watchdog: Enable --with-watchdog[=DEV] and improve log messages

This patch changes the configure option to enable the built-in watchdog
from --enable-watchdog to --with-watchdog[=DEV].  This is the convention
for features that take arguments.

Also, improve log messages to aid debugging when finit-watchdogd does
not start properly.  This means flushing logs to syslogd with closelog()

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

configure.ac

@@ -57,10 +57,6 @@ AC_ARG_ENABLE(auto_reload,
         AS_HELP_STRING([--enable-auto-reload], [Automatic reload on any .conf change]),,[
 	enable_auto_reload=no])
 
-AC_ARG_ENABLE(watchdog,
-        AS_HELP_STRING([--enable-watchdog], [Enable built-in watchdog, uses /dev/watchdog]),,[
-	enable_watchdog=no])
-
 AC_ARG_ENABLE(redirect,
         AS_HELP_STRING([--enable-redirect], [Redirect service output to /dev/null, default: no]),,[
 	enable_redirect_output=no])
@@ -124,6 +120,10 @@ AC_ARG_WITH(random-seed,
         AS_HELP_STRING([--with-random-seed=FILE], [Save a random seed for /dev/urandom across reboots, default /var/lib/misc/random-seed]),
 	[random_seed=$withval], [random_seed=yes])
 
+AC_ARG_WITH(watchdog,
+        AS_HELP_STRING([--with-watchdog=[DEV]], [Enable built-in watchdog, default: /dev/watchdog]),
+	[watchdog=$withval],[watchdog=])
+
 ### Enable features ###########################################################################
 
 # Create config.h from selected features and fallback defaults
@@ -133,9 +133,6 @@ AS_IF([test "x$enable_emergency_shell" = "xyes"], [
 AS_IF([test "x$enable_auto_reload" = "xyes"], [
         AC_DEFINE(AUTO_RELOAD, 1, [Finit automatically does `initctl reload` on any .conf change])])
 
-AS_IF([test "x$enable_watchdog" = "xyes"], [
-        AC_DEFINE(BUILTIN_WATCHDOG,  1, [Enable built-in watchdog, kicks on /dev/watchdog])])
-
 AS_IF([test "x$enable_redirect" = "xyes"], [
 	AC_DEFINE(REDIRECT_OUTPUT, 1, [Enable redirection of service output to /dev/null])])
 
@@ -197,9 +194,15 @@ AS_IF([test "x$with_random_seed" != "xno"], [
 	AC_EXPAND_DIR(random_path, "$random_seed")
 	AC_DEFINE_UNQUOTED(RANDOMSEED, "$random_path", [Improve random at boot by seeding it with sth from before.])])
 
+AS_IF([test "x$with_watchdog" != "xno"], [
+	AS_IF([test "x$watchdog" = "xyes"], [
+		watchdog=/dev/watchdog])
+	with_watchdog=yes
+        AC_DEFINE_UNQUOTED(WDT_DEVNODE, "$watchdog", [Built-in watchdog device node])])
+
 # Control build with automake flags
 AM_CONDITIONAL(STATIC,    [test "x$enable_static" = "xyes"])
-AM_CONDITIONAL(WATCHDOGD, [test "x$enable_watchdog" = "xyes"])
+AM_CONDITIONAL(WATCHDOGD, [test "x$with_watchdog" != "xno"])
 AM_CONDITIONAL(LOGIT,     [test "x$enable_logit" = "xyes"])
 AM_CONDITIONAL(DOC,       [test "x$enable_doc" = "xyes"])
 AM_CONDITIONAL(CONTRIB,   [test "x$enable_contrib" = "xyes"])
@@ -246,7 +249,7 @@ Behavior:
 Optional features:
   Install doc/..........: $enable_doc
   Install contrib/......: $enable_contrib
-  Built-in watchdogd....: $enable_watchdog
+  Built-in watchdogd....: $with_watchdog $watchdog
   Built-in logrotate....: $enable_logrotate
   Scripting tool logit..: $enable_logit
   Emergency shell.......: $enable_emergency_shell

src/watchdog.c

@@ -23,6 +23,8 @@
 
 #include <config.h>
 #include <stdio.h>
+#include <string.h>
+#include <sysexits.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
@@ -58,7 +60,7 @@ static int init(char *progname, char *devnode)
 	signal(SIGPWR,  sighandler);
 
 	openlog(&progname[1], LOG_CONS | LOG_PID, LOG_DAEMON);
-	syslog(LOG_INFO, "Finit v%s basic watchdogd starting ...", VERSION);
+	syslog(LOG_INFO, "Finit v%s watchdog %s starting ...", VERSION, devnode);
 
 	fd = open(devnode, O_WRONLY);
 	if (fd == -1)
@@ -89,24 +91,25 @@ static int loop(int fd, int timeout)
 	if (handover) {
 		syslog(LOG_INFO, "Handing over %s and exiting ...", WDT_DEVNODE);
 		ioctl(fd, WDIOC_KEEPALIVE, &dummy);
-		return !write(fd, "V", 1);
+		if (write(fd, "V", 1) == -1)
+			return EX_IOERR;
 	}
 
-	return 0;
+	return EX_OK;
 }
 
 int main(int argc, char *argv[])
 {
-	int fd, ret;
+	int fd, rc = EX_OK;
 
 	fd = init(argv[0], WDT_DEVNODE);
 	if (fd == -1) {
-		if (ENOENT != errno)
-			syslog(LOG_CRIT, "Failed connecting to watchdog %s", WDT_DEVNODE);
-		return 1;
+		syslog(LOG_CRIT, "Failed connecting to %s: %s", WDT_DEVNODE, strerror(errno));
+		rc = EX_OSFILE;
+		goto done;
 	}
 
-	ret = loop(fd, WDT_TIMEOUT);
+	rc = loop(fd, WDT_TIMEOUT);
 	while (!handover) {
 		syslog(LOG_ALERT, "System going down ...");
 
@@ -117,8 +120,10 @@ int main(int argc, char *argv[])
 		ioctl(fd, WDIOC_SETTIMEOUT, &shutdown);
 	}
 	close(fd);
+done:
+	closelog();
 
-	return ret;
+	return rc;
 }
 
 /**

src/watchdog.h

@@ -23,7 +23,9 @@
 
 #include "config.h"		/* Generated by configure script */
 
+#ifndef WDT_DEVNODE
 #define WDT_DEVNODE "/dev/watchdog"
+#endif
 #define WDT_TIMEOUT 30
 
 /**