http_config.h

/* 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.
 */

/**
 * @file http_config.h
 * @brief Apache Configuration
 *
 * @defgroup APACHE_CORE_CONFIG Configuration
 * @ingroup  APACHE_CORE
 * @{
 */

#ifndef APACHE_HTTP_CONFIG_H
#define APACHE_HTTP_CONFIG_H

#include "util_cfgtree.h"
#include "ap_config.h"
#include "apr_tables.h"

#ifdef __cplusplus
extern "C" {
#endif

/*
 * The central data structures around here...
 */

/* Command dispatch structures... */

/**
 * How the directives arguments should be parsed.
 * @remark Note that for all of these except RAW_ARGS, the config routine is
 *      passed a freshly allocated string which can be modified or stored
 *      or whatever...
 */
enum cmd_how {
    RAW_ARGS,           /**< cmd_func parses command line itself */
    TAKE1,              /**< one argument only */
    TAKE2,              /**< two arguments only */
    ITERATE,            /**< one argument, occurring multiple times
                         * (e.g., IndexIgnore)
                         */
    ITERATE2,           /**< two arguments, 2nd occurs multiple times
                         * (e.g., AddIcon)
                         */
    FLAG,               /**< One of 'On' or 'Off' */
    NO_ARGS,            /**< No args at all, e.g. &lt;/Directory&gt; */
    TAKE12,             /**< one or two arguments */
    TAKE3,              /**< three arguments only */
    TAKE23,             /**< two or three arguments */
    TAKE123,            /**< one, two or three arguments */
    TAKE13,             /**< one or three arguments */
    TAKE_ARGV           /**< an argc and argv are passed */
};

/**
 * This structure is passed to a command which is being invoked,
 * to carry a large variety of miscellaneous data which is all of
 * use to *somebody*...
 */
typedef struct cmd_parms_struct cmd_parms;

#if defined(AP_HAVE_DESIGNATED_INITIALIZER) || defined(DOXYGEN)

/**
 * All the types of functions that can be used in directives
 * @internal
 */
typedef union {
    /** function to call for a no-args */
    const char *(*no_args) (cmd_parms *parms, void *mconfig);
    /** function to call for a raw-args */
    const char *(*raw_args) (cmd_parms *parms, void *mconfig,
                             const char *args);
    /** function to call for a argv/argc */
    const char *(*take_argv) (cmd_parms *parms, void *mconfig,
                             int argc, char *const argv[]);
    /** function to call for a take1 */
    const char *(*take1) (cmd_parms *parms, void *mconfig, const char *w);
    /** function to call for a take2 */
    const char *(*take2) (cmd_parms *parms, void *mconfig, const char *w,
                          const char *w2);
    /** function to call for a take3 */
    const char *(*take3) (cmd_parms *parms, void *mconfig, const char *w,
                          const char *w2, const char *w3);
    /** function to call for a flag */
    const char *(*flag) (cmd_parms *parms, void *mconfig, int on);
} cmd_func;

/** This configuration directive does not take any arguments */
# define AP_NO_ARGS     func.no_args
/** This configuration directive will handle its own parsing of arguments*/
# define AP_RAW_ARGS    func.raw_args
/** This configuration directive will handle its own parsing of arguments*/
# define AP_TAKE_ARGV   func.take_argv
/** This configuration directive takes 1 argument*/
# define AP_TAKE1       func.take1
/** This configuration directive takes 2 arguments */
# define AP_TAKE2       func.take2
/** This configuration directive takes 3 arguments */
# define AP_TAKE3       func.take3
/** This configuration directive takes a flag (on/off) as a argument*/
# define AP_FLAG        func.flag

/** mechanism for declaring a directive with no arguments */
# define AP_INIT_NO_ARGS(directive, func, mconfig, where, help) \
    { directive, { .no_args=func }, mconfig, where, RAW_ARGS, help }
/** mechanism for declaring a directive with raw argument parsing */
# define AP_INIT_RAW_ARGS(directive, func, mconfig, where, help) \
    { directive, { .raw_args=func }, mconfig, where, RAW_ARGS, help }
/** mechanism for declaring a directive with raw argument parsing */
# define AP_INIT_TAKE_ARGV(directive, func, mconfig, where, help) \
    { directive, { .take_argv=func }, mconfig, where, TAKE_ARGV, help }
/** mechanism for declaring a directive which takes 1 argument */
# define AP_INIT_TAKE1(directive, func, mconfig, where, help) \
    { directive, { .take1=func }, mconfig, where, TAKE1, help }
/** mechanism for declaring a directive which takes multiple arguments */
# define AP_INIT_ITERATE(directive, func, mconfig, where, help) \
    { directive, { .take1=func }, mconfig, where, ITERATE, help }
/** mechanism for declaring a directive which takes 2 arguments */
# define AP_INIT_TAKE2(directive, func, mconfig, where, help) \
    { directive, { .take2=func }, mconfig, where, TAKE2, help }
/** mechanism for declaring a directive which takes 1 or 2 arguments */
# define AP_INIT_TAKE12(directive, func, mconfig, where, help) \
    { directive, { .take2=func }, mconfig, where, TAKE12, help }
/** mechanism for declaring a directive which takes multiple 2 arguments */
# define AP_INIT_ITERATE2(directive, func, mconfig, where, help) \
    { directive, { .take2=func }, mconfig, where, ITERATE2, help }
/** mechanism for declaring a directive which takes 1 or 3 arguments */
# define AP_INIT_TAKE13(directive, func, mconfig, where, help) \
    { directive, { .take3=func }, mconfig, where, TAKE13, help }
/** mechanism for declaring a directive which takes 2 or 3 arguments */
# define AP_INIT_TAKE23(directive, func, mconfig, where, help) \
    { directive, { .take3=func }, mconfig, where, TAKE23, help }
/** mechanism for declaring a directive which takes 1 to 3 arguments */
# define AP_INIT_TAKE123(directive, func, mconfig, where, help) \
    { directive, { .take3=func }, mconfig, where, TAKE123, help }
/** mechanism for declaring a directive which takes 3 arguments */
# define AP_INIT_TAKE3(directive, func, mconfig, where, help) \
    { directive, { .take3=func }, mconfig, where, TAKE3, help }
/** mechanism for declaring a directive which takes a flag (on/off) argument */
# define AP_INIT_FLAG(directive, func, mconfig, where, help) \
    { directive, { .flag=func }, mconfig, where, FLAG, help }

#else /* AP_HAVE_DESIGNATED_INITIALIZER */

typedef const char *(*cmd_func) ();

# define AP_NO_ARGS  func
# define AP_RAW_ARGS func
# define AP_TAKE_ARGV func
# define AP_TAKE1    func
# define AP_TAKE2    func
# define AP_TAKE3    func
# define AP_FLAG     func

# define AP_INIT_NO_ARGS(directive, func, mconfig, where, help) \
    { directive, func, mconfig, where, RAW_ARGS, help }
# define AP_INIT_RAW_ARGS(directive, func, mconfig, where, help) \
    { directive, func, mconfig, where, RAW_ARGS, help }
# define AP_INIT_TAKE_ARGV(directive, func, mconfig, where, help) \
    { directive, func, mconfig, where, TAKE_ARGV, help }
# define AP_INIT_TAKE1(directive, func, mconfig, where, help) \
    { directive, func, mconfig, where, TAKE1, help }
# define AP_INIT_ITERATE(directive, func, mconfig, where, help) \
    { directive, func, mconfig, where, ITERATE, help }
# define AP_INIT_TAKE2(directive, func, mconfig, where, help) \
    { directive, func, mconfig, where, TAKE2, help }
# define AP_INIT_TAKE12(directive, func, mconfig, where, help) \
    { directive, func, mconfig, where, TAKE12, help }
# define AP_INIT_ITERATE2(directive, func, mconfig, where, help) \
    { directive, func, mconfig, where, ITERATE2, help }
# define AP_INIT_TAKE13(directive, func, mconfig, where, help) \
    { directive, func, mconfig, where, TAKE13, help }
# define AP_INIT_TAKE23(directive, func, mconfig, where, help) \
    { directive, func, mconfig, where, TAKE23, help }
# define AP_INIT_TAKE123(directive, func, mconfig, where, help) \
    { directive, func, mconfig, where, TAKE123, help }
# define AP_INIT_TAKE3(directive, func, mconfig, where, help) \
    { directive, func, mconfig, where, TAKE3, help }
# define AP_INIT_FLAG(directive, func, mconfig, where, help) \
    { directive, func, mconfig, where, FLAG, help }

#endif /* AP_HAVE_DESIGNATED_INITIALIZER */

/**
 * The command record structure.  Modules can define a table of these
 * to define the directives it will implement.
 */
typedef struct command_struct command_rec;
struct command_struct {
    /** Name of this command */
    const char *name;
    /** The function to be called when this directive is parsed */
    cmd_func func;
    /** Extra data, for functions which implement multiple commands... */
    void *cmd_data;
    /** What overrides need to be allowed to enable this command. */
    int req_override;
    /** What the command expects as arguments */
    enum cmd_how args_how;

    /** 'usage' message, in case of syntax errors */
    const char *errmsg;
};

/**
 * @defgroup ConfigDirectives Allowed locations for configuration directives.
 *
 * The allowed locations for a configuration directive are the union of
 * those indicated by each set bit in the req_override mask.
 *
 * @{
 */
#define OR_NONE 0             /**< *.conf is not available anywhere in this override */
#define OR_LIMIT 1           /**< *.conf inside &lt;Directory&gt; or &lt;Location&gt;
                                and .htaccess when AllowOverride Limit */
#define OR_OPTIONS 2         /**< *.conf anywhere
                                and .htaccess when AllowOverride Options */
#define OR_FILEINFO 4        /**< *.conf anywhere
                                and .htaccess when AllowOverride FileInfo */
#define OR_AUTHCFG 8         /**< *.conf inside &lt;Directory&gt; or &lt;Location&gt;
                                and .htaccess when AllowOverride AuthConfig */
#define OR_INDEXES 16        /**< *.conf anywhere
                                and .htaccess when AllowOverride Indexes */
#define OR_UNSET 32          /**< bit to indicate that AllowOverride has not been set */
#define ACCESS_CONF 64       /**< *.conf inside &lt;Directory&gt; or &lt;Location&gt; */
#define RSRC_CONF 128        /**< *.conf outside &lt;Directory&gt; or &lt;Location&gt; */
#define EXEC_ON_READ 256     /**< force directive to execute a command
                which would modify the configuration (like including another
                file, or IFModule */
/* Flags to determine whether syntax errors in .htaccess should be
 * treated as nonfatal (log and ignore errors)
 */
#define NONFATAL_OVERRIDE 512    /* Violation of AllowOverride rule */
#define NONFATAL_UNKNOWN 1024    /* Unrecognised directive */
#define NONFATAL_ALL (NONFATAL_OVERRIDE|NONFATAL_UNKNOWN)

/** this directive can be placed anywhere */
#define OR_ALL (OR_LIMIT|OR_OPTIONS|OR_FILEINFO|OR_AUTHCFG|OR_INDEXES)

/** @} */

/**
 * This can be returned by a function if they don't wish to handle
 * a command. Make it something not likely someone will actually use
 * as an error code.
 */
#define DECLINE_CMD "\a\b"

/** Common structure for reading of config files / passwd files etc. */
typedef struct ap_configfile_t ap_configfile_t;
struct ap_configfile_t {
    /**< an apr_file_getc()-like function */
    apr_status_t (*getch) (char *ch, void *param);
    /**< an apr_file_gets()-like function */
    apr_status_t (*getstr) (void *buf, apr_size_t bufsiz, void *param);
    /**< a close handler function */
    apr_status_t (*close) (void *param);
    /**< the argument passed to getch/getstr/close */
    void *param;
    /**< the filename / description */
    const char *name;
    /**< current line number, starting at 1 */
    unsigned line_number;
};

/**
 * This structure is passed to a command which is being invoked,
 * to carry a large variety of miscellaneous data which is all of
 * use to *somebody*...
 */
struct cmd_parms_struct {
    /** Argument to command from cmd_table */
    void *info;
    /** Which allow-override bits are set */
    int override;
    /** Which allow-override-opts bits are set */
    int override_opts;
    /** Table of directives allowed per AllowOverrideList */
    apr_table_t *override_list;
    /** Which methods are &lt;Limit&gt;ed */
    apr_int64_t limited;
    /** methods which are limited */
    apr_array_header_t *limited_xmethods;
    /** methods which are xlimited */
    ap_method_list_t *xlimited;

    /** Config file structure. */
    ap_configfile_t *config_file;
    /** the directive specifying this command */
    ap_directive_t *directive;

    /** Pool to allocate new storage in */
    apr_pool_t *pool;
    /** Pool for scratch memory; persists during configuration, but
     *  wiped before the first request is served...  */
    apr_pool_t *temp_pool;
    /** Server_rec being configured for */
    server_rec *server;
    /** If configuring for a directory, pathname of that directory.
     *  NOPE!  That's what it meant previous to the existence of &lt;Files&gt;,
     * &lt;Location&gt; and regex matching.  Now the only usefulness that can be
     * derived from this field is whether a command is being called in a
     * server context (path == NULL) or being called in a dir context
     * (path != NULL).  */
    char *path;
    /** configuration command */
    const command_rec *cmd;

    /** per_dir_config vector passed to handle_command */
    struct ap_conf_vector_t *context;
    /** directive with syntax error */
    const ap_directive_t *err_directive;

};

/**
 * Module structures.  Just about everything is dispatched through
 * these, directly or indirectly (through the command and handler
 * tables).
 */
typedef struct module_struct module;
struct module_struct {
    /** API version, *not* module version; check that module is
     * compatible with this version of the server.
     */
    int version;
    /** API minor version. Provides API feature milestones. Not checked
     *  during module init */
    int minor_version;
    /** Index to this modules structures in config vectors.  */
    int module_index;

    /** The name of the module's C file */
    const char *name;
    /** The handle for the DSO.  Internal use only */
    void *dynamic_load_handle;

    /** A pointer to the next module in the list
     *  @var module_struct *next
     */
    struct module_struct *next;

    /** Magic Cookie to identify a module structure;  It's mainly
     *  important for the DSO facility (see also mod_so).  */
    unsigned long magic;

    /** Function to allow MPMs to re-write command line arguments.  This
     *  hook is only available to MPMs.
     *  @param The process that the server is running in.
     */
    void (*rewrite_args) (process_rec *process);
    /** Function to allow all modules to create per directory configuration
     *  structures.
     *  @param p The pool to use for all allocations.
     *  @param dir The directory currently being processed.
     *  @return The per-directory structure created
     */
    void *(*create_dir_config) (apr_pool_t *p, char *dir);
    /** Function to allow all modules to merge the per directory configuration
     *  structures for two directories.
     *  @param p The pool to use for all allocations.
     *  @param base_conf The directory structure created for the parent directory.
     *  @param new_conf The directory structure currently being processed.
     *  @return The new per-directory structure created
     */
    void *(*merge_dir_config) (apr_pool_t *p, void *base_conf, void *new_conf);
    /** Function to allow all modules to create per server configuration
     *  structures.
     *  @param p The pool to use for all allocations.
     *  @param s The server currently being processed.
     *  @return The per-server structure created
     */
    void *(*create_server_config) (apr_pool_t *p, server_rec *s);
    /** Function to allow all modules to merge the per server configuration
     *  structures for two servers.
     *  @param p The pool to use for all allocations.
     *  @param base_conf The directory structure created for the parent directory.
     *  @param new_conf The directory structure currently being processed.
     *  @return The new per-directory structure created
     */
    void *(*merge_server_config) (apr_pool_t *p, void *base_conf,
                                  void *new_conf);

    /** A command_rec table that describes all of the directives this module
     * defines. */
    const command_rec *cmds;

    /** A hook to allow modules to hook other points in the request processing.
     *  In this function, modules should call the ap_hook_*() functions to
     *  register an interest in a specific step in processing the current
     *  request.
     *  @param p the pool to use for all allocations
     */
    void (*register_hooks) (apr_pool_t *p);
};

/**
 * The AP_MAYBE_UNUSED macro is used for variable declarations that
 * might potentially exhibit "unused var" warnings on some compilers if
 * left untreated.
 * Since static intializers are not part of the C language (C89), making
 * (void) usage is not possible. However many compiler have proprietary 
 * mechanism to suppress those warnings.  
 */
#ifdef AP_MAYBE_UNUSED
#elif defined(__GNUC__)
# define AP_MAYBE_UNUSED(x) x __attribute__((unused)) 
#elif defined(__LCLINT__)
# define AP_MAYBE_UNUSED(x) /*@unused@*/ x  
#else
# define AP_MAYBE_UNUSED(x) x
#endif
    
/**
 * The APLOG_USE_MODULE macro is used choose which module a file belongs to.
 * This is necessary to allow per-module loglevel configuration.
 *
 * APLOG_USE_MODULE indirectly sets APLOG_MODULE_INDEX and APLOG_MARK.
 *
 * If a module should be backward compatible with versions before 2.3.6,
 * APLOG_USE_MODULE needs to be enclosed in a ifdef APLOG_USE_MODULE block.
 *
 * @param foo name of the module symbol of the current module, without the
 *            trailing "_module" part
 * @see APLOG_MARK
 */
#define APLOG_USE_MODULE(foo) \
    extern module AP_MODULE_DECLARE_DATA foo##_module;                  \
    AP_MAYBE_UNUSED(static int * const aplog_module_index) = &(foo##_module.module_index)

/**
 * AP_DECLARE_MODULE is a convenience macro that combines a call of
 * APLOG_USE_MODULE with the definition of the module symbol.
 *
 * If a module should be backward compatible with versions before 2.3.6,
 * APLOG_USE_MODULE should be used explicitly instead of AP_DECLARE_MODULE.
 */
#define AP_DECLARE_MODULE(foo) \
    APLOG_USE_MODULE(foo);                         \
    module AP_MODULE_DECLARE_DATA foo##_module

/**
 * @defgroup ModuleInit Module structure initializers
 *
 * Initializer for the first few module slots, which are only
 * really set up once we start running.  Note that the first two slots
 * provide a version check; this should allow us to deal with changes to
 * the API. The major number should reflect changes to the API handler table
 * itself or removal of functionality. The minor number should reflect
 * additions of functionality to the existing API. (the server can detect
 * an old-format module, and either handle it back-compatibly, or at least
 * signal an error). See src/include/ap_mmn.h for MMN version history.
 * @{
 */

/** The one used in Apache 1.3, which will deliberately cause an error */
#define STANDARD_MODULE_STUFF   this_module_needs_to_be_ported_to_apache_2_0

/** Use this in all standard modules */
#define STANDARD20_MODULE_STUFF MODULE_MAGIC_NUMBER_MAJOR, \
                                MODULE_MAGIC_NUMBER_MINOR, \
                                -1, \
                                __FILE__, \
                                NULL, \
                                NULL, \
                                MODULE_MAGIC_COOKIE, \
                                NULL      /* rewrite args spot */

/** Use this only in MPMs */
#define MPM20_MODULE_STUFF      MODULE_MAGIC_NUMBER_MAJOR, \
                                MODULE_MAGIC_NUMBER_MINOR, \
                                -1, \
                                __FILE__, \
                                NULL, \
                                NULL, \
                                MODULE_MAGIC_COOKIE

/** @} */

/* CONFIGURATION VECTOR FUNCTIONS */

/** configuration vector structure */
typedef struct ap_conf_vector_t ap_conf_vector_t;

/**
 * Generic accessors for other modules to get at their own module-specific
 * data
 * @param cv The vector in which the modules configuration is stored.
 *        usually r->per_dir_config or s->module_config
 * @param m The module to get the data for.
 * @return The module-specific data
 */
AP_DECLARE(void *) ap_get_module_config(const ap_conf_vector_t *cv,
                                        const module *m);

/**
 * Generic accessors for other modules to set their own module-specific
 * data
 * @param cv The vector in which the modules configuration is stored.
 *        usually r->per_dir_config or s->module_config
 * @param m The module to set the data for.
 * @param val The module-specific data to set
 */
AP_DECLARE(void) ap_set_module_config(ap_conf_vector_t *cv, const module *m,
                                      void *val);

#if !defined(AP_DEBUG)

#define ap_get_module_config(v,m)       \
    (((void **)(v))[(m)->module_index])
#define ap_set_module_config(v,m,val)   \
    ((((void **)(v))[(m)->module_index]) = (val))

#endif /* AP_DEBUG */


/**
 * Generic accessor for modules to get the module-specific loglevel
 * @param s The server from which to get the loglevel.
 * @param index The module_index of the module to get the loglevel for.
 * @return The module-specific loglevel
 */
AP_DECLARE(int) ap_get_server_module_loglevel(const server_rec *s, int index);

/**
 * Generic accessor for modules the module-specific loglevel
 * @param c The connection from which to get the loglevel.
 * @param index The module_index of the module to get the loglevel for.
 * @return The module-specific loglevel
 */
AP_DECLARE(int) ap_get_conn_module_loglevel(const conn_rec *c, int index);

/**
 * Generic accessor for modules the module-specific loglevel
 * @param c The connection from which to get the loglevel.
 * @param s The server from which to get the loglevel if c does not have a
 *          specific loglevel configuration.
 * @param index The module_index of the module to get the loglevel for.
 * @return The module-specific loglevel
 */
AP_DECLARE(int) ap_get_conn_server_module_loglevel(const conn_rec *c,
                                                   const server_rec *s,
                                                   int index);

/**
 * Generic accessor for modules to get the module-specific loglevel
 * @param r The request from which to get the loglevel.
 * @param index The module_index of the module to get the loglevel for.
 * @return The module-specific loglevel
 */
AP_DECLARE(int) ap_get_request_module_loglevel(const request_rec *r, int index);

/**
 * Accessor to set module-specific loglevel
 * @param p A pool
 * @param l The ap_logconf struct to modify.
 * @param index The module_index of the module to set the loglevel for.
 * @param level The new log level
 */
AP_DECLARE(void) ap_set_module_loglevel(apr_pool_t *p, struct ap_logconf *l,
                                        int index, int level);

#if !defined(AP_DEBUG)

#define ap_get_conn_logconf(c)                     \
    ((c)->log             ? (c)->log             : \
     &(c)->base_server->log)

#define ap_get_conn_server_logconf(c,s)                             \
    ( ( (c)->log != &(c)->base_server->log && (c)->log != NULL )  ? \
      (c)->log                                                    : \
      &(s)->log )

#define ap_get_request_logconf(r)                  \
    ((r)->log             ? (r)->log             : \
     (r)->connection->log ? (r)->connection->log : \
     &(r)->server->log)

#define ap_get_module_loglevel(l,i)                                     \
    (((i) < 0 || (l)->module_levels == NULL || (l)->module_levels[i] < 0) ?  \
     (l)->level :                                                         \
     (l)->module_levels[i])

#define ap_get_server_module_loglevel(s,i)  \
    (ap_get_module_loglevel(&(s)->log,i))

#define ap_get_conn_module_loglevel(c,i)  \
    (ap_get_module_loglevel(ap_get_conn_logconf(c),i))

#define ap_get_conn_server_module_loglevel(c,s,i)  \
    (ap_get_module_loglevel(ap_get_conn_server_logconf(c,s),i))

#define ap_get_request_module_loglevel(r,i)  \
    (ap_get_module_loglevel(ap_get_request_logconf(r),i))

#endif /* AP_DEBUG */

/**
 * Set all module-specific loglevels to val
 * @param l The log config for which to set the loglevels.
 * @param val the value to set all loglevels to
 */
AP_DECLARE(void) ap_reset_module_loglevels(struct ap_logconf *l, int val);

/**
 * Generic command handling function for strings
 * @param cmd The command parameters for this directive
 * @param struct_ptr pointer into a given type
 * @param arg The argument to the directive
 * @return An error string or NULL on success
 */
AP_DECLARE_NONSTD(const char *) ap_set_string_slot(cmd_parms *cmd,
                                                   void *struct_ptr,
                                                   const char *arg);

/**
 * Generic command handling function for integers
 * @param cmd The command parameters for this directive
 * @param struct_ptr pointer into a given type
 * @param arg The argument to the directive
 * @return An error string or NULL on success
 */
AP_DECLARE_NONSTD(const char *) ap_set_int_slot(cmd_parms *cmd,
                                                void *struct_ptr,
                                                const char *arg);

/**
 * Parsing function for log level
 * @param str The string to parse
 * @param val The parsed log level
 * @return An error string or NULL on success
 */
AP_DECLARE(const char *) ap_parse_log_level(const char *str, int *val);

/**
 * Return true if the specified method is limited by being listed in
 * a &lt;Limit&gt; container, or by *not* being listed in a &lt;LimitExcept&gt;
 * container.
 *
 * @param   method  Pointer to a string specifying the method to check.
 * @param   cmd     Pointer to the cmd_parms structure passed to the
 *                  directive handler.
 * @return  0 if the method is not limited in the current scope
 */
AP_DECLARE(int) ap_method_is_limited(cmd_parms *cmd, const char *method);

/**
 * Generic command handling function for strings, always sets the value
 * to a lowercase string
 * @param cmd The command parameters for this directive
 * @param struct_ptr pointer into a given type
 * @param arg The argument to the directive
 * @return An error string or NULL on success
 */
AP_DECLARE_NONSTD(const char *) ap_set_string_slot_lower(cmd_parms *cmd,
                                                         void *struct_ptr,
                                                         const char *arg);
/**
 * Generic command handling function for flags stored in an int
 * @param cmd The command parameters for this directive
 * @param struct_ptr pointer into a given type
 * @param arg The argument to the directive (either 1 or 0)
 * @return An error string or NULL on success
 */
AP_DECLARE_NONSTD(const char *) ap_set_flag_slot(cmd_parms *cmd,
                                                 void *struct_ptr,
                                                 int arg);
/**
 * Generic command handling function for flags stored in a char
 * @param cmd The command parameters for this directive
 * @param struct_ptr pointer into a given type
 * @param arg The argument to the directive (either 1 or 0)
 * @return An error string or NULL on success
 */
AP_DECLARE_NONSTD(const char *) ap_set_flag_slot_char(cmd_parms *cmd,
                                                      void *struct_ptr,
                                                      int arg);
/**
 * Generic command handling function for files
 * @param cmd The command parameters for this directive
 * @param struct_ptr pointer into a given type
 * @param arg The argument to the directive
 * @return An error string or NULL on success
 */
AP_DECLARE_NONSTD(const char *) ap_set_file_slot(cmd_parms *cmd,
                                                 void *struct_ptr,
                                                 const char *arg);
/**
 * Generic command handling function to respond with cmd->help as an error
 * @param cmd The command parameters for this directive
 * @param struct_ptr pointer into a given type
 * @param arg The argument to the directive
 * @return The cmd->help value as the error string
 * @note This allows simple declarations such as:
 * @code
 *     AP_INIT_RAW_ARGS("Foo", ap_set_deprecated, NULL, OR_ALL,
 *         "The Foo directive is no longer supported, use Bar"),
 * @endcode
 */
AP_DECLARE_NONSTD(const char *) ap_set_deprecated(cmd_parms *cmd,
                                                  void *struct_ptr,
                                                  const char *arg);
/**
 * For modules which need to read config files, open logs, etc. this returns
 * the canonical form of fname made absolute to ap_server_root.
 * @param p pool to allocate data from
 * @param fname The file name
 */
AP_DECLARE(char *) ap_server_root_relative(apr_pool_t *p, const char *fname);

/**
 * Compute the name of a run-time file (e.g., shared memory "file") relative
 * to the appropriate run-time directory.  Absolute paths are returned as-is.
 * The run-time directory is configured via the DefaultRuntimeDir directive or
 * at build time.
 */
AP_DECLARE(char *) ap_runtime_dir_relative(apr_pool_t *p, const char *fname);

/* Finally, the hook for dynamically loading modules in... */

/**
 * Add a module to the server
 * @param m The module structure of the module to add
 * @param p The pool of the same lifetime as the module
 * @param s The module's symbol name (used for logging)
 */
AP_DECLARE(const char *) ap_add_module(module *m, apr_pool_t *p,
                                       const char *s);

/**
 * Remove a module from the server.  There are some caveats:
 * when the module is removed, its slot is lost so all the current
 * per-dir and per-server configurations are invalid. So we should
 * only ever call this function when you are invalidating almost
 * all our current data. I.e. when doing a restart.
 * @param m the module structure of the module to remove
 */
AP_DECLARE(void) ap_remove_module(module *m);
/**
 * Add a module to the chained modules list and the list of loaded modules
 * @param mod The module structure of the module to add
 * @param p The pool with the same lifetime as the module
 * @param s The module's symbol name (used for logging)
 */
AP_DECLARE(const char *) ap_add_loaded_module(module *mod, apr_pool_t *p,
                                              const char *s);
/**
 * Remove a module fromthe chained modules list and the list of loaded modules
 * @param mod the module structure of the module to remove
 */
AP_DECLARE(void) ap_remove_loaded_module(module *mod);
/**
 * Find the name of the specified module
 * @param m The module to get the name for
 * @return the name of the module
 */
AP_DECLARE(const char *) ap_find_module_name(module *m);
/**
 * Find the short name of the module identified by the specified module index
 * @param module_index The module index to get the name for
 * @return the name of the module, NULL if not found
 */
AP_DECLARE(const char *) ap_find_module_short_name(int module_index);
/**
 * Find a module based on the name of the module
 * @param name the name of the module
 * @return the module structure if found, NULL otherwise
 */
AP_DECLARE(module *) ap_find_linked_module(const char *name);

/**
 * Open a ap_configfile_t as apr_file_t
 * @param ret_cfg open ap_configfile_t struct pointer
 * @param p The pool to allocate the structure from
 * @param name the name of the file to open
 */
AP_DECLARE(apr_status_t) ap_pcfg_openfile(ap_configfile_t **ret_cfg,
                                          apr_pool_t *p, const char *name);

/**
 * Allocate a ap_configfile_t handle with user defined functions and params
 * @param p The pool to allocate from
 * @param descr The name of the file
 * @param param The argument passed to getch/getstr/close
 * @param getc_func The getch function
 * @param gets_func The getstr function
 * @param close_func The close function
 */
AP_DECLARE(ap_configfile_t *) ap_pcfg_open_custom(apr_pool_t *p,
    const char *descr,
    void *param,
    apr_status_t (*getc_func) (char *ch, void *param),
    apr_status_t (*gets_func) (void *buf, apr_size_t bufsiz, void *param),
    apr_status_t (*close_func) (void *param));

/**
 * Read one line from open ap_configfile_t, strip leading and trailing
 * whitespace, increase line number
 * @param buf place to store the line read
 * @param bufsize size of the buffer
 * @param cfp File to read from
 * @return error status, APR_ENOSPC if bufsize is too small for the line
 */
AP_DECLARE(apr_status_t) ap_cfg_getline(char *buf, apr_size_t bufsize, ap_configfile_t *cfp);

/**
 * Read one char from open configfile_t, increase line number upon LF
 * @param ch place to store the char read
 * @param cfp The file to read from
 * @return error status
 */
AP_DECLARE(apr_status_t) ap_cfg_getc(char *ch, ap_configfile_t *cfp);

/**
 * Detach from open ap_configfile_t, calling the close handler
 * @param cfp The file to close
 * @return 1 on success, 0 on failure
 */
AP_DECLARE(int) ap_cfg_closefile(ap_configfile_t *cfp);

/**
 * Convert a return value from ap_cfg_getline or ap_cfg_getc to a user friendly
 * string.
 * @param p The pool to allocate the string from
 * @param cfp The config file
 * @param rc The return value to convert
 * @return The error string, NULL if rc == APR_SUCCESS
 */
AP_DECLARE(const char *) ap_pcfg_strerror(apr_pool_t *p, ap_configfile_t *cfp,
                                          apr_status_t rc);

/**
 * Read all data between the current &lt;foo&gt; and the matching &lt;/foo&gt;.  All
 * of this data is forgotten immediately.
 * @param cmd The cmd_parms to pass to the directives inside the container
 * @param directive The directive name to read until
 * @return Error string on failure, NULL on success
 * @note If cmd->pool == cmd->temp_pool, ap_soak_end_container() will assume
 *       .htaccess context and use a lower maximum line length.
 */
AP_DECLARE(const char *) ap_soak_end_container(cmd_parms *cmd, char *directive);

/**
 * Read all data between the current &lt;foo&gt; and the matching &lt;/foo&gt; and build
 * a config tree from it
 * @param p pool to allocate from
 * @param temp_pool Temporary pool to allocate from
 * @param parms The cmd_parms to pass to all directives read
 * @param current The current node in the tree
 * @param curr_parent The current parent node
 * @param orig_directive The directive to read until hit.
 * @return Error string on failure, NULL on success
 * @note If p == temp_pool, ap_build_cont_config() will assume .htaccess
 *       context and use a lower maximum line length.
*/
AP_DECLARE(const char *) ap_build_cont_config(apr_pool_t *p,
                                              apr_pool_t *temp_pool,
                                              cmd_parms *parms,
                                              ap_directive_t **current,
                                              ap_directive_t **curr_parent,
                                              char *orig_directive);

/**
 * Build a config tree from a config file
 * @param parms The cmd_parms to pass to all of the directives in the file
 * @param conf_pool The pconf pool
 * @param temp_pool The temporary pool
 * @param conftree Place to store the root node of the config tree
 * @return Error string on erro, NULL otherwise
 * @note If conf_pool == temp_pool, ap_build_config() will assume .htaccess
 *       context and use a lower maximum line length.
 */
AP_DECLARE(const char *) ap_build_config(cmd_parms *parms,
                                         apr_pool_t *conf_pool,
                                         apr_pool_t *temp_pool,
                                         ap_directive_t **conftree);

/**
 * Walk a config tree and setup the server's internal structures
 * @param conftree The config tree to walk
 * @param parms The cmd_parms to pass to all functions
 * @param section_vector The per-section config vector.
 * @return Error string on error, NULL otherwise
 */
AP_DECLARE(const char *) ap_walk_config(ap_directive_t *conftree,
                                        cmd_parms *parms,
                                        ap_conf_vector_t *section_vector);

/**
 * @defgroup ap_check_cmd_context Check command context
 * @{
 */
/**
 * Check the context a command is used in.
 * @param cmd The command to check
 * @param forbidden Where the command is forbidden.
 * @return Error string on error, NULL on success
 */
AP_DECLARE(const char *) ap_check_cmd_context(cmd_parms *cmd,
                                              unsigned forbidden);

#define  NOT_IN_VIRTUALHOST     0x01 /**< Forbidden in &lt;VirtualHost&gt; */
#define  NOT_IN_LIMIT           0x02 /**< Forbidden in &lt;Limit&gt; */
#define  NOT_IN_DIRECTORY       0x04 /**< Forbidden in &lt;Directory&gt; */
#define  NOT_IN_LOCATION        0x08 /**< Forbidden in &lt;Location&gt; */
#define  NOT_IN_FILES           0x10 /**< Forbidden in &lt;Files&gt; or &lt;If&gt;*/
#define  NOT_IN_HTACCESS        0x20 /**< Forbidden in .htaccess files */
/** Forbidden in &lt;Directory&gt;/&lt;Location&gt;/&lt;Files&gt;&lt;If&gt;*/
#define  NOT_IN_DIR_LOC_FILE    (NOT_IN_DIRECTORY|NOT_IN_LOCATION|NOT_IN_FILES)
/** Forbidden in &lt;VirtualHost&gt;/&lt;Limit&gt;/&lt;Directory&gt;/&lt;Location&gt;/&lt;Files&gt;/&lt;If&gt; */
#define  GLOBAL_ONLY            (NOT_IN_VIRTUALHOST|NOT_IN_LIMIT|NOT_IN_DIR_LOC_FILE)

/** @} */

/**
 * @brief This structure is used to assign symbol names to module pointers
 */
typedef struct {
    const char *name;
    module *modp;
} ap_module_symbol_t;

/**
 * The topmost module in the list
 * @var module *ap_top_module
 */
AP_DECLARE_DATA extern module *ap_top_module;

/**
 * Array of all statically linked modules
 * @var module *ap_prelinked_modules[]
 */
AP_DECLARE_DATA extern module *ap_prelinked_modules[];
/**
 * Array of all statically linked modulenames (symbols)
 * @var ap_module_symbol_t ap_prelinked_module_symbols[]
 */
AP_DECLARE_DATA extern ap_module_symbol_t ap_prelinked_module_symbols[];
/**
 * Array of all preloaded modules
 * @var module *ap_preloaded_modules[]
 */
AP_DECLARE_DATA extern module *ap_preloaded_modules[];
/**
 * Array of all loaded modules
 * @var module **ap_loaded_modules
 */
AP_DECLARE_DATA extern module **ap_loaded_modules;

/* For mod_so.c... */
/** Run a single module's two create_config hooks
 *  @param p the pool to allocate from
 *  @param s The server to configure for.
 *  @param m The module to configure
 */
AP_DECLARE(void) ap_single_module_configure(apr_pool_t *p, server_rec *s,
                                            module *m);

/* For http_main.c... */
/**
 * Add all of the prelinked modules into the loaded module list
 * @param process The process that is currently running the server
 */
AP_DECLARE(const char *) ap_setup_prelinked_modules(process_rec *process);

/**
 * Show the preloaded configuration directives, the help string explaining
 * the directive arguments, in what module they are handled, and in
 * what parts of the configuration they are allowed.  Used for httpd -h.
 */
AP_DECLARE(void) ap_show_directives(void);

/**
 * Show the preloaded module names.  Used for httpd -l.
 */
AP_DECLARE(void) ap_show_modules(void);

/**
 * Show the MPM name.  Used in reporting modules such as mod_info to
 * provide extra information to the user
 */
AP_DECLARE(const char *) ap_show_mpm(void);

/**
 * Read all config files and setup the server