syslog.c   [plain text]

/*
 * 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 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    8.8 (Berkeley) 8/30/95";
#endif /* LIBC_SCCS and not lint */

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

#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

#ifdef BSD4_4
# include <paths.h>
#else
# ifndef _PATH_CONSOLE
#  define _PATH_CONSOLE "/dev/console"
# endif
# ifndef _PATH_LOG
#  define _PATH_LOG     "/dev/log"
# endif
#endif

#ifdef HAVE_STDARG_H
# include <stdarg.h>
#else
# include <varargs.h>
# define const  /* */
#endif

#ifndef USESNPRINTF
# if defined(BSD4_4)
#  define USESNPRINTF   1       /* has snprintf(3), vsnprintf(3), etc. */
# else
#  define USESNPRINTF   0       /* cheesy old C library */
# endif
#endif

#ifndef LOG_PRI
# define LOG_PRI(p)     ((p) & LOG_PRIMASK)
#endif

#ifndef LOG_PERROR
# define LOG_PERROR     0
#endif

#define BUFSLOP         1024    /* overflow space */

static int      LogFile = -1;           /* fd for log */
static int      connected;              /* have done connect */
static int      LogStat = 0;            /* status bits, set by openlog() */
static const char *LogTag = NULL;       /* string to tag the entry with */
static int      LogFacility = LOG_USER; /* default facility code */
static int      LogMask = 0xff;         /* mask of priorities to be logged */
#if defined(BSD4_4)
extern char     *__progname;            /* Program name, from crt0. */
#else
char            *__progname = NULL;
#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;
        extern void vsyslog();

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

void
vsyslog(pri, fmt, ap)
        int pri;
        register const char *fmt;
        va_list ap;
{
        register int cnt;
        register char ch, *p, *t;
        time_t now;
        int fd, saved_errno;
        int panic = 0;
        static int maxsend = BUFSIZ;
        char *stdp, fmt_cpy[1024], tbuf[BUFSIZ + BUFSLOP];
        extern void openlog();

#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))
                return;

        saved_errno = errno;

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

        /* Get connected. */
        if (!connected)
                openlog(LogTag, LogStat | LOG_NDELAY, 0);

        /* Build the message. */
        (void)time(&now);
        sprintf(tbuf, "<%d>", pri);
        p = tbuf + strlen(tbuf);
        strftime(p, sizeof (tbuf) - (p - tbuf), "%h %d %T ", localtime(&now));
        p += strlen(p);
        stdp = p;
        if (LogTag == NULL)
                LogTag = __progname;
        if (LogTag != NULL) {
                sprintf(p, "%s", LogTag);
                p += strlen(p);
        }
        if (LogStat & LOG_PID) {
                sprintf(p, "[%d]", getpid());
                p += strlen(p);
        }
        if (LogTag != NULL) {
                *p++ = ':';
                *p++ = ' ';
        }

        /* Substitute error message for %m. */
        for (t = fmt_cpy; ch = *fmt; ++fmt)
                if (ch == '%' && fmt[1] == 'm') {
                        ++fmt;
                        sprintf(t, "%s", strerror(saved_errno));
                        t += strlen(t);
                } else
                        *t++ = ch;
        *t = '\0';

#if USESNPRINTF
        cnt = maxsend - (p - tbuf) + 1;
        p += vsnprintf(p, cnt, fmt_cpy, ap);
        cnt = p - tbuf;
#else
        vsprintf(p, fmt_cpy, ap);
        p += strlen(p);
        cnt = p - tbuf;
        if (cnt > sizeof tbuf) {
                /* Panic condition. */
                panic = 1;
        }
        if (cnt > maxsend)
                cnt = maxsend;
#endif

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

                v->iov_base = stdp;
                v->iov_len = cnt - (stdp - tbuf);
                ++v;
                v->iov_base = "\n";
                v->iov_len = 1;
                (void)writev(STDERR_FILENO, iov, 2);
        }

        /* Output the message to the local logger. */
        for (;;) {
                if (send(LogFile, tbuf, cnt, 0) >= 0)
                        goto done;
                if (errno != EMSGSIZE || maxsend <= 256)
                        break;

                /* Message was too large -- back it off. */
                do {
                        maxsend -= 128;
                } while (cnt < maxsend && maxsend > 256);
                cnt = maxsend;
        }

        /*
         * 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, 0)) >= 0) {
                (void)strcat(tbuf, "\r\n");
                cnt += 2;
                p = strchr(tbuf, '>') + 1;
                (void)write(fd, p, cnt - (p - tbuf));
                (void)close(fd);
        }

  done:
#if !USESNPRINTF
        /*
         * If we had a buffer overrun, log a panic and abort.
         * We can't return because our stack is probably toast.
         */
        if (panic) {
                syslog(LOG_EMERG, "SYSLOG BUFFER OVERRUN -- EXITING");
                abort();
        }
#endif
}

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

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

        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, SOCK_DGRAM, 0)) == -1)
                                return;
                        (void)fcntl(LogFile, F_SETFD, 1);
                }
        }
        if (LogFile != -1 && !connected)
                if (connect(LogFile, &SyslogAddr, sizeof(SyslogAddr)) == -1) {
                        (void)close(LogFile);
                        LogFile = -1;
                } else
                        connected = 1;
}

void
closelog()
{
        (void)close(LogFile);
        LogFile = -1;
        connected = 0;
}

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

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