daemonize.c

/*
 * Copyright (C) 2001-2003 FhG Fokus
 *
 * This file is part of opensips, a free SIP server.
 *
 * opensips is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version
 *
 * opensips is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA
 *
 * History:
 * --------
 *  2004-02-20  removed from ser main.c into its own file (andrei)
 *  2004-03-04  moved setuid/setgid in do_suid() (andrei)
 *  2004-03-25  added increase_open_fds & set_core_dump (andrei)
 *  2004-05-03  applied pgid patch from janakj
 */

/*!
 * \file
 * \brief Setup the OpenSIPS daemon prozess
 */


#include <sys/types.h>

#define _XOPEN_SOURCE   /* needed on linux for the  getpgid prototype, but
                           openbsd 3.2 won't include common types (uint a.s.o)
                           if defined before including sys/types.h */
#define _XOPEN_SOURCE_EXTENDED /* same as above */
#define __USE_XOPEN_EXTENDED /* same as above, overrides features.h */
#define __EXTENSIONS__ /* needed on solaris: if XOPEN_SOURCE is defined
                          struct timeval definition from <sys/time.h> won't
                          be included => workarround define _EXTENSIONS_ */
#include <signal.h>
#include <syslog.h>
#include <errno.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
#include <sys/resource.h> /* setrlimit */
#include <unistd.h>
#ifdef __OS_linux
#include <sys/prctl.h>
#endif

#include "mem/shm_mem.h"
#include "daemonize.h"
#include "sr_module.h"
#include "globals.h"
#include "dprint.h"
#include "pt.h"

/* working dir at startup, before daemonizing; may be NULL if daemonizing 
 * was not performed. It points to a allocated buffer in system memory */
char *startup_wdir = NULL;

static int status_pipe[2];

/* creates the status pipe which will be used for
 * proper status code returning
 *
 * must be called before any forking */
int create_status_pipe(void)
{
	int rc;

	status_pipe[0] = -1;
	status_pipe[1] = -1;

retry:
	rc = pipe(status_pipe);
	if (rc < 0) {
		if (errno == EINTR)
			goto retry;

		LM_ERR("pipe() failed (%d): %d, %s\n", rc, errno, strerror(errno));
	} else {
		LM_DBG("created status pipe, fds=[%d, %d]\n",
		       status_pipe[0], status_pipe[1]);
	}

	return rc;
}

/* attempts to send the val
 * status code to the waiting end */
int send_status_code(char val)
{
	int rc;

retry:
	rc = write(status_pipe[1], &val, 1);
	if (rc < 0) {
		if (errno == EINTR)
			goto retry;

		LM_ERR("write(%d) failed (%d): %d, %s\n", val, rc,
		       errno, strerror(errno));
	} else {
		LM_DBG("sent code %d (%d byte)\n", val, rc);
	}

	if (rc == 1)
		return 0;

	return -1;
}

/* blockingly waits on the pipe
 * until a child sends a status code */
static int wait_status_code(char *code)
{
	int rc;

	if (status_pipe[0] == -1) {
		LM_DBG("invalid read pipe\n");
		goto error;
	}

retry:
	rc = read(status_pipe[0], code, 1);
	if (rc < 0) {
		if (errno == EINTR)
			goto retry;

		LM_ERR("read(1) failed (%d): %d, %s\n", rc, errno, strerror(errno));
	} else {
		LM_DBG("read code %d (%d byte)\n", *code, rc);
	}

	if (rc == 1)
		return 0;

error:
	*code = -1;
	return -1;
}

int wait_for_one_child(void)
{
	char rc;

	if (wait_status_code(&rc)<0 || rc < 0)
		return -1;

	return 0;
}

int wait_for_all_children(void)
{
	int procs_no,i,ret;
	char rc;

	clean_write_pipeend();

	procs_no = count_init_child_processes();
	for (i=0;i<procs_no;i++) {
		ret = wait_status_code(&rc);
		if (ret < 0 || rc < 0)
			return -1;
	}

	return 0;
}

/* cleans read pipe end
 * for processes done reading */
void clean_read_pipeend(void)
{
	if (status_pipe[0] != -1) {
		close(status_pipe[0]);
		status_pipe[0] = -1;
	}
}

/* cleans write pipe end
 * for processes done writing the status code

 * MUST be called to ensure that the original
 * parent process does not keep waiting forever */
void clean_write_pipeend(void)
{
	if (status_pipe[1] != -1) {
		close(status_pipe[1]);
		status_pipe[1] = -1;
	}
}

/*!
 * \brief daemon init
 * \param name daemon name
 * \param own_pgid daemon process group
 * \return return 0 on success, -1 on error
 */
int daemonize(char* name, int * own_pgid)
{
	FILE *pid_stream = NULL;
	pid_t pid;
	int r, p,rc;
	int pid_items;

	p=-1;

	if ( (startup_wdir=getcwd(NULL,0))==NULL) {
		LM_ERR("failed to determin the working dir %d/%s\n", errno,
			strerror(errno));
		goto error;
	}

	/* flush std file descriptors to avoid flushes after fork
	 *  (same message appearing multiple times)
	 *  and switch to unbuffered
	 */
	setbuf(stdout, 0);
	setbuf(stderr, 0);
	if (chroot_dir&&(chroot(chroot_dir)<0)){
		LM_CRIT("Cannot chroot to %s: %s\n", chroot_dir, strerror(errno));
		goto error;
	}

	if (chdir(working_dir)<0){
		LM_CRIT("Cannot chdir to %s: %s\n", working_dir, strerror(errno));
		goto error;
	}

	if (!no_daemon_mode) {
		/* fork to become!= group leader*/
		if ((pid=fork())<0){
			LM_CRIT("Cannot fork:%s\n", strerror(errno));
			goto error;
		}else if (pid!=0){
			/* parent process => wait for status codes from children*/
			clean_write_pipeend();
			LM_DBG("waiting for status code from children\n");
			rc = wait_for_all_children();
			LM_INFO("pre-daemon process exiting with %d\n",rc);
			exit(rc);
		}

		/* cleanup read end - nobody should
		 * need to read from status pipe from this point on */
		clean_read_pipeend();

		/* become session leader to drop the ctrl. terminal */
		if (setsid()<0){
			LM_WARN("setsid failed: %s\n",strerror(errno));
		}else{
			*own_pgid=1;/* we have our own process group */
		}
		/* fork again to drop group  leadership */
		if ((pid=fork())<0){
			LM_CRIT("Cannot fork: %s\n", strerror(errno));
			goto error;
		}else if (pid!=0){
			/*parent process => exit */
			exit(0);
		}

		is_pre_daemon = 0;  /* attendant process at this point */
	}

#ifdef __OS_linux
	/* setsid may disables core dumping on linux, reenable it */
	if ( !disable_core_dump && prctl(PR_SET_DUMPABLE, 1)) {
		LM_ERR("Cannot enable core dumping after setuid\n");
	}
#endif

	/* added by noh: create a pid file for the main process */
	if (pid_file!=0){

		if ((pid_stream=fopen(pid_file, "r"))!=NULL){
			pid_items=fscanf(pid_stream, "%d", &p);
			fclose(pid_stream);
			if (p==-1 || pid_items <= 0){
				LM_WARN("pid file %s exists, but doesn't contain a valid"
					" pid number, replacing...\n", pid_file);
			} else
			if (kill((pid_t)p, 0)==0 || errno==EPERM){
				LM_CRIT("running process found in the pid file %s\n",
					pid_file);
				goto error;
			}else{
				LM_WARN("pid file contains old pid, replacing pid\n");
			}
		}
		pid=getpid();
		if ((pid_stream=fopen(pid_file, "w"))==NULL){
			LM_ERR("unable to create pid file %s: %s\n",
				pid_file, strerror(errno));
			goto error;
		}else{
			r = fprintf(pid_stream, "%i\n", (int)pid);
			fclose(pid_stream);
			if (r<=0)  {
				LM_ERR("unable to write pid to file %s: %s\n",
					pid_file, strerror(errno));
				goto error;
			}
		}
	}

	if (pgid_file!=0){
		if ((pid_stream=fopen(pgid_file, "r"))!=NULL){
			pid_items=fscanf(pid_stream, "%d", &p);
			fclose(pid_stream);
			if (p==-1 || pid_items <= 0){
				LM_WARN("pgid file %s exists, but doesn't contain a valid"
					" pgid number, replacing...\n", pgid_file);
			}
		}
		if (own_pgid){
			pid=getpgid(0);
			if ((pid_stream=fopen(pgid_file, "w"))==NULL){
				LM_ERR("unable to create pgid file %s: %s\n",
					pgid_file, strerror(errno));
				goto error;
			}else{
				r = fprintf(pid_stream, "%i\n", (int)pid);
				fclose(pid_stream);
				if (r<=0)  {
					LM_ERR("unable to write pgid to file %s: %s\n",
						pid_file, strerror(errno));
					goto error;
				}
			}
		}else{
			LM_WARN("we don't have our own process so we won't save"
					" our pgid\n");
			unlink(pgid_file); /* just to be sure nobody will miss-use the old
								  value*/
		}
	}

	/* try to replace stdin, stdout & stderr with /dev/null */
	if (freopen("/dev/null", "r", stdin)==0){
		LM_WARN("unable to replace stdin with /dev/null: %s\n",
			strerror(errno));
		/* continue, leave it open */
	};
	if (!log_stdout && freopen("/dev/null", "w", stdout)==0){
		LM_WARN("unable to replace stdout with /dev/null: %s\n",
			strerror(errno));
		/* continue, leave it open */
	};
	/* close stderr only if not to be used */
	if (!log_stderr && (freopen("/dev/null", "w", stderr)==0)){
		LM_WARN("unable to replace stderr with /dev/null: %s\n",
			strerror(errno));
		/* continue, leave it open */
	};

	/* close any open file descriptors */
	closelog();

	/* 32 is the maximum number of inherited open file descriptors */
	for (r=3; r < 32; r++){
		/* future children must still inherit
		 * and write to this pipe end */
		if (r != status_pipe[1])
			close(r);
	}

	if (!log_stderr)
		openlog(name, LOG_PID|LOG_CONS, log_facility);
		/* LOG_CONS, LOG_PERRROR ? */

	return  0;

error:
	return -1;
}


/*!
 * \brief set daemon user and group id
 * \param uid user id
 * \param gid group id
 * \return return 0 on success, -1 on error
 */
int do_suid(const int uid, const int gid)
{
	/* if running in debug mode, do not do anything about the PID file
	 * as they are not created (daemonize() is not used in debug mode) */
	if (!debug_mode) {
		if (pid_file) {
			/* pid file should be already created by deamonize function
			   -> change the owner and group also
			*/
			if (chown( pid_file , uid?uid:-1, gid?gid:-1)!=0) {
				LM_ERR("failed to change owner of pid file %s: %s(%d)\n",
					pid_file, strerror(errno), errno);
				goto error;
			}
		}
		if (pgid_file) {
			/* pgid file should be already created by deamonize function
			   -> change the owner and group also
			*/
			if (chown( pgid_file , uid?uid:-1, gid?gid:-1)!=0) {
				LM_ERR("failed to change owner of pid file %s: %s(%d)\n",
					pgid_file, strerror(errno), errno);
				goto error;
			}
		}
	}

	if (gid){
		if(setgid(gid)<0){
			LM_CRIT("cannot change gid to %d: %s\n", gid, strerror(errno));
			goto error;
		}
	}

	if(uid){
		if(setuid(uid)<0){
			LM_CRIT("cannot change uid to %d: %s\n", uid, strerror(errno));
			goto error;
		}
	}

#ifdef __OS_linux
	/* setuid disables core dumping on linux, reenable it */
	if ( !disable_core_dump && prctl(PR_SET_DUMPABLE, 1)) {
		LM_ERR("Cannot enable core dumping after setuid\n");
	}
#endif

	return 0;
error:
	return -1;
}



/*!
 * \brief try to increase the open file limit to the value given by the global
 *        option "open_files_limit" ; the value is updated back in case of a
 *        partial increase of the limit
 * \return return 0 on success, -1 on error
 */
int set_open_fds_limit(void)
{
	struct rlimit lim, orig;

	if (getrlimit(RLIMIT_NOFILE, &lim)<0){
		LM_CRIT("cannot get the maximum number of file descriptors: %s\n",
				strerror(errno));
		goto error;
	}
	orig=lim;
	LM_DBG("current open file limits: %lu/%lu\n",
			(unsigned long)lim.rlim_cur, (unsigned long)lim.rlim_max);
	if ((lim.rlim_cur==RLIM_INFINITY) || (open_files_limit<=lim.rlim_cur))
		/* nothing to do (we do no reduce the limit) */
		goto done;
	if ((lim.rlim_max==RLIM_INFINITY) || (open_files_limit<=lim.rlim_max)) {
		lim.rlim_cur=open_files_limit; /* increase soft limit to target */
	} else {
		/* more than the hard limit */
		LM_INFO("trying to increase the open file limit"
				" past the hard limit (%ld -> %d)\n",
				(unsigned long)lim.rlim_max, open_files_limit);
		lim.rlim_max=open_files_limit;
		lim.rlim_cur=open_files_limit;
	}
	LM_DBG("increasing open file limits to: %lu/%lu\n",
			(unsigned long)lim.rlim_cur, (unsigned long)lim.rlim_max);
	if (setrlimit(RLIMIT_NOFILE, &lim)<0){
		LM_CRIT("cannot increase the open file limit to"
				" %lu/%lu: %s\n",
				(unsigned long)lim.rlim_cur, (unsigned long)lim.rlim_max,
				strerror(errno));
		if (orig.rlim_max>orig.rlim_cur){
			/* try to increase to previous maximum, better than not increasing
		 	* at all */
			lim.rlim_max=orig.rlim_max;
			lim.rlim_cur=orig.rlim_max;
			if (setrlimit(RLIMIT_NOFILE, &lim)==0){
				LM_CRIT("maximum number of file descriptors increased to"
					" %u\n",(unsigned)orig.rlim_max);
				open_files_limit = orig.rlim_max;
				goto done;
			}
		}
		goto error;
	}
done:
	LM_DBG("open files limit set to %d\n",open_files_limit);
	return 0;
error:
	return -1;
}



/*!
 * \brief enable or disable core dumps
 * \param enable set to 1 to enable, to 0 to disable
 * \param size core dump size
 * \return return 0 on success, -1 on error
 */
int set_core_dump(int enable, unsigned int size)
{
	struct rlimit lim, newlim;

	if (enable){
		if (getrlimit(RLIMIT_CORE, &lim)<0){
			LM_CRIT("cannot get the maximum core size: %s\n",
					strerror(errno));
			goto error;
		}
		if (lim.rlim_cur<size){
			/* first try max limits */
			newlim.rlim_max=RLIM_INFINITY;
			newlim.rlim_cur=newlim.rlim_max;
			if (setrlimit(RLIMIT_CORE, &newlim)==0) goto done;
			/* now try with size */
			if (lim.rlim_max<size){
				newlim.rlim_max=size;
			}
			newlim.rlim_cur=newlim.rlim_max;
			if (setrlimit(RLIMIT_CORE, &newlim)==0) goto done;
			/* if this failed too, try rlim_max, better than nothing */
			newlim.rlim_max=lim.rlim_max;
			newlim.rlim_cur=newlim.rlim_max;
			if (setrlimit(RLIMIT_CORE, &newlim)<0){
				LM_CRIT("could increase core limits at all: %s\n",
					strerror (errno));
			}else{
				LM_CRIT("core limits increased only to %lu\n",
					(unsigned long)lim.rlim_max);
			}
			goto error; /* it's an error we haven't got the size we wanted*/
		} else {
			/* using the same limit as before - disable uninitialized warning */
			newlim.rlim_cur = lim.rlim_cur;
		}
		goto done; /*nothing to do */
	}else{
		/* disable */
		newlim.rlim_cur=0;
		newlim.rlim_max=0;
		if (setrlimit(RLIMIT_CORE, &newlim)<0){
			LM_CRIT("failed to disable core dumps: %s\n",
				strerror(errno));
			goto error;
		}
	}
done:
	LM_DBG("core dump limits set to %lu\n", (unsigned long)newlim.rlim_cur);
	return 0;
error:
	return -1;
}