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/** @file
* daemon_init function, does sanity checks and calls daemon().
*
* Author: Jeff Moyer <jmoyer@redhat.com>
*/
/*
* TODO: Clean this up so that only one function constructs the
* pidfile /var/run/loggerd.PID, and perhaps only one function
* forms the /proc/PID/ path.
*
* Also need to add file locking for the pid file.
*/
#include "config.h"
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/param.h>
#include <fcntl.h>
#include <dirent.h>
#include <sys/mman.h>
#include <sys/errno.h>
#include <libgen.h>
#include <signal.h>
#include <syslog.h>
/*
* This should ultimately go in a header file.
*/
void daemon_init(const char *prog, const char *pid_file, int nofork);
void daemon_cleanup(void);
int check_process_running(const char *cmd, const char *pid_file, pid_t * pid);
/*
* Local prototypes.
*/
static void update_pidfile(const char *filename);
static int setup_sigmask(void);
static char pid_filename[PATH_MAX];
static int
check_pid_valid(pid_t pid, const char *prog)
{
FILE *fp;
DIR *dir;
char filename[PATH_MAX];
char dirpath[PATH_MAX];
char proc_cmdline[64]; /* yank this from kernel somewhere */
char *s = NULL;
memset(filename, 0, PATH_MAX);
memset(dirpath, 0, PATH_MAX);
snprintf(dirpath, sizeof (dirpath), "/proc/%d", pid);
if ((dir = opendir(dirpath)) == NULL) {
return 0; /* Pid has gone away. */
}
closedir(dir);
/*
* proc-pid directory exists. Now check to see if this
* PID corresponds to the daemon we want to start.
*/
snprintf(filename, sizeof (filename), "/proc/%d/cmdline", pid);
fp = fopen(filename, "r");
if (fp == NULL) {
perror("check_pid_valid");
return 0; /* Who cares.... Let's boogy on. */
}
if (!fgets(proc_cmdline, sizeof (proc_cmdline) - 1, fp)) {
/*
* Okay, we've seen processes keep a reference to a
* /proc/PID/stat file and not let go. Then when
* you try to read /proc/PID/cmline, you get either
* \000 or -1. In either case, we can safely assume
* the process has gone away.
*/
fclose(fp);
return 0;
}
fclose(fp);
s = &(proc_cmdline[strlen(proc_cmdline)]);
if (*s == '\n')
*s = 0;
/*
* Check to see if this is the same executable.
*/
if (strstr(proc_cmdline, prog) == NULL) {
return 0;
} else {
return 1;
}
}
int
check_process_running(const char *cmd, const char *filename, pid_t * pid)
{
pid_t oldpid;
FILE *fp = NULL;
int ret;
*pid = -1;
/*
* Read the pid from the file.
*/
fp = fopen(filename, "r");
if (fp == NULL) { /* error */
return 0;
}
ret = fscanf(fp, "%d\n", &oldpid);
fclose(fp);
if ((ret == EOF) || (ret != 1))
return 0;
if (check_pid_valid(oldpid, cmd)) {
*pid = oldpid;
return 1;
}
return 0;
}
static void
update_pidfile(const char *filename)
{
FILE *fp = NULL;
strncpy(pid_filename, filename, PATH_MAX - 1);
fp = fopen(pid_filename, "w");
if (fp == NULL) {
syslog(LOG_ERR, "daemon_init: Unable to create pidfile %s: %s\n",
filename, strerror(errno));
exit(1);
}
fprintf(fp, "%d", getpid());
fclose(fp);
}
static int
setup_sigmask(void)
{
sigset_t set;
sigfillset(&set);
/*
* Dont't block signals which would cause us to dump core.
*/
sigdelset(&set, SIGQUIT);
sigdelset(&set, SIGILL);
sigdelset(&set, SIGTRAP);
sigdelset(&set, SIGABRT);
sigdelset(&set, SIGFPE);
sigdelset(&set, SIGSEGV);
sigdelset(&set, SIGBUS);
/*
* Don't block SIGTERM or SIGCHLD
*/
sigdelset(&set, SIGTERM);
sigdelset(&set, SIGINT);
sigdelset(&set, SIGQUIT);
sigdelset(&set, SIGCHLD);
return (sigprocmask(SIG_BLOCK, &set, NULL));
}
void
daemon_init(const char *prog, const char *pid_file, int nofork)
{
pid_t pid;
if (check_process_running(prog, pid_file, &pid) && (pid != getpid())) {
syslog(LOG_ERR,
"daemon_init: Process \"%s\" already running.\n",
prog);
exit(1);
}
if (setup_sigmask() < 0) {
syslog(LOG_ERR, "daemon_init: Unable to set signal mask.\n");
exit(1);
}
if (!nofork && daemon(0, 0)) {
syslog(LOG_ERR, "daemon_init: Unable to daemonize.\n");
exit(1);
}
update_pidfile(pid_file);
}
void
daemon_cleanup(void)
{
if (strlen(pid_filename))
unlink(pid_filename);
}
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