/* Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*
 * http_log.c: Dealing with the logs and errors
 *
 * Rob McCool
 *
 */

#include "apr.h"
#include "apr_general.h"        /* for signal stuff */
#include "apr_strings.h"
#include "apr_errno.h"
#include "apr_thread_proc.h"
#include "apr_lib.h"
#include "apr_signal.h"

#define APR_WANT_STDIO
#define APR_WANT_STRFUNC
#include "apr_want.h"

#if APR_HAVE_STDARG_H
#include <stdarg.h>
#endif
#if APR_HAVE_UNISTD_H
#include <unistd.h>
#endif

#define CORE_PRIVATE

#include "ap_config.h"
#include "httpd.h"
#include "http_config.h"
#include "http_core.h"
#include "http_log.h"
#include "http_main.h"
#include "util_time.h"
#include "ap_mpm.h"

typedef struct {
    char    *t_name;
    int      t_val;
} TRANS;

APR_HOOK_STRUCT(
    APR_HOOK_LINK(error_log)
)

int AP_DECLARE_DATA ap_default_loglevel = DEFAULT_LOGLEVEL;

#ifdef HAVE_SYSLOG

static const TRANS facilities[] = {
    {"auth",    LOG_AUTH},
#ifdef LOG_AUTHPRIV
    {"authpriv",LOG_AUTHPRIV},
#endif
#ifdef LOG_CRON
    {"cron",    LOG_CRON},
#endif
#ifdef LOG_DAEMON
    {"daemon",  LOG_DAEMON},
#endif
#ifdef LOG_FTP
    {"ftp", LOG_FTP},
#endif
#ifdef LOG_KERN
    {"kern",    LOG_KERN},
#endif
#ifdef LOG_LPR
    {"lpr", LOG_LPR},
#endif
#ifdef LOG_MAIL
    {"mail",    LOG_MAIL},
#endif
#ifdef LOG_NEWS
    {"news",    LOG_NEWS},
#endif
#ifdef LOG_SYSLOG
    {"syslog",  LOG_SYSLOG},
#endif
#ifdef LOG_USER
    {"user",    LOG_USER},
#endif
#ifdef LOG_UUCP
    {"uucp",    LOG_UUCP},
#endif
#ifdef LOG_LOCAL0
    {"local0",  LOG_LOCAL0},
#endif
#ifdef LOG_LOCAL1
    {"local1",  LOG_LOCAL1},
#endif
#ifdef LOG_LOCAL2
    {"local2",  LOG_LOCAL2},
#endif
#ifdef LOG_LOCAL3
    {"local3",  LOG_LOCAL3},
#endif
#ifdef LOG_LOCAL4
    {"local4",  LOG_LOCAL4},
#endif
#ifdef LOG_LOCAL5
    {"local5",  LOG_LOCAL5},
#endif
#ifdef LOG_LOCAL6
    {"local6",  LOG_LOCAL6},
#endif
#ifdef LOG_LOCAL7
    {"local7",  LOG_LOCAL7},
#endif
    {NULL,      -1},
};
#endif

static const TRANS priorities[] = {
    {"emerg",   APLOG_EMERG},
    {"alert",   APLOG_ALERT},
    {"crit",    APLOG_CRIT},
    {"error",   APLOG_ERR},
    {"warn",    APLOG_WARNING},
    {"notice",  APLOG_NOTICE},
    {"info",    APLOG_INFO},
    {"debug",   APLOG_DEBUG},
    {NULL,      -1},
};

static apr_pool_t *stderr_pool = NULL;

static apr_file_t *stderr_log = NULL;

/* track pipe handles to close in child process */
typedef struct read_handle_t {
    struct read_handle_t *next;
    apr_file_t *handle;
} read_handle_t;

static read_handle_t *read_handles;

/* clear_handle_list() is called when plog is cleared; at that
 * point we need to forget about our old list of pipe read
 * handles.  We let the plog cleanups close the actual pipes.
 */
static apr_status_t clear_handle_list(void *v)
{
    read_handles = NULL;
    return APR_SUCCESS;
}

/* remember to close this handle in the child process
 *
 * On Win32 this makes zero sense, because we don't
 * take the parent process's child procs.
 * If the win32 parent instead passed each and every
 * logger write handle from itself down to the child,
 * and the parent manages all aspects of keeping the 
 * reliable pipe log children alive, this would still
 * make no sense :)  Cripple it on Win32.
 */
static void close_handle_in_child(apr_pool_t *p, apr_file_t *f)
{
#ifndef WIN32
    read_handle_t *new_handle;

    new_handle = apr_pcalloc(p, sizeof(read_handle_t));
    new_handle->next = read_handles;
    new_handle->handle = f;
    read_handles = new_handle;
#endif
}

void ap_logs_child_init(apr_pool_t *p, server_rec *s)
{
    read_handle_t *cur = read_handles;

    while (cur) {
        apr_file_close(cur->handle);
        cur = cur->next;
    }
}

AP_DECLARE(void) ap_open_stderr_log(apr_pool_t *p)
{
    apr_file_open_stderr(&stderr_log, p);
}

AP_DECLARE(apr_status_t) ap_replace_stderr_log(apr_pool_t *p,
                                               const char *fname)
{
    apr_file_t *stderr_file;
    apr_status_t rc;
    char *filename = ap_server_root_relative(p, fname);
    if (!filename) {
        ap_log_error(APLOG_MARK, APLOG_STARTUP|APLOG_CRIT,
                     APR_EBADPATH, NULL, "Invalid -E error log file %s",
                     fname);
        return APR_EBADPATH;
    }
    if ((rc = apr_file_open(&stderr_file, filename,
                            APR_APPEND | APR_WRITE | APR_CREATE | APR_LARGEFILE,
                            APR_OS_DEFAULT, p)) != APR_SUCCESS) {
        ap_log_error(APLOG_MARK, APLOG_STARTUP, rc, NULL,
                     "%s: could not open error log file %s.",
                     ap_server_argv0, fname);
        return rc;
    }
    if (!stderr_pool) {
        /* This is safe provided we revert it when we are finished.
         * We don't manager the callers pool!
         */
        stderr_pool = p;
    }
    if ((rc = apr_file_open_stderr(&stderr_log, stderr_pool)) 
            == APR_SUCCESS) {
        apr_file_flush(stderr_log);
        if ((rc = apr_file_dup2(stderr_log, stderr_file, stderr_pool)) 
                == APR_SUCCESS) {
            apr_file_close(stderr_file);
            /*
             * You might ponder why stderr_pool should survive?
             * The trouble is, stderr_pool may have s_main->error_log,
             * so we aren't in a position to destory stderr_pool until
             * the next recycle.  There's also an apparent bug which 
             * is not; if some folk decided to call this function before 
             * the core open error logs hook, this pool won't survive.
             * Neither does the stderr logger, so this isn't a problem.
             */
        }
    }
    /* Revert, see above */
    if (stderr_pool == p)
        stderr_pool = NULL;

    if (rc != APR_SUCCESS) {
        ap_log_error(APLOG_MARK, APLOG_CRIT, rc, NULL,
                     "unable to replace stderr with error log file");
    }
    return rc;
}

static void log_child_errfn(apr_pool_t *pool, apr_status_t err,
                            const char *description)
{
    ap_log_error(APLOG_MARK, APLOG_ERR, err, NULL,
                 "%s", description);
}

/* Create a child process running PROGNAME with a pipe connected to
 * the childs stdin.  The write-end of the pipe will be placed in
 * *FPIN on successful return.  If dummy_stderr is non-zero, the
 * stderr for the child will be the same as the stdout of the parent.
 * Otherwise the child will inherit the stderr from the parent. */
static int log_child(apr_pool_t *p, const char *progname,
                     apr_file_t **fpin, int dummy_stderr)
{
    /* Child process code for 'ErrorLog "|..."';
     * may want a common framework for this, since I expect it will
     * be common for other foo-loggers to want this sort of thing...
     */
    apr_status_t rc;
    apr_procattr_t *procattr;
    apr_proc_t *procnew;
    apr_file_t *outfile, *errfile;

    if (((rc = apr_procattr_create(&procattr, p)) == APR_SUCCESS)
        && ((rc = apr_procattr_cmdtype_set(procattr,
                                           APR_SHELLCMD_ENV)) == APR_SUCCESS)
        && ((rc = apr_procattr_io_set(procattr,
                                      APR_FULL_BLOCK,
                                      APR_NO_PIPE,
                                      APR_NO_PIPE)) == APR_SUCCESS)
        && ((rc = apr_procattr_error_check_set(procattr, 1)) == APR_SUCCESS)
        && ((rc = apr_procattr_child_errfn_set(procattr, log_child_errfn)) 
                == APR_SUCCESS)) {
        char **args;
        const char *pname;

        apr_tokenize_to_argv(progname, &args, p);
        pname = apr_pstrdup(p, args[0]);
        procnew = (apr_proc_t *)apr_pcalloc(p, sizeof(*procnew));

        if ((rc = apr_file_open_stdout(&outfile, p)) == APR_SUCCESS) {
            rc = apr_procattr_child_out_set(procattr, outfile, NULL);
            if (dummy_stderr)
                rc = apr_procattr_child_err_set(procattr, outfile, NULL);
            else if ((rc = apr_file_open_stderr(&errfile, p)) == APR_SUCCESS)
                rc = apr_procattr_child_err_set(procattr, errfile, NULL);
        }

        rc = apr_proc_create(procnew, pname, (const char * const *)args,
                             NULL, procattr, p);

        if (rc == APR_SUCCESS) {
            apr_pool_note_subprocess(p, procnew, APR_KILL_AFTER_TIMEOUT);
            (*fpin) = procnew->in;
            /* read handle to pipe not kept open, so no need to call
             * close_handle_in_child()
             */
        }
    }

    return rc;
}

/* Open the error log for the given server_rec.  If IS_MAIN is
 * non-zero, s is the main server. */
static int open_error_log(server_rec *s, int is_main, apr_pool_t *p)
{
    const char *fname;
    int rc;

    if (*s->error_fname == '|') {
        apr_file_t *dummy = NULL;

        /* Spawn a new child logger.  If this is the main server_rec,
         * the new child must use a dummy stderr since the current
         * stderr might be a pipe to the old logger.  Otherwise, the
         * child inherits the parents stderr. */
        rc = log_child(p, s->error_fname + 1, &dummy, is_main);
        if (rc != APR_SUCCESS) {
            ap_log_error(APLOG_MARK, APLOG_STARTUP, rc, NULL,
                         "Couldn't start ErrorLog process");
            return DONE;
        }

        s->error_log = dummy;
    }

#ifdef HAVE_SYSLOG
    else if (!strncasecmp(s->error_fname, "syslog", 6)) {
        if ((fname = strchr(s->error_fname, ':'))) {
            const TRANS *fac;

            fname++;
            for (fac = facilities; fac->t_name; fac++) {
                if (!strcasecmp(fname, fac->t_name)) {
                    openlog(ap_server_argv0, LOG_NDELAY|LOG_CONS|LOG_PID,
                            fac->t_val);
                    s->error_log = NULL;
                    return OK;
                }
            }
        }
        else {
            openlog(ap_server_argv0, LOG_NDELAY|LOG_CONS|LOG_PID, LOG_LOCAL7);
        }

        s->error_log = NULL;
    }
#endif
    else {
        fname = ap_server_root_relative(p, s->error_fname);
        if (!fname) {
            ap_log_error(APLOG_MARK, APLOG_STARTUP, APR_EBADPATH, NULL,
                         "%s: Invalid error log path %s.",
                         ap_server_argv0, s->error_fname);
            return DONE;
        }
        if ((rc = apr_file_open(&s->error_log, fname,
                               APR_APPEND | APR_WRITE | APR_CREATE | APR_LARGEFILE,
                               APR_OS_DEFAULT, p)) != APR_SUCCESS) {
            ap_log_error(APLOG_MARK, APLOG_STARTUP, rc, NULL,
                         "%s: could not open error log file %s.",
                         ap_server_argv0, fname);
            return DONE;
        }
    }

    return OK;
}

int ap_open_logs(apr_pool_t *pconf, apr_pool_t *p /* plog */,
                 apr_pool_t *ptemp, server_rec *s_main)
{
    apr_pool_t *stderr_p;
    server_rec *virt, *q;
    int replace_stderr;


    /* Register to throw away the read_handles list when we
     * cleanup plog.  Upon fork() for the apache children,
     * this read_handles list is closed so only the parent
     * can relaunch a lost log child.  These read handles 
     * are always closed on exec.
     * We won't care what happens to our stderr log child 
     * between log phases, so we don't mind losing stderr's 
     * read_handle a little bit early.
     */
    apr_pool_cleanup_register(p, NULL, clear_handle_list,
                              apr_pool_cleanup_null);

    /* HERE we need a stdout log that outlives plog.
     * We *presume* the parent of plog is a process 
     * or global pool which spans server restarts.
     * Create our stderr_pool as a child of the plog's
     * parent pool.
     */
    apr_pool_create(&stderr_p, apr_pool_parent_get(p));
    apr_pool_tag(stderr_p, "stderr_pool");
    
    if (open_error_log(s_main, 1, stderr_p) != OK) {
        return DONE;
    }

    replace_stderr = 1;
    if (s_main->error_log) {
        apr_status_t rv;
        
        /* Replace existing stderr with new log. */
        apr_file_flush(s_main->error_log);
        rv = apr_file_dup2(stderr_log, s_main->error_log, stderr_p);
        if (rv != APR_SUCCESS) {
            ap_log_error(APLOG_MARK, APLOG_CRIT, rv, s_main,
                         "unable to replace stderr with error_log");
        }
        else {
            /* We are done with stderr_pool, close it, killing
             * the previous generation's stderr logger
             */
            if (stderr_pool)
                apr_pool_destroy(stderr_pool);
            stderr_pool = stderr_p;
            replace_stderr = 0;
            /*
             * Now that we have dup'ed s_main->error_log to stderr_log
             * close it and set s_main->error_log to stderr_log. This avoids
             * this fd being inherited by the next piped logger who would
             * keep open the writing end of the pipe that this one uses
             * as stdin. This in turn would prevent the piped logger from
             * exiting.
             */
             apr_file_close(s_main->error_log);
             s_main->error_log = stderr_log;
        }
    }
    /* note that stderr may still need to be replaced with something
     * because it points to the old error log, or back to the tty
     * of the submitter.
     * XXX: This is BS - /dev/null is non-portable
     */
    if (replace_stderr && freopen("/dev/null", "w", stderr) == NULL) {
        ap_log_error(APLOG_MARK, APLOG_CRIT, errno, s_main,
                     "unable to replace stderr with /dev/null");
    }

    for (virt = s_main->next; virt; virt = virt->next) {
        if (virt->error_fname) {
            for (q=s_main; q != virt; q = q->next) {
                if (q->error_fname != NULL
                    && strcmp(q->error_fname, virt->error_fname) == 0) {
                    break;
                }
            }

            if (q == virt) {
                if (open_error_log(virt, 0, p) != OK) {
                    return DONE;
                }
            }
            else {
                virt->error_log = q->error_log;
            }
        }
        else {
            virt->error_log = s_main->error_log;
        }
    }
    return OK;
}

AP_DECLARE(void) ap_error_log2stderr(server_rec *s) {
    apr_file_t *errfile = NULL;

    apr_file_open_stderr(&errfile, s->process->pool);
    if (s->error_log != NULL) {
        apr_file_dup2(s->error_log, errfile, s->process->pool);
    }
}

static void log_error_core(const char *file, int line, int level,
                           apr_status_t status, const server_rec *s,
                           const conn_rec *c,
                           const request_rec *r, apr_pool_t *pool,
                           const char *fmt, va_list args)
{
    char errstr[MAX_STRING_LEN];
#ifndef AP_UNSAFE_ERROR_LOG_UNESCAPED
    char scratch[MAX_STRING_LEN];
#endif
    apr_size_t len, errstrlen;
    apr_file_t *logf = NULL;
    const char *referer;
    int level_and_mask = level & APLOG_LEVELMASK;

    if (r && r->connection) {
        c = r->connection;
    }

    if (s == NULL) {
        /*
         * If we are doing stderr logging (startup), don't log messages that are
         * above the default server log level unless it is a startup/shutdown
         * notice
         */
        if ((level_and_mask != APLOG_NOTICE)
            && (level_and_mask > ap_default_loglevel)) {
            return;
        }

        logf = stderr_log;
    }
    else if (s->error_log) {
        /*
         * If we are doing normal logging, don't log messages that are
         * above the server log level unless it is a startup/shutdown notice
         */
        if ((level_and_mask != APLOG_NOTICE)
            && (level_and_mask > s->loglevel)) {
            return;
        }

        logf = s->error_log;
    }
#ifdef TPF
    else if (tpf_child) {
        /*
         * If we are doing normal logging, don't log messages that are
         * above the server log level unless it is a startup/shutdown notice
         */
        if ((level_and_mask != APLOG_NOTICE)
            && (level_and_mask > s->loglevel)) {
            return;
        }

        logf = stderr;
    }
#endif /* TPF */
    else {
        /*
         * If we are doing syslog logging, don't log messages that are
         * above the server log level (including a startup/shutdown notice)
         */
        if (level_and_mask > s->loglevel) {
            return;
        }
    }

    if (logf && ((level & APLOG_STARTUP) != APLOG_STARTUP)) {
        errstr[0] = '[';
        ap_recent_ctime(errstr + 1, apr_time_now());
        errstr[1 + APR_CTIME_LEN - 1] = ']';
        errstr[1 + APR_CTIME_LEN    ] = ' ';
        len = 1 + APR_CTIME_LEN + 1;
    } else {
        len = 0;
    }

    if ((level & APLOG_STARTUP) != APLOG_STARTUP) {
        len += apr_snprintf(errstr + len, MAX_STRING_LEN - len,
                            "[%s] ", priorities[level_and_mask].t_name);
    }

#ifndef TPF
    if (file && level_and_mask == APLOG_DEBUG) {
#if defined(_OSD_POSIX) || defined(WIN32) || defined(__MVS__)
        char tmp[256];
        char *e = strrchr(file, '/');
#ifdef WIN32
        if (!e) {
            e = strrchr(file, '\\');
        }
#endif

        /* In OSD/POSIX, the compiler returns for __FILE__
         * a string like: __FILE__="*POSIX(/usr/include/stdio.h)"
         * (it even returns an absolute path for sources in
         * the current directory). Here we try to strip this
         * down to the basename.
         */
        if (e != NULL && e[1] != '\0') {
            apr_snprintf(tmp, sizeof(tmp), "%s", &e[1]);
            e = &tmp[strlen(tmp)-1];
            if (*e == ')') {
                *e = '\0';
            }
            file = tmp;
        }
#else /* _OSD_POSIX || WIN32 */
        const char *p;
        /* On Unix, __FILE__ may be an absolute path in a
         * VPATH build. */
        if (file[0] == '/' && (p = ap_strrchr_c(file, '/')) != NULL) {
            file = p + 1;
        }
#endif /*_OSD_POSIX || WIN32 */
        len += apr_snprintf(errstr + len, MAX_STRING_LEN - len,
                            "%s(%d): ", file, line);
    }
#endif /* TPF */

    if (c) {
        /* XXX: TODO: add a method of selecting whether logged client
         * addresses are in dotted quad or resolved form... dotted
         * quad is the most secure, which is why I'm implementing it
         * first. -djg
         */
        len += apr_snprintf(errstr + len, MAX_STRING_LEN - len,
                            "[client %s] ", c->remote_ip);
    }
    if (status != 0) {
        if (status < APR_OS_START_EAIERR) {
            len += apr_snprintf(errstr + len, MAX_STRING_LEN - len,
                                "(%d)", status);
        }
        else if (status < APR_OS_START_SYSERR) {
            len += apr_snprintf(errstr + len, MAX_STRING_LEN - len,
                                "(EAI %d)", status - APR_OS_START_EAIERR);
        }
        else if (status < 100000 + APR_OS_START_SYSERR) {
            len += apr_snprintf(errstr + len, MAX_STRING_LEN - len,
                                "(OS %d)", status - APR_OS_START_SYSERR);
        }
        else {
            len += apr_snprintf(errstr + len, MAX_STRING_LEN - len,
                                "(os 0x%08x)", status - APR_OS_START_SYSERR);
        }
        apr_strerror(status, errstr + len, MAX_STRING_LEN - len);
        len += strlen(errstr + len);
        if (MAX_STRING_LEN - len > 2) {
            errstr[len++] = ':';
            errstr[len++] = ' ';
            errstr[len] = '\0';
        }
    }

    errstrlen = len;
#ifndef AP_UNSAFE_ERROR_LOG_UNESCAPED
    if (apr_vsnprintf(scratch, MAX_STRING_LEN - len, fmt, args)) {
        len += ap_escape_errorlog_item(errstr + len, scratch,
                                       MAX_STRING_LEN - len);
    }
#else
    len += apr_vsnprintf(errstr + len, MAX_STRING_LEN - len, fmt, args);
#endif

    if (   r && (referer = apr_table_get(r->headers_in, "Referer"))
#ifndef AP_UNSAFE_ERROR_LOG_UNESCAPED
        && ap_escape_errorlog_item(scratch, referer, MAX_STRING_LEN - len)
#endif
        ) {
        len += apr_snprintf(errstr + len, MAX_STRING_LEN - len,
                            ", referer: %s",
#ifndef AP_UNSAFE_ERROR_LOG_UNESCAPED
                            scratch
#else
                            referer
#endif
                            );
    }

    /* NULL if we are logging to syslog */
    if (logf) {
        /* Truncate for the terminator (as apr_snprintf does) */
        if (len > MAX_STRING_LEN - sizeof(APR_EOL_STR)) {
            len = MAX_STRING_LEN - sizeof(APR_EOL_STR);
        }
        strcpy(errstr + len, APR_EOL_STR);
        apr_file_puts(errstr, logf);
        apr_file_flush(logf);
    }
#ifdef HAVE_SYSLOG
    else {
        syslog(level_and_mask, "%s", errstr);
    }
#endif

    ap_run_error_log(file, line, level, status, s, r, pool, errstr + errstrlen);
}

AP_DECLARE(void) ap_log_error(const char *file, int line, int level,
                              apr_status_t status, const server_rec *s,
                              const char *fmt, ...)
{
    va_list args;

    va_start(args, fmt);
    log_error_core(file, line, level, status, s, NULL, NULL, NULL, fmt, args);
    va_end(args);
}

AP_DECLARE(void) ap_log_perror(const char *file, int line, int level,
                               apr_status_t status, apr_pool_t *p,
                               const char *fmt, ...)
{
    va_list args;

    va_start(args, fmt);
    log_error_core(file, line, level, status, NULL, NULL, NULL, p, fmt, args);
    va_end(args);
}

AP_DECLARE(void) ap_log_rerror(const char *file, int line, int level,
                               apr_status_t status, const request_rec *r,
                               const char *fmt, ...)
{
    va_list args;

    va_start(args, fmt);
    log_error_core(file, line, level, status, r->server, NULL, r, NULL, fmt,
                   args);

    /*
     * IF APLOG_TOCLIENT is set,
     * AND the error level is 'warning' or more severe,
     * AND there isn't already error text associated with this request,
     * THEN make the message text available to ErrorDocument and
     * other error processors.
     */
    va_end(args);
    va_start(args,fmt);
    if ((level & APLOG_TOCLIENT)
        && ((level & APLOG_LEVELMASK) <= APLOG_WARNING)
        && (apr_table_get(r->notes, "error-notes") == NULL)) {
        apr_table_setn(r->notes, "error-notes",
                       ap_escape_html(r->pool, apr_pvsprintf(r->pool, fmt,
                                                             args)));
    }
    va_end(args);
}

AP_DECLARE(void) ap_log_cerror(const char *file, int line, int level,
                               apr_status_t status, const conn_rec *c,
                               const char *fmt, ...)
{
    va_list args;

    va_start(args, fmt);
    log_error_core(file, line, level, status, c->base_server, c, NULL, NULL,
                   fmt, args);
    va_end(args);
}

AP_DECLARE(void) ap_log_pid(apr_pool_t *p, const char *filename)
{
    apr_file_t *pid_file = NULL;
    apr_finfo_t finfo;
    static pid_t saved_pid = -1;
    pid_t mypid;
    apr_status_t rv;
    const char *fname;

    if (!filename) {
        return;
    }

    fname = ap_server_root_relative(p, filename);
    if (!fname) {
        ap_log_error(APLOG_MARK, APLOG_STARTUP|APLOG_CRIT, APR_EBADPATH,
                     NULL, "Invalid PID file path %s, ignoring.", filename);
        return;
    }

    mypid = getpid();
    if (mypid != saved_pid
        && apr_stat(&finfo, fname, APR_FINFO_MTIME, p) == APR_SUCCESS) {
        /* AP_SIG_GRACEFUL and HUP call this on each restart.
         * Only warn on first time through for this pid.
         *
         * XXX: Could just write first time through too, although
         *      that may screw up scripts written to do something
         *      based on the last modification time of the pid file.
         */
        ap_log_perror(APLOG_MARK, APLOG_WARNING, 0, p,
                      "pid file %s overwritten -- Unclean "
                      "shutdown of previous Apache run?",
                      fname);
    }

    if ((rv = apr_file_open(&pid_file, fname,
                            APR_WRITE | APR_CREATE | APR_TRUNCATE,
                            APR_UREAD | APR_UWRITE | APR_GREAD | APR_WREAD, p))
        != APR_SUCCESS) {
        ap_log_error(APLOG_MARK, APLOG_ERR, rv, NULL,
                     "could not create %s", fname);
        ap_log_error(APLOG_MARK, APLOG_ERR, 0, NULL,
                     "%s: could not log pid to file %s",
                     ap_server_argv0, fname);
        exit(1);
    }
    apr_file_printf(pid_file, "%ld" APR_EOL_STR, (long)mypid);
    apr_file_close(pid_file);
    saved_pid = mypid;
}

AP_DECLARE(apr_status_t) ap_read_pid(apr_pool_t *p, const char *filename,
                                     pid_t *mypid)
{
    const apr_size_t BUFFER_SIZE = sizeof(long) * 3 + 2; /* see apr_ltoa */
    apr_file_t *pid_file = NULL;
    apr_status_t rv;
    const char *fname;
    char *buf, *endptr;
    apr_size_t bytes_read;

    if (!filename) {
        return APR_EGENERAL;
    }

    fname = ap_server_root_relative(p, filename);
    if (!fname) {
        ap_log_error(APLOG_MARK, APLOG_STARTUP|APLOG_CRIT, APR_EBADPATH,
                     NULL, "Invalid PID file path %s, ignoring.", filename);
        return APR_EGENERAL;
    }

    rv = apr_file_open(&pid_file, fname, APR_READ, APR_OS_DEFAULT, p);
    if (rv != APR_SUCCESS) {
        return rv;
    }

    buf = apr_palloc(p, BUFFER_SIZE);

    rv = apr_file_read_full(pid_file, buf, BUFFER_SIZE - 1, &bytes_read);
    if (rv != APR_SUCCESS && rv != APR_EOF) {
        return rv;
    }

    /* If we fill the buffer, we're probably reading a corrupt pid file.
     * To be nice, let's also ensure the first char is a digit. */
    if (bytes_read == 0 || bytes_read == BUFFER_SIZE - 1 || !apr_isdigit(*buf)) {
        return APR_EGENERAL;
    }

    buf[bytes_read] = '\0';
    *mypid = strtol(buf, &endptr, 10);

    apr_file_close(pid_file);
    return APR_SUCCESS;
}

AP_DECLARE(void) ap_log_assert(const char *szExp, const char *szFile,
                               int nLine)
{
    char time_str[APR_CTIME_LEN];

    apr_ctime(time_str, apr_time_now());
    ap_log_error(APLOG_MARK, APLOG_CRIT, 0, NULL,
                 "[%s] file %s, line %d, assertion \"%s\" failed",
                 time_str, szFile, nLine, szExp);
#if defined(WIN32)
    DebugBreak();
#else
    /* unix assert does an abort leading to a core dump */
    abort();
#endif
}

/* piped log support */

#ifdef AP_HAVE_RELIABLE_PIPED_LOGS
/* forward declaration */
static void piped_log_maintenance(int reason, void *data, apr_wait_t status);

/* Spawn the piped logger process pl->program. */
static apr_status_t piped_log_spawn(piped_log *pl)
{
    apr_procattr_t *procattr;
    apr_proc_t *procnew = NULL;
    apr_status_t status;

    if (((status = apr_procattr_create(&procattr, pl->p)) != APR_SUCCESS) ||
        ((status = apr_procattr_cmdtype_set(procattr,
                                            APR_SHELLCMD_ENV)) != APR_SUCCESS) ||
        ((status = apr_procattr_child_in_set(procattr,
                                             ap_piped_log_read_fd(pl),
                                             ap_piped_log_write_fd(pl)))
        != APR_SUCCESS) ||
        ((status = apr_procattr_child_errfn_set(procattr, log_child_errfn))
         != APR_SUCCESS) ||
        ((status = apr_procattr_error_check_set(procattr, 1)) != APR_SUCCESS)) {
        char buf[120];
        /* Something bad happened, give up and go away. */
        ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL,
                     "piped_log_spawn: unable to setup child process '%s': %s",
                     pl->program, apr_strerror(status, buf, sizeof(buf)));
    }
    else {
        char **args;
        const char *pname;
        apr_file_t *outfile, *errfile;

        if ((status = apr_file_open_stdout(&outfile, pl->p)) == APR_SUCCESS)
            status = apr_procattr_child_out_set(procattr, outfile, NULL);
        if ((status = apr_file_open_stderr(&errfile, pl->p)) == APR_SUCCESS)
            status = apr_procattr_child_err_set(procattr, errfile, NULL);

        apr_tokenize_to_argv(pl->program, &args, pl->p);
        pname = apr_pstrdup(pl->p, args[0]);
        procnew = apr_pcalloc(pl->p, sizeof(apr_proc_t));
        status = apr_proc_create(procnew, pname, (const char * const *) args,
                                 NULL, procattr, pl->p);

        if (status == APR_SUCCESS) {
            pl->pid = procnew;
            /* procnew->in was dup2'd from ap_piped_log_write_fd(pl);
             * since the original fd is still valid, close the copy to
             * avoid a leak. */
            apr_file_close(procnew->in);
            procnew->in = NULL;
            apr_proc_other_child_register(procnew, piped_log_maintenance, pl,
                                          ap_piped_log_write_fd(pl), pl->p);
            close_handle_in_child(pl->p, ap_piped_log_read_fd(pl));
        }
        else {
            char buf[120];
            /* Something bad happened, give up and go away. */
            ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL,
                         "unable to start piped log program '%s': %s",
                         pl->program, apr_strerror(status, buf, sizeof(buf)));
        }
    }

    return status;
}


static void piped_log_maintenance(int reason, void *data, apr_wait_t status)
{
    piped_log *pl = data;
    apr_status_t stats;
    int mpm_state;

    switch (reason) {
    case APR_OC_REASON_DEATH:
    case APR_OC_REASON_LOST:
        pl->pid = NULL; /* in case we don't get it going again, this
                         * tells other logic not to try to kill it
                         */
        apr_proc_other_child_unregister(pl);
        stats = ap_mpm_query(AP_MPMQ_MPM_STATE, &mpm_state);
        if (stats != APR_SUCCESS) {
            ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL,
                         "can't query MPM state; not restarting "
                         "piped log program '%s'",
                         pl->program);
        }
        else if (mpm_state != AP_MPMQ_STOPPING) {
            ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL,
                         "piped log program '%s' failed unexpectedly",
                         pl->program);
            if ((stats = piped_log_spawn(pl)) != APR_SUCCESS) {
                /* what can we do?  This could be the error log we're having
                 * problems opening up... */
                char buf[120];
                ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL,
                             "piped_log_maintenance: unable to respawn '%s': %s",
                             pl->program, apr_strerror(stats, buf, sizeof(buf)));
            }
        }
        break;

    case APR_OC_REASON_UNWRITABLE:
        /* We should not kill off the pipe here, since it may only be full.
         * If it really is locked, we should kill it off manually. */
    break;

    case APR_OC_REASON_RESTART:
        if (pl->pid != NULL) {
            apr_proc_kill(pl->pid, SIGTERM);
            pl->pid = NULL;
        }
        break;

    case APR_OC_REASON_UNREGISTER:
        break;
    }
}


static apr_status_t piped_log_cleanup_for_exec(void *data)
{
    piped_log *pl = data;

    apr_file_close(ap_piped_log_read_fd(pl));
    apr_file_close(ap_piped_log_write_fd(pl));
    return APR_SUCCESS;
}


static apr_status_t piped_log_cleanup(void *data)
{
    piped_log *pl = data;

    if (pl->pid != NULL) {
        apr_proc_kill(pl->pid, SIGTERM);
    }
    return piped_log_cleanup_for_exec(data);
}


AP_DECLARE(piped_log *) ap_open_piped_log(apr_pool_t *p, const char *program)
{
    piped_log *pl;

    pl = apr_palloc(p, sizeof (*pl));
    pl->p = p;
    pl->program = apr_pstrdup(p, program);
    pl->pid = NULL;
    if (apr_file_pipe_create(&ap_piped_log_read_fd(pl),
                             &ap_piped_log_write_fd(pl), p) != APR_SUCCESS) {
        return NULL;
    }
    apr_pool_cleanup_register(p, pl, piped_log_cleanup,
                              piped_log_cleanup_for_exec);
    if (piped_log_spawn(pl) != APR_SUCCESS) {
        apr_pool_cleanup_kill(p, pl, piped_log_cleanup);
        apr_file_close(ap_piped_log_read_fd(pl));
        apr_file_close(ap_piped_log_write_fd(pl));
        return NULL;
    }
    return pl;
}

#else /* !AP_HAVE_RELIABLE_PIPED_LOGS */

static apr_status_t piped_log_cleanup(void *data)
{
    piped_log *pl = data;

    apr_file_close(ap_piped_log_write_fd(pl));
    return APR_SUCCESS;
}

AP_DECLARE(piped_log *) ap_open_piped_log(apr_pool_t *p, const char *program)
{
    piped_log *pl;
    apr_file_t *dummy = NULL;
    int rc;

    rc = log_child(p, program, &dummy, 0);
    if (rc != APR_SUCCESS) {
        ap_log_error(APLOG_MARK, APLOG_STARTUP, rc, NULL,
                     "Couldn't start piped log process");
        return NULL;
    }

    pl = apr_palloc(p, sizeof (*pl));
    pl->p = p;
    ap_piped_log_read_fd(pl) = NULL;
    ap_piped_log_write_fd(pl) = dummy;
    apr_pool_cleanup_register(p, pl, piped_log_cleanup, piped_log_cleanup);

    return pl;
}

#endif

AP_DECLARE(void) ap_close_piped_log(piped_log *pl)
{
    apr_pool_cleanup_run(pl->p, pl, piped_log_cleanup);
}

AP_IMPLEMENT_HOOK_VOID(error_log,
                       (const char *file, int line, int level,
                        apr_status_t status, const server_rec *s,
                        const request_rec *r, apr_pool_t *pool,
                        const char *errstr), (file, line, level,
                        status, s, r, pool, errstr))

