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watchdog: Add simple built-in watchdog daemon

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This patch adds a simple but effective watchdog daemon with support for
handover to an external daemon, should one register using the API.

Disabled by default, enable by:

    configure --enable-watchdog

The watchdog forks to the background, opening /dev/watchdog setting a
three second timeout, and kicking every second.  At shutdown/reboot the
daemon will receive SIGPWR from Finit to exit and cause a WDT reboot.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>
This commit is contained in:
Joachim Nilsson
2016-10-24 00:06:04 +02:00
parent 88f9458c6e
commit b674aad802
5 changed files with 193 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files
Makefile.am
+3
View File
@@ -19,6 +19,9 @@ pkginclude_HEADERS = cond.h finit.h helpers.h inetd.h plugin.h svc.h
if INETD
finit_SOURCES += inetd.c inetd.h
endif
if WATCHDOGD
finit_SOURCES += watchdog.c watchdog.h
endif
finit_CFLAGS = -W -Wall -Wextra -std=gnu99 $(lite_CFLAGS) $(uev_CFLAGS)
finit_LDADD = $(lite_LIBS) $(uev_LIBS)
configure.ac
+9 -2
View File
@@ -50,6 +50,9 @@ AC_ARG_ENABLE(rw-rootfs,
AC_ARG_ENABLE(silent,
AS_HELP_STRING([--enable-silent], [Completely silent operation, not even boot messages]))
AC_ARG_ENABLE(watchdog,
AS_HELP_STRING([--enable-watchdog], [Enable built-in watchdog, uses /dev/watchdog]))
AC_ARG_ENABLE(inetd,
AS_HELP_STRING([--disable-inetd], [Disable built-in inetd super server, default enabled]))
@@ -134,6 +137,9 @@ AS_IF([test "x$enable_silent" = "xyes"], [
], [
AC_DEFINE(SILENT_MODE, 0, [Normal output, default])])
AS_IF([test "x$enable_watchdog" = "xyes"], [
AC_DEFINE(BUILTIN_WATCHDOG, 1, [Enable built-in watchdog, kicks on /dev/watchdog])])
### Disable features ###########################################################################
AS_IF([test "x$enable_inetd" != "xno"], enable_inetd="yes", [
AC_DEFINE(INETD_DISABLED, 1, [Disable built-in inetd])])
@@ -200,8 +206,9 @@ AS_IF([test "x$with_random_seed" != "xno"], [
AC_DEFINE_UNQUOTED(RANDOMSEED, "$lurvig", [Improve random at boot by seeding it with sth from before.])])
# Control build with automake flags
AM_CONDITIONAL(STATIC, [test "x$enable_static" = "xyes"])
AM_CONDITIONAL(INETD, [test "x$enable_inetd" = "xyes"])
AM_CONDITIONAL(STATIC, [test "x$enable_static" = "xyes"])
AM_CONDITIONAL(INETD, [test "x$enable_inetd" = "xyes"])
AM_CONDITIONAL(WATCHDOGD, [test "x$enable_watchdog" = "xyes"])
# Generate all files
AC_OUTPUT
finit.c
+6
View File
@@ -46,6 +46,7 @@
#include "sm.h"
#include "tty.h"
#include "utmp-api.h"
#include "watchdog.h"
int debug = 0;
int quiet = QUIET_MODE; /* Delayed disable of silent mode. */
@@ -343,6 +344,11 @@ int main(int argc, char* argv[])
*/
conf_parse_config();
/*
* Start built-in watchdog as soon as possible, if enabled
*/
watchdog(argv[0]);
/* Set hostname as soon as possible, for syslog et al. */
set_hostname(&hostname);
watchdog.c
+135
View File
@@ -0,0 +1,135 @@
/* Built-in watchdog daemon
*
* Copyright (c) 2016 Joachim Nilsson <troglobit@gmail.com>
*
* 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 <paths.h>
#include <sys/un.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <linux/watchdog.h>
#include "finit.h"
#include "helpers.h"
#include "watchdog.h"
int running = 1;
int handover = 0;
static int notify(void)
{
int sd, result = 255;
ssize_t len;
struct sockaddr_un sun = {
.sun_family = AF_UNIX,
.sun_path = INIT_SOCKET,
};
struct init_request rq;
sd = socket(AF_UNIX, SOCK_STREAM, 0);
if (-1 == sd)
return -1;
if (connect(sd, (struct sockaddr*)&sun, sizeof(sun)) == -1)
goto exit;
rq.cmd = INIT_CMD_WDOG_HELLO;
rq.magic = INIT_MAGIC;
rq.runlevel = getpid();
len = sizeof(rq);
if (write(sd, &rq, len) != len)
goto exit;
if (read(sd, &rq, len) != len)
goto exit;
result = 0;
exit:
close(sd);
return result;
}
static void sighandler(int signo)
{
if (signo == SIGTERM)
handover = 1;
running = 0;
}
static int init(char *progname, char *devnode, int timeout)
{
int fd;
sprintf(progname, "@finit-watchdog");
signal(SIGTERM, sighandler);
signal(SIGPWR, sighandler);
fd = open(devnode, O_WRONLY);
if (fd == -1)
return -1;
ioctl(fd, WDIOC_SETTIMEOUT, &timeout);
return fd;
}
static int loop(int fd)
{
int done = 0;
while (running) {
do_sleep(1);
ioctl(fd, WDIOC_KEEPALIVE, &done);
if (!done && !notify())
done = 1;
}
if (handover)
return !write(fd, "V", 1);
return 0;
}
void watchdog(char *progname)
{
if (fork() == 0) {
int fd, ret;
fd = init(progname, WDT_DEVNODE, WDT_TIMEOUT);
if (fd == -1) {
_pe("Failed connecting to watchdog %s", WDT_DEVNODE);
_exit(1);
}
ret = loop(fd);
close(fd);
_exit(ret);
}
}
/**
* Local Variables:
* indent-tabs-mode: t
* c-file-style: "linux"
* End:
*/
watchdog.h
+40
View File
@@ -0,0 +1,40 @@
/* Built-in watchdog daemon
*
* Copyright (c) 2016 Joachim Nilsson <troglobit@gmail.com>
*
* 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 "config.h" /* Generated by configure script */
#define WDT_DEVNODE "/dev/watchdog"
#define WDT_TIMEOUT 3
#ifdef BUILTIN_WATCHDOG
void watchdog(char *progname);
#else
#define watchdog(progname)
#endif /* BUILTIN_WATCHDOG */
/**
* Local Variables:
* indent-tabs-mode: t
* c-file-style: "linux"
* End:
*/