ap_hook.c

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#if 0
=pod
#endif
/* ====================================================================
 * Copyright (c) 1998-2000 The Apache Group.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the Apache Group
 *    for use in the Apache HTTP server project (http://www.apache.org/)."
 *
 * 4. The names "Apache Server" and "Apache Group" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    [e-mail].
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Group.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the Apache Group
 *    for use in the Apache HTTP server project (http://www.apache.org/)."
 *
 * THIS SOFTWARE IS PROVIDED BY THE APACHE GROUP ``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 GROUP 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 Group and was originally based
 * on public domain software written at the National Center for
 * Supercomputing Applications, University of Illinois, Urbana-Champaign.
 * For more information on the Apache Group and the Apache HTTP server
 * project, please see <http://www.apache.org/>.
 *
 */

/*
**  Implementation of a Generic Hook Interface for Apache
**  Written by Ralf S. Engelschall <[e-mail]> 
**
**  See POD document at end of ap_hook.h for description.
**  View it with the command ``pod2man ap_hook.h | nroff -man | more''
**
**  Attention: This source file is a little bit tricky.
**             It's a combination of a C source and an embedded Perl script
**             (which updates the C source). The purpose of this is to have
**             both things together at one place. So you can both pass
**             this file to the C compiler and the Perl interpreter.
*/

                                      /*
                                       * Premature optimization is 
                                       * the root of all evil.
                                       *       -- D. E. Knuth
                                       */

#ifdef EAPI

#include "httpd.h"
#include "http_log.h"
#include "ap_config.h"
#include "ap_hook.h"

/* 
 * the internal hook pool
 */
static ap_hook_entry **ap_hook_pool = NULL;

/* 
 * forward prototypes for internal functions
 */
static int            ap_hook_call_func(va_list ap, ap_hook_entry *he, ap_hook_func *hf);
static ap_hook_entry *ap_hook_create(char *hook);
static ap_hook_entry *ap_hook_find(char *hook);
static void           ap_hook_destroy(ap_hook_entry *he);

/*
 * Initialize the hook mechanism
 */
API_EXPORT(void) ap_hook_init(void)
{
    int i;

    if (ap_hook_pool != NULL)
        return;
    ap_hook_pool = (ap_hook_entry **)malloc(sizeof(ap_hook_entry *)
                                            *(AP_HOOK_MAX_ENTRIES+1));
    for (i = 0; i < AP_HOOK_MAX_ENTRIES; i++)
        ap_hook_pool[i] = NULL;
    return;
}

/*
 * Kill the hook mechanism
 */
API_EXPORT(void) ap_hook_kill(void)
{
    int i;

    if (ap_hook_pool == NULL)
        return;
    for (i = 0; ap_hook_pool[i] != NULL; i++)
        ap_hook_destroy(ap_hook_pool[i]);
    free(ap_hook_pool);
    ap_hook_pool = NULL;
    return;
}
    
/*
 * Smart creation of a hook (when it exist this is the same as
 * ap_hook_find, when it doesn't exists it is created)
 */
static ap_hook_entry *ap_hook_create(char *hook)
{
    int i;
    ap_hook_entry *he;

    for (i = 0; ap_hook_pool[i] != NULL; i++)
        if (strcmp(ap_hook_pool[i]->he_hook, hook) == 0)
            return ap_hook_pool[i];

    if (i >= AP_HOOK_MAX_ENTRIES)
        return NULL;

    if ((he = (ap_hook_entry *)malloc(sizeof(ap_hook_entry))) == NULL)
        return NULL;
    ap_hook_pool[i] = he;

    he->he_hook          = strdup(hook);
    he->he_sig           = AP_HOOK_SIG_UNKNOWN;
    he->he_modeid        = AP_HOOK_MODE_UNKNOWN;
    he->he_modeval.v_int = 0;

    he->he_func = (ap_hook_func **)malloc(sizeof(ap_hook_func *)
                                          *(AP_HOOK_MAX_FUNCS+1));
    if (he->he_func == NULL)
        return FALSE;

    for (i = 0; i < AP_HOOK_MAX_FUNCS; i++)
        he->he_func[i] = NULL;
    return he;
}

/*
 * Find a particular hook
 */
static ap_hook_entry *ap_hook_find(char *hook)
{
    int i;

    for (i = 0; ap_hook_pool[i] != NULL; i++)
        if (strcmp(ap_hook_pool[i]->he_hook, hook) == 0)
            return ap_hook_pool[i];
    return NULL;
}

/*
 * Destroy a particular hook
 */
static void ap_hook_destroy(ap_hook_entry *he)
{
    int i;

    if (he == NULL)
        return;
    free(he->he_hook);
    for (i = 0; he->he_func[i] != NULL; i++)
        free(he->he_func[i]);
    free(he->he_func);
    free(he);
    return;
}

/*
 * Configure a particular hook, 
 * i.e. remember its signature and return value mode
 */
API_EXPORT(int) ap_hook_configure(char *hook, ap_hook_sig sig, ap_hook_mode modeid, ...)
{
    ap_hook_entry *he;
    va_list ap;
    int rc;

    va_start(ap, modeid);
    if ((he = ap_hook_create(hook)) == NULL)
        rc = FALSE;
    else {
        he->he_sig = sig;
        he->he_modeid = modeid;
        if (modeid == AP_HOOK_MODE_DECLINE || modeid == AP_HOOK_MODE_DECLTMP) {
            if (AP_HOOK_SIG_HAS(sig, RC, char))
                he->he_modeval.v_char = va_arg(ap, va_type(char));
            else if (AP_HOOK_SIG_HAS(sig, RC, int))
                he->he_modeval.v_int = va_arg(ap, va_type(int));
            else if (AP_HOOK_SIG_HAS(sig, RC, long))
                he->he_modeval.v_long = va_arg(ap, va_type(long));
            else if (AP_HOOK_SIG_HAS(sig, RC, float))
                he->he_modeval.v_float = va_arg(ap, va_type(float));
            else if (AP_HOOK_SIG_HAS(sig, RC, double))
                he->he_modeval.v_double = va_arg(ap, va_type(double));
            else if (AP_HOOK_SIG_HAS(sig, RC, ptr))
                he->he_modeval.v_ptr = va_arg(ap, va_type(ptr));
        }
        rc = TRUE;
    }
    va_end(ap);
    return rc;
}

/*
 * Register a function to call for a hook
 */
API_EXPORT(int) ap_hook_register_I(char *hook, void *func, void *ctx)
{
    int i, j;
    ap_hook_entry *he;
    ap_hook_func *hf;

    if ((he = ap_hook_create(hook)) == NULL)
        return FALSE;

    for (i = 0; he->he_func[i] != NULL; i++)
        if (he->he_func[i]->hf_ptr == func)
            return FALSE;

    if (i == AP_HOOK_MAX_FUNCS)
        return FALSE;

    if ((hf = (ap_hook_func *)malloc(sizeof(ap_hook_func))) == NULL)
        return FALSE;

    for (j = i; j >= 0; j--)
        he->he_func[j+1] = he->he_func[j];
    he->he_func[0] = hf;

    hf->hf_ptr = func;
    hf->hf_ctx = ctx;

    return TRUE;
}

/*
 * Unregister a function to call for a hook
 */
API_EXPORT(int) ap_hook_unregister_I(char *hook, void *func)
{
    int i, j;
    ap_hook_entry *he;

    if ((he = ap_hook_find(hook)) == NULL)
        return FALSE;
    for (i = 0; he->he_func[i] != NULL; i++) {
        if (he->he_func[i]->hf_ptr == func) {
            free(he->he_func[i]);
            for (j = i; he->he_func[j] != NULL; j++)
                he->he_func[j] = he->he_func[j+1];
            return TRUE;
        }
    }
    return FALSE;
}

/*
 * Retrieve the status of a particular hook
 */
API_EXPORT(ap_hook_state) ap_hook_status(char *hook)
{
    ap_hook_entry *he;

    if ((he = ap_hook_find(hook)) == NULL)
        return AP_HOOK_STATE_NOTEXISTANT;
    if (   he->he_func[0] != NULL 
        && he->he_sig != AP_HOOK_SIG_UNKNOWN
        && he->he_modeid != AP_HOOK_MODE_UNKNOWN)
        return AP_HOOK_STATE_REGISTERED;
    if (   he->he_sig != AP_HOOK_SIG_UNKNOWN 
        && he->he_modeid != AP_HOOK_MODE_UNKNOWN)
        return AP_HOOK_STATE_CONFIGURED;
    return AP_HOOK_STATE_ESTABLISHED;
}

/*
 * Use a hook, i.e. optional on-the-fly configure it before calling it
 */
API_EXPORT(int) ap_hook_use(char *hook, ap_hook_sig sig, ap_hook_mode modeid, ...)
{
    int i;