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Diffstat (limited to 'src/Daemon.cxx')
| -rw-r--r-- | src/Daemon.cxx | 244 |
1 files changed, 244 insertions, 0 deletions
diff --git a/src/Daemon.cxx b/src/Daemon.cxx new file mode 100644 index 000000000..8e22ed131 --- /dev/null +++ b/src/Daemon.cxx @@ -0,0 +1,244 @@ +/* + * Copyright (C) 2003-2013 The Music Player Daemon Project + * http://www.musicpd.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., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + */ + +#include "config.h" +#include "Daemon.hxx" +#include "system/FatalError.hxx" +#include "fs/Path.hxx" +#include "fs/FileSystem.hxx" +#include "util/Domain.hxx" +#include "Log.hxx" + +#include <glib.h> + +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <string.h> +#include <sys/types.h> +#include <sys/stat.h> +#include <fcntl.h> + +#ifndef WIN32 +#include <signal.h> +#include <pwd.h> +#include <grp.h> +#endif + +static constexpr Domain daemon_domain("daemon"); + +#ifndef WIN32 + +/** the Unix user name which MPD runs as */ +static char *user_name; + +/** the Unix user id which MPD runs as */ +static uid_t user_uid = (uid_t)-1; + +/** the Unix group id which MPD runs as */ +static gid_t user_gid = (pid_t)-1; + +/** the absolute path of the pidfile */ +static Path pidfile = Path::Null(); + +/* whether "group" conf. option was given */ +static bool had_group = false; + + +void +daemonize_kill(void) +{ + FILE *fp; + int pid, ret; + + if (pidfile.IsNull()) + FatalError("no pid_file specified in the config file"); + + fp = FOpen(pidfile, "r"); + if (fp == nullptr) { + const std::string utf8 = pidfile.ToUTF8(); + FormatFatalSystemError("Unable to open pid file \"%s\"", + utf8.c_str()); + } + + if (fscanf(fp, "%i", &pid) != 1) { + const std::string utf8 = pidfile.ToUTF8(); + FormatFatalError("unable to read the pid from file \"%s\"", + utf8.c_str()); + } + fclose(fp); + + ret = kill(pid, SIGTERM); + if (ret < 0) + FormatFatalSystemError("unable to kill process %i", + int(pid)); + + exit(EXIT_SUCCESS); +} + +void +daemonize_close_stdin(void) +{ + close(STDIN_FILENO); + open("/dev/null", O_RDONLY); +} + +void +daemonize_set_user(void) +{ + if (user_name == nullptr) + return; + + /* set gid */ + if (user_gid != (gid_t)-1 && user_gid != getgid()) { + if (setgid(user_gid) == -1) { + FormatFatalSystemError("Failed to set group %d", + (int)user_gid); + } + } + +#ifdef _BSD_SOURCE + /* init suplementary groups + * (must be done before we change our uid) + */ + if (!had_group && initgroups(user_name, user_gid) == -1) { + FormatFatalSystemError("Failed to set supplementary groups " + "of user \"%s\"", + user_name); + } +#endif + + /* set uid */ + if (user_uid != (uid_t)-1 && user_uid != getuid() && + setuid(user_uid) == -1) { + FormatFatalSystemError("Failed to set user \"%s\"", + user_name); + } +} + +static void +daemonize_detach(void) +{ + /* flush all file handles before duplicating the buffers */ + + fflush(nullptr); + +#ifdef HAVE_DAEMON + + if (daemon(0, 1)) + FatalSystemError("daemon() failed"); + +#elif defined(HAVE_FORK) + + /* detach from parent process */ + + switch (fork()) { + case -1: + FatalSystemError("fork() failed"); + case 0: + break; + default: + /* exit the parent process */ + _exit(EXIT_SUCCESS); + } + + /* release the current working directory */ + + if (chdir("/") < 0) + FatalError("problems changing to root directory"); + + /* detach from the current session */ + + setsid(); + +#else + FatalError("no support for daemonizing"); +#endif + + LogDebug(daemon_domain, "daemonized"); +} + +void +daemonize(bool detach) +{ + FILE *fp = nullptr; + + if (!pidfile.IsNull()) { + /* do this before daemon'izing so we can fail gracefully if we can't + * write to the pid file */ + LogDebug(daemon_domain, "opening pid file"); + fp = FOpen(pidfile, "w+"); + if (!fp) { + const std::string utf8 = pidfile.ToUTF8(); + FormatFatalSystemError("Failed to create pid file \"%s\"", + pidfile.c_str()); + } + } + + if (detach) + daemonize_detach(); + + if (!pidfile.IsNull()) { + LogDebug(daemon_domain, "writing pid file"); + fprintf(fp, "%lu\n", (unsigned long)getpid()); + fclose(fp); + } +} + +void +daemonize_init(const char *user, const char *group, Path &&_pidfile) +{ + if (user) { + struct passwd *pwd = getpwnam(user); + if (pwd == nullptr) + FormatFatalError("no such user \"%s\"", user); + + user_uid = pwd->pw_uid; + user_gid = pwd->pw_gid; + + user_name = g_strdup(user); + + /* this is needed by libs such as arts */ + g_setenv("HOME", pwd->pw_dir, true); + } + + if (group) { + struct group *grp = getgrnam(group); + if (grp == nullptr) + FormatFatalError("no such group \"%s\"", group); + user_gid = grp->gr_gid; + had_group = true; + } + + + pidfile = std::move(_pidfile); +} + +void +daemonize_finish(void) +{ + if (!pidfile.IsNull()) { + RemoveFile(pidfile); + pidfile = Path::Null(); + } + + g_free(user_name); +} + +#endif |