.cap * 2 : 8);
void *ptr = realloc(services.ptr, sizeof(*services.ptr) * cap);
if (!ptr) return -1;
services.cap = cap;
services.ptr = ptr;
}
service = &services.ptr[services.len];
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*service = (struct Service) {
.outPipe = { -1, -1 },
.errPipe = { -1, -1 },
.restartInterval = restartInterval,
};
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service->name = strdup(name);
if (!service->name) goto err;
service->command = strdup(command);
if (!service->command) goto err;
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int error = pipe2(service->outPipe, O_CLOEXEC);
if (error) goto err;
error = pipe2(service->errPipe, O_CLOEXEC);
if (error) goto err;
fcntl(service->outPipe[0], F_SETFL, O_NONBLOCK);
fcntl(service->errPipe[0], F_SETFL, O_NONBLOCK);
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services.len++;
return 0;
err:
serviceFree(service);
return -1;
}
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static void setDeadline(struct Service *service) {
clock_gettime(CLOCK_MONOTONIC_FAST, &service->restartDeadline);
timespecadd(
&service->restartDeadline, &service->restartInterval,
&service->restartDeadline
);
}
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void serviceStart(struct Service *service) {
if (service->state != Stop) return;
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if (service->intent == Start) {
struct timespec backoff = service->restartInterval;
timespecadd(&backoff, &backoff, &service->restartInterval);
} else {
service->restartInterval = restartInterval;
}
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setDeadline(service);
service->intent = Start;
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service->pid = fork();
if (service->pid < 0) {
syslog(LOG_ERR, "fork: %m");
return;
}
if (service->pid) {
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syslog(
LOG_INFO, "%s[%jd] start",
service->name, (intmax_t)service->pid
);
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service->state = Start;
return;
}
closelog();
dup2(service->outPipe[1], STDOUT_FILENO);
dup2(service->errPipe[1], STDERR_FILENO);
int error = chdir(serviceDir);
if (error) err(StopExit, "%s", serviceDir);
error = setgid(serviceGID);
if (error) err(StopExit, "setgid");
error = setuid(serviceUID);
if (error) err(StopExit, "setuid");
size_t len = 0;
char command[ARG_MAX];
for (size_t i = 0; i < prepend.len; ++i) {
int n = snprintf(
&command[len], sizeof(command) - len, "%s;", prepend.commands[i]
);
assert(n > 0);
len += n;
}
snprintf(&command[len], sizeof(command) - len, "exec %s", service->command);
execle(
_PATH_BSHELL,
_PATH_BSHELL, "-c", command, service->name, NULL,
serviceEnviron
);
err(StopExit, "%s", _PATH_BSHELL);
}
void serviceSignal(struct Service *service, int signal) {
if (service->state != Start) return;
int error = kill(service->pid, signal);
if (error) {
syslog(
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LOG_ERR, "kill(%s[%jd], %s): %m",
service->name, (intmax_t)service->pid, sys_signame[signal]
);
}
}
void serviceStop(struct Service *service) {
service->intent = Stop;
serviceSignal(service, SIGTERM);
}
void serviceRestart(struct Service *service) {
if (service->state == Start) {
service->intent = Restart;
serviceSignal(service, SIGTERM);
} else {
serviceStart(service);
}
}
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void serviceReap(pid_t pid, int status) {
struct Service *service = NULL;
for (size_t i = 0; i < services.len; ++i) {
if (services.ptr[i].state != Start) continue;
if (services.ptr[i].pid != pid) continue;
service = &services.ptr[i];
break;
}
if (!service) {
syslog(LOG_WARNING, "reaping unknown child %jd", (intmax_t)pid);
return;
}
// TODO: Flush line buffers.
service->state = Stop;
if (WIFEXITED(status)) {
int exit = WEXITSTATUS(status);
if (exit == StopExit || setTest(&stopExits, exit)) {
service->intent = Stop;
}
if (exit) {
syslog(
LOG_WARNING, "%s[%jd] exit %d",
service->name, (intmax_t)pid, exit
);
}
} else if (WIFSIGNALED(status)) {
syslog(
LOG_WARNING, "%s[%jd] signal %s",
service->name, (intmax_t)pid, sys_signame[WTERMSIG(status)]
);
}
if (service->intent == Start) {
setDeadline(service);
syslog(
LOG_INFO, "%s[%jd] restart in %jds",
service->name, (intmax_t)pid,
(intmax_t)service->restartInterval.tv_sec
);
} else {
syslog(LOG_INFO, "%s[%jd] stop", service->name, (intmax_t)pid);
}
if (service->intent == Restart) {
serviceStart(service);
}
}