ulog.c

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/*
 * ulog - simple logging functions
 *
 * Copyright (C) 2015 Jo-Philipp Wich <jow@openwrt.org>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
 
#include "ulog.h"
 
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
 
static int _ulog_channels = -1;
static int _ulog_facility = -1;
static int _ulog_threshold = LOG_DEBUG;
static int _ulog_initialized = 0;
static const char *_ulog_ident = NULL;
static struct udebug_buf *udb = NULL;
 
static const char *ulog_default_ident(void)
{
        FILE *self;
        static char line[64];
        char *p = NULL;
        char *sbuf;
 
        if ((self = fopen("/proc/self/status", "r")) != NULL) {
                while (fgets(line, sizeof(line), self)) {
                        if (!strncmp(line, "Name:", 5)) {
                                strtok_r(line, "\t\n", &sbuf);
                                p = strtok_r(NULL, "\t\n", &sbuf);
                                break;
                        }
                }
                fclose(self);
        }
 
        return p;
}
 
static void ulog_defaults(void)
{
        char *env;
 
        if (_ulog_initialized)
                return;
 
        env = getenv("PREINIT");
 
        if (_ulog_channels < 0) {
                if (env && !strcmp(env, "1"))
                        _ulog_channels = ULOG_KMSG;
                else if (isatty(1))
                        _ulog_channels = ULOG_STDIO;
                else
                        _ulog_channels = ULOG_SYSLOG;
        }
 
        if (_ulog_facility < 0) {
                if (env && !strcmp(env, "1"))
                        _ulog_facility = LOG_DAEMON;
                else if (isatty(1))
                        _ulog_facility = LOG_USER;
                else
                        _ulog_facility = LOG_DAEMON;
        }
 
        if (_ulog_ident == NULL && _ulog_channels != ULOG_STDIO)
                _ulog_ident = ulog_default_ident();
 
        if (_ulog_channels & ULOG_SYSLOG)
                openlog(_ulog_ident, 0, _ulog_facility);
 
        _ulog_initialized = 1;
}
 
__attribute__((format(printf, 2, 0)))
static void ulog_kmsg(int priority, const char *fmt, va_list ap)
{
        FILE *kmsg;
 
        if ((kmsg = fopen("/dev/kmsg", "r+")) != NULL) {
                fprintf(kmsg, "<%u>", priority);
 
                if (_ulog_ident)
                        fprintf(kmsg, "%s: ", _ulog_ident);
 
                vfprintf(kmsg, fmt, ap);
                fclose(kmsg);
        }
}
 
__attribute__((format(printf, 2, 0)))
static void ulog_stdio(int priority, const char *fmt, va_list ap)
{
        FILE *out = stderr;
 
        if (_ulog_ident)
                fprintf(out, "%s: ", _ulog_ident);
 
        vfprintf(out, fmt, ap);
}
 
__attribute__((format(printf, 2, 0)))
static void ulog_syslog(int priority, const char *fmt, va_list ap)
{
        vsyslog(priority, fmt, ap);
}
 
void ulog_udebug(struct udebug_buf *_udb)
{
        udb = _udb;
}
 
void ulog_open(int channels, int facility, const char *ident)
{
        ulog_close();
 
        _ulog_channels = channels;
        _ulog_facility = facility;
        _ulog_ident = ident;
}
 
void ulog_close(void)
{
        if (!_ulog_initialized)
                return;
 
        if (_ulog_channels & ULOG_SYSLOG)
                closelog();
 
        _ulog_initialized = 0;
}
 
void ulog_threshold(int threshold)
{
        _ulog_threshold = threshold;
}
 
void ulog(int priority, const char *fmt, ...)
{
        va_list ap;
 
        if (udb) {
                va_start(ap, fmt);
                udebug_entry_init(udb);
                udebug_entry_vprintf(udb, fmt, ap);
                udebug_entry_add(udb);
                va_end(ap);
        }
 
        if (priority > _ulog_threshold)
                return;
 
        ulog_defaults();
 
        if (_ulog_channels & ULOG_KMSG)
        {
                va_start(ap, fmt);
                ulog_kmsg(priority, fmt, ap);
                va_end(ap);
        }
 
        if (_ulog_channels & ULOG_STDIO)
        {
                va_start(ap, fmt);
                ulog_stdio(priority, fmt, ap);
                va_end(ap);
        }
 
        if (_ulog_channels & ULOG_SYSLOG)
        {
                va_start(ap, fmt);
                ulog_syslog(priority, fmt, ap);
                va_end(ap);
        }
}