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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/***************************************************************************
* daemon.cc
*
* Thu Jun 9 10:27:59 CEST 2005
* Copyright 2005 Bent Bisballe Nyeng
* deva@aasimon.org
****************************************************************************/
/*
* This program 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.
*
* This program 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "daemon.h"
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
// For getgrent and getgrent
#include <sys/types.h>
#include <grp.h>
#include <pwd.h>
// For strcmp
#include <string.h>
// Resolve a group's name or id into a numeric gid
static gid_t get_gid(const char *grp)
{
char *eptr;
gid_t xid = strtoul(grp, &eptr, 10);
struct group *gr;
errno = 0; // Per getgrnam(3) and getgrgid(3) manual page
if(!*eptr)
gr = getgrgid(xid);
else
gr = getgrnam(grp);
return !gr ? 0 : gr->gr_gid;
}
// Resolve a user's name or id into a numeric uid with associated gid
static uid_t get_uid(const char *usr, gid_t *gid)
{
char *eptr;
uid_t xid = strtoul(usr, &eptr, 10);
struct passwd *pw;
errno = 0; // Per getpwnam(3) and getpwuid(3) manual page
if(!*eptr)
pw = getpwuid(xid);
else
pw = getpwnam(usr);
if(!pw)
return 0;
if(!gid)
*gid = pw->pw_gid;
return pw->pw_uid;
}
Daemon::Daemon()
{}
Daemon::~Daemon()
{}
int Daemon::run(const char *user, const char* group, bool detach,
std::string pidfile)
{
// Fetch user and group IDs
gid_t gid = 0;
uid_t uid = 0;
if(user && *user) {
uid = get_uid(user, &gid);
if(errno) {
fprintf(stderr, "Could resolve user \"%s\"", user);
perror("");
}
}
if(group && *group) {
gid = get_gid(group);
if(errno) {
fprintf(stderr, "Could not resolve group \"%s\"", group);
perror("");
}
}
umask(0);
if(pidfile != "" ) {
FILE *fp = fopen(pidfile.c_str(), "r");
if(fp != NULL) {
fclose(fp);
fprintf(stderr, "Could not write pid file \"%s\""
" - file already exists.\n",
pidfile.c_str());
return -1;
}
}
if(detach) {
if(daemon(0, 0) == -1) {
perror("");
return -1;
}
}
if(pidfile != "" ) {
pid_t pid = getpid();
FILE *fp = fopen(pidfile.c_str(), "w");
if(fp == NULL) {
fprintf(stderr, "Could not write pid file \"%s\"", pidfile.c_str());
perror("");
return -1;
} else {
fprintf(fp, "%lu", (unsigned long int)pid);
fclose(fp);
}
}
if(gid) {
// Switch to given group
if(setgid(gid) != 0) {
fprintf(stderr, "Failed to change to group \"%s\" (gid: %d).\n",
group, gid);
perror("");
fprintf(stderr, "Runnning daemon as current group\n");
}
}
if(uid) {
// Switch to given user
if(setuid(uid) != 0) {
fprintf(stderr, "Failed to change to user \"%s\" (uid: %d).\n",
user, uid);
perror("");
fprintf(stderr, "Runnning daemon as current user\n");
}
}
setsid();
signal (SIGTERM, SIG_IGN);
//signal (SIGHUP, SIG_IGN);
// Don't disable Ctrl+c when running in foreground.
//if(detach) signal (SIGINT, SIG_IGN);
int ret = daemon_main();
if(pidfile != "") {
unlink(pidfile.c_str());
}
return ret;
}
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