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 int      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 #ifndef NO_SIGPIPE
  78 static void sigpipe_handler (int);
  79 #endif
  80
  81 #ifndef send_flags
  82 # define send_flags 0
  83 #endif
  84
  85 struct cleanup_arg
  86 {
  87   void *buf;
  88   struct sigaction *oldaction;
  89 };
  90
  91 static void
  92 cancel_handler (void *ptr)
  93 {
  94   /* Restore the old signal handler.  */
  95   struct cleanup_arg *clarg = (struct cleanup_arg *) ptr;
  96
  97   if (clarg != NULL)
  98     {
  99 #ifndef NO_SIGPIPE
 100       if (clarg->oldaction != NULL)
 101         __sigaction (SIGPIPE, clarg->oldaction, NULL);
 102 #endif
 103
 104       /* Free the memstream buffer,  */
 105       free (clarg->buf);
 106     }
 107
 108   /* Free the lock.  */
 109   __libc_lock_unlock (syslog_lock);
 110 }
 111
 112
 113 /*
 114  * syslog, vsyslog --
 115  *      print message on log file; output is intended for syslogd(8).
 116  */
 117 void
 118 __syslog(int pri, const char *fmt, ...)
 119 {
 120         va_list ap;
 121
 122         va_start(ap, fmt);
 123         __vsyslog_internal(pri, fmt, ap, 0);
 124         va_end(ap);
 125 }
 126 ldbl_hidden_def (__syslog, syslog)
 127 ldbl_strong_alias (__syslog, syslog)
 128
 129 void
 130 __vsyslog(int pri, const char *fmt, va_list ap)
 131 {
 132         __vsyslog_internal(pri, fmt, ap, 0);
 133 }
 134 ldbl_weak_alias (__vsyslog, vsyslog)
 135
 136 void
 137 __syslog_chk(int pri, int flag, const char *fmt, ...)
 138 {
 139         va_list ap;
 140
 141         va_start(ap, fmt);
 142         __vsyslog_internal(pri, fmt, ap, (flag > 0) ? PRINTF_FORTIFY : 0);
 143         va_end(ap);
 144 }
 145
 146 void
 147 __vsyslog_chk(int pri, int flag, const char *fmt, va_list ap)
 148 {
 149         __vsyslog_internal(pri, fmt, ap, (flag > 0) ? PRINTF_FORTIFY : 0);
 150 }
 151
 152 void
 153 __vsyslog_internal(int pri, const char *fmt, va_list ap,
 154                    unsigned int mode_flags)
 155 {
 156         struct tm now_tm;
 157         time_t now;
 158         int fd;
 159         FILE *f;
 160         char *buf = 0;
 161         size_t bufsize = 0;
 162         size_t msgoff;
 163 #ifndef NO_SIGPIPE
 164         struct sigaction action, oldaction;
 165         int sigpipe;
 166 #endif
 167         int saved_errno = errno;
 168         char failbuf[3 * sizeof (pid_t) + sizeof "out of memory []"];
 169
 170 #define INTERNALLOG     LOG_ERR|LOG_CONS|LOG_PERROR|LOG_PID
 171         /* Check for invalid bits. */
 172         if (pri & ~(LOG_PRIMASK|LOG_FACMASK)) {
 173                 syslog(INTERNALLOG,
 174                     "syslog: unknown facility/priority: %x", pri);
 175                 pri &= LOG_PRIMASK|LOG_FACMASK;
 176         }
 177
 178         /* Prepare for multiple users.  We have to take care: most
 179            syscalls we are using are cancellation points.  */
 180         struct cleanup_arg clarg;
 181         clarg.buf = NULL;
 182         clarg.oldaction = NULL;
 183         __libc_cleanup_push (cancel_handler, &clarg);
 184         __libc_lock_lock (syslog_lock);
 185
 186         /* Check priority against setlogmask values. */
 187         if ((LOG_MASK (LOG_PRI (pri)) & LogMask) == 0)
 188                 goto out;
 189
 190         /* Set default facility if none specified. */
 191         if ((pri & LOG_FACMASK) == 0)
 192                 pri |= LogFacility;
 193
 194         /* Build the message in a memory-buffer stream.  */
 195         f = __open_memstream (&buf, &bufsize);
 196         if (f == NULL)
 197           {
 198             /* We cannot get a stream.  There is not much we can do but
 199                emitting an error messages.  */
 200             char numbuf[3 * sizeof (pid_t)];
 201             char *nump;
 202             char *endp = __stpcpy (failbuf, "out of memory [");
 203             pid_t pid = __getpid ();
 204
 205             nump = numbuf + sizeof (numbuf);
 206             /* The PID can never be zero.  */
 207             do
 208               *--nump = '0' + pid % 10;
 209             while ((pid /= 10) != 0);
 210
 211             endp = __mempcpy (endp, nump, (numbuf + sizeof (numbuf)) - nump);
 212             *endp++ = ']';
 213             *endp = '\0';
 214             buf = failbuf;
 215             bufsize = endp - failbuf;
 216             msgoff = 0;
 217           }
 218         else
 219           {
 220             __fsetlocking (f, FSETLOCKING_BYCALLER);
 221             fprintf (f, "<%d>", pri);
 222             now = time_now ();
 223             f->_IO_write_ptr += __strftime_l (f->_IO_write_ptr,
 224                                               f->_IO_write_end
 225                                               - f->_IO_write_ptr,
 226                                               "%h %e %T ",
 227                                               __localtime_r (&now, &now_tm),
 228                                               _nl_C_locobj_ptr);
 229             msgoff = ftell (f);
 230             if (LogTag == NULL)
 231               LogTag = __progname;
 232             if (LogTag != NULL)
 233               __fputs_unlocked (LogTag, f);
 234             if (LogStat & LOG_PID)
 235               fprintf (f, "[%d]", (int) __getpid ());
 236             if (LogTag != NULL)
 237               {
 238                 __putc_unlocked (':', f);
 239                 __putc_unlocked (' ', f);
 240               }
 241
 242             /* Restore errno for %m format.  */
 243             __set_errno (saved_errno);
 244
 245             /* We have the header.  Print the user's format into the
 246                buffer.  */
 247             __vfprintf_internal (f, fmt, ap, mode_flags);
 248
 249             /* Close the memory stream; this will finalize the data
 250                into a malloc'd buffer in BUF.  */
 251             fclose (f);
 252
 253             /* Tell the cancellation handler to free this buffer.  */
 254             clarg.buf = buf;
 255           }
 256
 257         /* Output to stderr if requested. */
 258         if (LogStat & LOG_PERROR) {
 259                 struct iovec iov[2];
 260                 struct iovec *v = iov;
 261
 262                 v->iov_base = buf + msgoff;
 263                 v->iov_len = bufsize - msgoff;
 264                 /* Append a newline if necessary.  */
 265                 if (buf[bufsize - 1] != '\n')
 266                   {
 267                     ++v;
 268                     v->iov_base = (char *) "\n";
 269                     v->iov_len = 1;
 270                   }
 271
 272                 /* writev is a cancellation point.  */
 273                 (void)__writev(STDERR_FILENO, iov, v - iov + 1);
 274         }
 275
 276 #ifndef NO_SIGPIPE
 277         /* Prepare for a broken connection.  */
 278         memset (&action, 0, sizeof (action));
 279         action.sa_handler = sigpipe_handler;
 280         sigemptyset (&action.sa_mask);
 281         sigpipe = __sigaction (SIGPIPE, &action, &oldaction);
 282         if (sigpipe == 0)
 283           clarg.oldaction = &oldaction;
 284 #endif
 285
 286         /* Get connected, output the message to the local logger. */
 287         if (!connected)
 288                 openlog_internal(NULL, LogStat | LOG_NDELAY, LogFacility);
 289
 290         /* If we have a SOCK_STREAM connection, also send ASCII NUL as
 291            a record terminator.  */
 292         if (LogType == SOCK_STREAM)
 293           ++bufsize;
 294
 295         if (!connected || __send(LogFile, buf, bufsize, send_flags) < 0)
 296           {
 297             if (connected)
 298               {
 299                 /* Try to reopen the syslog connection.  Maybe it went
 300                    down.  */
 301                 closelog_internal ();
 302                 openlog_internal(NULL, LogStat | LOG_NDELAY, LogFacility);
 303               }
 304
 305             if (!connected || __send(LogFile, buf, bufsize, send_flags) < 0)
 306               {
 307                 closelog_internal ();   /* attempt re-open next time */
 308                 /*
 309                  * Output the message to the console; don't worry
 310                  * about blocking, if console blocks everything will.
 311                  * Make sure the error reported is the one from the
 312                  * syslogd failure.
 313                  */
 314                 if (LogStat & LOG_CONS &&
 315                     (fd = __open(_PATH_CONSOLE, O_WRONLY|O_NOCTTY, 0)) >= 0)
 316                   {
 317                     __dprintf (fd, "%s\r\n", buf + msgoff);
 318                     (void)__close(fd);
 319                   }
 320               }
 321           }
 322
 323 #ifndef NO_SIGPIPE
 324         if (sigpipe == 0)
 325                 __sigaction (SIGPIPE, &oldaction, (struct sigaction *) NULL);
 326 #endif
 327
 328  out:
 329         /* End of critical section.  */
 330         __libc_cleanup_pop (0);
 331         __libc_lock_unlock (syslog_lock);
 332
 333         if (buf != failbuf)
 334                 free (buf);
 335 }
 336
 337 static struct sockaddr_un SyslogAddr;   /* AF_UNIX address of local logger */
 338
 339
 340 static void
 341 openlog_internal(const char *ident, int logstat, int logfac)
 342 {
 343         if (ident != NULL)
 344                 LogTag = ident;
 345         LogStat = logstat;
 346         if ((logfac &~ LOG_FACMASK) == 0)
 347                 LogFacility = logfac;
 348
 349         int retry = 0;
 350         while (retry < 2) {
 351                 if (LogFile == -1) {
 352                         SyslogAddr.sun_family = AF_UNIX;
 353                         (void)strncpy(SyslogAddr.sun_path, _PATH_LOG,
 354                                       sizeof(SyslogAddr.sun_path));
 355                         if (LogStat & LOG_NDELAY) {
 356                           LogFile = __socket(AF_UNIX, LogType | SOCK_CLOEXEC, 0);
 357                           if (LogFile == -1)
 358                             return;
 359                         }
 360                 }
 361                 if (LogFile != -1 && !connected)
 362                 {
 363                         int old_errno = errno;
 364                         if (__connect(LogFile, &SyslogAddr, sizeof(SyslogAddr))
 365                             == -1)
 366                         {
 367                                 int saved_errno = errno;
 368                                 int fd = LogFile;
 369                                 LogFile = -1;
 370                                 (void)__close(fd);
 371                                 __set_errno (old_errno);
 372                                 if (saved_errno == EPROTOTYPE)
 373                                 {
 374                                         /* retry with the other type: */
 375                                         LogType = (LogType == SOCK_DGRAM
 376                                                    ? SOCK_STREAM : SOCK_DGRAM);
 377                                         ++retry;
 378                                         continue;
 379                                 }
 380                         } else
 381                                 connected = 1;
 382                 }
 383                 break;
 384         }
 385 }
 386
 387 void
 388 openlog (const char *ident, int logstat, int logfac)
 389 {
 390   /* Protect against multiple users and cancellation.  */
 391   __libc_cleanup_push (cancel_handler, NULL);
 392   __libc_lock_lock (syslog_lock);
 393
 394   openlog_internal (ident, logstat, logfac);
 395
 396   __libc_cleanup_pop (1);
 397 }
 398
 399 #ifndef NO_SIGPIPE
 400 static void
 401 sigpipe_handler (int signo)
 402 {
 403   closelog_internal ();
 404 }
 405 #endif
 406
 407 static void
 408 closelog_internal (void)
 409 {
 410   if (!connected)
 411     return;
 412
 413   __close (LogFile);
 414   LogFile = -1;
 415   connected = 0;
 416 }
 417
 418 void
 419 closelog (void)
 420 {
 421   /* Protect against multiple users and cancellation.  */
 422   __libc_cleanup_push (cancel_handler, NULL);
 423   __libc_lock_lock (syslog_lock);
 424
 425   closelog_internal ();
 426   LogTag = NULL;
 427   LogType = SOCK_DGRAM; /* this is the default */
 428
 429   /* Free the lock.  */
 430   __libc_cleanup_pop (1);
 431 }
 432
 433 /* setlogmask -- set the log mask level */
 434 int
 435 setlogmask (int pmask)
 436 {
 437         int omask;
 438
 439         /* Protect against multiple users.  */
 440         __libc_lock_lock (syslog_lock);
 441
 442         omask = LogMask;
 443         if (pmask != 0)
 444                 LogMask = pmask;
 445
 446         __libc_lock_unlock (syslog_lock);
 447
 448         return (omask);
 449 }