[CRIU] [PATCH] systemd socket activation support
Shawn Landden
shawn at churchofgit.com
Wed Dec 11 14:54:48 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
v2: stripped down sd-daemon.[ch]
moved units to scripts/sd
v3: stripped down further by removing unneeded includes
---
Makefile | 3 ++
Makefile.crtools | 1 +
Makefile.inc | 1 +
cr-service.c | 73 ++++++++++++++------------
scripts/sd/criu.service | 5 ++
scripts/sd/criu.socket | 8 +++
sd-daemon.c | 132 ++++++++++++++++++++++++++++++++++++++++++++++++
sd-daemon.h | 91 +++++++++++++++++++++++++++++++++
8 files changed, 282 insertions(+), 32 deletions(-)
create mode 100644 scripts/sd/criu.service
create mode 100644 scripts/sd/criu.socket
create mode 100644 sd-daemon.c
create mode 100644 sd-daemon.h
diff --git a/Makefile b/Makefile
index cd312e7..c9a6042 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 scripts/sd/criu.socket $(DESTDIR)$(SYSTEMDUNITDIR)
+ $(Q) install -m 644 scripts/sd/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..88ae183 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/scripts/sd/criu.service b/scripts/sd/criu.service
new file mode 100644
index 0000000..803ce46
--- /dev/null
+++ b/scripts/sd/criu.service
@@ -0,0 +1,5 @@
+[Unit]
+Description=Checkpoint Restore in Userspace daemon
+
+[Service]
+ExecStart=/usr/sbin/criu service
diff --git a/scripts/sd/criu.socket b/scripts/sd/criu.socket
new file mode 100644
index 0000000..7ccf7b4
--- /dev/null
+++ b/scripts/sd/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..653fbf5
--- /dev/null
+++ b/sd-daemon.c
@@ -0,0 +1,132 @@
+/* stripped down version */
+/***
+ 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 <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+
+#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
+}
+
diff --git a/sd-daemon.h b/sd-daemon.h
new file mode 100644
index 0000000..f6f2959
--- /dev/null
+++ b/sd-daemon.h
@@ -0,0 +1,91 @@
+/* stripped down version */
+
+#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.
+***/
+
+#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.
+*/
+
+/* 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);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
--
1.8.5.1
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