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syslog.c

/*
 * 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 <sys/types.h>
#include <sys/socket.h>
#include <sys/syslog.h>
#include <sys/uio.h>
#include <netdb.h>

#include <errno.h>
#include <fcntl.h>
#include <paths.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <stdlib.h>
#include <bits/libc-lock.h>
#include <signal.h>

#if __STDC__
#include <stdarg.h>
#else
#include <varargs.h>
#endif

#ifdef USE_IN_LIBIO
# include <libio/iolibio.h>
# define ftell(s) INTUSE(_IO_ftell) (s)
#endif

static int  LogType = SOCK_DGRAM;   /* type of socket connection */
static int  LogFile = -1;           /* fd for log */
static int  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) internal_function;
static void closelog_internal(void);
static void sigpipe_handler (int);
#ifdef _LIBC_REENTRANT
static void cancel_handler (void *);
#endif

/*
 * syslog, vsyslog --
 *    print message on log file; output is intended for syslogd(8).
 */
void
#if __STDC__
syslog(int pri, const char *fmt, ...)
#else
syslog(pri, fmt, va_alist)
      int pri;
      char *fmt;
      va_dcl
#endif
{
      va_list ap;

#if __STDC__
      va_start(ap, fmt);
#else
      va_start(ap);
#endif
      vsyslog(pri, fmt, ap);
      va_end(ap);
}
libc_hidden_def (syslog)

void
vsyslog(pri, fmt, ap)
      int pri;
      register const char *fmt;
      va_list ap;
{
      struct tm now_tm;
      time_t now;
      int fd;
      FILE *f;
      char *buf = 0;
      size_t bufsize = 0;
      size_t prioff, msgoff;
      struct sigaction action, oldaction;
      struct sigaction *oldaction_ptr = NULL;
      int sigpipe;
      int saved_errno = errno;
      char failbuf[3 * sizeof (pid_t) + sizeof "out of memory []"];

#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;
      }

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

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

      /* Build the message in a memory-buffer stream.  */
      f = open_memstream (&buf, &bufsize);
      if (f == NULL)
        {
          /* We cannot get a stream.  There is not much we can do but
             emitting an error messages.  */
          char numbuf[3 * sizeof (pid_t)];
          char *nump;
          char *endp = __stpcpy (failbuf, "out of memory [");
          pid_t pid = __getpid ();

          nump = numbuf + sizeof (numbuf);
          /* The PID can never be zero.  */
          do
            *--nump = '0' + pid % 10;
          while ((pid /= 10) != 0);

          endp = __mempcpy (endp, nump, (nump + sizeof (numbuf)) - nump);
          *endp++ = ']';
          *endp = '\0';
          buf = failbuf;
          bufsize = endp - failbuf;
          msgoff = 0;
        }
      else
        {
          prioff = fprintf (f, "<%d>", pri);
          (void) time (&now);
#ifdef USE_IN_LIBIO
          f->_IO_write_ptr += strftime (f->_IO_write_ptr,
                                f->_IO_write_end - f->_IO_write_ptr,
                                "%h %e %T ",
                                __localtime_r (&now, &now_tm));
#else
          f->__bufp += strftime (f->__bufp, f->__put_limit - f->__bufp,
                           "%h %e %T ", __localtime_r (&now, &now_tm));
#endif
          msgoff = ftell (f);
          if (LogTag == NULL)
            LogTag = __progname;
          if (LogTag != NULL)
            fputs_unlocked (LogTag, f);
          if (LogStat & LOG_PID)
            fprintf (f, "[%d]", __getpid ());
          if (LogTag != NULL)
            putc_unlocked (':', f), putc_unlocked (' ', f);

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

          /* We have the header.  Print the user's format into the
               buffer.  */
          vfprintf (f, fmt, ap);

          /* Close the memory stream; this will finalize the data
             into a malloc'd buffer in BUF.  */
          fclose (f);
        }

      /* Output to stderr if requested. */
      if (LogStat & LOG_PERROR) {
            struct iovec iov[2];
            register struct iovec *v = iov;

            v->iov_base = buf + msgoff;
            v->iov_len = bufsize - msgoff;
            /* Append a newline if necessary.  */
            if (buf[bufsize - 1] != '\n')
              {
                ++v;
                v->iov_base = (char *) "\n";
                v->iov_len = 1;
              }
            (void)__writev(STDERR_FILENO, iov, v - iov + 1);
      }

#ifdef _LIBC_REENTRANT
      /* Prepare for multiple users.  We have to take care: open and
         write are cancellation points.  */
      __libc_cleanup_region_start (1, (void (*) (void *)) cancel_handler,
                             &oldaction_ptr);
      __libc_lock_lock (syslog_lock);
#endif

      /* Prepare for a broken connection.  */
      memset (&action, 0, sizeof (action));
      action.sa_handler = sigpipe_handler;
      sigemptyset (&action.sa_mask);
      sigpipe = __sigaction (SIGPIPE, &action, &oldaction);
      if (sigpipe == 0)
        oldaction_ptr = &oldaction;

      /* Get connected, output the message to the local logger. */
      if (!connected)
            openlog_internal(LogTag, LogStat | LOG_NDELAY, 0);

      /* 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, 0) < 0)
        {
          if (connected)
            {
            /* Try to reopen the syslog connection.  Maybe it went
               down.  */
            closelog_internal ();
            openlog_internal(LogTag, LogStat | LOG_NDELAY, 0);
            }

          if (!connected || __send(LogFile, buf, bufsize, 0) < 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.
             */
            if (LogStat & LOG_CONS &&
                (fd = __open(_PATH_CONSOLE, O_WRONLY|O_NOCTTY, 0)) >= 0)
              {
                dprintf (fd, "%s\r\n", buf + msgoff);
                (void)__close(fd);
              }
            }
        }

      if (sigpipe == 0)
            __sigaction (SIGPIPE, &oldaction, (struct sigaction *) NULL);

#ifdef _LIBC_REENTRANT
      /* End of critical section.  */
      __libc_cleanup_region_end (0);
      __libc_lock_unlock (syslog_lock);
#endif

      free (buf);
}
libc_hidden_def (vsyslog)

static struct sockaddr SyslogAddr;  /* AF_UNIX address of local logger */

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

      while (1) {
            if (LogFile == -1) {
                  SyslogAddr.sa_family = AF_UNIX;
                  (void)strncpy(SyslogAddr.sa_data, _PATH_LOG,
                              sizeof(SyslogAddr.sa_data));
                  if (LogStat & LOG_NDELAY) {
                        if ((LogFile = __socket(AF_UNIX, LogType, 0))
                            == -1)
                              return;
                        (void)__fcntl(LogFile, F_SETFD, 1);
                  }
            }
            if (LogFile != -1 && !connected)
            {
                  int old_errno = errno;
                  if (__connect(LogFile, &SyslogAddr, sizeof(SyslogAddr))
                      == -1)
                  {
                        int saved_errno = errno;
                        (void)__close(LogFile);
                        LogFile = -1;
                        if (LogType == SOCK_DGRAM
                            && saved_errno == EPROTOTYPE)
                        {
                              /* retry with next SOCK_STREAM: */
                              LogType = SOCK_STREAM;
                              __set_errno (old_errno);
                              continue;
                        }
                  } else
                        connected = 1;
            }
            break;
      }
}


static void
log_cleanup (void *arg)
{
  __libc_lock_unlock (syslog_lock);
}

void
openlog (const char *ident, int logstat, int logfac)
{
#ifdef _LIBC_REENTRANT
  /* Protect against multiple users.  */
  __libc_cleanup_region_start (1, log_cleanup, NULL);
  __libc_lock_lock (syslog_lock);
#endif

  openlog_internal (ident, logstat, logfac);

#ifdef _LIBC_REENTRANT
  /* Free the lock.  */
  __libc_cleanup_region_end (1);
#endif
}

static void
sigpipe_handler (int signo)
{
  closelog_internal ();
}

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

  __close (LogFile);
  LogFile = -1;
  connected = 0;
}

void
closelog ()
{
#ifdef _LIBC_REENTRANT
  /* Protect against multiple users.  */
  __libc_cleanup_region_start (1, log_cleanup, NULL);
  __libc_lock_lock (syslog_lock);
#endif

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

#ifdef _LIBC_REENTRANT
  /* Free the lock.  */
  __libc_cleanup_region_end (1);
#endif
}

#ifdef _LIBC_REENTRANT
static void
cancel_handler (void *ptr)
{
  /* Restore the old signal handler.  */
  struct sigaction *oldaction = *((struct sigaction **) ptr);

  if (oldaction != (struct sigaction *) NULL)
    __sigaction (SIGPIPE, oldaction, (struct sigaction *) NULL);

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

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

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

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