about summary refs log tree commit diff
path: root/misc/syslog.c
blob: 1b8cb722c51981a88b5964a4ce51843ae7ac62ca (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
/*
 * Copyright (c) 1983, 1988, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)syslog.c	8.4 (Berkeley) 3/18/94";
#endif /* LIBC_SCCS and not lint */

#include <libio/libioP.h>
#include <paths.h>
#include <stdarg.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdio_ext.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <sys/un.h>
#include <syslog.h>

static int LogType = SOCK_DGRAM;	/* type of socket connection */
static int LogFile = -1;		/* fd for log */
static bool connected;			/* have done connect */
static int LogStat;			/* status bits, set by openlog() */
static const char *LogTag;		/* string to tag the entry with */
static int LogFacility = LOG_USER;	/* default facility code */
static int LogMask = 0xff;		/* mask of priorities to be logged */
extern char *__progname;		/* Program name, from crt0. */

/* Define the lock.  */
__libc_lock_define_initialized (static, syslog_lock)
static void openlog_internal (const char *, int, int);
static void closelog_internal (void);

struct cleanup_arg
{
  void *buf;
  struct sigaction *oldaction;
};

static void
cancel_handler (void *ptr)
{
  /* Restore the old signal handler.  */
  struct cleanup_arg *clarg = (struct cleanup_arg *) ptr;

  if (clarg != NULL)
    /* Free the memstream buffer,  */
    free (clarg->buf);

  /* Free the lock.  */
  __libc_lock_unlock (syslog_lock);
}


/*
 * syslog, vsyslog --
 *	print message on log file; output is intended for syslogd(8).
 */
void
__syslog (int pri, const char *fmt, ...)
{
  va_list ap;

  va_start (ap, fmt);
  __vsyslog_internal (pri, fmt, ap, 0);
  va_end (ap);
}
ldbl_hidden_def (__syslog, syslog)
ldbl_strong_alias (__syslog, syslog)

void
__vsyslog (int pri, const char *fmt, va_list ap)
{
  __vsyslog_internal (pri, fmt, ap, 0);
}
ldbl_weak_alias (__vsyslog, vsyslog)

void
___syslog_chk (int pri, int flag, const char *fmt, ...)
{
  va_list ap;

  va_start (ap, fmt);
  __vsyslog_internal (pri, fmt, ap, (flag > 0) ? PRINTF_FORTIFY : 0);
  va_end (ap);
}
ldbl_hidden_def (___syslog_chk, __syslog_chk)
ldbl_strong_alias (___syslog_chk, __syslog_chk)

void
__vsyslog_chk (int pri, int flag, const char *fmt, va_list ap)
{
  __vsyslog_internal (pri, fmt, ap, (flag > 0) ? PRINTF_FORTIFY : 0);
}

void
__vsyslog_internal (int pri, const char *fmt, va_list ap,
		    unsigned int mode_flags)
{
  /* Try to use a static buffer as an optimization.  */
  char bufs[1024];
  char *buf = NULL;
  size_t bufsize = 0;
  int msgoff;
  int saved_errno = errno;

#define	INTERNALLOG LOG_ERR|LOG_CONS|LOG_PERROR|LOG_PID
  /* Check for invalid bits. */
  if (pri & ~(LOG_PRIMASK | LOG_FACMASK))
    {
      syslog (INTERNALLOG, "syslog: unknown facility/priority: %x", pri);
      pri &= LOG_PRIMASK | LOG_FACMASK;
    }

  /* Prepare for multiple users.  We have to take care: most syscalls we are
     using are cancellation points.  */
  struct cleanup_arg clarg = { NULL, NULL };
  __libc_cleanup_push (cancel_handler, &clarg);
  __libc_lock_lock (syslog_lock);

  /* Check priority against setlogmask values. */
  if ((LOG_MASK (LOG_PRI (pri)) & LogMask) == 0)
    goto out;

  /* Set default facility if none specified. */
  if ((pri & LOG_FACMASK) == 0)
    pri |= LogFacility;

  pid_t pid = LogStat & LOG_PID ? __getpid () : 0;

  /* "%b %e %H:%M:%S "  */
  char timestamp[sizeof "MMM DD hh:mm:ss "];
  __time64_t now = time64_now ();
  struct tm now_tm;
  struct tm *now_tmp = __localtime64_r (&now, &now_tm);
  bool has_ts = now_tmp != NULL;

  /* In the unlikely case of localtime_r failure (tm_year out of int range)
     skip the hostname so the message is handled as valid PRI but without
     TIMESTAMP or invalid TIMESTAMP (which should force the relay to add the
     timestamp itself).  */
  if (has_ts)
    __strftime_l (timestamp, sizeof timestamp, "%h %e %T ", now_tmp,
		  _nl_C_locobj_ptr);

#define SYSLOG_HEADER(__pri, __timestamp, __msgoff, pid) \
  "<%d>%s%n%s%s%.0d%s: ",                                \
  __pri, __timestamp, __msgoff,                          \
  LogTag == NULL ? __progname : LogTag,                  \
  "[" + (pid == 0), pid, "]" + (pid == 0)

#define SYSLOG_HEADER_WITHOUT_TS(__pri, __msgoff)        \
  "<%d>: %n", __pri, __msgoff

  int l;
  if (has_ts)
    l = __snprintf (bufs, sizeof bufs,
		    SYSLOG_HEADER (pri, timestamp, &msgoff, pid));
  else
    l = __snprintf (bufs, sizeof bufs,
		    SYSLOG_HEADER_WITHOUT_TS (pri, &msgoff));
  if (0 <= l && l < sizeof bufs)
    {
      va_list apc;
      va_copy (apc, ap);

      /* Restore errno for %m format.  */
      __set_errno (saved_errno);

      int vl = __vsnprintf_internal (bufs + l, sizeof bufs - l, fmt, apc,
                                     mode_flags);
      if (0 <= vl && vl < sizeof bufs - l)
        buf = bufs;
      bufsize = l + vl;

      va_end (apc);
    }

  if (buf == NULL)
    {
      buf = malloc ((bufsize + 1) * sizeof (char));
      if (buf != NULL)
	{
	  /* Tell the cancellation handler to free this buffer.  */
	  clarg.buf = buf;

	  if (has_ts)
	    __snprintf (buf, l + 1,
			SYSLOG_HEADER (pri, timestamp, &msgoff, pid));
	  else
	    __snprintf (buf, l + 1,
			SYSLOG_HEADER_WITHOUT_TS (pri, &msgoff));

	  va_list apc;
	  va_copy (apc, ap);
	  __vsnprintf_internal (buf + l, bufsize - l + 1, fmt, apc,
				mode_flags);
	  va_end (apc);
	}
      else
        {
	  /* Nothing much to do but emit an error message.  */
          bufsize = __snprintf (bufs, sizeof bufs,
                                "out of memory[%d]", __getpid ());
          buf = bufs;
        }
    }

  /* Output to stderr if requested. */
  if (LogStat & LOG_PERROR)
    __dprintf (STDERR_FILENO, "%s%s", buf + msgoff,
	       "\n" + (buf[bufsize - 1] == '\n'));

  /* Get connected, output the message to the local logger.  */
  if (!connected)
    openlog_internal (NULL, LogStat | LOG_NDELAY, LogFacility);

  /* If we have a SOCK_STREAM connection, also send ASCII NUL as a record
     terminator.  */
  if (LogType == SOCK_STREAM)
    ++bufsize;

  if (!connected || __send (LogFile, buf, bufsize, MSG_NOSIGNAL) < 0)
    {
      if (connected)
	{
	  /* Try to reopen the syslog connection.  Maybe it went down.  */
	  closelog_internal ();
	  openlog_internal (NULL, LogStat | LOG_NDELAY, LogFacility);
	}

      if (!connected || __send (LogFile, buf, bufsize, MSG_NOSIGNAL) < 0)
	{
	  closelog_internal ();	/* attempt re-open next time */
	  /*
	   * Output the message to the console; don't worry
	   * about blocking, if console blocks everything will.
	   * Make sure the error reported is the one from the
	   * syslogd failure.
	   */
	  int fd;
	  if (LogStat & LOG_CONS &&
	      (fd = __open (_PATH_CONSOLE, O_WRONLY | O_NOCTTY
			    | O_CLOEXEC, 0)) >= 0)
	    {
	      __dprintf (fd, "%s\r\n", buf + msgoff);
	      __close (fd);
	    }
	}
    }

out:
  /* End of critical section.  */
  __libc_cleanup_pop (0);
  __libc_lock_unlock (syslog_lock);

  if (buf != bufs)
    free (buf);
}

/* AF_UNIX address of local logger  */
static const struct sockaddr_un SyslogAddr =
  {
    .sun_family = AF_UNIX,
    .sun_path = _PATH_LOG
  };

static void
openlog_internal (const char *ident, int logstat, int logfac)
{
  if (ident != NULL)
    LogTag = ident;
  LogStat = logstat;
  if ((logfac & ~LOG_FACMASK) == 0)
    LogFacility = logfac;

  int retry = 0;
  while (retry < 2)
    {
      if (LogFile == -1)
	{
	  if (LogStat & LOG_NDELAY)
	    {
	      LogFile = __socket (AF_UNIX, LogType | SOCK_CLOEXEC, 0);
	      if (LogFile == -1)
		return;
	    }
	}
      if (LogFile != -1 && !connected)
	{
	  int old_errno = errno;
	  if (__connect (LogFile, &SyslogAddr, sizeof (SyslogAddr)) == -1)
	    {
	      int saved_errno = errno;
	      int fd = LogFile;
	      LogFile = -1;
	      __close (fd);
	      __set_errno (old_errno);
	      if (saved_errno == EPROTOTYPE)
		{
		  /* retry with the other type: */
		  LogType = LogType == SOCK_DGRAM ? SOCK_STREAM : SOCK_DGRAM;
		  ++retry;
		  continue;
		}
	    }
	  else
	    connected = true;
	}
      break;
    }
}

void
openlog (const char *ident, int logstat, int logfac)
{
  /* Protect against multiple users and cancellation.  */
  __libc_cleanup_push (cancel_handler, NULL);
  __libc_lock_lock (syslog_lock);

  openlog_internal (ident, logstat, logfac);

  __libc_cleanup_pop (1);
}

static void
closelog_internal (void)
{
  if (!connected)
    return;

  __close (LogFile);
  LogFile = -1;
  connected = false;
}

void
closelog (void)
{
  /* Protect against multiple users and cancellation.  */
  __libc_cleanup_push (cancel_handler, NULL);
  __libc_lock_lock (syslog_lock);

  closelog_internal ();
  LogTag = NULL;
  LogType = SOCK_DGRAM; /* this is the default */

  /* Free the lock.  */
  __libc_cleanup_pop (1);
}

/* setlogmask -- set the log mask level */
int
setlogmask (int pmask)
{
  int omask;

  /* Protect against multiple users.  */
  __libc_lock_lock (syslog_lock);

  omask = LogMask;
  if (pmask != 0)
    LogMask = pmask;

  __libc_lock_unlock (syslog_lock);

  return (omask);
}