mirror of
https://github.com/MariaDB/server.git
synced 2025-11-03 14:33:32 +03:00
344 lines
9.4 KiB
C++
344 lines
9.4 KiB
C++
/* Copyright (C) 2003 MySQL AB & MySQL Finland AB & TCX DataKonsult AB
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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#include <my_global.h>
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#include "manager.h"
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#include "options.h"
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#include "log.h"
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#include <my_sys.h>
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#include <string.h>
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#include <signal.h>
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#include <pwd.h>
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#include <grp.h>
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#include <sys/wait.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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/*
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Few notes about Instance Manager architecture:
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Instance Manager consisits of two processes: the angel process, and the
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instance manager process. Responsibilities of the angel process is to
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monitor the instance manager process, and restart it in case of
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failure/shutdown. The angel process is started only if startup option
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'--run-as-service' is provided.
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The Instance Manager process consists of several
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subsystems (thread sets):
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- the signal handling thread: it's responsibilities are to handle
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user signals and propogate them to the other threads. All other threads
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are accounted in the signal handler thread Thread Registry.
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- the listener: listens all sockets. There is a listening
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socket for each (mysql, http, snmp, rendezvous (?)) subsystem.
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- mysql subsystem: Instance Manager acts like an ordinary MySQL Server,
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but with very restricted command set. Each MySQL client connection is
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handled in a separate thread. All MySQL client connections threads
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constitute mysql subsystem.
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- http subsystem: it is also possible to talk with Instance Manager via
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http. One thread per http connection is used. Threads are pooled.
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- 'snmp' connections (FIXME: I know nothing about it yet)
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- rendezvous threads
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*/
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static void init_environment(char *progname);
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static void daemonize(const char *log_file_name);
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static void angel(const Options &options);
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static struct passwd *check_user(const char *user);
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static int set_user(const char *user, struct passwd *user_info);
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/*
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main, entry point
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- init environment
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- handle options
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- daemonize and run angel process (if necessary)
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- run manager process
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*/
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int main(int argc, char *argv[])
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{
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init_environment(argv[0]);
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Options options;
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struct passwd *user_info;
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if (options.load(argc, argv))
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goto err;
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if ((user_info= check_user(options.user)))
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{
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if (set_user(options.user, user_info))
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{
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options.cleanup();
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return 1;
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}
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}
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if (options.run_as_service)
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{
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/* forks, and returns only in child */
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daemonize(options.log_file_name);
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/* forks again, and returns only in child: parent becomes angel */
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angel(options);
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}
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manager(options);
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options.cleanup();
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my_end(0);
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return 0;
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err:
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my_end(0);
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return 1;
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}
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/******************* Auxilary functions implementation **********************/
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/* Change to run as another user if started with --user */
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static struct passwd *check_user(const char *user)
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{
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#if !defined(__WIN__) && !defined(OS2) && !defined(__NETWARE__)
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struct passwd *user_info;
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uid_t user_id= geteuid();
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/* Don't bother if we aren't superuser */
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if (user_id)
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{
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if (user)
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{
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/* Don't give a warning, if real user is same as given with --user */
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user_info= getpwnam(user);
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if ((!user_info || user_id != user_info->pw_uid))
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log_info("One can only use the --user switch if running as root\n");
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}
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return NULL;
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}
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if (!user)
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{
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log_info("You are running mysqlmanager as root! This might introduce security problems. It is safer to use --user option istead.\n");
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return NULL;
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}
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if (!strcmp(user, "root"))
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return NULL; /* Avoid problem with dynamic libraries */
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if (!(user_info= getpwnam(user)))
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{
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/* Allow a numeric uid to be used */
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const char *pos;
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for (pos= user; my_isdigit(default_charset_info, *pos); pos++) ;
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if (*pos) /* Not numeric id */
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goto err;
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if (!(user_info= getpwuid(atoi(user))))
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goto err;
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else
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return user_info;
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}
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else
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return user_info;
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err:
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log_error("Fatal error: Can't change to run as user '%s' ; Please check that the user exists!\n", user);
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#endif
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return NULL;
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}
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static int set_user(const char *user, struct passwd *user_info)
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{
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DBUG_ASSERT(user_info);
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#ifdef HAVE_INITGROUPS
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initgroups((char*) user,user_info->pw_gid);
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#endif
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if (setgid(user_info->pw_gid) == -1)
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{
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log_error("setgid() failed");
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return 1;
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}
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if (setuid(user_info->pw_uid) == -1)
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{
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log_error("setuid() failed");
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return 1;
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}
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return 0;
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}
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/*
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Init environment, common for daemon and non-daemon
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*/
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static void init_environment(char *progname)
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{
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MY_INIT(progname);
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log_init();
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umask(0117);
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srand(time(0));
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}
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/*
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Become a UNIX service
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SYNOPSYS
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daemonize()
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*/
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static void daemonize(const char *log_file_name)
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{
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pid_t pid= fork();
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switch (pid) {
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case -1: // parent, fork error
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die("daemonize(): fork failed, %s", strerror(errno));
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case 0: // child, fork ok
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int fd;
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/*
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Become a session leader: setsid must succeed because child is
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guaranteed not to be a process group leader (it belongs to the
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process group of the parent.)
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The goal is not to have a controlling terminal.
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*/
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setsid();
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/*
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As we now don't have a controlling terminal we will not receive
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tty-related signals - no need to ignore them.
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*/
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close(STDIN_FILENO);
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fd= open(log_file_name, O_WRONLY | O_CREAT | O_APPEND | O_NOCTTY,
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S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP);
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if (fd < 0)
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die("daemonize(): failed to open log file %s, %s", log_file_name,
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strerror(errno));
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dup2(fd, STDOUT_FILENO);
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dup2(fd, STDERR_FILENO);
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if (fd != STDOUT_FILENO && fd != STDERR_FILENO)
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close(fd);
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/* TODO: chroot() and/or chdir() here */
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break;
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default:
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/* successfully exit from parent */
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exit(0);
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}
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}
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enum { CHILD_OK= 0, CHILD_NEED_RESPAWN, CHILD_EXIT_ANGEL };
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static volatile sig_atomic_t child_status= CHILD_OK;
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/*
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Signal handler for SIGCHLD: reap child, analyze child exit status, and set
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child_status appropriately.
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*/
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void reap_child(int __attribute__((unused)) signo)
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{
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int child_exit_status;
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/* As we have only one child, no need to cycle waitpid */
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if (waitpid(0, &child_exit_status, WNOHANG) > 0)
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{
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if (WIFSIGNALED(child_exit_status))
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child_status= CHILD_NEED_RESPAWN;
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else
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/*
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As reap_child is not called for SIGSTOP, we should be here only
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if the child exited normally.
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*/
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child_status= CHILD_EXIT_ANGEL;
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}
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}
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static volatile sig_atomic_t is_terminated= 0;
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/*
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Signal handler for terminate signals - SIGTERM, SIGHUP, SIGINT.
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Set termination status and return.
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(q) do we need to handle SIGQUIT?
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*/
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void terminate(int signo)
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{
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is_terminated= signo;
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}
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/*
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Fork a child and monitor it.
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User can explicitly kill the angel process with SIGTERM/SIGHUP/SIGINT.
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Angel process will exit silently if mysqlmanager exits normally.
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*/
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static void angel(const Options &options)
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{
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/* install signal handlers */
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sigset_t zeromask; // to sigsuspend in parent
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struct sigaction sa_chld, sa_term;
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struct sigaction sa_chld_out, sa_term_out, sa_int_out, sa_hup_out;
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sigemptyset(&zeromask);
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sigemptyset(&sa_chld.sa_mask);
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sigemptyset(&sa_term.sa_mask);
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sa_chld.sa_handler= reap_child;
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sa_chld.sa_flags= SA_NOCLDSTOP;
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sa_term.sa_handler= terminate;
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sa_term.sa_flags= 0;
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/* sigaction can fail only on wrong arguments */
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sigaction(SIGCHLD, &sa_chld, &sa_chld_out);
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sigaction(SIGTERM, &sa_term, &sa_term_out);
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sigaction(SIGINT, &sa_term, &sa_int_out);
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sigaction(SIGHUP, &sa_term, &sa_hup_out);
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/* spawn a child */
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spawn:
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pid_t pid= fork();
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switch (pid) {
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case -1:
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die("angel(): fork failed, %s", strerror(errno));
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case 0: // child, success
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/*
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restore default actions for signals to let the manager work with
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signals as he wishes
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*/
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sigaction(SIGCHLD, &sa_chld_out, 0);
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sigaction(SIGTERM, &sa_term_out, 0);
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sigaction(SIGINT, &sa_int_out, 0);
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sigaction(SIGHUP, &sa_hup_out, 0);
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/* Here we return to main, and fall into manager */
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break;
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default: // parent, success
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while (child_status == CHILD_OK && is_terminated == 0)
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sigsuspend(&zeromask);
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if (is_terminated)
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log_info("angel got signal %d, exiting", is_terminated);
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else if (child_status == CHILD_NEED_RESPAWN)
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{
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child_status= CHILD_OK;
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log_error("angel(): mysqlmanager exited abnormally: respawning...");
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sleep(1); /* don't respawn too fast */
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goto spawn;
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}
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/*
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mysqlmanager successfully exited, let's silently evaporate
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If we return to main we fall into the manager() function, so let's
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simply exit().
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*/
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exit(0);
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}
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}
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