misc/syslog.c

   1 /*
   2  * Copyright (c) 1983, 1988, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 4. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  29
  30 #if defined(LIBC_SCCS) && !defined(lint)
  31 static char sccsid[] = "@(#)syslog.c    8.4 (Berkeley) 3/18/94";
  32 #endif /* LIBC_SCCS and not lint */
  33
  34 #include <sys/types.h>
  35 #include <sys/socket.h>
  36 #include <sys/syslog.h>
  37 #include <sys/uio.h>
  38 #include <sys/un.h>
  39 #include <netdb.h>
  40
  41 #include <errno.h>
  42 #include <fcntl.h>
  43 #include <paths.h>
  44 #include <stdio.h>
  45 #include <stdio_ext.h>
  46 #include <string.h>
  47 #include <time.h>
  48 #include <unistd.h>
  49 #include <stdlib.h>
  50 #include <libc-lock.h>
  51 #include <signal.h>
  52 #include <locale.h>
  53
  54 #include <stdarg.h>
  55
  56 #include <libio/libioP.h>
  57 #include <math_ldbl_opt.h>
  58
  59 #include <kernel-features.h>
  60
  61 #define ftell(s) _IO_ftell (s)
  62
  63 static int      LogType = SOCK_DGRAM;   /* type of socket connection */
  64 static int      LogFile = -1;           /* fd for log */
  65 static bool     connected;              /* have done connect */
  66 static int      LogStat;                /* status bits, set by openlog() */
  67 static const char *LogTag;              /* string to tag the entry with */
  68 static int      LogFacility = LOG_USER; /* default facility code */
  69 static int      LogMask = 0xff;         /* mask of priorities to be logged */
  70 extern char     *__progname;            /* Program name, from crt0. */
  71
  72 /* Define the lock.  */
  73 __libc_lock_define_initialized (static, syslog_lock)
  74
  75 static void openlog_internal(const char *, int, int);
  76 static void closelog_internal(void);
  77
  78 struct cleanup_arg
  79 {
  80   void *buf;
  81   struct sigaction *oldaction;
  82 };
  83
  84 static void
  85 cancel_handler (void *ptr)
  86 {
  87   /* Restore the old signal handler.  */
  88   struct cleanup_arg *clarg = (struct cleanup_arg *) ptr;
  89
  90   if (clarg != NULL)
  91     /* Free the memstream buffer,  */
  92     free (clarg->buf);
  93
  94   /* Free the lock.  */
  95   __libc_lock_unlock (syslog_lock);
  96 }
  97
  98
  99 /*
 100  * syslog, vsyslog --
 101  *      print message on log file; output is intended for syslogd(8).
 102  */
 103 void
 104 __syslog(int pri, const char *fmt, ...)
 105 {
 106         va_list ap;
 107
 108         va_start(ap, fmt);
 109         __vsyslog_internal(pri, fmt, ap, 0);
 110         va_end(ap);
 111 }
 112 ldbl_hidden_def (__syslog, syslog)
 113 ldbl_strong_alias (__syslog, syslog)
 114
 115 void
 116 __vsyslog(int pri, const char *fmt, va_list ap)
 117 {
 118         __vsyslog_internal(pri, fmt, ap, 0);
 119 }
 120 ldbl_weak_alias (__vsyslog, vsyslog)
 121
 122 void
 123 __syslog_chk(int pri, int flag, const char *fmt, ...)
 124 {
 125         va_list ap;
 126
 127         va_start(ap, fmt);
 128         __vsyslog_internal(pri, fmt, ap, (flag > 0) ? PRINTF_FORTIFY : 0);
 129         va_end(ap);
 130 }
 131
 132 void
 133 __vsyslog_chk(int pri, int flag, const char *fmt, va_list ap)
 134 {
 135         __vsyslog_internal(pri, fmt, ap, (flag > 0) ? PRINTF_FORTIFY : 0);
 136 }
 137
 138 void
 139 __vsyslog_internal(int pri, const char *fmt, va_list ap,
 140                    unsigned int mode_flags)
 141 {
 142         struct tm now_tm;
 143         time_t now;
 144         int fd;
 145         FILE *f;
 146         char *buf = 0;
 147         size_t bufsize = 0;
 148         size_t msgoff;
 149         int saved_errno = errno;
 150         char failbuf[3 * sizeof (pid_t) + sizeof "out of memory []"];
 151
 152 #define INTERNALLOG     LOG_ERR|LOG_CONS|LOG_PERROR|LOG_PID
 153         /* Check for invalid bits. */
 154         if (pri & ~(LOG_PRIMASK|LOG_FACMASK)) {
 155                 syslog(INTERNALLOG,
 156                     "syslog: unknown facility/priority: %x", pri);
 157                 pri &= LOG_PRIMASK|LOG_FACMASK;
 158         }
 159
 160         /* Prepare for multiple users.  We have to take care: most
 161            syscalls we are using are cancellation points.  */
 162         struct cleanup_arg clarg;
 163         clarg.buf = NULL;
 164         clarg.oldaction = NULL;
 165         __libc_cleanup_push (cancel_handler, &clarg);
 166         __libc_lock_lock (syslog_lock);
 167
 168         /* Check priority against setlogmask values. */
 169         if ((LOG_MASK (LOG_PRI (pri)) & LogMask) == 0)
 170                 goto out;
 171
 172         /* Set default facility if none specified. */
 173         if ((pri & LOG_FACMASK) == 0)
 174                 pri |= LogFacility;
 175
 176         /* Build the message in a memory-buffer stream.  */
 177         f = __open_memstream (&buf, &bufsize);
 178         if (f == NULL)
 179           {
 180             /* We cannot get a stream.  There is not much we can do but
 181                emitting an error messages.  */
 182             char numbuf[3 * sizeof (pid_t)];
 183             char *nump;
 184             char *endp = __stpcpy (failbuf, "out of memory [");
 185             pid_t pid = __getpid ();
 186
 187             nump = numbuf + sizeof (numbuf);
 188             /* The PID can never be zero.  */
 189             do
 190               *--nump = '0' + pid % 10;
 191             while ((pid /= 10) != 0);
 192
 193             endp = __mempcpy (endp, nump, (numbuf + sizeof (numbuf)) - nump);
 194             *endp++ = ']';
 195             *endp = '\0';
 196             buf = failbuf;
 197             bufsize = endp - failbuf;
 198             msgoff = 0;
 199           }
 200         else
 201           {
 202             __fsetlocking (f, FSETLOCKING_BYCALLER);
 203             fprintf (f, "<%d>", pri);
 204             now = time_now ();
 205             f->_IO_write_ptr += __strftime_l (f->_IO_write_ptr,
 206                                               f->_IO_write_end
 207                                               - f->_IO_write_ptr,
 208                                               "%h %e %T ",
 209                                               __localtime_r (&now, &now_tm),
 210                                               _nl_C_locobj_ptr);
 211             msgoff = ftell (f);
 212             if (LogTag == NULL)
 213               LogTag = __progname;
 214             if (LogTag != NULL)
 215               __fputs_unlocked (LogTag, f);
 216             if (LogStat & LOG_PID)
 217               fprintf (f, "[%d]", (int) __getpid ());
 218             if (LogTag != NULL)
 219               {
 220                 __putc_unlocked (':', f);
 221                 __putc_unlocked (' ', f);
 222               }
 223
 224             /* Restore errno for %m format.  */
 225             __set_errno (saved_errno);
 226
 227             /* We have the header.  Print the user's format into the
 228                buffer.  */
 229             __vfprintf_internal (f, fmt, ap, mode_flags);
 230
 231             /* Close the memory stream; this will finalize the data
 232                into a malloc'd buffer in BUF.  */
 233             fclose (f);
 234
 235             /* Tell the cancellation handler to free this buffer.  */
 236             clarg.buf = buf;
 237           }
 238
 239         /* Output to stderr if requested. */
 240         if (LogStat & LOG_PERROR) {
 241                 struct iovec iov[2];
 242                 struct iovec *v = iov;
 243
 244                 v->iov_base = buf + msgoff;
 245                 v->iov_len = bufsize - msgoff;
 246                 /* Append a newline if necessary.  */
 247                 if (buf[bufsize - 1] != '\n')
 248                   {
 249                     ++v;
 250                     v->iov_base = (char *) "\n";
 251                     v->iov_len = 1;
 252                   }
 253
 254                 /* writev is a cancellation point.  */
 255                 (void)__writev(STDERR_FILENO, iov, v - iov + 1);
 256         }
 257
 258         /* Get connected, output the message to the local logger. */
 259         if (!connected)
 260                 openlog_internal(NULL, LogStat | LOG_NDELAY, LogFacility);
 261
 262         /* If we have a SOCK_STREAM connection, also send ASCII NUL as
 263            a record terminator.  */
 264         if (LogType == SOCK_STREAM)
 265           ++bufsize;
 266
 267         if (!connected || __send(LogFile, buf, bufsize, MSG_NOSIGNAL) < 0)
 268           {
 269             if (connected)
 270               {
 271                 /* Try to reopen the syslog connection.  Maybe it went
 272                    down.  */
 273                 closelog_internal ();
 274                 openlog_internal(NULL, LogStat | LOG_NDELAY, LogFacility);
 275               }
 276
 277             if (!connected || __send(LogFile, buf, bufsize, MSG_NOSIGNAL) < 0)
 278               {
 279                 closelog_internal ();   /* attempt re-open next time */
 280                 /*
 281                  * Output the message to the console; don't worry
 282                  * about blocking, if console blocks everything will.
 283                  * Make sure the error reported is the one from the
 284                  * syslogd failure.
 285                  */
 286                 if (LogStat & LOG_CONS &&
 287                     (fd = __open(_PATH_CONSOLE, O_WRONLY|O_NOCTTY|O_CLOEXEC,
 288                                  0)) >= 0)
 289                   {
 290                     __dprintf (fd, "%s\r\n", buf + msgoff);
 291                     (void)__close(fd);
 292                   }
 293               }
 294           }
 295
 296  out:
 297         /* End of critical section.  */
 298         __libc_cleanup_pop (0);
 299         __libc_lock_unlock (syslog_lock);
 300
 301         if (buf != failbuf)
 302                 free (buf);
 303 }
 304
 305 /* AF_UNIX address of local logger  */
 306 static const struct sockaddr_un SyslogAddr =
 307   {
 308     .sun_family = AF_UNIX,
 309     .sun_path = _PATH_LOG
 310   };
 311
 312 static void
 313 openlog_internal(const char *ident, int logstat, int logfac)
 314 {
 315         if (ident != NULL)
 316                 LogTag = ident;
 317         LogStat = logstat;
 318         if ((logfac &~ LOG_FACMASK) == 0)
 319                 LogFacility = logfac;
 320
 321         int retry = 0;
 322         while (retry < 2) {
 323                 if (LogFile == -1) {
 324                         if (LogStat & LOG_NDELAY) {
 325                           LogFile = __socket(AF_UNIX, LogType | SOCK_CLOEXEC, 0);
 326                           if (LogFile == -1)
 327                             return;
 328                         }
 329                 }
 330                 if (LogFile != -1 && !connected)
 331                 {
 332                         int old_errno = errno;
 333                         if (__connect(LogFile, &SyslogAddr, sizeof(SyslogAddr))
 334                             == -1)
 335                         {
 336                                 int saved_errno = errno;
 337                                 int fd = LogFile;
 338                                 LogFile = -1;
 339                                 (void)__close(fd);
 340                                 __set_errno (old_errno);
 341                                 if (saved_errno == EPROTOTYPE)
 342                                 {
 343                                         /* retry with the other type: */
 344                                         LogType = (LogType == SOCK_DGRAM
 345                                                    ? SOCK_STREAM : SOCK_DGRAM);
 346                                         ++retry;
 347                                         continue;
 348                                 }
 349                         } else
 350                                 connected = true;
 351                 }
 352                 break;
 353         }
 354 }
 355
 356 void
 357 openlog (const char *ident, int logstat, int logfac)
 358 {
 359   /* Protect against multiple users and cancellation.  */
 360   __libc_cleanup_push (cancel_handler, NULL);
 361   __libc_lock_lock (syslog_lock);
 362
 363   openlog_internal (ident, logstat, logfac);
 364
 365   __libc_cleanup_pop (1);
 366 }
 367
 368 static void
 369 closelog_internal (void)
 370 {
 371   if (!connected)
 372     return;
 373
 374   __close (LogFile);
 375   LogFile = -1;
 376   connected = false;
 377 }
 378
 379 void
 380 closelog (void)
 381 {
 382   /* Protect against multiple users and cancellation.  */
 383   __libc_cleanup_push (cancel_handler, NULL);
 384   __libc_lock_lock (syslog_lock);
 385
 386   closelog_internal ();
 387   LogTag = NULL;
 388   LogType = SOCK_DGRAM; /* this is the default */
 389
 390   /* Free the lock.  */
 391   __libc_cleanup_pop (1);
 392 }
 393
 394 /* setlogmask -- set the log mask level */
 395 int
 396 setlogmask (int pmask)
 397 {
 398         int omask;
 399
 400         /* Protect against multiple users.  */
 401         __libc_lock_lock (syslog_lock);
 402
 403         omask = LogMask;
 404         if (pmask != 0)
 405                 LogMask = pmask;
 406
 407         __libc_lock_unlock (syslog_lock);
 408
 409         return (omask);
 410 }