libdaemon/dpid.c

/***
  This file is part of libdaemon.

  Copyright 2003-2008 Lennart Poettering

  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:

  The above copyright notice and this permission notice shall be included in
  all copies or substantial portions of the Software.

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  SOFTWARE.

***/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <time.h>
#include <sys/select.h>
#include <fcntl.h>
#include <stddef.h>
#include <sys/time.h>

#include "dpid.h"
#include "dlog.h"

#ifndef ETIME
#define ETIME ETIMEDOUT /* For FreeBSD */
#endif

#ifndef PATH_MAX
#define PATH_MAX 512
#endif

#define VARRUN LOCALSTATEDIR "/run"

const char *daemon_pid_file_ident = NULL;
daemon_pid_file_proc_t daemon_pid_file_proc = daemon_pid_file_proc_default;

const char *daemon_pid_file_proc_default(void) {
#ifdef HAVE_ASPRINTF
    static char *fn = NULL;
    free(fn);
    asprintf(&fn,  "%s/%s.pid", VARRUN, daemon_pid_file_ident ? daemon_pid_file_ident : "unknown");
#else
    static char fn[PATH_MAX];
    snprintf(fn, sizeof(fn), "%s/%s.pid", VARRUN, daemon_pid_file_ident ? daemon_pid_file_ident : "unknown");
#endif

    return fn;
}

static int lock_file(int fd, int enable) {
    struct flock f;

    memset(&f, 0, sizeof(f));
    f.l_type = enable ? F_WRLCK : F_UNLCK;
    f.l_whence = SEEK_SET;
    f.l_start = 0;
    f.l_len = 0;

    if (fcntl(fd, F_SETLKW, &f) < 0) {

        if (enable && errno == EBADF) {
            f.l_type = F_RDLCK;

            if (fcntl(fd, F_SETLKW, &f) >= 0)
                return 0;
        }

        daemon_log(LOG_WARNING, "fcntl(F_SETLKW) failed: %s", strerror(errno));
        return -1;
    }

    return 0;
}

pid_t daemon_pid_file_is_running(void) {
    const char *fn;
    static char txt[256];
    int fd = -1, locked = -1;
    pid_t ret = (pid_t) -1, pid;
    ssize_t l;
    long lpid;
    char *e = NULL;

    if (!(fn = daemon_pid_file_proc())) {
        errno = EINVAL;
        goto finish;
    }

    if ((fd = open(fn, O_RDWR, 0644)) < 0) {
        if ((fd = open(fn, O_RDONLY, 0644)) < 0) {
            if (errno != ENOENT)
                daemon_log(LOG_WARNING, "Failed to open PID file: %s", strerror(errno));

            goto finish;
        }
    }

    if ((locked = lock_file(fd, 1)) < 0)
        goto finish;

    if ((l = read(fd, txt, sizeof(txt)-1)) < 0) {
        int saved_errno = errno;
        daemon_log(LOG_WARNING, "read(): %s", strerror(errno));
        unlink(fn);
        errno = saved_errno;
        goto finish;
    }

    txt[l] = 0;
    txt[strcspn(txt, "\r\n")] = 0;

    errno = 0;
    lpid = strtol(txt, &e, 10);
    pid = (pid_t) lpid;

    if (errno != 0 || !e || *e || (long) pid != lpid) {
        daemon_log(LOG_WARNING, "PID file corrupt, removing. (%s)", fn);
        unlink(fn);
        errno = EINVAL;
        goto finish;
    }

    if (kill(pid, 0) != 0 && errno != EPERM) {
        int saved_errno = errno;
        daemon_log(LOG_WARNING, "Process %lu died: %s; trying to remove PID file. (%s)", (unsigned long) pid, strerror(errno), fn);
        unlink(fn);
        errno = saved_errno;
        goto finish;
    }

    ret = pid;

finish:

    if (fd >= 0) {
        int saved_errno = errno;
        if (locked >= 0)
            lock_file(fd, 0);
        close(fd);
        errno = saved_errno;
    }

    return ret;
}

int daemon_pid_file_kill(int s) {
    pid_t pid;

    if ((pid = daemon_pid_file_is_running()) == (pid_t) -1)
        return -1;

    if (kill(pid, s) < 0)
        return -1;

    return 0;
}

int daemon_pid_file_kill_wait(int s, int m) {
    pid_t pid;
    time_t t;

    if ((pid = daemon_pid_file_is_running()) < 0)
        return -1;

    if (kill(pid, s) < 0)
        return -1;

    t = time(NULL) + m;

    for (;;) {
        int r;
        struct timeval tv = { 0, 100000 };

        if (time(NULL) > t) {
            errno = ETIME;
            return -1;
        }

        if ((r = kill(pid, 0)) < 0 && errno != ESRCH)
            return -1;

        if (r)
            return 0;

        if (select(0, NULL, NULL, NULL, &tv) < 0)
            return -1;
    }
}

int daemon_pid_file_create(void) {
    const char *fn;
    int fd = -1;
    int ret = -1;
    int locked = -1;
    char t[64];
    ssize_t l;
    mode_t u;

    u = umask(022);

    if (!(fn = daemon_pid_file_proc())) {
        errno = EINVAL;
        goto finish;
    }

    if ((fd = open(fn, O_CREAT|O_RDWR|O_EXCL, 0644)) < 0) {
        daemon_log(LOG_ERR, "open(%s): %s", fn, strerror(errno));
        goto finish;
    }

    if ((locked = lock_file(fd, 1)) < 0) {
        int saved_errno = errno;
        unlink(fn);
        errno = saved_errno;
        goto finish;
    }

    snprintf(t, sizeof(t), "%lu\n", (unsigned long) getpid());

    l = strlen(t);
    if (write(fd, t, l) != l) {
        int saved_errno = errno;
        daemon_log(LOG_WARNING, "write(): %s", strerror(errno));
        unlink(fn);
        errno = saved_errno;
        goto finish;
    }

    ret = 0;

finish:

    if (fd >= 0) {
        int saved_errno = errno;

        if (locked >= 0)
            lock_file(fd, 0);

        close(fd);
        errno = saved_errno;
    }

    umask(u);

    return ret;
}

int daemon_pid_file_remove(void) {
    const char *fn;

    if (!(fn = daemon_pid_file_proc())) {
        errno = EINVAL;
        return -1;
    }

    return unlink(fn);
}