ulog.c

   1 /*
   2  * ulog - simple logging functions
   3  *
   4  * Copyright (C) 2015 Jo-Philipp Wich <jow@openwrt.org>
   5  *
   6  * Permission to use, copy, modify, and/or distribute this software for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  17  */
  18
  19 #include "ulog.h"
  20
  21 #include <stdio.h>
  22 #include <stdarg.h>
  23 #include <stdlib.h>
  24 #include <unistd.h>
  25 #include <string.h>
  26
  27 static int _ulog_channels = -1;
  28 static int _ulog_facility = -1;
  29 static int _ulog_threshold = LOG_DEBUG;
  30 static int _ulog_initialized = 0;
  31 static const char *_ulog_ident = NULL;
  32
  33 static const char *ulog_default_ident(void)
  34 {
  35         FILE *self;
  36         static char line[64];
  37         char *p = NULL;
  38         char *sbuf;
  39
  40         if ((self = fopen("/proc/self/status", "r")) != NULL) {
  41                 while (fgets(line, sizeof(line), self)) {
  42                         if (!strncmp(line, "Name:", 5)) {
  43                                 strtok_r(line, "\t\n", &sbuf);
  44                                 p = strtok_r(NULL, "\t\n", &sbuf);
  45                                 break;
  46                         }
  47                 }
  48                 fclose(self);
  49         }
  50
  51         return p;
  52 }
  53
  54 static void ulog_defaults(void)
  55 {
  56         char *env;
  57
  58         if (_ulog_initialized)
  59                 return;
  60
  61         env = getenv("PREINIT");
  62
  63         if (_ulog_channels < 0) {
  64                 if (env && !strcmp(env, "1"))
  65                         _ulog_channels = ULOG_KMSG;
  66                 else if (isatty(1))
  67                         _ulog_channels = ULOG_STDIO;
  68                 else
  69                         _ulog_channels = ULOG_SYSLOG;
  70         }
  71
  72         if (_ulog_facility < 0) {
  73                 if (env && !strcmp(env, "1"))
  74                         _ulog_facility = LOG_DAEMON;
  75                 else if (isatty(1))
  76                         _ulog_facility = LOG_USER;
  77                 else
  78                         _ulog_facility = LOG_DAEMON;
  79         }
  80
  81         if (_ulog_ident == NULL && _ulog_channels != ULOG_STDIO)
  82                 _ulog_ident = ulog_default_ident();
  83
  84         if (_ulog_channels & ULOG_SYSLOG)
  85                 openlog(_ulog_ident, 0, _ulog_facility);
  86
  87         _ulog_initialized = 1;
  88 }
  89
  90 static void ulog_kmsg(int priority, const char *fmt, va_list ap)
  91 {
  92         FILE *kmsg;
  93
  94         if ((kmsg = fopen("/dev/kmsg", "r+")) != NULL) {
  95                 fprintf(kmsg, "<%u>", priority);
  96
  97                 if (_ulog_ident)
  98                         fprintf(kmsg, "%s: ", _ulog_ident);
  99
 100                 vfprintf(kmsg, fmt, ap);
 101                 fclose(kmsg);
 102         }
 103 }
 104
 105 static void ulog_stdio(int priority, const char *fmt, va_list ap)
 106 {
 107         FILE *out = stderr;
 108
 109         if (_ulog_ident)
 110                 fprintf(out, "%s: ", _ulog_ident);
 111
 112         vfprintf(out, fmt, ap);
 113 }
 114
 115 static void ulog_syslog(int priority, const char *fmt, va_list ap)
 116 {
 117         vsyslog(priority, fmt, ap);
 118 }
 119
 120 void ulog_open(int channels, int facility, const char *ident)
 121 {
 122         ulog_close();
 123
 124         _ulog_channels = channels;
 125         _ulog_facility = facility;
 126         _ulog_ident = ident;
 127 }
 128
 129 void ulog_close(void)
 130 {
 131         if (!_ulog_initialized)
 132                 return;
 133
 134         if (_ulog_channels & ULOG_SYSLOG)
 135                 closelog();
 136
 137         _ulog_initialized = 0;
 138 }
 139
 140 void ulog_threshold(int threshold)
 141 {
 142         _ulog_threshold = threshold;
 143 }
 144
 145 void ulog(int priority, const char *fmt, ...)
 146 {
 147         va_list ap;
 148
 149         if (priority > _ulog_threshold)
 150                 return;
 151
 152         ulog_defaults();
 153
 154         if (_ulog_channels & ULOG_KMSG)
 155         {
 156                 va_start(ap, fmt);
 157                 ulog_kmsg(priority, fmt, ap);
 158                 va_end(ap);
 159         }
 160
 161         if (_ulog_channels & ULOG_STDIO)
 162         {
 163                 va_start(ap, fmt);
 164                 ulog_stdio(priority, fmt, ap);
 165                 va_end(ap);
 166         }
 167
 168         if (_ulog_channels & ULOG_SYSLOG)
 169         {
 170                 va_start(ap, fmt);
 171                 ulog_syslog(priority, fmt, ap);
 172                 va_end(ap);
 173         }
 174 }