[CRIU] [PATCH] systemd socket activation support
Shawn Landden
shawn at churchofgit.com
Tue Dec 10 19:30:21 PST 2013
Makes the criu RPC socket socket-activated with
systemd [1], meaning that systemd will create and listen to
the UNIX socket /var/run/criu-srvice.socket
on behalf of criu until a connection comes in, when it will
then pass control of the socket, along with the first connection
over to a newly spawned criu daemon.
This is similar to inetd, but criu stays around after getting
started, listening itsself on the socket.
[1] http://0pointer.de/blog/projects/socket-activation.html
---
Makefile | 3 +
Makefile.crtools | 1 +
Makefile.inc | 1 +
cr-service.c | 73 ++++----
criu.service | 5 +
criu.socket | 8 +
sd-daemon.c | 521 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
sd-daemon.h | 282 ++++++++++++++++++++++++++++++
8 files changed, 862 insertions(+), 32 deletions(-)
create mode 100644 criu.service
create mode 100644 criu.socket
create mode 100644 sd-daemon.c
create mode 100644 sd-daemon.h
diff --git a/Makefile b/Makefile
index cd312e7..02282f4 100644
--- a/Makefile
+++ b/Makefile
@@ -232,6 +232,9 @@ install: $(PROGRAM) install-man
$(E) " INSTALL " $(PROGRAM)
$(Q) mkdir -p $(DESTDIR)$(SBINDIR)
$(Q) install -m 755 $(PROGRAM) $(DESTDIR)$(SBINDIR)
+ $(Q) mkdir -p $(DESTDIR)$(SYSTEMDUNITDIR)
+ $(Q) install -m 644 criu.socket $(DESTDIR)$(SYSTEMDUNITDIR)
+ $(Q) install -m 644 criu.service $(DESTDIR)$(SYSTEMDUNITDIR)
install-man:
$(Q) $(MAKE) -C Documentation install
diff --git a/Makefile.crtools b/Makefile.crtools
index 71e9d1c..18140fd 100644
--- a/Makefile.crtools
+++ b/Makefile.crtools
@@ -57,6 +57,7 @@ obj-y += string.o
obj-y += sigframe.o
obj-y += arch/$(ARCH)/vdso.o
obj-y += cr-service.o
+obj-y += sd-daemon.o
ifneq ($(MAKECMDGOALS),clean)
incdeps := y
diff --git a/Makefile.inc b/Makefile.inc
index 23b4d9e..87a267a 100644
--- a/Makefile.inc
+++ b/Makefile.inc
@@ -14,3 +14,4 @@ export E Q
PREFIX := /usr/local
SBINDIR := $(PREFIX)/sbin
MANDIR := $(PREFIX)/share/man
+SYSTEMDUNITDIR := $(PREFIX)/lib/systemd/system/
diff --git a/cr-service.c b/cr-service.c
index a82ef9e..3b9cb02 100644
--- a/cr-service.c
+++ b/cr-service.c
@@ -19,6 +19,7 @@
#include "log.h"
#include "pstree.h"
#include "cr-service.h"
+#include "sd-daemon.h"
unsigned int service_sk_ino = -1;
@@ -332,53 +333,61 @@ static int restore_sigchld_handler()
int cr_service(bool daemon_mode)
{
- int server_fd = -1;
+ int server_fd = -1, n;
int child_pid;
- struct sockaddr_un server_addr;
struct sockaddr_un client_addr;
-
- socklen_t server_addr_len;
socklen_t client_addr_len;
- server_fd = socket(AF_LOCAL, SOCK_SEQPACKET, 0);
- if (server_fd == -1) {
- pr_perror("Can't initialize service socket.");
+ n = sd_listen_fds(0);
+ if (n > 1) {
+ pr_perror("Too many file descriptors (%d) recieved.", n);
goto err;
- }
+ } else if (n == 1)
+ server_fd = SD_LISTEN_FDS_START + 0;
+ else {
+ struct sockaddr_un server_addr;
+ socklen_t server_addr_len;
+
+ server_fd = socket(AF_LOCAL, SOCK_SEQPACKET, 0);
+ if (server_fd == -1) {
+ pr_perror("Can't initialize service socket.");
+ goto err;
+ }
- memset(&server_addr, 0, sizeof(server_addr));
- memset(&client_addr, 0, sizeof(client_addr));
- server_addr.sun_family = AF_LOCAL;
+ memset(&server_addr, 0, sizeof(server_addr));
+ memset(&client_addr, 0, sizeof(client_addr));
+ server_addr.sun_family = AF_LOCAL;
- if (opts.addr == NULL)
- opts.addr = CR_DEFAULT_SERVICE_ADDRESS;
+ if (opts.addr == NULL)
+ opts.addr = CR_DEFAULT_SERVICE_ADDRESS;
- strcpy(server_addr.sun_path, opts.addr);
+ strcpy(server_addr.sun_path, opts.addr);
- server_addr_len = strlen(server_addr.sun_path)
- + sizeof(server_addr.sun_family);
- client_addr_len = sizeof(client_addr);
+ server_addr_len = strlen(server_addr.sun_path)
+ + sizeof(server_addr.sun_family);
+ client_addr_len = sizeof(client_addr);
- unlink(server_addr.sun_path);
+ unlink(server_addr.sun_path);
- if (bind(server_fd, (struct sockaddr *) &server_addr,
- server_addr_len) == -1) {
- pr_perror("Can't bind.");
- goto err;
- }
+ if (bind(server_fd, (struct sockaddr *) &server_addr,
+ server_addr_len) == -1) {
+ pr_perror("Can't bind.");
+ goto err;
+ }
- pr_info("The service socket is bound to %s\n", server_addr.sun_path);
+ pr_info("The service socket is bound to %s\n", server_addr.sun_path);
- /* change service socket permissions, so anyone can connect to it */
- if (chmod(server_addr.sun_path, 0666)) {
- pr_perror("Can't change permissions of the service socket.");
- goto err;
- }
+ /* change service socket permissions, so anyone can connect to it */
+ if (chmod(server_addr.sun_path, 0666)) {
+ pr_perror("Can't change permissions of the service socket.");
+ goto err;
+ }
- if (listen(server_fd, 16) == -1) {
- pr_perror("Can't listen for socket connections.");
- goto err;
+ if (listen(server_fd, 16) == -1) {
+ pr_perror("Can't listen for socket connections.");
+ goto err;
+ }
}
if (daemon_mode) {
diff --git a/criu.service b/criu.service
new file mode 100644
index 0000000..803ce46
--- /dev/null
+++ b/criu.service
@@ -0,0 +1,5 @@
+[Unit]
+Description=Checkpoint Restore in Userspace daemon
+
+[Service]
+ExecStart=/usr/sbin/criu service
diff --git a/criu.socket b/criu.socket
new file mode 100644
index 0000000..7ccf7b4
--- /dev/null
+++ b/criu.socket
@@ -0,0 +1,8 @@
+[Unit]
+Description=Checkpoint Restore in Userspace socket
+
+[Socket]
+ListenSequentialPacket=/var/run/criu-service.socket
+
+[Install]
+WantedBy=sockets.target
diff --git a/sd-daemon.c b/sd-daemon.c
new file mode 100644
index 0000000..2bf506e
--- /dev/null
+++ b/sd-daemon.c
@@ -0,0 +1,521 @@
+#define SD_DAEMON_DISABLE_MQ
+/*-*- 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 <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 <stddef.h>
+#include <limits.h>
+
+#if defined(__linux__) && !defined(SD_DAEMON_DISABLE_MQ)
+# include <mqueue.h>
+#endif
+
+#include "sd-daemon.h"
+
+#if (__GNUC__ >= 4)
+# ifdef SD_EXPORT_SYMBOLS
+/* Export symbols */
+# define _sd_export_ __attribute__ ((visibility("default")))
+# else
+/* Don't export the symbols */
+# define _sd_export_ __attribute__ ((visibility("hidden")))
+# endif
+#else
+# define _sd_export_
+#endif
+
+_sd_export_ 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;
+
+ e = getenv("LISTEN_PID");
+ if (!e) {
+ r = 0;
+ goto finish;
+ }
+
+ errno = 0;
+ l = strtoul(e, &p, 10);
+
+ if (errno > 0) {
+ r = -errno;
+ goto finish;
+ }
+
+ if (!p || p == e || *p || l <= 0) {
+ r = -EINVAL;
+ goto finish;
+ }
+
+ /* Is this for us? */
+ if (getpid() != (pid_t) l) {
+ r = 0;
+ goto finish;
+ }
+
+ e = getenv("LISTEN_FDS");
+ if (!e) {
+ r = 0;
+ goto finish;
+ }
+
+ errno = 0;
+ l = strtoul(e, &p, 10);
+
+ if (errno > 0) {
+ r = -errno;
+ goto finish;
+ }
+
+ if (!p || p == e || *p) {
+ r = -EINVAL;
+ goto finish;
+ }
+
+ for (fd = SD_LISTEN_FDS_START; fd < SD_LISTEN_FDS_START + (int) l; fd ++) {
+ int flags;
+
+ flags = fcntl(fd, F_GETFD);
+ if (flags < 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
+}
+
+_sd_export_ int sd_is_fifo(int fd, const char *path) {
+ struct stat st_fd;
+
+ if (fd < 0)
+ return -EINVAL;
+
+ if (fstat(fd, &st_fd) < 0)
+ return -errno;
+
+ if (!S_ISFIFO(st_fd.st_mode))
+ return 0;
+
+ if (path) {
+ struct stat 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;
+}
+
+_sd_export_ int sd_is_special(int fd, const char *path) {
+ struct stat st_fd;
+
+ if (fd < 0)
+ return -EINVAL;
+
+ if (fstat(fd, &st_fd) < 0)
+ return -errno;
+
+ if (!S_ISREG(st_fd.st_mode) && !S_ISCHR(st_fd.st_mode))
+ return 0;
+
+ if (path) {
+ struct stat st_path;
+
+ if (stat(path, &st_path) < 0) {
+
+ if (errno == ENOENT || errno == ENOTDIR)
+ return 0;
+
+ return -errno;
+ }
+
+ if (S_ISREG(st_fd.st_mode) && S_ISREG(st_path.st_mode))
+ return
+ st_path.st_dev == st_fd.st_dev &&
+ st_path.st_ino == st_fd.st_ino;
+ else if (S_ISCHR(st_fd.st_mode) && S_ISCHR(st_path.st_mode))
+ return st_path.st_rdev == st_fd.st_rdev;
+ else
+ return 0;
+ }
+
+ 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;
+};
+
+_sd_export_ int sd_is_socket(int fd, int family, int type, int listening) {
+ int r;
+
+ if (family < 0)
+ return -EINVAL;
+
+ r = sd_is_socket_internal(fd, type, listening);
+ if (r <= 0)
+ return r;
+
+ if (family > 0) {
+ union sockaddr_union sockaddr = {};
+ socklen_t 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;
+}
+
+_sd_export_ int sd_is_socket_inet(int fd, int family, int type, int listening, uint16_t port) {
+ union sockaddr_union sockaddr = {};
+ socklen_t l = sizeof(sockaddr);
+ int r;
+
+ if (family != 0 && family != AF_INET && family != AF_INET6)
+ return -EINVAL;
+
+ r = sd_is_socket_internal(fd, type, listening);
+ if (r <= 0)
+ return r;
+
+ 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;
+}
+
+_sd_export_ int sd_is_socket_unix(int fd, int type, int listening, const char *path, size_t length) {
+ union sockaddr_union sockaddr = {};
+ socklen_t l = sizeof(sockaddr);
+ int r;
+
+ r = sd_is_socket_internal(fd, type, listening);
+ if (r <= 0)
+ return r;
+
+ 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 == offsetof(struct sockaddr_un, sun_path);
+
+ if (path[0])
+ /* Normal path socket */
+ return
+ (l >= offsetof(struct sockaddr_un, sun_path) + length + 1) &&
+ memcmp(path, sockaddr.un.sun_path, length+1) == 0;
+ else
+ /* Abstract namespace socket */
+ return
+ (l == offsetof(struct sockaddr_un, sun_path) + length) &&
+ memcmp(path, sockaddr.un.sun_path, length) == 0;
+ }
+
+ return 1;
+}
+
+_sd_export_ int sd_is_mq(int fd, const char *path) {
+#if !defined(__linux__) || defined(SD_DAEMON_DISABLE_MQ)
+ return 0;
+#else
+ struct mq_attr attr;
+
+ if (fd < 0)
+ return -EINVAL;
+
+ if (mq_getattr(fd, &attr) < 0)
+ return -errno;
+
+ if (path) {
+ char fpath[PATH_MAX];
+ struct stat a, b;
+
+ if (path[0] != '/')
+ return -EINVAL;
+
+ if (fstat(fd, &a) < 0)
+ return -errno;
+
+ strncpy(stpcpy(fpath, "/dev/mqueue"), path, sizeof(fpath) - 12);
+ fpath[sizeof(fpath)-1] = 0;
+
+ if (stat(fpath, &b) < 0)
+ return -errno;
+
+ if (a.st_dev != b.st_dev ||
+ a.st_ino != b.st_ino)
+ return 0;
+ }
+
+ return 1;
+#endif
+}
+
+_sd_export_ 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;
+ }
+
+ e = getenv("NOTIFY_SOCKET");
+ if (!e)
+ return 0;
+
+ /* Must be an abstract socket, or an absolute path */
+ if ((e[0] != '@' && e[0] != '/') || e[1] == 0) {
+ r = -EINVAL;
+ goto finish;
+ }
+
+ fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0);
+ if (fd < 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 = offsetof(struct sockaddr_un, sun_path) + 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
+}
+
+_sd_export_ 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
+}
+
+_sd_export_ int sd_booted(void) {
+#if defined(DISABLE_SYSTEMD) || !defined(__linux__)
+ return 0;
+#else
+ struct stat st;
+
+ /* We test whether the runtime unit file directory has been
+ * created. This takes place in mount-setup.c, so is
+ * guaranteed to happen very early during boot. */
+
+ if (lstat("/run/systemd/system/", &st) < 0)
+ return 0;
+
+ return !!S_ISDIR(st.st_mode);
+#endif
+}
diff --git a/sd-daemon.h b/sd-daemon.h
new file mode 100644
index 0000000..daa3f4c
--- /dev/null
+++ b/sd-daemon.h
@@ -0,0 +1,282 @@
+/*-*- 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/systemd/plain/src/systemd/sd-daemon.h
+ http://cgit.freedesktop.org/systemd/systemd/plain/src/libsystemd-daemon/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(3) for more information.
+*/
+
+#ifndef _sd_printf_attr_
+# if __GNUC__ >= 4
+# define _sd_printf_attr_(a,b) __attribute__ ((format (printf, a, b)))
+# else
+# define _sd_printf_attr_(a,b)
+# endif
+#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);
+
+/*
+ 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);
+
+/*
+ Helper call for identifying a passed file descriptor. Returns 1 if
+ the file descriptor is a special character device on 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 special character.
+ Returns a negative errno style error code on failure.
+
+ See sd_is_special(3) for more information.
+*/
+int sd_is_special(int fd, const char *path);
+
+/*
+ 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);
+
+/*
+ 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);
+
+/*
+ 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);
+
+/*
+ Helper call for identifying a passed file descriptor. Returns 1 if
+ the file descriptor is a POSIX Message Queue of the specified name,
+ 0 otherwise. If path is NULL a message queue name check is not
+ done. Returns a negative errno style error code on failure.
+*/
+int sd_is_mq(int fd, const char *path);
+
+/*
+ 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 signaling 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"
+
+ WATCHDOG=1 Tells systemd to update the watchdog timestamp.
+ Services using this feature should do this in
+ regular intervals. A watchdog framework can use the
+ timestamps to detect failed services.
+
+ Daemons can choose to send additional variables. However, it is
+ recommended 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);
+
+/*
+ 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);
+
+/*
+ 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 user and system services.
+
+ See sd_booted(3) for more information.
+*/
+int sd_booted(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
--
1.8.5.1
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