- acquire /dev/log socket optionally from systemd

  thanks to Lennart Poettering for this patch

#include "sd-daemon.h"

       if (strcmp(path, _PATH_LOG) == 0) {

               int r;

               /* Check whether an FD was passed in from systemd. If

                * so, it's the /dev/log socket, so use it. */

               r = sd_listen_fds(0);

               if (r < 0) {

                       errmsg.LogError(-r, NO_ERRCODE, "Failed to acquire systemd socket");

                       return -1;

               }

               if (r > 1) {

                       errmsg.LogError(EINVAL, NO_ERRCODE, "Wrong number of systemd sockets passed");

                       return -1;

               }

               if (r == 1) {

                       fd = SD_LISTEN_FDS_START;

                       r = sd_is_socket_unix(fd, SOCK_DGRAM, -1, _PATH_LOG, 0);

                       if (r < 0) {

                               errmsg.LogError(-r, NO_ERRCODE, "Failed to verify systemd socket type");

                               return -1;

                       }

                       if (!r) {

                               errmsg.LogError(EINVAL, NO_ERRCODE, "Passed systemd socket of wrong type");

                               return -1;

                       }

                       return fd;

               }

       }

       sd-daemon.c \

       sd-daemon.h \

update-systemd:

       curl http://cgit.freedesktop.org/systemd/plain/src/sd-daemon.c > sd-daemon.c

       curl http://cgit.freedesktop.org/systemd/plain/src/sd-daemon.h > sd-daemon.h

/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/

/***

  Copyright 2010 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.

***/

#ifndef _GNU_SOURCE

#define _GNU_SOURCE

#endif

#include <sys/types.h>

#include <sys/stat.h>

#include <sys/socket.h>

#include <sys/un.h>

#include <sys/fcntl.h>

#include <netinet/in.h>

#include <stdlib.h>

#include <errno.h>

#include <unistd.h>

#include <string.h>

#include <stdarg.h>

#include <stdio.h>

#include "sd-daemon.h"

int sd_listen_fds(int unset_environment) {

#if defined(DISABLE_SYSTEMD) || !defined(__linux__)

        return 0;

#else

        int r, fd;

        const char *e;

        char *p = NULL;

        unsigned long l;

        if (!(e = getenv("LISTEN_PID"))) {

                r = 0;

                goto finish;

        }

        errno = 0;

        l = strtoul(e, &p, 10);

        if (errno != 0) {

                r = -errno;

                goto finish;

        }

        if (!p || *p || l <= 0) {

                r = -EINVAL;

                goto finish;

        }

        /* Is this for us? */

        if (getpid() != (pid_t) l) {

                r = 0;

                goto finish;

        }

        if (!(e = getenv("LISTEN_FDS"))) {

                r = 0;

                goto finish;

        }

        errno = 0;

        l = strtoul(e, &p, 10);

        if (errno != 0) {

                r = -errno;

                goto finish;

        }

        if (!p || *p) {

                r = -EINVAL;

                goto finish;

        }

        for (fd = SD_LISTEN_FDS_START; fd < SD_LISTEN_FDS_START + (int) l; fd ++) {

                int flags;

                if ((flags = fcntl(fd, F_GETFD)) < 0) {

                        r = -errno;

                        goto finish;

                }

                if (flags & FD_CLOEXEC)

                        continue;

                if (fcntl(fd, F_SETFD, flags | FD_CLOEXEC) < 0) {

                        r = -errno;

                        goto finish;

                }

        }

        r = (int) l;

finish:

        if (unset_environment) {

                unsetenv("LISTEN_PID");

                unsetenv("LISTEN_FDS");

        }

        return r;

#endif

}

int sd_is_fifo(int fd, const char *path) {

        struct stat st_fd;

        if (fd < 0)

                return -EINVAL;

        memset(&st_fd, 0, sizeof(st_fd));

        if (fstat(fd, &st_fd) < 0)

                return -errno;

        if (!S_ISFIFO(st_fd.st_mode))

                return 0;

        if (path) {

                struct stat st_path;

                memset(&st_path, 0, sizeof(st_path));

                if (stat(path, &st_path) < 0) {

                        if (errno == ENOENT || errno == ENOTDIR)

                                return 0;

                        return -errno;

                }

                return

                        st_path.st_dev == st_fd.st_dev &&

                        st_path.st_ino == st_fd.st_ino;

        }

        return 1;

}

static int sd_is_socket_internal(int fd, int type, int listening) {

        struct stat st_fd;

        if (fd < 0 || type < 0)

                return -EINVAL;

        if (fstat(fd, &st_fd) < 0)

                return -errno;

        if (!S_ISSOCK(st_fd.st_mode))

                return 0;

        if (type != 0) {

                int other_type = 0;

                socklen_t l = sizeof(other_type);

                if (getsockopt(fd, SOL_SOCKET, SO_TYPE, &other_type, &l) < 0)

                        return -errno;

                if (l != sizeof(other_type))

                        return -EINVAL;

                if (other_type != type)

                        return 0;

        }

        if (listening >= 0) {

                int accepting = 0;

                socklen_t l = sizeof(accepting);

                if (getsockopt(fd, SOL_SOCKET, SO_ACCEPTCONN, &accepting, &l) < 0)

                        return -errno;

                if (l != sizeof(accepting))

                        return -EINVAL;

                if (!accepting != !listening)

                        return 0;

        }

        return 1;

}

union sockaddr_union {

        struct sockaddr sa;

        struct sockaddr_in in4;

        struct sockaddr_in6 in6;

        struct sockaddr_un un;

        struct sockaddr_storage storage;

};

int sd_is_socket(int fd, int family, int type, int listening) {

        int r;

        if (family < 0)

                return -EINVAL;

        if ((r = sd_is_socket_internal(fd, type, listening)) <= 0)

                return r;

        if (family > 0) {

                union sockaddr_union sockaddr;

                socklen_t l;

                memset(&sockaddr, 0, sizeof(sockaddr));

                l = sizeof(sockaddr);

                if (getsockname(fd, &sockaddr.sa, &l) < 0)

                        return -errno;

                if (l < sizeof(sa_family_t))

                        return -EINVAL;

                return sockaddr.sa.sa_family == family;

        }

        return 1;

}

int sd_is_socket_inet(int fd, int family, int type, int listening, uint16_t port) {

        union sockaddr_union sockaddr;

        socklen_t l;

        int r;

        if (family != 0 && family != AF_INET && family != AF_INET6)

                return -EINVAL;

        if ((r = sd_is_socket_internal(fd, type, listening)) <= 0)

                return r;

        memset(&sockaddr, 0, sizeof(sockaddr));

        l = sizeof(sockaddr);

        if (getsockname(fd, &sockaddr.sa, &l) < 0)

                return -errno;

        if (l < sizeof(sa_family_t))

                return -EINVAL;

        if (sockaddr.sa.sa_family != AF_INET &&

            sockaddr.sa.sa_family != AF_INET6)

                return 0;

        if (family > 0)

                if (sockaddr.sa.sa_family != family)

                        return 0;

        if (port > 0) {

                if (sockaddr.sa.sa_family == AF_INET) {

                        if (l < sizeof(struct sockaddr_in))

                                return -EINVAL;

                        return htons(port) == sockaddr.in4.sin_port;

                } else {

                        if (l < sizeof(struct sockaddr_in6))

                                return -EINVAL;

                        return htons(port) == sockaddr.in6.sin6_port;

                }

        }

        return 1;

}

int sd_is_socket_unix(int fd, int type, int listening, const char *path, size_t length) {

        union sockaddr_union sockaddr;

        socklen_t l;

        int r;

        if ((r = sd_is_socket_internal(fd, type, listening)) <= 0)

                return r;

        memset(&sockaddr, 0, sizeof(sockaddr));

        l = sizeof(sockaddr);

        if (getsockname(fd, &sockaddr.sa, &l) < 0)

                return -errno;

        if (l < sizeof(sa_family_t))

                return -EINVAL;

        if (sockaddr.sa.sa_family != AF_UNIX)

                return 0;

        if (path) {

                if (length <= 0)

                        length = strlen(path);

                if (length <= 0)

                        /* Unnamed socket */

                        return l == sizeof(sa_family_t);

                if (path[0])

                        /* Normal path socket */

                        return

                                (l >= sizeof(sa_family_t) + length + 1) &&

                                memcmp(path, sockaddr.un.sun_path, length+1) == 0;

                else

                        /* Abstract namespace socket */

                        return

                                (l == sizeof(sa_family_t) + length) &&

                                memcmp(path, sockaddr.un.sun_path, length) == 0;

        }

        return 1;

}

int sd_notify(int unset_environment, const char *state) {

#if defined(DISABLE_SYSTEMD) || !defined(__linux__) || !defined(SOCK_CLOEXEC)

        return 0;

#else

        int fd = -1, r;

        struct msghdr msghdr;

        struct iovec iovec;

        union sockaddr_union sockaddr;

        const char *e;

        if (!state) {

                r = -EINVAL;

                goto finish;

        }

        if (!(e = getenv("NOTIFY_SOCKET")))

                return 0;

        /* Must be an abstract socket, or an absolute path */

        if ((e[0] != '@' && e[0] != '/') || e[1] == 0) {

                r = -EINVAL;

                goto finish;

        }

        if ((fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0)) < 0) {

                r = -errno;

                goto finish;

        }

        memset(&sockaddr, 0, sizeof(sockaddr));

        sockaddr.sa.sa_family = AF_UNIX;

        strncpy(sockaddr.un.sun_path, e, sizeof(sockaddr.un.sun_path));

        if (sockaddr.un.sun_path[0] == '@')

                sockaddr.un.sun_path[0] = 0;

        memset(&iovec, 0, sizeof(iovec));

        iovec.iov_base = (char*) state;

        iovec.iov_len = strlen(state);

        memset(&msghdr, 0, sizeof(msghdr));

        msghdr.msg_name = &sockaddr;

        msghdr.msg_namelen = sizeof(sa_family_t) + strlen(e);

        if (msghdr.msg_namelen > sizeof(struct sockaddr_un))

                msghdr.msg_namelen = sizeof(struct sockaddr_un);

        msghdr.msg_iov = &iovec;

        msghdr.msg_iovlen = 1;

        if (sendmsg(fd, &msghdr, MSG_NOSIGNAL) < 0) {

                r = -errno;

                goto finish;

        }

        r = 1;

finish:

        if (unset_environment)

                unsetenv("NOTIFY_SOCKET");

        if (fd >= 0)

                close(fd);

        return r;

#endif

}

int sd_notifyf(int unset_environment, const char *format, ...) {

#if defined(DISABLE_SYSTEMD) || !defined(__linux__)

        return 0;

#else

        va_list ap;

        char *p = NULL;

        int r;

        va_start(ap, format);

        r = vasprintf(&p, format, ap);

        va_end(ap);

        if (r < 0 || !p)

                return -ENOMEM;

        r = sd_notify(unset_environment, p);

        free(p);

        return r;

#endif

}

int sd_booted(void) {

#if defined(DISABLE_SYSTEMD) || !defined(__linux__)

        return 0;

#else

        struct stat a, b;

        /* We simply test whether the systemd cgroup hierarchy is

         * mounted */

        if (lstat("/sys/fs/cgroup", &a) < 0)

                return 0;

        if (lstat("/sys/fs/cgroup/systemd", &b) < 0)

                return 0;

        return a.st_dev != b.st_dev;

#endif

}

/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/

#ifndef foosddaemonhfoo

#define foosddaemonhfoo

/***

  Copyright 2010 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.

***/

#include <sys/types.h>

#include <inttypes.h>

#ifdef __cplusplus

extern "C" {

#endif

/*

  Reference implementation of a few systemd related interfaces for

  writing daemons. These interfaces are trivial to implement. To

  simplify porting we provide this reference implementation.

  Applications are welcome to reimplement the algorithms described

  here if they do not want to include these two source files.

  The following functionality is provided:

  - Support for logging with log levels on stderr

  - File descriptor passing for socket-based activation

  - Daemon startup and status notification

  - Detection of systemd boots

  You may compile this with -DDISABLE_SYSTEMD to disable systemd

  support. This makes all those calls NOPs that are directly related to

  systemd (i.e. only sd_is_xxx() will stay useful).

  Since this is drop-in code we don't want any of our symbols to be

  exported in any case. Hence we declare hidden visibility for all of

  them.

  You may find an up-to-date version of these source files online:

  http://cgit.freedesktop.org/systemd/plain/src/sd-daemon.h

  http://cgit.freedesktop.org/systemd/plain/src/sd-daemon.c

  This should compile on non-Linux systems, too, but with the

  exception of the sd_is_xxx() calls all functions will become NOPs.

  See sd-daemon(7) for more information.

*/

#if (__GNUC__ >= 4)

#define _sd_printf_attr_(a,b) __attribute__ ((format (printf, a, b)))

#  if defined(SD_EXPORT_SYMBOLS)

#    define _sd_hidden_

#  else

#    define _sd_hidden_ __attribute__ ((visibility("hidden")))

#  endif

#else

#define _sd_printf_attr_(a,b)

#define _sd_hidden_

#endif

/*

  Log levels for usage on stderr:

          fprintf(stderr, SD_NOTICE "Hello World!\n");

  This is similar to printk() usage in the kernel.

*/

#define SD_EMERG   "<0>"  /* system is unusable */

#define SD_ALERT   "<1>"  /* action must be taken immediately */

#define SD_CRIT    "<2>"  /* critical conditions */

#define SD_ERR     "<3>"  /* error conditions */

#define SD_WARNING "<4>"  /* warning conditions */

#define SD_NOTICE  "<5>"  /* normal but significant condition */

#define SD_INFO    "<6>"  /* informational */

#define SD_DEBUG   "<7>"  /* debug-level messages */

/* The first passed file descriptor is fd 3 */

#define SD_LISTEN_FDS_START 3

/*

  Returns how many file descriptors have been passed, or a negative

  errno code on failure. Optionally, removes the $LISTEN_FDS and

  $LISTEN_PID file descriptors from the environment (recommended, but

  problematic in threaded environments). If r is the return value of

  this function you'll find the file descriptors passed as fds

  SD_LISTEN_FDS_START to SD_LISTEN_FDS_START+r-1. Returns a negative

  errno style error code on failure. This function call ensures that

  the FD_CLOEXEC flag is set for the passed file descriptors, to make

  sure they are not passed on to child processes. If FD_CLOEXEC shall

  not be set, the caller needs to unset it after this call for all file

  descriptors that are used.

  See sd_listen_fds(3) for more information.

*/

int sd_listen_fds(int unset_environment) _sd_hidden_;

/*

  Helper call for identifying a passed file descriptor. Returns 1 if

  the file descriptor is a FIFO in the file system stored under the

  specified path, 0 otherwise. If path is NULL a path name check will

  not be done and the call only verifies if the file descriptor

  refers to a FIFO. Returns a negative errno style error code on

  failure.

  See sd_is_fifo(3) for more information.

*/

int sd_is_fifo(int fd, const char *path) _sd_hidden_;

/*

  Helper call for identifying a passed file descriptor. Returns 1 if

  the file descriptor is a socket of the specified family (AF_INET,

  ...) and type (SOCK_DGRAM, SOCK_STREAM, ...), 0 otherwise. If

  family is 0 a socket family check will not be done. If type is 0 a

  socket type check will not be done and the call only verifies if

  the file descriptor refers to a socket. If listening is > 0 it is

  verified that the socket is in listening mode. (i.e. listen() has

  been called) If listening is == 0 it is verified that the socket is

  not in listening mode. If listening is < 0 no listening mode check

  is done. Returns a negative errno style error code on failure.

  See sd_is_socket(3) for more information.

*/

int sd_is_socket(int fd, int family, int type, int listening) _sd_hidden_;

/*

  Helper call for identifying a passed file descriptor. Returns 1 if

  the file descriptor is an Internet socket, of the specified family

  (either AF_INET or AF_INET6) and the specified type (SOCK_DGRAM,

  SOCK_STREAM, ...), 0 otherwise. If version is 0 a protocol version

  check is not done. If type is 0 a socket type check will not be

  done. If port is 0 a socket port check will not be done. The

  listening flag is used the same way as in sd_is_socket(). Returns a

  negative errno style error code on failure.

  See sd_is_socket_inet(3) for more information.

*/

int sd_is_socket_inet(int fd, int family, int type, int listening, uint16_t port) _sd_hidden_;

/*

  Helper call for identifying a passed file descriptor. Returns 1 if

  the file descriptor is an AF_UNIX socket of the specified type

  (SOCK_DGRAM, SOCK_STREAM, ...) and path, 0 otherwise. If type is 0

  a socket type check will not be done. If path is NULL a socket path

  check will not be done. For normal AF_UNIX sockets set length to

  0. For abstract namespace sockets set length to the length of the

  socket name (including the initial 0 byte), and pass the full

  socket path in path (including the initial 0 byte). The listening

  flag is used the same way as in sd_is_socket(). Returns a negative

  errno style error code on failure.

  See sd_is_socket_unix(3) for more information.

*/

int sd_is_socket_unix(int fd, int type, int listening, const char *path, size_t length) _sd_hidden_;

/*

  Informs systemd about changed daemon state. This takes a number of

  newline separated environment-style variable assignments in a

  string. The following variables are known:

     READY=1      Tells systemd that daemon startup is finished (only

                  relevant for services of Type=notify). The passed

                  argument is a boolean "1" or "0". Since there is

                  little value in signalling non-readiness the only

                  value daemons should send is "READY=1".

     STATUS=...   Passes a single-line status string back to systemd

                  that describes the daemon state. This is free-from

                  and can be used for various purposes: general state

                  feedback, fsck-like programs could pass completion

                  percentages and failing programs could pass a human

                  readable error message. Example: "STATUS=Completed

                  66% of file system check..."

     ERRNO=...    If a daemon fails, the errno-style error code,

                  formatted as string. Example: "ERRNO=2" for ENOENT.

     BUSERROR=... If a daemon fails, the D-Bus error-style error

                  code. Example: "BUSERROR=org.freedesktop.DBus.Error.TimedOut"

     MAINPID=...  The main pid of a daemon, in case systemd did not

                  fork off the process itself. Example: "MAINPID=4711"

  Daemons can choose to send additional variables. However, it is

  recommened to prefix variable names not listed above with X_.

  Returns a negative errno-style error code on failure. Returns > 0

  if systemd could be notified, 0 if it couldn't possibly because

  systemd is not running.

  Example: When a daemon finished starting up, it could issue this

  call to notify systemd about it:

     sd_notify(0, "READY=1");

  See sd_notifyf() for more complete examples.

  See sd_notify(3) for more information.

*/

int sd_notify(int unset_environment, const char *state) _sd_hidden_;

/*

  Similar to sd_notify() but takes a format string.

  Example 1: A daemon could send the following after initialization:

     sd_notifyf(0, "READY=1\n"

                   "STATUS=Processing requests...\n"

                   "MAINPID=%lu",

                   (unsigned long) getpid());

  Example 2: A daemon could send the following shortly before

  exiting, on failure:

     sd_notifyf(0, "STATUS=Failed to start up: %s\n"

                   "ERRNO=%i",

                   strerror(errno),

                   errno);

  See sd_notifyf(3) for more information.

*/

int sd_notifyf(int unset_environment, const char *format, ...) _sd_printf_attr_(2,3) _sd_hidden_;

/*

  Returns > 0 if the system was booted with systemd. Returns < 0 on

  error. Returns 0 if the system was not booted with systemd. Note

  that all of the functions above handle non-systemd boots just

  fine. You should NOT protect them with a call to this function. Also

  note that this function checks whether the system, not the user

  session is controlled by systemd. However the functions above work

  for both session and system services.

  See sd_booted(3) for more information.

*/

int sd_booted(void) _sd_hidden_;

#ifdef __cplusplus

}

#endif

#endif

#include "sd-daemon.h"

                       if (sd_listen_fds(0) <= 0)