log.c

/*
 * Copyright (C) 2018 Marco d'Itri
 *
 * Inspired by log.c from the cowdancer package by James Clarke.
 *
 * 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 St, Fifth Floor, Boston, MA  02110-1301 USA
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <syslog.h>

#include "log.h"
#include "utils.h"

static log_level filter_level = log_info;

/*
 * Return the appropriate file handle (stdout vs. stderr) for the log level.
 */
static FILE *file_for_level(log_level level)
{
    if (level & log_stderr || filter_level & log_stderr)
	return stderr;

    if ((level & LOG_LEVEL_MASK) > log_warning)
	return stdout;
    else
	return stderr;
}

static void log_doit(log_level level, const char *format, va_list args)
{
    static int syslog_initialized;

    if ((level & LOG_LEVEL_MASK) > (filter_level & LOG_LEVEL_MASK))
	return;

    if (level & log_syslog || filter_level & log_syslog) {
	if (!syslog_initialized) {
	    openlog(NULL, LOG_PID, LOG_DAEMON);
	    syslog_initialized = 1;
	}

	if (level & log_strerror) {
	    int len = strlen(format);
	    char *format2;

	    format2 = NOFAIL(malloc(len + 4 + 1));
	    strcpy(format2, format);
	    strcpy(format2 + len, ": %m");
	    vsyslog(level & LOG_LEVEL_MASK, format2, args);
	    free(format2);
	} else {
	    vsyslog(level & LOG_LEVEL_MASK, format, args);
	}
	return;
    }

    vfprintf(file_for_level(level), format, args);
    if (level & log_strerror)
	fprintf(file_for_level(level), ": %s", strerror(errno));
    fprintf(file_for_level(level), "\n");
}

log_level log_get_filter_level(void)
{
    return filter_level;
}

void log_set_options(log_level filter_level_new)
{
    filter_level = filter_level_new;
}

void log_printf(log_level level, const char *format, ...)
{
    va_list args;

    va_start(args, format);
    log_doit(level, format, args);
    va_end(args);
}

void log_printf_exit(int status, log_level level, const char *format, ...)
{
    va_list args;

    va_start(args, format);
    log_doit(level, format, args);
    va_end(args);

    exit(status);
}

void log_printf_err(log_level level, const char *format, ...)
{
    va_list args;

    va_start(args, format);
    log_doit(level | log_strerror, format, args);
    va_end(args);
}

void log_printf_err_exit(int status, log_level level, const char *format, ...)
{
    va_list args;

    va_start(args, format);
    log_doit(level | log_strerror, format, args);
    va_end(args);

    exit(status);
}