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authorChris Boot <bootc@bootc.net>2013-05-12 13:47:40 +0100
committerEric Leblond <eric@regit.org>2013-05-21 19:57:07 +0200
commite04f1ce916965464318f882376eef04a8b6759f2 (patch)
treec389ac064344111ef0f99566fc8c167f1ef868cd /src
parent401c446ce73dfee19afb668a2761f335bcb91877 (diff)
ulogd: Implement PID file writing
The deamon currently does not have the ability to write a PID file to track its process ID. This is very useful to an init script and to ensure there is only one running instance. This patch implements this functionality. Signed-off-by: Chris Boot <bootc@bootc.net>
Diffstat (limited to 'src')
-rw-r--r--src/ulogd.c147
1 files changed, 146 insertions, 1 deletions
diff --git a/src/ulogd.c b/src/ulogd.c
index 76190d9..4309201 100644
--- a/src/ulogd.c
+++ b/src/ulogd.c
@@ -4,6 +4,7 @@
*
* (C) 2000-2005 by Harald Welte <laforge@gnumonks.org>
* (C) 2013 by Eric Leblond <eric@regit.org>
+ * (C) 2013 Chris Boot <bootc@bootc.net>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
@@ -55,12 +56,14 @@
#include <signal.h>
#include <dlfcn.h>
#include <sys/types.h>
+#include <fcntl.h>
#include <dirent.h>
#include <getopt.h>
#include <pwd.h>
#include <grp.h>
#include <syslog.h>
#include <sys/time.h>
+#include <sys/stat.h>
#include <ulogd/conffile.h>
#include <ulogd/ulogd.h>
#ifdef DEBUG
@@ -78,11 +81,13 @@
static FILE *logfile = NULL; /* logfile pointer */
static char *ulogd_logfile = NULL;
static const char *ulogd_configfile = ULOGD_CONFIGFILE;
+static const char *ulogd_pidfile = NULL;
static FILE syslog_dummy;
static int info_mode = 0;
static int verbose = 0;
+static int created_pidfile = 0;
/* linked list for all registered plugins */
static LLIST_HEAD(ulogd_plugins);
@@ -94,6 +99,7 @@ static LLIST_HEAD(ulogd_pi_stacks);
static int load_plugin(const char *file);
static int create_stack(const char *file);
static int logfile_open(const char *name);
+static void cleanup_pidfile();
static struct config_keyset ulogd_kset = {
.num_ces = 4,
@@ -457,6 +463,8 @@ void __ulogd_log(int level, char *file, int line, const char *format, ...)
static void warn_and_exit(int daemonize)
{
+ cleanup_pidfile();
+
if (!daemonize) {
if (logfile && !verbose) {
fprintf(stderr, "Fatal error, check logfile \"%s\""
@@ -1002,6 +1010,131 @@ static int parse_conffile(const char *section, struct config_keyset *ce)
return 1;
}
+/*
+ * Apply F_WRLCK to fd using fcntl().
+ *
+ * This function is copied verbatim from atd's daemon.c file, published under
+ * the GPL2+ license with the following copyright statement:
+ * Copyright (C) 1996 Thomas Koenig
+ */
+static int lock_fd(int fd)
+{
+ struct flock lock;
+
+ lock.l_type = F_WRLCK;
+ lock.l_whence = SEEK_SET;
+ lock.l_start = 0;
+ lock.l_len = 0;
+
+ return fcntl(fd, F_SETLK, &lock);
+}
+
+/*
+ * Manage ulogd's pidfile.
+ *
+ * This function is based on atd's daemon.c:daemon_setup() function, published
+ * under the GPL2+ license with the following copyright statement:
+ * Copyright (C) 1996 Thomas Koenig
+ */
+static int write_pidfile()
+{
+ int fd;
+ FILE *fp;
+ pid_t pid = -1;
+
+ fd = open(ulogd_pidfile, O_RDWR | O_CREAT | O_EXCL, 0644);
+ if (fd < 0) {
+ if (errno != EEXIST) {
+ ulogd_log(ULOGD_ERROR, "cannot open %s: %d\n",
+ ulogd_pidfile, errno);
+ return -1;
+ }
+
+ fd = open(ulogd_pidfile, O_RDWR);
+ if (fd < 0) {
+ ulogd_log(ULOGD_ERROR, "cannot open %s: %d\n",
+ ulogd_pidfile, errno);
+ return -1;
+ }
+
+ fp = fdopen(fd, "rw");
+ if (fp == NULL) {
+ ulogd_log(ULOGD_ERROR, "cannot fdopen %s: %d\n",
+ ulogd_pidfile, errno);
+ return -1;
+ }
+
+ if ((fscanf(fp, "%d", &pid) != 1) || (pid == getpid())
+ || (lock_fd(fd) == 0)) {
+ ulogd_log(ULOGD_NOTICE,
+ "removing stale pidfile for pid %d\n", pid);
+
+ if (unlink(ulogd_pidfile) < 0) {
+ ulogd_log(ULOGD_ERROR, "cannot unlink %s: %d\n",
+ ulogd_pidfile, errno);
+ return -1;
+ }
+ } else {
+ ulogd_log(ULOGD_FATAL,
+ "another ulogd already running with pid %d\n",
+ pid);
+ return -1;
+ }
+
+ fclose(fp);
+ unlink(ulogd_pidfile);
+
+ fd = open(ulogd_pidfile, O_RDWR | O_CREAT | O_EXCL, 0644);
+
+ if (fd < 0) {
+ ulogd_log(ULOGD_ERROR,
+ "cannot open %s (2nd time round): %d\n",
+ ulogd_pidfile, errno);
+ return -1;
+ }
+ }
+
+ if (lock_fd(fd) < 0) {
+ ulogd_log(ULOGD_ERROR, "cannot lock %s: %d\n", ulogd_pidfile,
+ errno);
+ return -1;
+ }
+
+ fp = fdopen(fd, "w");
+ if (fp == NULL) {
+ ulogd_log(ULOGD_ERROR, "cannot fdopen %s: %d\n", ulogd_pidfile,
+ errno);
+ return -1;
+ }
+
+ fprintf(fp, "%d\n", getpid());
+ fflush(fp);
+
+ if (ftruncate(fileno(fp), ftell(fp)) < 0)
+ ulogd_log(ULOGD_NOTICE, "cannot ftruncate %s: %d\n",
+ ulogd_pidfile, errno);
+
+ /*
+ * We do NOT close fd, since we want to keep the lock. However, we don't
+ * want to keep the file descriptor in case of an exec().
+ */
+ fcntl(fd, F_SETFD, FD_CLOEXEC);
+
+ created_pidfile = 1;
+
+ return 0;
+}
+
+static void cleanup_pidfile()
+{
+ if (!ulogd_pidfile || !created_pidfile)
+ return;
+
+ if (unlink(ulogd_pidfile) != 0)
+ ulogd_log(ULOGD_ERROR, "PID file %s could not be deleted: %d\n",
+ ulogd_pidfile, errno);
+}
+
static void deliver_signal_pluginstances(int signal)
{
struct ulogd_pluginstance_stack *stack;
@@ -1080,6 +1213,8 @@ static void sigterm_handler(int signal)
config_stop();
+ cleanup_pidfile();
+
exit(0);
}
@@ -1121,6 +1256,7 @@ static void print_usage(void)
printf("\t-v --verbose\tOutput info on standard output\n");
printf("\t-l --loglevel\tSet log level\n");
printf("\t-c --configfile\tUse alternative Configfile\n");
+ printf("\t-p --pidfile\tRecord ulogd PID in file\n");
printf("\t-u --uid\tChange UID/GID\n");
printf("\t-i --info\tDisplay infos about plugin\n");
}
@@ -1134,6 +1270,7 @@ static struct option opts[] = {
{ "info", 1, NULL, 'i' },
{ "verbose", 0, NULL, 'v' },
{ "loglevel", 1, NULL, 'l' },
+ { "pidfile", 1, NULL, 'p' },
{NULL, 0, NULL, 0}
};
@@ -1150,7 +1287,7 @@ int main(int argc, char* argv[])
ulogd_logfile = strdup(ULOGD_LOGFILE_DEFAULT);
- while ((argch = getopt_long(argc, argv, "c:dvl:h::Vu:i:", opts, NULL)) != -1) {
+ while ((argch = getopt_long(argc, argv, "c:p:dvl:h::Vu:i:", opts, NULL)) != -1) {
switch (argch) {
default:
case '?':
@@ -1179,6 +1316,9 @@ int main(int argc, char* argv[])
case 'c':
ulogd_configfile = optarg;
break;
+ case 'p':
+ ulogd_pidfile = optarg;
+ break;
case 'u':
change_uid = 1;
user = strdup(optarg);
@@ -1280,6 +1420,11 @@ int main(int argc, char* argv[])
setsid();
}
+ if (ulogd_pidfile) {
+ if (write_pidfile() < 0)
+ warn_and_exit(daemonize);
+ }
+
signal(SIGTERM, &sigterm_handler);
signal(SIGINT, &sigterm_handler);
signal(SIGHUP, &signal_handler);