/*      $OpenBSD: syslog_r.c,v 1.20 2024/04/03 04:36:53 deraadt Exp $ */
/*
 * 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. 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.
 */

#include <sys/types.h>
#include <sys/uio.h>
#include <netdb.h>

#include <errno.h>
#include <fcntl.h>
#include <paths.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <time.h>
#include <unistd.h>
#include <limits.h>
#include <stdarg.h>

/* Reentrant version of syslog, i.e. syslog_r() */
void
syslog_r(int pri, struct syslog_data *data, const char *fmt, ...)
{
        va_list ap;

        va_start(ap, fmt);
        vsyslog_r(pri, data, fmt, ap);
        va_end(ap);
}
DEF_WEAK(syslog_r);

void
vsyslog_r(int pri, struct syslog_data *data, const char *fmt, va_list ap)
{
        __vsyslog_r(pri, data, 1, fmt, ap);
}
DEF_WEAK(vsyslog_r);

/*
 * This is used by both syslog_r and syslog.
 */
void
__vsyslog_r(int pri, struct syslog_data *data,
    int reentrant, const char *fmt, va_list ap)
{
        int cnt;
        char ch, *p, *t;
        int saved_errno = errno;        /* use original errno */
#define TBUF_SIZE       (LOG_MAXLINE+1)
#define FMT_SIZE        (1024+1)
        char *stdp = NULL, tbuf[TBUF_SIZE], fmt_cpy[FMT_SIZE];
        int tbuf_left, fmt_left, prlen;

#define INTERNALLOG     LOG_ERR|LOG_CONS|LOG_PERROR|LOG_PID
        /* Check for invalid bits. */
        if (pri & ~(LOG_PRIMASK|LOG_FACMASK)) {
                syslog_r(INTERNALLOG, data,
                    "syslog%s: unknown facility/priority: %x",
                    reentrant ? "_r" : "", pri);
                pri &= LOG_PRIMASK|LOG_FACMASK;
        }

        /* Check priority against setlogmask values. */
        if (!(LOG_MASK(LOG_PRI(pri)) & data->log_mask))
                goto done;

        /* Set default facility if none specified. */
        if ((pri & LOG_FACMASK) == 0)
                pri |= data->log_fac;

        p = tbuf;
        tbuf_left = TBUF_SIZE;

#define DEC()   \
        do {                                    \
                if (prlen < 0)                  \
                        prlen = 0;              \
                if (prlen >= tbuf_left)         \
                        prlen = tbuf_left - 1;  \
                p += prlen;                     \
                tbuf_left -= prlen;             \
        } while (0)

        prlen = snprintf(p, tbuf_left, "<%d>", pri);
        DEC();

        if (data->log_stat & LOG_PERROR)
                stdp = p;
        if (data->log_tag == NULL)
                data->log_tag = __progname;
        if (data->log_tag != NULL) {
                prlen = snprintf(p, tbuf_left, "%.*s", NAME_MAX, data->log_tag);
                DEC();
        }
        if (data->log_stat & LOG_PID) {
                prlen = snprintf(p, tbuf_left, "[%ld]", (long)getpid());
                DEC();
        }
        if (data->log_tag != NULL) {
                if (tbuf_left > 1) {
                        *p++ = ':';
                        tbuf_left--;
                }
                if (tbuf_left > 1) {
                        *p++ = ' ';
                        tbuf_left--;
                }
        }

        for (t = fmt_cpy, fmt_left = FMT_SIZE;
            (ch = *fmt) != '\0' && fmt_left > 1;
            ++fmt) {
                if (ch == '%' && fmt[1] == 'm') {
                        char ebuf[NL_TEXTMAX];

                        ++fmt;
                        (void)strerror_r(saved_errno, ebuf, sizeof(ebuf));
                        prlen = snprintf(t, fmt_left, "%s", ebuf);
                        if (prlen < 0)
                                prlen = 0;
                        if (prlen >= fmt_left)
                                prlen = fmt_left - 1;
                        t += prlen;
                        fmt_left -= prlen;
                } else if (ch == '%' && fmt[1] == '%' && fmt_left > 2) {
                        ++fmt;
                        *t++ = '%';
                        *t++ = '%';
                        fmt_left -= 2;
                } else {
                        *t++ = ch;
                        fmt_left--;
                }
        }
        *t = '\0';

        prlen = vsnprintf(p, tbuf_left, fmt_cpy, ap);
        DEC();
        cnt = p - tbuf;
        while (cnt > 0 && p[-1] == '\n') {
                *(--p) = '\0';
                --cnt;
        }

        /* Output to stderr if requested. */
        if (data->log_stat & LOG_PERROR) {
                struct iovec iov[2];

                iov[0].iov_base = stdp;
                iov[0].iov_len = cnt > stdp - tbuf ? cnt - (stdp - tbuf) : 0;
                iov[1].iov_base = "\n";
                iov[1].iov_len = 1;
                (void)writev(STDERR_FILENO, iov, 2);
        }

        /*
         * If the sendsyslog() fails, it means that syslogd
         * is not running or the kernel ran out of buffers.
         */
        sendsyslog(tbuf, cnt, data->log_stat & LOG_CONS);
done:
        errno = saved_errno;
}

void
openlog_r(const char *ident, int logstat, int logfac, struct syslog_data *data)
{
        if (ident != NULL)
                data->log_tag = ident;
        data->log_stat = logstat;
        if (logfac != 0 && (logfac &~ LOG_FACMASK) == 0)
                data->log_fac = logfac;
}
DEF_WEAK(openlog_r);

void
closelog_r(struct syslog_data *data)
{
        data->log_tag = NULL;
}
DEF_WEAK(closelog_r);