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 __attribute__((format(printf, 2, 0)))
  91 static void ulog_kmsg(int priority, const char *fmt, va_list ap)
  92 {
  93         FILE *kmsg;
  94
  95         if ((kmsg = fopen("/dev/kmsg", "r+")) != NULL) {
  96                 fprintf(kmsg, "<%u>", priority);
  97
  98                 if (_ulog_ident)
  99                         fprintf(kmsg, "%s: ", _ulog_ident);
 100
 101                 vfprintf(kmsg, fmt, ap);
 102                 fclose(kmsg);
 103         }
 104 }
 105
 106 __attribute__((format(printf, 2, 0)))
 107 static void ulog_stdio(int priority, const char *fmt, va_list ap)
 108 {
 109         FILE *out = stderr;
 110
 111         if (_ulog_ident)
 112                 fprintf(out, "%s: ", _ulog_ident);
 113
 114         vfprintf(out, fmt, ap);
 115 }
 116
 117 __attribute__((format(printf, 2, 0)))
 118 static void ulog_syslog(int priority, const char *fmt, va_list ap)
 119 {
 120         vsyslog(priority, fmt, ap);
 121 }
 122
 123 void ulog_open(int channels, int facility, const char *ident)
 124 {
 125         ulog_close();
 126
 127         _ulog_channels = channels;
 128         _ulog_facility = facility;
 129         _ulog_ident = ident;
 130 }
 131
 132 void ulog_close(void)
 133 {
 134         if (!_ulog_initialized)
 135                 return;
 136
 137         if (_ulog_channels & ULOG_SYSLOG)
 138                 closelog();
 139
 140         _ulog_initialized = 0;
 141 }
 142
 143 void ulog_threshold(int threshold)
 144 {
 145         _ulog_threshold = threshold;
 146 }
 147
 148 void ulog(int priority, const char *fmt, ...)
 149 {
 150         va_list ap;
 151
 152         if (priority > _ulog_threshold)
 153                 return;
 154
 155         ulog_defaults();
 156
 157         if (_ulog_channels & ULOG_KMSG)
 158         {
 159                 va_start(ap, fmt);
 160                 ulog_kmsg(priority, fmt, ap);
 161                 va_end(ap);
 162         }
 163
 164         if (_ulog_channels & ULOG_STDIO)
 165         {
 166                 va_start(ap, fmt);
 167                 ulog_stdio(priority, fmt, ap);
 168                 va_end(ap);
 169         }
 170
 171         if (_ulog_channels & ULOG_SYSLOG)
 172         {
 173                 va_start(ap, fmt);
 174                 ulog_syslog(priority, fmt, ap);
 175                 va_end(ap);
 176         }
 177 }