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+/* Copyright (C) 2003-2006 MySQL AB
+
+ 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; version 2 of the License.
+
+ 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 */
+
+#ifndef __WIN__
+
+#include "angel.h"
+
+#include <signal.h>
+#include <string.h>
+
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+/*
+ Include my_global.h right after system includes so that we can change
+ system defines if needed.
+*/
+
+#include "my_global.h"
+
+/* Include other IM files. */
+
+#include "log.h"
+#include "manager.h"
+#include "options.h"
+#include "priv.h"
+
+/************************************************************************/
+
+enum { CHILD_OK= 0, CHILD_NEED_RESPAWN, CHILD_EXIT_ANGEL };
+
+static int log_fd;
+
+static volatile sig_atomic_t child_status= CHILD_OK;
+static volatile sig_atomic_t shutdown_request_signo= 0;
+
+
+/************************************************************************/
+/**
+ Open log file.
+
+ @return
+ TRUE on error;
+ FALSE on success.
+*************************************************************************/
+
+static bool open_log_file()
+{
+ log_info("Angel: opening log file '%s'...",
+ (const char *) Options::Daemon::log_file_name);
+
+ log_fd= open(Options::Daemon::log_file_name,
+ O_WRONLY | O_CREAT | O_APPEND | O_NOCTTY,
+ S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP);
+
+ if (log_fd < 0)
+ {
+ log_error("Can not open log file '%s': %s.",
+ (const char *) Options::Daemon::log_file_name,
+ (const char *) strerror(errno));
+
+ return TRUE;
+ }
+
+ return FALSE;
+}
+
+
+/************************************************************************/
+/**
+ Detach the process from controlling tty.
+
+ @return
+ TRUE on error;
+ FALSE on success.
+*************************************************************************/
+
+static bool detach_process()
+{
+ /*
+ Become a session leader (the goal is not to have a controlling tty).
+
+ setsid() must succeed because child is guaranteed not to be a process
+ group leader (it belongs to the process group of the parent).
+
+ NOTE: if we now don't have a controlling tty we will not receive
+ tty-related signals - no need to ignore them.
+ */
+
+ if (setsid() < 0)
+ {
+ log_error("setsid() failed: %s.", (const char *) strerror(errno));
+ return -1;
+ }
+
+ /* Close STDIN. */
+
+ log_info("Angel: preparing standard streams.");
+
+ if (close(STDIN_FILENO) < 0)
+ {
+ log_error("Warning: can not close stdin (%s)."
+ "Trying to continue...",
+ (const char *) strerror(errno));
+ }
+
+ /* Dup STDOUT and STDERR to the log file. */
+
+ if (dup2(log_fd, STDOUT_FILENO) < 0 ||
+ dup2(log_fd, STDERR_FILENO) < 0)
+ {
+ log_error("Can not redirect stdout and stderr to the log file: %s.",
+ (const char *) strerror(errno));
+
+ return TRUE;
+ }
+
+ if (log_fd != STDOUT_FILENO && log_fd != STDERR_FILENO)
+ {
+ if (close(log_fd) < 0)
+ {
+ log_error("Can not close original log file handler (%d): %s. "
+ "Trying to continue...",
+ (int) log_fd,
+ (const char *) strerror(errno));
+ }
+ }
+
+ return FALSE;
+}
+
+
+/************************************************************************/
+/**
+ Create PID file.
+
+ @return
+ TRUE on error;
+ FALSE on success.
+*************************************************************************/
+
+static bool create_pid_file()
+{
+ if (create_pid_file(Options::Daemon::angel_pid_file_name, getpid()))
+ {
+ log_error("Angel: can not create pid file (%s).",
+ (const char *) Options::Daemon::angel_pid_file_name);
+
+ return TRUE;
+ }
+
+ log_info("Angel: pid file (%s) created.",
+ (const char *) Options::Daemon::angel_pid_file_name);
+
+ return FALSE;
+}
+
+
+/************************************************************************/
+/**
+ SIGCHLD handler.
+
+ Reap child, analyze child exit status, and set child_status
+ appropriately.
+*************************************************************************/
+
+void reap_child(int __attribute__((unused)) signo)
+{
+ /* NOTE: As we have only one child, no need to cycle waitpid(). */
+
+ int child_exit_status;
+
+ if (waitpid(0, &child_exit_status, WNOHANG) > 0)
+ {
+ child_status= WIFSIGNALED(child_exit_status) ?
+ CHILD_NEED_RESPAWN :
+ CHILD_EXIT_ANGEL;
+ }
+}
+
+
+/************************************************************************/
+/**
+ SIGTERM, SIGHUP, SIGINT handler.
+
+ Set termination status and return.
+*************************************************************************/
+
+void terminate(int signo)
+{
+ shutdown_request_signo= signo;
+}
+
+
+/************************************************************************/
+/**
+ Angel main loop.
+
+ @return
+ The function returns exit status for global main():
+ 0 -- program completed successfully;
+ !0 -- error occurred.
+*************************************************************************/
+
+static int angel_main_loop()
+{
+ /*
+ Install signal handlers.
+
+ NOTE: Although signal handlers are needed only for parent process
+ (IM-angel), we should install them before fork() in order to avoid race
+ condition (i.e. to be sure, that IM-angel will receive SIGCHLD in any
+ case).
+ */
+
+ sigset_t wait_for_signals_mask;
+
+ struct sigaction sa_chld;
+ struct sigaction sa_term;
+ struct sigaction sa_chld_orig;
+ struct sigaction sa_term_orig;
+ struct sigaction sa_int_orig;
+ struct sigaction sa_hup_orig;
+
+ log_info("Angel: setting necessary signal actions...");
+
+ sigemptyset(&wait_for_signals_mask);
+
+ sigemptyset(&sa_chld.sa_mask);
+ sa_chld.sa_handler= reap_child;
+ sa_chld.sa_flags= SA_NOCLDSTOP;
+
+ sigemptyset(&sa_term.sa_mask);
+ sa_term.sa_handler= terminate;
+ sa_term.sa_flags= 0;
+
+ /* NOTE: sigaction() fails only if arguments are wrong. */
+
+ DBUG_ASSERT(!sigaction(SIGCHLD, &sa_chld, &sa_chld_orig));
+ DBUG_ASSERT(!sigaction(SIGTERM, &sa_term, &sa_term_orig));
+ DBUG_ASSERT(!sigaction(SIGINT, &sa_term, &sa_int_orig));
+ DBUG_ASSERT(!sigaction(SIGHUP, &sa_term, &sa_hup_orig));
+
+ /* The main Angel loop. */
+
+ while (true)
+ {
+ /* Spawn a new Manager. */
+
+ log_info("Angel: forking Manager process...");
+
+ switch (fork()) {
+ case -1:
+ log_error("Angel: can not fork IM-main: %s.",
+ (const char *) strerror(errno));
+
+ return -1;
+
+ case 0:
+ /*
+ We are in child process, which will be IM-main:
+ - Restore default signal actions to let the IM-main work with
+ signals as he wishes;
+ - Call Manager::main();
+ */
+
+ log_info("Angel: Manager process created successfully.");
+
+ /* NOTE: sigaction() fails only if arguments are wrong. */
+
+ DBUG_ASSERT(!sigaction(SIGCHLD, &sa_chld_orig, NULL));
+ DBUG_ASSERT(!sigaction(SIGTERM, &sa_term_orig, NULL));
+ DBUG_ASSERT(!sigaction(SIGINT, &sa_int_orig, NULL));
+ DBUG_ASSERT(!sigaction(SIGHUP, &sa_hup_orig, NULL));
+
+ log_info("Angel: executing Manager...");
+
+ return Manager::main();
+ }
+
+ /* Wait for signals. */
+
+ log_info("Angel: waiting for signals...");
+
+ while (child_status == CHILD_OK && shutdown_request_signo == 0)
+ sigsuspend(&wait_for_signals_mask);
+
+ /* Exit if one of shutdown signals has been caught. */
+
+ if (shutdown_request_signo)
+ {
+ log_info("Angel: received shutdown signal (%d). Exiting...",
+ (int) shutdown_request_signo);
+
+ return 0;
+ }
+
+ /* Manager process died. Respawn it if it was a failure. */
+
+ if (child_status == CHILD_NEED_RESPAWN)
+ {
+ child_status= CHILD_OK;
+
+ log_error("Angel: Manager exited abnormally.");
+
+ log_info("Angel: sleeping 1 second...");
+
+ sleep(1); /* don't respawn too fast */
+
+ log_info("Angel: respawning Manager...");
+
+ continue;
+ }
+
+ log_info("Angel: Manager exited normally. Exiting...");
+
+ return 0;
+ }
+}
+
+
+/************************************************************************/
+/**
+ Angel main function.
+
+ @return
+ The function returns exit status for global main():
+ 0 -- program completed successfully;
+ !0 -- error occurred.
+*************************************************************************/
+
+int Angel::main()
+{
+ int ret_status;
+
+ log_info("Angel: started.");
+
+ /* Open log file. */
+
+ if (open_log_file())
+ return -1;
+
+ /* Fork a new process. */
+
+ log_info("Angel: daemonizing...");
+
+ switch (fork()) {
+ case -1:
+ /*
+ This is the main Instance Manager process, fork() failed.
+ Log an error and bail out with error code.
+ */
+
+ log_error("fork() failed: %s.", (const char *) strerror(errno));
+ return -1;
+
+ case 0:
+ /* We are in child process. Continue Angel::main() execution. */
+
+ break;
+
+ default:
+ /*
+ We are in the parent process. Return 0 so that parent exits
+ successfully.
+ */
+
+ log_info("Angel: exiting from the original process...");
+
+ return 0;
+ }
+
+ /* Detach child from controlling tty. */
+
+ if (detach_process())
+ return -1;
+
+ /* Create PID file. */
+
+ if (create_pid_file())
+ return -1;
+
+ /* Start Angel main loop. */
+
+ return angel_main_loop();
+}
+
+#endif // __WIN__
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