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
  39         if ((self = fopen("/proc/self/status", "r")) != NULL) {
  40                 while (fgets(line, sizeof(line), self)) {
  41                         if (!strncmp(line, "Name:", 5)) {
  42                                 strtok(line, "\t\n");
  43                                 p = strtok(NULL, "\t\n");
  44                                 break;
  45                         }
  46                 }
  47                 fclose(self);
  48         }
  49
  50         return p;
  51 }
  52
  53 static void ulog_defaults(void)
  54 {
  55         char *env;
  56
  57         if (_ulog_initialized)
  58                 return;
  59
  60         env = getenv("PREINIT");
  61
  62         if (_ulog_channels < 0) {
  63                 if (env && !strcmp(env, "1"))
  64                         _ulog_channels = ULOG_KMSG;
  65                 else if (isatty(1))
  66                         _ulog_channels = ULOG_STDIO;
  67                 else
  68                         _ulog_channels = ULOG_SYSLOG;
  69         }
  70
  71         if (_ulog_facility < 0) {
  72                 if (env && !strcmp(env, "1"))
  73                         _ulog_facility = LOG_DAEMON;
  74                 else if (isatty(1))
  75                         _ulog_facility = LOG_USER;
  76                 else
  77                         _ulog_facility = LOG_DAEMON;
  78         }
  79
  80         if (_ulog_ident == NULL && _ulog_channels != ULOG_STDIO)
  81                 _ulog_ident = ulog_default_ident();
  82
  83         if (_ulog_channels & ULOG_SYSLOG)
  84                 openlog(_ulog_ident, 0, _ulog_facility);
  85
  86         _ulog_initialized = 1;
  87 }
  88
  89 static void ulog_kmsg(int priority, const char *fmt, va_list ap)
  90 {
  91         FILE *kmsg;
  92
  93         if ((kmsg = fopen("/dev/kmsg", "r+")) != NULL) {
  94                 fprintf(kmsg, "<%u>", priority);
  95
  96                 if (_ulog_ident)
  97                         fprintf(kmsg, "%s: ", _ulog_ident);
  98
  99                 vfprintf(kmsg, fmt, ap);
 100                 fclose(kmsg);
 101         }
 102 }
 103
 104 static void ulog_stdio(int priority, const char *fmt, va_list ap)
 105 {
 106         FILE *out = stderr;
 107
 108         if (_ulog_ident)
 109                 fprintf(out, "%s: ", _ulog_ident);
 110
 111         vfprintf(out, fmt, ap);
 112 }
 113
 114 static void ulog_syslog(int priority, const char *fmt, va_list ap)
 115 {
 116         vsyslog(priority, fmt, ap);
 117 }
 118
 119 void ulog_open(int channels, int facility, const char *ident)
 120 {
 121         ulog_close();
 122
 123         _ulog_channels = channels;
 124         _ulog_facility = facility;
 125         _ulog_ident = ident;
 126 }
 127
 128 void ulog_close(void)
 129 {
 130         if (!_ulog_initialized)
 131                 return;
 132
 133         if (_ulog_channels & ULOG_SYSLOG)
 134                 closelog();
 135
 136         _ulog_initialized = 0;
 137 }
 138
 139 void ulog_threshold(int threshold)
 140 {
 141         _ulog_threshold = threshold;
 142 }
 143
 144 void ulog(int priority, const char *fmt, ...)
 145 {
 146         va_list ap;
 147
 148         if (priority > _ulog_threshold)
 149                 return;
 150
 151         ulog_defaults();
 152
 153         if (_ulog_channels & ULOG_KMSG)
 154         {
 155                 va_start(ap, fmt);
 156                 ulog_kmsg(priority, fmt, ap);
 157                 va_end(ap);
 158         }
 159
 160         if (_ulog_channels & ULOG_STDIO)
 161         {
 162                 va_start(ap, fmt);
 163                 ulog_stdio(priority, fmt, ap);
 164                 va_end(ap);
 165         }
 166
 167         if (_ulog_channels & ULOG_SYSLOG)
 168         {
 169                 va_start(ap, fmt);
 170                 ulog_syslog(priority, fmt, ap);
 171                 va_end(ap);
 172         }
 173 }