import less(1)

[unleashed/tickless.git] / usr / src / lib / libc / port / gen / syslog.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*      Copyright (c) 1988 AT&T */
/*        All Rights Reserved   */

/*
 * University Copyright- Copyright (c) 1982, 1986, 1988
 * The Regents of the University of California
 * All Rights Reserved
 *
 * University Acknowledgment- Portions of this document are derived from
 * software developed by the University of California, Berkeley, and its
 * contributors.
 */


/*
 * SYSLOG -- print message on log file
 *
 * This routine looks a lot like printf, except that it
 * outputs to the log file instead of the standard output.
 * Also:
 *      adds a timestamp,
 *      prints the module name in front of the message,
 *      has some other formatting types (or will sometime),
 *      adds a newline on the end of the message.
 *
 * The output of this routine is intended to be read by /etc/syslogd.
 */

#pragma weak _syslog = syslog

#include "lint.h"
#include <sys/types.h>
#include <sys/types32.h>
#include <sys/mman.h>
#include <sys/stropts.h>
#include <sys/strlog.h>
#include <sys/log.h>            /* for LOG_MAXPS */
#include <stdlib.h>
#include <procfs.h>
#include <syslog.h>
#include <signal.h>
#include <fcntl.h>
#include <string.h>
#include <stdarg.h>
#include <unistd.h>
#include <wait.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <thread.h>
#include <synch.h>
#include <sys/door.h>
#include <sys/stat.h>
#include <stropts.h>
#include <sys/fork.h>
#include <sys/wait.h>
#include "libc.h"

#define MAXLINE         1024            /* max message size (but see below) */

#define PRIMASK(p)      (1 << ((p) & LOG_PRIMASK))
#define PRIFAC(p)       (((p) & LOG_FACMASK) >> 3)
#define IMPORTANT       LOG_ERR

#ifndef FALSE
#define FALSE   0
#endif

#ifndef TRUE
#define TRUE    1
#endif

#define logname         "/dev/conslog"
#define ctty            "/dev/syscon"
#define sysmsg          "/dev/sysmsg"

#define DOORFILE        "/var/run/syslog_door"

static struct __syslog {
        int     _LogFile;
        int     _LogStat;
        const char *_LogTag;
        int     _LogMask;
        char    *_SyslogHost;
        int     _LogFacility;
        int     _LogFileInvalid;
        int     _OpenLogCalled;
        dev_t   _LogDev;
        char    _ProcName[PRFNSZ + 1];
} __syslog = {
        -1,             /* fd for log */
        0,              /* status bits, set by openlog() */
        "syslog",       /* string to tag the entry with */
        0xff,           /* mask of priorities to be logged */
        NULL,
        LOG_USER,       /* default facility code */
        FALSE,          /* check for validity of fd for log */
        0,              /* openlog has not yet been called */
};

#define LogFile (__syslog._LogFile)
#define LogStat (__syslog._LogStat)
#define LogTag (__syslog._LogTag)
#define LogMask (__syslog._LogMask)
#define SyslogHost (__syslog._SyslogHost)
#define LogFacility (__syslog._LogFacility)
#define LogFileInvalid (__syslog._LogFileInvalid)
#define OpenLogCalled (__syslog._OpenLogCalled)
#define LogDev (__syslog._LogDev)
#define ProcName (__syslog._ProcName)

static int syslogd_ok(void);

/*
 * Regrettably, there are several instances inside libc where
 * syslog() is called from the bottom of a deep call stack
 * and a critical lock was acquired near the top of the stack.
 *
 * Because syslog() uses stdio (and it is called from within stdio)
 * it runs the danger of deadlocking, perhaps with an interposed
 * malloc() when fork() is occurring concurrently, perhaps with
 * some other lock within libc.
 *
 * The only fix for this problem is to restructure libc not to do
 * this thing and always to call syslog() with no locks held.
 * This restructuring will require a substantial effort.
 *
 * Meanwhile, we just hope that on the rare occasion that syslog()
 * is called from within libc (such occurrences should "never happen")
 * that we don't get caught in a race condition deadlock.
 */
void
syslog(int pri, const char *fmt, ...)
{
        va_list ap;

        va_start(ap, fmt);
        vsyslog(pri, fmt, ap);
        va_end(ap);
}


void
vsyslog(int pri, const char *fmt, va_list ap)
{
        char *b, *f, *o;
        char c;
        int clen;
        char buf[MAXLINE + 2];
        char outline[MAXLINE + 256];  /* pad to allow date, system name... */
        time_t now;
        pid_t pid;
        struct log_ctl hdr;
        struct strbuf dat;
        struct strbuf ctl;
        char timestr[26];       /* hardwired value 26 due to Posix */
        size_t taglen;
        int olderrno = errno;
        struct stat statbuff;
        int procfd;
        char procfile[32];
        psinfo_t p;
        int showpid;
        uint32_t msgid;
        char *msgid_start, *msgid_end;
        int nowait;

/*
 * Maximum tag length is 256 (the pad in outline) minus the size of the
 * other things that can go in the pad.
 */
#define MAX_TAG         230

        /* see if we should just throw out this message */
        if (pri < 0 || PRIFAC(pri) >= LOG_NFACILITIES ||
            (PRIMASK(pri) & LogMask) == 0)
                return;

        if (LogFileInvalid)
                return;

        /*
         * if openlog() has not been called by the application,
         * try to get the name of the application and set it
         * as the ident string for messages. If unable to get
         * it for any reason, fall back to using the default
         * of syslog. If we succeed in getting the name, also
         * turn on LOG_PID, to provide greater detail.
         */
        showpid = 0;
        if (OpenLogCalled == 0) {
                (void) sprintf(procfile, "/proc/%d/psinfo", (int)getpid());
                if ((procfd = open(procfile, O_RDONLY)) >= 0) {
                        if (read(procfd, &p, sizeof (psinfo_t)) >= 0) {
                                (void) strncpy(ProcName, p.pr_fname, PRFNSZ);
                                LogTag = (const char *) &ProcName;
                                showpid = LOG_PID;
                        }
                        (void) close(procfd);
                }
        }
        if (LogFile < 0)
                openlog(LogTag, LogStat|LOG_NDELAY|showpid, 0);

        if ((fstat(LogFile, &statbuff) != 0) ||
            (!S_ISCHR(statbuff.st_mode)) || (statbuff.st_rdev != LogDev)) {
                LogFileInvalid = TRUE;
                return;
        }

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

        /* build the header */
        hdr.pri = pri;
        hdr.flags = SL_CONSOLE;
        hdr.level = 0;

        /* build the message */
        /*
         * To avoid potential security problems, bounds checking is done
         * on outline and buf.
         * The following code presumes that the header information will
         * fit in 250-odd bytes, as was accounted for in the buffer size
         * allocation.  This is dependent on the assumption that the LogTag
         * and the string returned by sprintf() for getpid() will return
         * be less than 230-odd characters combined.
         */
        o = outline;
        (void) time(&now);
        (void) sprintf(o, "%.15s ", ctime_r(&now, timestr) + 4);
        o += strlen(o);

        if (LogTag) {
                taglen = strlen(LogTag) < MAX_TAG ? strlen(LogTag) : MAX_TAG;
                (void) strncpy(o, LogTag, taglen);
                o[taglen] = '\0';
                o += strlen(o);
        }
        if (LogStat & LOG_PID) {
                (void) sprintf(o, "[%d]", (int)getpid());
                o += strlen(o);
        }
        if (LogTag) {
                (void) strcpy(o, ": ");
                o += 2;
        }

        STRLOG_MAKE_MSGID(fmt, msgid);
        (void) sprintf(o, "[ID %u FACILITY_AND_PRIORITY] ", msgid);
        o += strlen(o);

        b = buf;
        f = (char *)fmt;
        while ((c = *f++) != '\0' && b < &buf[MAXLINE]) {
                char *errmsg;
                if (c != '%') {
                        *b++ = c;
                        continue;
                }
                if ((c = *f++) != 'm') {
                        *b++ = '%';
                        *b++ = c;
                        continue;
                }
                if ((errmsg = strerror(olderrno)) == NULL)
                        (void) snprintf(b, &buf[MAXLINE] - b, "error %d",
                            olderrno);
                else {
                        while (*errmsg != '\0' && b < &buf[MAXLINE]) {
                                if (*errmsg == '%') {
                                        (void) strcpy(b, "%%");
                                        b += 2;
                                }
                                else
                                        *b++ = *errmsg;
                                errmsg++;
                        }
                        *b = '\0';
                }
                b += strlen(b);
        }
        if (b > buf && *(b-1) != '\n')  /* ensure at least one newline */
                *b++ = '\n';
        *b = '\0';
        /* LINTED variable format specifier */
        (void) vsnprintf(o, &outline[sizeof (outline)] - o, buf, ap);
        clen  = (int)strlen(outline) + 1;       /* add one for NULL byte */
        if (clen > MAXLINE) {
                clen = MAXLINE;
                outline[MAXLINE-1] = '\0';
        }

        /*
         * 1136432 points out that the underlying log driver actually
         * refuses to accept (ERANGE) messages longer than LOG_MAXPS
         * bytes.  So it really doesn't make much sense to putmsg a
         * longer message..
         */
        if (clen > LOG_MAXPS) {
                clen = LOG_MAXPS;
                outline[LOG_MAXPS-1] = '\0';
        }

        /* set up the strbufs */
        ctl.maxlen = sizeof (struct log_ctl);
        ctl.len = sizeof (struct log_ctl);
        ctl.buf = (caddr_t)&hdr;
        dat.maxlen = sizeof (outline);
        dat.len = clen;
        dat.buf = outline;

        /* output the message to the local logger */
        if ((putmsg(LogFile, &ctl, &dat, 0) >= 0) && syslogd_ok())
                return;
        if (!(LogStat & LOG_CONS))
                return;

        /*
         * Output the message to the console directly.  To reduce visual
         * clutter, we strip out the message ID.
         */
        if ((msgid_start = strstr(outline, "[ID ")) != NULL &&
            (msgid_end = strstr(msgid_start, "] ")) != NULL)
                (void) strcpy(msgid_start, msgid_end + 2);

        clen = strlen(outline) + 1;

        nowait = (LogStat & LOG_NOWAIT);
        pid = forkx(nowait? 0 : (FORK_NOSIGCHLD | FORK_WAITPID));
        if (pid == -1)
                return;

        if (pid == 0) {
                sigset_t sigs;
                int fd;

                (void) sigset(SIGALRM, SIG_DFL);
                (void) sigemptyset(&sigs);
                (void) sigaddset(&sigs, SIGALRM);
                (void) sigprocmask(SIG_UNBLOCK, &sigs, NULL);
                (void) alarm(5);
                if (((fd = open(sysmsg, O_WRONLY)) >= 0) ||
                    (fd = open(ctty, O_WRONLY)) >= 0) {
                        (void) alarm(0);
                        outline[clen - 1] = '\r';
                        (void) write(fd, outline, clen);
                        (void) close(fd);
                }
                _exit(0);
        }
        if (!nowait)
                while (waitpid(pid, NULL, 0) == -1 && errno == EINTR)
                        continue;
}

/*
 * Use a door call to syslogd to see if it's alive.
 */
static int
syslogd_ok(void)
{
        int d;
        int s;
        door_arg_t darg;
        door_info_t info;

        if ((d = open(DOORFILE, O_RDONLY)) < 0)
                return (0);
        /*
         * see if our pid matches the pid of the door server.
         * If so, syslogd has called syslog(), probably as
         * a result of some name service library error, and
         * we don't want to let syslog continue and possibly
         * fork here.
         */
        info.di_target = 0;
        if (__door_info(d, &info) < 0 || info.di_target == getpid()) {
                (void) close(d);
                return (0);
        }
        darg.data_ptr = NULL;
        darg.data_size = 0;
        darg.desc_ptr = NULL;
        darg.desc_num = 0;
        darg.rbuf = NULL;
        darg.rsize = 0;
        s = __door_call(d, &darg);
        (void) close(d);
        if (s < 0)
                return (0);             /* failure - syslogd dead */
        else
                return (1);
}

/*
 * OPENLOG -- open system log
 */

void
openlog(const char *ident, int logstat, int logfac)
{
        struct  stat    statbuff;

        OpenLogCalled = 1;
        if (ident != NULL)
                LogTag = ident;
        LogStat = logstat;
        if (logfac != 0)
                LogFacility = logfac & LOG_FACMASK;

        /*
         * if the fstat(2) fails or the st_rdev has changed
         * then we must open the file
         */
        if ((fstat(LogFile, &statbuff) == 0) &&
            (S_ISCHR(statbuff.st_mode)) && (statbuff.st_rdev == LogDev))
                return;

        if (LogStat & LOG_NDELAY) {
                LogFile = open(logname, O_WRONLY);
                (void) fcntl(LogFile, F_SETFD, 1);
                (void) fstat(LogFile, &statbuff);
                LogDev = statbuff.st_rdev;
        }
}

/*
 * CLOSELOG -- close the system log
 */

void
closelog(void)
{
        struct  stat    statbuff;

        OpenLogCalled = 0;

        /* if the LogFile is invalid it can not be closed */
        if (LogFileInvalid)
                return;

        /*
         * if the fstat(2) fails or the st_rdev has changed
         * then we can not close the file
         */
        if ((fstat(LogFile, &statbuff) == 0) && (statbuff.st_rdev == LogDev)) {
                (void) close(LogFile);
                LogFile = -1;
                LogStat = 0;
        }
}

/*
 * SETLOGMASK -- set the log mask level
 */
int
setlogmask(int pmask)
{
        int omask = 0;

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