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/*
* This file is part of the ZFS Event Daemon (ZED)
* for ZFS on Linux (ZoL) <http://zfsonlinux.org/>.
* Developed at Lawrence Livermore National Laboratory (LLNL-CODE-403049).
* Copyright (C) 2013-2014 Lawrence Livermore National Security, LLC.
* Refer to the ZoL git commit log for authoritative copyright attribution.
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License Version 1.0 (CDDL-1.0).
* You can obtain a copy of the license from the top-level file
* "OPENSOLARIS.LICENSE" or at <http://opensource.org/licenses/CDDL-1.0>.
* You may not use this file except in compliance with the license.
*/
#include <assert.h>
#include <errno.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include "zed_log.h"
#define ZED_LOG_MAX_LOG_LEN 1024
static struct {
unsigned do_stderr:1;
unsigned do_syslog:1;
const char *identity;
int priority;
int pipe_fd[2];
} _ctx;
/*
* Initialize the logging subsystem.
*/
void
zed_log_init(const char *identity)
{
if (identity) {
const char *p = strrchr(identity, '/');
_ctx.identity = (p != NULL) ? p + 1 : identity;
} else {
_ctx.identity = NULL;
}
_ctx.pipe_fd[0] = -1;
_ctx.pipe_fd[1] = -1;
}
/*
* Shutdown the logging subsystem.
*/
void
zed_log_fini(void)
{
zed_log_stderr_close();
zed_log_syslog_close();
}
/*
* Create pipe for communicating daemonization status between the parent and
* child processes across the double-fork().
*/
void
zed_log_pipe_open(void)
{
if ((_ctx.pipe_fd[0] != -1) || (_ctx.pipe_fd[1] != -1))
zed_log_die("Invalid use of zed_log_pipe_open in PID %d",
(int)getpid());
if (pipe(_ctx.pipe_fd) < 0)
zed_log_die("Failed to create daemonize pipe in PID %d: %s",
(int)getpid(), strerror(errno));
}
/*
* Close the read-half of the daemonize pipe.
*
* This should be called by the child after fork()ing from the parent since
* the child will never read from this pipe.
*/
void
zed_log_pipe_close_reads(void)
{
if (_ctx.pipe_fd[0] < 0)
zed_log_die(
"Invalid use of zed_log_pipe_close_reads in PID %d",
(int)getpid());
if (close(_ctx.pipe_fd[0]) < 0)
zed_log_die(
"Failed to close reads on daemonize pipe in PID %d: %s",
(int)getpid(), strerror(errno));
_ctx.pipe_fd[0] = -1;
}
/*
* Close the write-half of the daemonize pipe.
*
* This should be called by the parent after fork()ing its child since the
* parent will never write to this pipe.
*
* This should also be called by the child once initialization is complete
* in order to signal the parent that it can safely exit.
*/
void
zed_log_pipe_close_writes(void)
{
if (_ctx.pipe_fd[1] < 0)
zed_log_die(
"Invalid use of zed_log_pipe_close_writes in PID %d",
(int)getpid());
if (close(_ctx.pipe_fd[1]) < 0)
zed_log_die(
"Failed to close writes on daemonize pipe in PID %d: %s",
(int)getpid(), strerror(errno));
_ctx.pipe_fd[1] = -1;
}
/*
* Block on reading from the daemonize pipe until signaled by the child
* (via zed_log_pipe_close_writes()) that initialization is complete.
*
* This should only be called by the parent while waiting to exit after
* fork()ing the child.
*/
void
zed_log_pipe_wait(void)
{
ssize_t n;
char c;
if (_ctx.pipe_fd[0] < 0)
zed_log_die("Invalid use of zed_log_pipe_wait in PID %d",
(int)getpid());
for (;;) {
n = read(_ctx.pipe_fd[0], &c, sizeof (c));
if (n < 0) {
if (errno == EINTR)
continue;
zed_log_die(
"Failed to read from daemonize pipe in PID %d: %s",
(int)getpid(), strerror(errno));
}
if (n == 0) {
break;
}
}
}
/*
* Start logging messages at the syslog [priority] level or higher to stderr.
* Refer to syslog(3) for valid priority values.
*/
void
zed_log_stderr_open(int priority)
{
_ctx.do_stderr = 1;
_ctx.priority = priority;
}
/*
* Stop logging messages to stderr.
*/
void
zed_log_stderr_close(void)
{
if (_ctx.do_stderr)
_ctx.do_stderr = 0;
}
/*
* Start logging messages to syslog.
* Refer to syslog(3) for valid option/facility values.
*/
void
zed_log_syslog_open(int facility)
{
_ctx.do_syslog = 1;
openlog(_ctx.identity, LOG_NDELAY | LOG_PID, facility);
}
/*
* Stop logging messages to syslog.
*/
void
zed_log_syslog_close(void)
{
if (_ctx.do_syslog) {
_ctx.do_syslog = 0;
closelog();
}
}
/*
* Auxiliary function to log a message to syslog and/or stderr.
*/
static void
_zed_log_aux(int priority, const char *fmt, va_list vargs)
{
char buf[ZED_LOG_MAX_LOG_LEN];
int n;
if (!fmt)
return;
n = vsnprintf(buf, sizeof (buf), fmt, vargs);
if ((n < 0) || (n >= sizeof (buf))) {
buf[sizeof (buf) - 2] = '+';
buf[sizeof (buf) - 1] = '\0';
}
if (_ctx.do_syslog)
syslog(priority, "%s", buf);
if (_ctx.do_stderr && (priority <= _ctx.priority))
fprintf(stderr, "%s\n", buf);
}
/*
* Log a message at the given [priority] level specified by the printf-style
* format string [fmt].
*/
void
zed_log_msg(int priority, const char *fmt, ...)
{
va_list vargs;
if (fmt) {
va_start(vargs, fmt);
_zed_log_aux(priority, fmt, vargs);
va_end(vargs);
}
}
/*
* Log a fatal error message specified by the printf-style format string [fmt].
*/
void
zed_log_die(const char *fmt, ...)
{
va_list vargs;
if (fmt) {
va_start(vargs, fmt);
_zed_log_aux(LOG_ERR, fmt, vargs);
va_end(vargs);
}
exit(EXIT_FAILURE);
}
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