From e04f1ce916965464318f882376eef04a8b6759f2 Mon Sep 17 00:00:00 2001 From: Chris Boot Date: Sun, 12 May 2013 13:47:40 +0100 Subject: 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 --- src/ulogd.c | 147 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++- ulogd.8 | 3 ++ 2 files changed, 149 insertions(+), 1 deletion(-) 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 * (C) 2013 by Eric Leblond + * (C) 2013 Chris Boot * * 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 #include #include +#include #include #include #include #include #include #include +#include #include #include #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); diff --git a/ulogd.8 b/ulogd.8 index 9cbad7c..9d16aeb 100644 --- a/ulogd.8 +++ b/ulogd.8 @@ -57,6 +57,9 @@ change UID/GID .TP .B -i , --info display infos about plugin +.TP +.B -p , --pidfile +record the ulogd process ID to the given file name .SH FILES .I /etc/ulogd.conf .br -- cgit v1.2.3