282 lines
6.8 KiB
C
282 lines
6.8 KiB
C
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/*
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* This file is part of the ZFS Event Daemon (ZED)
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* for ZFS on Linux (ZoL) <http://zfsonlinux.org/>.
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* Developed at Lawrence Livermore National Laboratory (LLNL-CODE-403049).
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* Copyright (C) 2013-2014 Lawrence Livermore National Security, LLC.
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* Refer to the ZoL git commit log for authoritative copyright attribution.
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*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License Version 1.0 (CDDL-1.0).
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* You can obtain a copy of the license from the top-level file
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* "OPENSOLARIS.LICENSE" or at <http://opensource.org/licenses/CDDL-1.0>.
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* You may not use this file except in compliance with the license.
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*/
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#include <errno.h>
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#include <fcntl.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include "zed.h"
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#include "zed_conf.h"
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#include "zed_event.h"
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#include "zed_file.h"
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#include "zed_log.h"
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static volatile sig_atomic_t _got_exit = 0;
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static volatile sig_atomic_t _got_hup = 0;
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/*
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* Signal handler for SIGINT & SIGTERM.
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*/
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static void
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_exit_handler(int signum)
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{
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_got_exit = 1;
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}
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/*
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* Signal handler for SIGHUP.
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*/
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static void
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_hup_handler(int signum)
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{
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_got_hup = 1;
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}
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/*
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* Register signal handlers.
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*/
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static void
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_setup_sig_handlers(void)
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{
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struct sigaction sa;
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if (sigemptyset(&sa.sa_mask) < 0)
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zed_log_die("Failed to initialize sigset");
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sa.sa_flags = SA_RESTART;
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sa.sa_handler = SIG_IGN;
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if (sigaction(SIGPIPE, &sa, NULL) < 0)
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zed_log_die("Failed to ignore SIGPIPE");
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sa.sa_handler = _exit_handler;
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if (sigaction(SIGINT, &sa, NULL) < 0)
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zed_log_die("Failed to register SIGINT handler");
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if (sigaction(SIGTERM, &sa, NULL) < 0)
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zed_log_die("Failed to register SIGTERM handler");
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sa.sa_handler = _hup_handler;
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if (sigaction(SIGHUP, &sa, NULL) < 0)
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zed_log_die("Failed to register SIGHUP handler");
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}
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/*
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* Lock all current and future pages in the virtual memory address space.
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* Access to locked pages will never be delayed by a page fault.
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*
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* EAGAIN is tested up to max_tries in case this is a transient error.
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*
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* Note that memory locks are not inherited by a child created via fork()
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* and are automatically removed during an execve(). As such, this must
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* be called after the daemon fork()s (when running in the background).
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*/
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static void
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_lock_memory(void)
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{
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#if HAVE_MLOCKALL
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int i = 0;
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const int max_tries = 10;
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for (i = 0; i < max_tries; i++) {
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if (mlockall(MCL_CURRENT | MCL_FUTURE) == 0) {
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zed_log_msg(LOG_INFO, "Locked all pages in memory");
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return;
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}
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if (errno != EAGAIN)
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break;
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}
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zed_log_die("Failed to lock memory pages: %s", strerror(errno));
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#else /* HAVE_MLOCKALL */
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zed_log_die("Failed to lock memory pages: mlockall() not supported");
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#endif /* HAVE_MLOCKALL */
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}
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/*
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* Start daemonization of the process including the double fork().
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*
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* The parent process will block here until _finish_daemonize() is called
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* (in the grandchild process), at which point the parent process will exit.
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* This prevents the parent process from exiting until initialization is
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* complete.
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*/
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static void
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_start_daemonize(void)
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{
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pid_t pid;
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struct sigaction sa;
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/* Create pipe for communicating with child during daemonization. */
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zed_log_pipe_open();
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/* Background process and ensure child is not process group leader. */
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pid = fork();
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if (pid < 0) {
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zed_log_die("Failed to create child process: %s",
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strerror(errno));
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} else if (pid > 0) {
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/* Close writes since parent will only read from pipe. */
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zed_log_pipe_close_writes();
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/* Wait for notification that daemonization is complete. */
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zed_log_pipe_wait();
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zed_log_pipe_close_reads();
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_exit(EXIT_SUCCESS);
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}
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/* Close reads since child will only write to pipe. */
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zed_log_pipe_close_reads();
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/* Create independent session and detach from terminal. */
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if (setsid() < 0)
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zed_log_die("Failed to create new session: %s",
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strerror(errno));
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/* Prevent child from terminating on HUP when session leader exits. */
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if (sigemptyset(&sa.sa_mask) < 0)
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zed_log_die("Failed to initialize sigset");
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sa.sa_flags = 0;
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sa.sa_handler = SIG_IGN;
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if (sigaction(SIGHUP, &sa, NULL) < 0)
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zed_log_die("Failed to ignore SIGHUP");
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/* Ensure process cannot re-acquire terminal. */
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pid = fork();
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if (pid < 0) {
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zed_log_die("Failed to create grandchild process: %s",
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strerror(errno));
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} else if (pid > 0) {
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_exit(EXIT_SUCCESS);
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}
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}
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/*
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* Finish daemonization of the process by closing stdin/stdout/stderr.
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*
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* This must be called at the end of initialization after all external
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* communication channels are established and accessible.
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*/
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static void
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_finish_daemonize(void)
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{
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int devnull;
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/* Preserve fd 0/1/2, but discard data to/from stdin/stdout/stderr. */
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devnull = open("/dev/null", O_RDWR);
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if (devnull < 0)
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zed_log_die("Failed to open /dev/null: %s", strerror(errno));
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if (dup2(devnull, STDIN_FILENO) < 0)
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zed_log_die("Failed to dup /dev/null onto stdin: %s",
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strerror(errno));
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if (dup2(devnull, STDOUT_FILENO) < 0)
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zed_log_die("Failed to dup /dev/null onto stdout: %s",
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strerror(errno));
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if (dup2(devnull, STDERR_FILENO) < 0)
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zed_log_die("Failed to dup /dev/null onto stderr: %s",
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strerror(errno));
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if ((devnull > STDERR_FILENO) && (close(devnull) < 0))
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zed_log_die("Failed to close /dev/null: %s", strerror(errno));
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/* Notify parent that daemonization is complete. */
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zed_log_pipe_close_writes();
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}
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/*
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* ZFS Event Daemon (ZED).
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*/
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int
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main(int argc, char *argv[])
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{
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struct zed_conf *zcp;
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uint64_t saved_eid;
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int64_t saved_etime[2];
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zed_log_init(argv[0]);
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zed_log_stderr_open(LOG_NOTICE);
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zcp = zed_conf_create();
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zed_conf_parse_opts(zcp, argc, argv);
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if (zcp->do_verbose)
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zed_log_stderr_open(LOG_INFO);
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if (geteuid() != 0)
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zed_log_die("Must be run as root");
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zed_conf_parse_file(zcp);
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zed_file_close_from(STDERR_FILENO + 1);
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(void) umask(0);
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if (chdir("/") < 0)
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zed_log_die("Failed to change to root directory");
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if (zed_conf_scan_dir(zcp) < 0)
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exit(EXIT_FAILURE);
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if (!zcp->do_foreground) {
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_start_daemonize();
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zed_log_syslog_open(LOG_DAEMON);
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}
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_setup_sig_handlers();
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if (zcp->do_memlock)
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_lock_memory();
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if ((zed_conf_write_pid(zcp) < 0) && (!zcp->do_force))
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exit(EXIT_FAILURE);
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if (!zcp->do_foreground)
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_finish_daemonize();
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zed_log_msg(LOG_NOTICE,
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"ZFS Event Daemon %s-%s (PID %d)",
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ZFS_META_VERSION, ZFS_META_RELEASE, (int)getpid());
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if (zed_conf_open_state(zcp) < 0)
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exit(EXIT_FAILURE);
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if (zed_conf_read_state(zcp, &saved_eid, saved_etime) < 0)
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exit(EXIT_FAILURE);
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zed_event_init(zcp);
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zed_event_seek(zcp, saved_eid, saved_etime);
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while (!_got_exit) {
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if (_got_hup) {
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_got_hup = 0;
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(void) zed_conf_scan_dir(zcp);
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}
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zed_event_service(zcp);
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}
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zed_log_msg(LOG_NOTICE, "Exiting");
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zed_event_fini(zcp);
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zed_conf_destroy(zcp);
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zed_log_fini();
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exit(EXIT_SUCCESS);
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}
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