/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2000-2002 The Apache Software Foundation.  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. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    nor may "Apache" appear in their name, without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED 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 APACHE SOFTWARE FOUNDATION OR
 * ITS 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 * Portions of this software are based upon public domain software
 * originally written at the National Center for Supercomputing Applications,
 * University of Illinois, Urbana-Champaign.
 */

/*
 * Modified by djm@va.pubnix.com:
 * If no TransferLog is given explicitly, decline to log.
 *
 * This is module implements the TransferLog directive (same as the
 * common log module), and additional directives, LogFormat and CustomLog.
 *
 *
 * Syntax:
 *
 *    TransferLog fn      Logs transfers to fn in standard log format, unless
 *                        a custom format is set with LogFormat
 *    LogFormat format    Set a log format from TransferLog files
 *    CustomLog fn format
 *                        Log to file fn with format given by the format
 *                        argument
 *
 *    CookieLog fn        For backwards compatability with old Cookie
 *                        logging module - now deprecated.
 *
 * There can be any number of TransferLog and CustomLog
 * commands. Each request will be logged to _ALL_ the
 * named files, in the appropriate format.
 *
 * If no TransferLog or CustomLog directive appears in a VirtualHost,
 * the request will be logged to the log file(s) defined outside
 * the virtual host section. If a TransferLog or CustomLog directive
 * appears in the VirtualHost section, the log files defined outside
 * the VirtualHost will _not_ be used. This makes this module compatable
 * with the CLF and config log modules, where the use of TransferLog
 * inside the VirtualHost section overrides its use outside.
 * 
 * Examples:
 *
 *    TransferLog    logs/access_log
 *    <VirtualHost>
 *    LogFormat      "... custom format ..."
 *    TransferLog    log/virtual_only
 *    CustomLog      log/virtual_useragents "%t %{user-agent}i"
 *    </VirtualHost>
 *
 * This will log using CLF to access_log any requests handled by the
 * main server, while any requests to the virtual host will be logged
 * with the "... custom format..." to virtual_only _AND_ using
 * the custom user-agent log to virtual_useragents.
 *
 * Note that the NCSA referer and user-agent logs are easily added with
 * CustomLog:
 *   CustomLog   logs/referer  "%{referer}i -> %U"
 *   CustomLog   logs/agent    "%{user-agent}i"
 *
 * RefererIgnore functionality can be obtained with conditional
 * logging (SetEnvIf and CustomLog ... env=!VAR).
 *
 * But using this method allows much easier modification of the
 * log format, e.g. to log hosts along with UA:
 *   CustomLog   logs/referer "%{referer}i %U %h"
 *
 * The argument to LogFormat and CustomLog is a string, which can include
 * literal characters copied into the log files, and '%' directives as
 * follows:
 *
 * %...B:  bytes sent, excluding HTTP headers.
 * %...b:  bytes sent, excluding HTTP headers in CLF format, i.e. a '-'
 *         when no bytes where sent (rather than a '0'.
 * %...{FOOBAR}C:  The contents of the HTTP cookie FOOBAR
 * %...{FOOBAR}e:  The contents of the environment variable FOOBAR
 * %...f:  filename
 * %...h:  remote host
 * %...a:  remote IP-address
 * %...A:  local IP-address
 * %...{Foobar}i:  The contents of Foobar: header line(s) in the request
 *                 sent to the client.
 * %...l:  remote logname (from identd, if supplied)
 * %...{Foobar}n:  The contents of note "Foobar" from another module.
 * %...{Foobar}o:  The contents of Foobar: header line(s) in the reply.
 * %...p:  the port the request was served to
 * %...P:  the process ID of the child that serviced the request.
 * %...r:  first line of request
 * %...s:  status.  For requests that got internally redirected, this
 *         is status of the *original* request --- %...>s for the last.
 * %...t:  time, in common log format time format
 * %...{format}t:  The time, in the form given by format, which should
 *                 be in strftime(3) format.
 * %...T:  the time taken to serve the request, in seconds.
 * %...D:  the time taken to serve the request, in micro seconds.
 * %...u:  remote user (from auth; may be bogus if return status (%s) is 401)
 * %...U:  the URL path requested.
 * %...v:  the configured name of the server (i.e. which virtual host?)
 * %...V:  the server name according to the UseCanonicalName setting
 * %...m:  the request method
 * %...H:  the request protocol
 * %...q:  the query string prepended by "?", or empty if no query string
 * %...X:  Status of the connection.
 *         'X' = connection aborted before the response completed.
 *         '+' = connection may be kept alive after the response is sent.
 *         '-' = connection will be closed after the response is sent.
           (This directive was %...c in late versions of Apache 1.3, but
            this conflicted with the historical ssl %...{var}c syntax.)
*
 * The '...' can be nothing at all (e.g. "%h %u %r %s %b"), or it can
 * indicate conditions for inclusion of the item (which will cause it
 * to be replaced with '-' if the condition is not met).  Note that
 * there is no escaping performed on the strings from %r, %...i and
 * %...o; some with long memories may remember that I thought this was
 * a bad idea, once upon a time, and I'm still not comfortable with
 * it, but it is difficult to see how to "do the right thing" with all
 * of '%..i', unless we URL-escape everything and break with CLF.
 *
 * The forms of condition are a list of HTTP status codes, which may
 * or may not be preceded by '!'.  Thus, '%400,501{User-agent}i' logs
 * User-agent: on 400 errors and 501 errors (Bad Request, Not
 * Implemented) only; '%!200,304,302{Referer}i' logs Referer: on all
 * requests which did *not* return some sort of normal status.
 *
 * The default LogFormat reproduces CLF; see below.
 *
 * The way this is supposed to work with virtual hosts is as follows:
 * a virtual host can have its own LogFormat, or its own TransferLog.
 * If it doesn't have its own LogFormat, it inherits from the main
 * server.  If it doesn't have its own TransferLog, it writes to the
 * same descriptor (meaning the same process for "| ...").
 *
 * --- rst */

#include "apr_strings.h"
#include "apr_lib.h"
#include "apr_hash.h"
#include "apr_optional.h"

#define APR_WANT_STRFUNC
#include "apr_want.h"

#include "ap_config.h"
#include "mod_log_config.h"
#include "httpd.h"
#include "http_config.h"
#include "http_core.h"          /* For REMOTE_NAME */
#include "http_log.h"
#include "http_protocol.h"
#include "util_time.h"

#if APR_HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef HAVE_LIMITS_H
#include <limits.h>
#endif

#define DEFAULT_LOG_FORMAT "%h %l %u %t \"%r\" %>s %b"

module AP_MODULE_DECLARE_DATA log_config_module;

static int xfer_flags = (APR_WRITE | APR_APPEND | APR_CREATE);
static apr_fileperms_t xfer_perms = APR_OS_DEFAULT;
static apr_hash_t *log_hash;

/* POSIX.1 defines PIPE_BUF as the maximum number of bytes that is
 * guaranteed to be atomic when writing a pipe.  And PIPE_BUF >= 512
 * is guaranteed.  So we'll just guess 512 in the event the system
 * doesn't have this.  Now, for file writes there is actually no limit,
 * the entire write is atomic.  Whether all systems implement this
 * correctly is another question entirely ... so we'll just use PIPE_BUF
 * because it's probably a good guess as to what is implemented correctly
 * everywhere.
 */
#ifdef PIPE_BUF
#define LOG_BUFSIZE     PIPE_BUF
#else
#define LOG_BUFSIZE     (512)
#endif

/*
 * multi_log_state is our per-(virtual)-server configuration. We store
 * an array of the logs we are going to use, each of type config_log_state.
 * If a default log format is given by LogFormat, store in default_format
 * (backward compat. with mod_log_config).  We also store for each virtual
 * server a pointer to the logs specified for the main server, so that if this
 * vhost has no logs defined, we can use the main server's logs instead.
 *
 * So, for the main server, config_logs contains a list of the log files
 * and server_config_logs is empty. For a vhost, server_config_logs
 * points to the same array as config_logs in the main server, and
 * config_logs points to the array of logs defined inside this vhost,
 * which might be empty.
 */

typedef struct {
    const char *default_format_string;
    apr_array_header_t *default_format;
    apr_array_header_t *config_logs;
    apr_array_header_t *server_config_logs;
    apr_table_t *formats;
} multi_log_state;

/*
 * config_log_state holds the status of a single log file. fname might
 * be NULL, which means this module does no logging for this
 * request. format might be NULL, in which case the default_format
 * from the multi_log_state should be used, or if that is NULL as
 * well, use the CLF. log_fd is NULL before the log file is opened and
 * set to a valid fd after it is opened.
 */

typedef struct {
    const char *fname;
    const char *format_string;
    apr_array_header_t *format;
    apr_file_t *log_fd;
    char *condition_var;
#ifdef BUFFERED_LOGS
    apr_size_t outcnt;
    char outbuf[LOG_BUFSIZE];
#endif
} config_log_state;

/*
 * Format items...
 * Note that many of these could have ap_sprintfs replaced with static buffers.
 */

typedef struct {
    ap_log_handler_fn_t *func;
    char *arg;
    int condition_sense;
    int want_orig;
    apr_array_header_t *conditions;
} log_format_item;

static char *format_integer(apr_pool_t *p, int i)
{
    return apr_itoa(p, i);
}

static char *pfmt(apr_pool_t *p, int i)
{
    if (i <= 0) {
        return "-";
    }
    else {
        return format_integer(p, i);
    }
}

static const char *constant_item(request_rec *dummy, char *stuff)
{
    return stuff;
}

static const char *log_remote_host(request_rec *r, char *a)
{
    return ap_get_remote_host(r->connection, r->per_dir_config,
                                    REMOTE_NAME, NULL);
}

static const char *log_remote_address(request_rec *r, char *a)
{
    return r->connection->remote_ip;
}

static const char *log_local_address(request_rec *r, char *a)
{
    return r->connection->local_ip;
}

static const char *log_remote_logname(request_rec *r, char *a)
{
    return ap_get_remote_logname(r);
}

static const char *log_remote_user(request_rec *r, char *a)
{
    char *rvalue = r->user;

    if (rvalue == NULL) {
        rvalue = "-";
    }
    else if (strlen(rvalue) == 0) {
        rvalue = "\"\"";
    }
    return rvalue;
}

static const char *log_request_line(request_rec *r, char *a)
{
	    /* NOTE: If the original request contained a password, we
	     * re-write the request line here to contain XXXXXX instead:
	     * (note the truncation before the protocol string for HTTP/0.9 requests)
	     * (note also that r->the_request contains the unmodified request)
	     */
    return (r->parsed_uri.password) ? apr_pstrcat(r->pool, r->method, " ",
					 apr_uri_unparse(r->pool, &r->parsed_uri, 0),
					 r->assbackwards ? NULL : " ", r->protocol, NULL)
					: r->the_request;
}

static const char *log_request_file(request_rec *r, char *a)
{
    return r->filename;
}
static const char *log_request_uri(request_rec *r, char *a)
{
    return r->uri;
}
static const char *log_request_method(request_rec *r, char *a)
{
    return r->method;
}
static const char *log_request_protocol(request_rec *r, char *a)
{
    return r->protocol;
}
static const char *log_request_query(request_rec *r, char *a)
{
    return (r->args != NULL) ? apr_pstrcat(r->pool, "?", r->args, NULL)
                             : "";
}
static const char *log_status(request_rec *r, char *a)
{
    return pfmt(r->pool, r->status);
}

static const char *clf_log_bytes_sent(request_rec *r, char *a)
{
    if (!r->sent_bodyct) {
        return "-";
    }
    else {
	return apr_off_t_toa(r->pool, r->bytes_sent);
    }
}

static const char *log_bytes_sent(request_rec *r, char *a)
{
    if (!r->sent_bodyct) {
        return "0";
    }
    else {
	return apr_psprintf(r->pool, "%" APR_OFF_T_FMT, r->bytes_sent);
    }
}


static const char *log_header_in(request_rec *r, char *a)
{
    return apr_table_get(r->headers_in, a);
}

static const char *log_header_out(request_rec *r, char *a)
{
    const char *cp = apr_table_get(r->headers_out, a);
    if (!strcasecmp(a, "Content-type") && r->content_type) {
        cp = ap_field_noparam(r->pool, r->content_type);
    }
    if (cp) {
        return cp;
    }
    return apr_table_get(r->err_headers_out, a);
}

static const char *log_note(request_rec *r, char *a)
{
    return apr_table_get(r->notes, a);
}
static const char *log_env_var(request_rec *r, char *a)
{
    return apr_table_get(r->subprocess_env, a);
}

static const char *log_cookie(request_rec *r, char *a)
{
    const char *cookies;
    const char *start_cookie;

    if ((cookies = apr_table_get(r->headers_in, "Cookie"))) {
        if ((start_cookie = ap_strstr_c(cookies,a))) {
            char *cookie, *end_cookie;
            start_cookie += strlen(a) + 1; /* cookie_name + '=' */
            cookie = apr_pstrdup(r->pool, start_cookie);
            /* kill everything in cookie after ';' */
            end_cookie = strchr(cookie, ';'); 
            if (end_cookie) {
                *end_cookie = '\0';
            }
            return cookie;
        }
    }
    return NULL;
}

static const char *log_request_time_custom(request_rec *r, char *a,
                                           apr_time_exp_t *xt)
{
    apr_size_t retcode;
    char tstr[MAX_STRING_LEN];
    apr_strftime(tstr, &retcode, sizeof(tstr), a, xt);
    return apr_pstrdup(r->pool, tstr);
}

static const char *log_request_time(request_rec *r, char *a)
{
    apr_time_exp_t xt;

    /*
	hi.  i think getting the time again at the end of the request
	just for logging is dumb.  i know it's "required" for CLF.
	folks writing log parsing tools don't realise that out of order
	times have always been possible (consider what happens if one
	process calculates the time to log, but then there's a context
	switch before it writes and before that process is run again the
	log rotation occurs) and they should just fix their tools rather
	than force the server to pay extra cpu cycles.	if you've got
	a problem with this, you can set the define.  -djg
    */
#ifdef I_INSIST_ON_EXTRA_CYCLES_FOR_CLF_COMPLIANCE
    ap_explode_recent_localtime(&xt, apr_time_now());
#else
    ap_explode_recent_localtime(&xt, r->request_time);
#endif
    if (a && *a) {              /* Custom format */
        /* The custom time formatting uses a very large temp buffer
         * on the stack.  To avoid using so much stack space in the
         * common case where we're not using a custom format, the code
         * for the custom format in a separate function.  (That's why
         * log_request_time_custom is not inlined right here.)
         */
        return log_request_time_custom(r, a, &xt);
    }
    else {                      /* CLF format */
	char sign;
	int timz;

	timz = xt.tm_gmtoff;
	if (timz < 0) {
	    timz = -timz;
	    sign = '-';
	}
	else {
	    sign = '+';
	}

        return apr_psprintf(r->pool, "[%02d/%s/%d:%02d:%02d:%02d %c%.2d%.2d]",
                xt.tm_mday, apr_month_snames[xt.tm_mon], xt.tm_year+1900,
                xt.tm_hour, xt.tm_min, xt.tm_sec,
                sign, timz / (60*60), timz % (60*60));
    }
}

static const char *log_request_duration(request_rec *r, char *a)
{
    return apr_psprintf(r->pool, "%qd", (apr_time_now() - r->request_time) 
                                             / APR_USEC_PER_SEC);
}

static const char *log_request_duration_microseconds(request_rec *r, char *a)
{
    return apr_psprintf(r->pool, "%qd", (apr_time_now() - r->request_time));
}

/* These next two routines use the canonical name:port so that log
 * parsers don't need to duplicate all the vhost parsing crud.
 */
static const char *log_virtual_host(request_rec *r, char *a)
{
    return r->server->server_hostname;
}

static const char *log_server_port(request_rec *r, char *a)
{
    return apr_psprintf(r->pool, "%u",
	r->server->port ? r->server->port : ap_default_port(r));
}

/* This respects the setting of UseCanonicalName so that
 * the dynamic mass virtual hosting trick works better.
 */
static const char *log_server_name(request_rec *r, char *a)
{
    return ap_get_server_name(r);
}

static const char *log_child_pid(request_rec *r, char *a)
{
    return apr_psprintf(r->pool, "%ld", (long) getpid());
}

static const char *log_connection_status(request_rec *r, char *a)
{
    if (r->connection->aborted)
        return "X";

    if (r->connection->keepalive && 
        (!r->server->keep_alive_max ||
         (r->server->keep_alive_max - r->connection->keepalives) > 0)) {
        return "+";
    }
    return "-";
}

/*****************************************************************
 *
 * Parsing the log format string
 */

static char *parse_log_misc_string(apr_pool_t *p, log_format_item *it,
                                   const char **sa)
{
    const char *s;
    char *d;

    it->func = constant_item;
    it->conditions = NULL;

    s = *sa;
    while (*s && *s != '%') {
	s++;
    }
    /*
     * This might allocate a few chars extra if there's a backslash
     * escape in the format string.
     */
    it->arg = apr_palloc(p, s - *sa + 1);

    d = it->arg;
    s = *sa;
    while (*s && *s != '%') {
	if (*s != '\\') {
	    *d++ = *s++;
	}
	else {
	    s++;
	    switch (*s) {
	    case '\\':
		*d++ = '\\';
		s++;
		break;
	    case 'r':
		*d++ = '\r';
		s++;
		break;
	    case 'n':
		*d++ = '\n';
		s++;
		break;
	    case 't':	
		*d++ = '\t';
		s++;
		break;
	    default:
		/* copy verbatim */
		*d++ = '\\';
		/*
		 * Allow the loop to deal with this *s in the normal
		 * fashion so that it handles end of string etc.
		 * properly.
		 */
		break;
	    }
	}
    }
    *d = '\0';

    *sa = s;
    return NULL;
}

static char *parse_log_item(apr_pool_t *p, log_format_item *it, const char **sa)
{
    const char *s = *sa;
    ap_log_handler *handler;

    if (*s != '%') {
        return parse_log_misc_string(p, it, sa);
    }

    ++s;
    it->condition_sense = 0;
    it->conditions = NULL;
    it->want_orig = -1;
    it->arg = "";               /* For safety's sake... */

    while (*s) {
        int i;

        switch (*s) {
        case '!':
            ++s;
            it->condition_sense = !it->condition_sense;
            break;

        case '<':
            ++s;
            it->want_orig = 1;
            break;

        case '>':
            ++s;
            it->want_orig = 0;
            break;

        case ',':
            ++s;
            break;

        case '{':
            ++s;
            it->arg = ap_getword(p, &s, '}');
            break;

        case '0':
        case '1':
        case '2':
        case '3':
        case '4':
        case '5':
        case '6':
        case '7':
        case '8':
        case '9':
            i = *s - '0';
            while (apr_isdigit(*++s)) {
                i = i * 10 + (*s) - '0';
            }
            if (!it->conditions) {
                it->conditions = apr_array_make(p, 4, sizeof(int));
            }
            *(int *) apr_array_push(it->conditions) = i;
            break;

        default:
            handler = (ap_log_handler *)apr_hash_get(log_hash, s++, 1);
            if (!handler) {
                char dummy[2];

                dummy[0] = s[-1];
                dummy[1] = '\0';
                return apr_pstrcat(p, "Unrecognized LogFormat directive %",
                               dummy, NULL);
            }
            it->func = handler->func;
            if (it->want_orig == -1) {
                it->want_orig = handler->want_orig_default;
            }
            *sa = s;
            return NULL;
        }
    }

    return "Ran off end of LogFormat parsing args to some directive";
}

static apr_array_header_t *parse_log_string(apr_pool_t *p, const char *s, const char **err)
{
    apr_array_header_t *a = apr_array_make(p, 30, sizeof(log_format_item));
    char *res;

    while (*s) {
        if ((res = parse_log_item(p, (log_format_item *) apr_array_push(a), &s))) {
            *err = res;
            return NULL;
        }
    }

    s = APR_EOL_STR;
    parse_log_item(p, (log_format_item *) apr_array_push(a), &s);
    return a;
}

/*****************************************************************
 *
 * Actually logging.
 */

static const char *process_item(request_rec *r, request_rec *orig,
                          log_format_item *item)
{
    const char *cp;

    /* First, see if we need to process this thing at all... */

    if (item->conditions && item->conditions->nelts != 0) {
        int i;
        int *conds = (int *) item->conditions->elts;
        int in_list = 0;

        for (i = 0; i < item->conditions->nelts; ++i) {
            if (r->status == conds[i]) {
                in_list = 1;
                break;
            }
        }

        if ((item->condition_sense && in_list)
            || (!item->condition_sense && !in_list)) {
            return "-";
        }
    }

    /* We do.  Do it... */

    cp = (*item->func) (item->want_orig ? orig : r, item->arg);
    return cp ? cp : "-";
}

#ifdef BUFFERED_LOGS
static void flush_log(config_log_state *cls)
{
    if (cls->outcnt && cls->log_fd != NULL) {
        apr_file_write(cls->log_fd, cls->outbuf, &cls->outcnt);
        cls->outcnt = 0;
    }
}
#endif

static int config_log_transaction(request_rec *r, config_log_state *cls,
                                  apr_array_header_t *default_format)
{
    log_format_item *items;
    char *str, *s;
    const char **strs;
    int *strl;
    request_rec *orig;
    int i;
    apr_size_t len = 0;
    apr_array_header_t *format;
    char *envar;

    if (cls->fname == NULL) {
        return DECLINED;
    }

    /*
     * See if we've got any conditional envariable-controlled logging decisions
     * to make.
     */
    if (cls->condition_var != NULL) {
	envar = cls->condition_var;
	if (*envar != '!') {
	    if (apr_table_get(r->subprocess_env, envar) == NULL) {
		return DECLINED;
	    }
	}
	else {
	    if (apr_table_get(r->subprocess_env, &envar[1]) != NULL) {
		return DECLINED;
	    }
	}
    }

    format = cls->format ? cls->format : default_format;

    strs = apr_palloc(r->pool, sizeof(char *) * (format->nelts));
    strl = apr_palloc(r->pool, sizeof(int) * (format->nelts));
    items = (log_format_item *) format->elts;

    orig = r;
    while (orig->prev) {
        orig = orig->prev;
    }
    while (r->next) {
        r = r->next;
    }

    for (i = 0; i < format->nelts; ++i) {
        strs[i] = process_item(r, orig, &items[i]);
    }

    for (i = 0; i < format->nelts; ++i) {
        len += strl[i] = strlen(strs[i]);
    }

#ifdef BUFFERED_LOGS
    if (len + cls->outcnt > LOG_BUFSIZE) {
        flush_log(cls);
    }
    if (len >= LOG_BUFSIZE) {
        apr_size_t w;

        str = apr_palloc(r->pool, len + 1);
        for (i = 0, s = str; i < format->nelts; ++i) {
            memcpy(s, strs[i], strl[i]);
            s += strl[i];
        }
        w = len;
        apr_file_write(cls->log_fd, str, &w);
    }
    else {
        for (i = 0, s = &cls->outbuf[cls->outcnt]; i < format->nelts; ++i) {
            memcpy(s, strs[i], strl[i]);
            s += strl[i];
        }
        cls->outcnt += len;
    }
#else
    str = apr_palloc(r->pool, len + 1);

    for (i = 0, s = str; i < format->nelts; ++i) {
        memcpy(s, strs[i], strl[i]);
        s += strl[i];
    }

    apr_file_write(cls->log_fd, str, &len);
#endif

    return OK;
}

static int multi_log_transaction(request_rec *r)
{
    multi_log_state *mls = ap_get_module_config(r->server->module_config,
						&log_config_module);
    config_log_state *clsarray;
    int i;

    /*
     * Log this transaction..
     */
    if (mls->config_logs->nelts) {
        clsarray = (config_log_state *) mls->config_logs->elts;
        for (i = 0; i < mls->config_logs->nelts; ++i) {
            config_log_state *cls = &clsarray[i];

            config_log_transaction(r, cls, mls->default_format);
        }
    }
    else if (mls->server_config_logs) {
        clsarray = (config_log_state *) mls->server_config_logs->elts;
        for (i = 0; i < mls->server_config_logs->nelts; ++i) {
            config_log_state *cls = &clsarray[i];

            config_log_transaction(r, cls, mls->default_format);
        }
    }

    return OK;
}

/*****************************************************************
 *
 * Module glue...
 */

static void *make_config_log_state(apr_pool_t *p, server_rec *s)
{
    multi_log_state *mls;

    mls = (multi_log_state *) apr_palloc(p, sizeof(multi_log_state));
    mls->config_logs = apr_array_make(p, 1, sizeof(config_log_state));
    mls->default_format_string = NULL;
    mls->default_format = NULL;
    mls->server_config_logs = NULL;
    mls->formats = apr_table_make(p, 4);
    apr_table_setn(mls->formats, "CLF", DEFAULT_LOG_FORMAT);

    return mls;
}

/*
 * Use the merger to simply add a pointer from the vhost log state
 * to the log of logs specified for the non-vhost configuration.  Make sure
 * vhosts inherit any globally-defined format names.
 */

static void *merge_config_log_state(apr_pool_t *p, void *basev, void *addv)
{
    multi_log_state *base = (multi_log_state *) basev;
    multi_log_state *add = (multi_log_state *) addv;

    add->server_config_logs = base->config_logs;
    if (!add->default_format) {
        add->default_format_string = base->default_format_string;
        add->default_format = base->default_format;
    }
    add->formats = apr_table_overlay(p, base->formats, add->formats);

    return add;
}

/*
 * Set the default logfile format, or define a nickname for a format string.
 */
static const char *log_format(cmd_parms *cmd, void *dummy, const char *fmt,
                              const char *name)
{
    const char *err_string = NULL;
    multi_log_state *mls = ap_get_module_config(cmd->server->module_config,
						&log_config_module);

    /*
     * If we were given two arguments, the second is a name to be given to the
     * format.  This syntax just defines the nickname - it doesn't actually
     * make the format the default.
     */
    if (name != NULL) {
        parse_log_string(cmd->pool, fmt, &err_string);
        if (err_string == NULL) {
            apr_table_setn(mls->formats, name, fmt);
        }
    }
    else {
        mls->default_format_string = fmt;
        mls->default_format = parse_log_string(cmd->pool, fmt, &err_string);
    }
    return err_string;
}


static const char *add_custom_log(cmd_parms *cmd, void *dummy, const char *fn,
                                  const char *fmt, const char *envclause)
{
    const char *err_string = NULL;
    multi_log_state *mls = ap_get_module_config(cmd->server->module_config,
						&log_config_module);
    config_log_state *cls;

    cls = (config_log_state *) apr_array_push(mls->config_logs);
    cls->condition_var = NULL;
    if (envclause != NULL) {
	if (strncasecmp(envclause, "env=", 4) != 0) {
	    return "error in condition clause";
	}
	if ((envclause[4] == '\0')
	    || ((envclause[4] == '!') && (envclause[5] == '\0'))) {
	    return "missing environment variable name";
	}
	cls->condition_var = apr_pstrdup(cmd->pool, &envclause[4]);
    }

    cls->fname = fn;
    cls->format_string = fmt;
    if (fmt == NULL) {
        cls->format = NULL;
    }
    else {
        cls->format = parse_log_string(cmd->pool, fmt, &err_string);
    }
    cls->log_fd = NULL;

    return err_string;
}

static const char *set_transfer_log(cmd_parms *cmd, void *dummy,
				    const char *fn)
{
    return add_custom_log(cmd, dummy, fn, NULL, NULL);
}

static const char *set_cookie_log(cmd_parms *cmd, void *dummy, const char *fn)
{
    return add_custom_log(cmd, dummy, fn, "%{Cookie}n \"%r\" %t", NULL);
}

static const command_rec config_log_cmds[] =
{
AP_INIT_TAKE23("CustomLog", add_custom_log, NULL, RSRC_CONF,
     "a file name, a custom log format string or format name, "
     "and an optional \"env=\" clause (see docs)"),
AP_INIT_TAKE1("TransferLog", set_transfer_log, NULL, RSRC_CONF,
     "the filename of the access log"),
AP_INIT_TAKE12("LogFormat", log_format, NULL, RSRC_CONF,
     "a log format string (see docs) and an optional format name"),
AP_INIT_TAKE1("CookieLog", set_cookie_log, NULL, RSRC_CONF,
     "the filename of the cookie log"),
    {NULL}
};

static config_log_state *open_config_log(server_rec *s, apr_pool_t *p,
                                         config_log_state *cls,
                                         apr_array_header_t *default_format)
{
    apr_status_t status;
    void *data;
    const char *userdata_key = "open_config_log";

    /* Skip opening the log the first time through. It's really
     * good to avoid starting the piped log process during preflight.
     */
    apr_pool_userdata_get(&data, userdata_key, s->process->pool);
    if (!data) {
        apr_pool_userdata_set((const void *)1, userdata_key,
                              NULL, s->process->pool);
        /* If logging for the first time after a restart, keep going. */
        if (!ap_my_generation) {
            return cls;
        }
    }

    if (cls->log_fd != NULL) {
        return cls;             /* virtual config shared w/main server */
    }

    if (cls->fname == NULL) {
        return cls;             /* Leave it NULL to decline.  */
    }

    if (*cls->fname == '|') {
        piped_log *pl;

        pl = ap_open_piped_log(p, cls->fname + 1);
        if (pl == NULL) {
            exit(1);
        }
        cls->log_fd = ap_piped_log_write_fd(pl);
    }
    else {
        const char *fname = ap_server_root_relative(p, cls->fname);
        if (!fname) {
            ap_log_error(APLOG_MARK, APLOG_ERR, APR_EBADPATH, s,
                         "invalid transfer log path %s.", cls->fname);
            exit(1);
        }
        if ((status = apr_file_open(&cls->log_fd, fname, xfer_flags,
                                    xfer_perms, p)) != APR_SUCCESS) {
            ap_log_error(APLOG_MARK, APLOG_ERR, status, s,
                         "could not open transfer log file %s.", fname);
            exit(1);
        }
        apr_file_set_inherit(cls->log_fd);
    }
#ifdef BUFFERED_LOGS
    cls->outcnt = 0;
#endif

    return cls;
}

static config_log_state *open_multi_logs(server_rec *s, apr_pool_t *p)
{
    int i;
    multi_log_state *mls = ap_get_module_config(s->module_config,
                                             &log_config_module);
    config_log_state *clsarray;
    const char *dummy;
    const char *format;

    if (mls->default_format_string) {
	format = apr_table_get(mls->formats, mls->default_format_string);
	if (format) {
	    mls->default_format = parse_log_string(p, format, &dummy);
	}
    }    

    if (!mls->default_format) {
        mls->default_format = parse_log_string(p, DEFAULT_LOG_FORMAT, &dummy);
    }

    if (mls->config_logs->nelts) {
        clsarray = (config_log_state *) mls->config_logs->elts;
        for (i = 0; i < mls->config_logs->nelts; ++i) {
            config_log_state *cls = &clsarray[i];

	    if (cls->format_string) {
		format = apr_table_get(mls->formats, cls->format_string);
		if (format) {
		    cls->format = parse_log_string(p, format, &dummy);
		}
	    }

            cls = open_config_log(s, p, cls, mls->default_format);
        }
    }
    else if (mls->server_config_logs) {
        clsarray = (config_log_state *) mls->server_config_logs->elts;
        for (i = 0; i < mls->server_config_logs->nelts; ++i) {
            config_log_state *cls = &clsarray[i];

	    if (cls->format_string) {
		format = apr_table_get(mls->formats, cls->format_string);
		if (format) {
		    cls->format = parse_log_string(p, format, &dummy);
		}
	    }

            cls = open_config_log(s, p, cls, mls->default_format);
        }
    }

    return NULL;
}

#ifdef BUFFERED_LOGS
static apr_status_t flush_all_logs(void *data)
{
    server_rec *s = data;
    multi_log_state *mls;
    apr_array_header_t *log_list;
    config_log_state *clsarray;
    int i;

    for (; s; s = s->next) {
        mls = ap_get_module_config(s->module_config, &log_config_module);
        log_list = NULL;
        if (mls->config_logs->nelts) {
            log_list = mls->config_logs;
        }
        else if (mls->server_config_logs) {
            log_list = mls->server_config_logs;
        }
        if (log_list) {
            clsarray = (config_log_state *) log_list->elts;
            for (i = 0; i < log_list->nelts; ++i) {
                flush_log(&clsarray[i]);
            }
        }
    }
    return APR_SUCCESS;
}
#endif

static int init_config_log(apr_pool_t *pc, apr_pool_t *p, apr_pool_t *pt, server_rec *s)
{
    /* First, do "physical" server, which gets default log fd and format
     * for the virtual servers, if they don't override...
     */

    open_multi_logs(s, p);

    /* Then, virtual servers */

    for (s = s->next; s; s = s->next) {
        open_multi_logs(s, p);
    }
    return OK;
}

static void init_child(apr_pool_t *p, server_rec *s)
{
#ifdef BUFFERED_LOGS
	/* Now register the last buffer flush with the cleanup engine */
	apr_pool_cleanup_register(p, s, flush_all_logs, flush_all_logs);
#endif
}

static void ap_register_log_handler(apr_pool_t *p, char *tag, 
                                    ap_log_handler_fn_t *handler, int def)
{
    ap_log_handler *log_struct = apr_palloc(p, sizeof(*log_struct));
    log_struct->func = handler;
    log_struct->want_orig_default = def;

    apr_hash_set(log_hash, tag, 1, (const void *)log_struct);
}

static int log_pre_config(apr_pool_t *p, apr_pool_t *plog, apr_pool_t *ptemp)
{
    static APR_OPTIONAL_FN_TYPE(ap_register_log_handler) *log_pfn_register;

    log_pfn_register = APR_RETRIEVE_OPTIONAL_FN(ap_register_log_handler);

    if (log_pfn_register) {
        log_pfn_register(p, "h", log_remote_host, 0);
        log_pfn_register(p, "a", log_remote_address, 0 );
        log_pfn_register(p, "A", log_local_address, 0 );
        log_pfn_register(p, "l", log_remote_logname, 0);
        log_pfn_register(p, "u", log_remote_user, 0);
        log_pfn_register(p, "t", log_request_time, 0);
        log_pfn_register(p, "f", log_request_file, 0);
        log_pfn_register(p, "b", clf_log_bytes_sent, 0);
        log_pfn_register(p, "B", log_bytes_sent, 0);
        log_pfn_register(p, "i", log_header_in, 0);
        log_pfn_register(p, "o", log_header_out, 0);
        log_pfn_register(p, "n", log_note, 0);
        log_pfn_register(p, "e", log_env_var, 0);
        log_pfn_register(p, "V", log_server_name, 0);
        log_pfn_register(p, "v", log_virtual_host, 0);
        log_pfn_register(p, "p", log_server_port, 0);
        log_pfn_register(p, "P", log_child_pid, 0);
        log_pfn_register(p, "H", log_request_protocol, 0);
        log_pfn_register(p, "m", log_request_method, 0);
        log_pfn_register(p, "q", log_request_query, 0);
        log_pfn_register(p, "X", log_connection_status, 0);
        log_pfn_register(p, "C", log_cookie, 0);
        log_pfn_register(p, "r", log_request_line, 1);
        log_pfn_register(p, "D", log_request_duration_microseconds, 1);
        log_pfn_register(p, "T", log_request_duration, 1);
        log_pfn_register(p, "U", log_request_uri, 1);
        log_pfn_register(p, "s", log_status, 1);
    }

    return OK;
}

static void register_hooks(apr_pool_t *p)
{
    ap_hook_pre_config(log_pre_config,NULL,NULL,APR_HOOK_REALLY_FIRST);
    ap_hook_child_init(init_child,NULL,NULL,APR_HOOK_MIDDLE);
    ap_hook_open_logs(init_config_log,NULL,NULL,APR_HOOK_MIDDLE);
    ap_hook_log_transaction(multi_log_transaction,NULL,NULL,APR_HOOK_MIDDLE);

    /* Init log_hash before we register the optional function. It is 
     * possible for the optional function, ap_register_log_handler,
     * to be called before any other mod_log_config hooks are called.
     * As a policy, we should init everything required by an optional function
     * before calling APR_REGISTER_OPTIONAL_FN.
     */ 
    log_hash = apr_hash_make(p);
    APR_REGISTER_OPTIONAL_FN(ap_register_log_handler);
}

module AP_MODULE_DECLARE_DATA log_config_module =
{
    STANDARD20_MODULE_STUFF,
    NULL,                       /* create per-dir config */
    NULL,                       /* merge per-dir config */
    make_config_log_state,      /* server config */
    merge_config_log_state,     /* merge server config */
    config_log_cmds,            /* command apr_table_t */
    register_hooks              /* register hooks */
};
