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/* 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
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
* @file util_varbuf.h
* @brief Apache resizable variable length buffer library
* This set of functions provides resizable buffers. While the primary
* usage is with NUL-terminated strings, most functions also work with
* arbitrary binary data.
* @ingroup APACHE_CORE
* @{
#ifndef AP_VARBUF_H
#define AP_VARBUF_H
#include "apr.h"
#include "apr_allocator.h"
#include "httpd.h"
#ifdef __cplusplus
extern "C" {
struct ap_varbuf_info;
/** A resizable buffer */
struct ap_varbuf {
/** the actual buffer; will point to a const '\0' if avail == 0 and
* to memory of the same lifetime as the pool otherwise */
char *buf;
/** allocated size of the buffer (minus one for the final \0);
* must only be changed using ap_varbuf_grow() */
apr_size_t avail;
/** length of string in buffer, or AP_VARBUF_UNKNOWN. This determines how
* much memory is copied by ap_varbuf_grow() and where
* ap_varbuf_strmemcat() will append to the buffer. */
apr_size_t strlen;
/** the pool for memory allocations and for registering the cleanup;
* the buffer memory will be released when this pool is cleared */
apr_pool_t *pool;
/** opaque info for memory allocation */
struct ap_varbuf_info *info;
/** initialize a resizable buffer. It is safe to re-initialize a prevously
* used ap_varbuf. The old buffer will be released when the corresponding
* pool is cleared. The buffer remains usable until the pool is cleared,
* even if the ap_varbuf was located on the stack and has gone out of scope.
* @param pool the pool to allocate small buffers from and to register the
* cleanup with
* @param vb pointer to the ap_varbuf struct
* @param init_size the initial size of the buffer (see ap_varbuf_grow() for details)
AP_DECLARE(void) ap_varbuf_init(apr_pool_t *pool, struct ap_varbuf *vb,
apr_size_t init_size);
/** grow a resizable buffer. If the vb->buf cannot be grown in place, it will
* be reallocated and the first vb->strlen + 1 bytes of memory will be copied
* to the new location. If vb->strlen == AP_VARBUF_UNKNOWN, the whole buffer
* is copied.
* @param vb pointer to the ap_varbuf struct
* @param new_size the minimum new size of the buffer
* @note ap_varbuf_grow() will usually at least double vb->buf's size with
* every invocation in order to reduce reallications.
* @note ap_varbuf_grow() will use pool memory for small and allocator
* mem nodes for larger allocations.
* @note ap_varbuf_grow() will call vb->pool's abort function if out of memory.
AP_DECLARE(void) ap_varbuf_grow(struct ap_varbuf *vb, apr_size_t new_size);
/** Release memory from a ap_varbuf immediately, if possible.
* This allows to free large buffers before the corresponding pool is
* cleared. Only larger allocations using mem nodes will be freed.
* @param vb pointer to the ap_varbuf struct
* @note After ap_varbuf_free(), vb must not be used unless ap_varbuf_init()
* is called again.
AP_DECLARE(void) ap_varbuf_free(struct ap_varbuf *vb);
/** Concatenate a string to an ap_varbuf. vb->strlen determines where
* the string is appended in the buffer. If vb->strlen == AP_VARBUF_UNKNOWN,
* the string will be appended at the first NUL byte in the buffer.
* If len == 0, ap_varbuf_strmemcat() does nothing.
* @param vb pointer to the ap_varbuf struct
* @param str the string to append; must be at least len bytes long
* @param len the number of characters of *str to concatenate to the buf
* @note vb->strlen will be set to the length of the new string
* @note if len != 0, vb->buf will always be NUL-terminated
AP_DECLARE(void) ap_varbuf_strmemcat(struct ap_varbuf *vb, const char *str,
int len);
/** Duplicate an ap_varbuf's content into pool memory
* @param p the pool to allocate from
* @param vb the ap_varbuf to copy from
* @param prepend an optional buffer to prepend (may be NULL)
* @param prepend_len length of prepend
* @param append an optional buffer to append (may be NULL)
* @param append_len length of append
* @param new_len where to store the length of the resulting string
* (may be NULL)
* @return the new string
* @note ap_varbuf_pdup() uses vb->strlen to determine how much memory to
* copy. It works even if 0-bytes are embedded in vb->buf, prepend, or
* append.
* @note If vb->strlen equals AP_VARBUF_UNKNOWN, it will be set to
* strlen(vb->buf).
AP_DECLARE(char *) ap_varbuf_pdup(apr_pool_t *p, struct ap_varbuf *vb,
const char *prepend, apr_size_t prepend_len,
const char *append, apr_size_t append_len,
apr_size_t *new_len);
/** Concatenate a string to an ap_varbuf
* @param vb pointer to the ap_varbuf struct
* @param str the string to append
* @note vb->strlen will be set to the length of the new string
#define ap_varbuf_strcat(vb, str) ap_varbuf_strmemcat(vb, str, strlen(str))
/** Perform string substitutions based on regexp match, using an ap_varbuf.
* This function behaves like ap_pregsub(), but appends to an ap_varbuf
* instead of allocating the result from a pool.
* @param vb The ap_varbuf to which the string will be appended
* @param input An arbitrary string containing $1 through $9. These are
* replaced with the corresponding matched sub-expressions
* @param source The string that was originally matched to the regex
* @param nmatch the nmatch returned from ap_pregex
* @param pmatch the pmatch array returned from ap_pregex
* @param maxlen the maximum string length to append to vb, 0 for unlimited
* @return APR_SUCCESS if successful
* @note Just like ap_pregsub(), this function does not copy the part of
* *source before the matching part (i.e. the first pmatch[0].rm_so
* characters).
* @note If vb->strlen equals AP_VARBUF_UNKNOWN, it will be set to
* strlen(vb->buf) first.
AP_DECLARE(apr_status_t) ap_varbuf_regsub(struct ap_varbuf *vb,
const char *input,
const char *source,
apr_size_t nmatch,
ap_regmatch_t pmatch[],
apr_size_t maxlen);
/** Read a line from an ap_configfile_t and append it to an ap_varbuf.
* @param vb pointer to the ap_varbuf struct
* @param cfg pointer to the ap_configfile_t
* @param max_len maximum line length, including leading/trailing whitespace
* @return see ap_cfg_getline()
* @note vb->strlen will be set to the length of the line
* @note If vb->strlen equals AP_VARBUF_UNKNOWN, it will be set to
* strlen(vb->buf) first.
AP_DECLARE(apr_status_t) ap_varbuf_cfg_getline(struct ap_varbuf *vb,
ap_configfile_t *cfp,
apr_size_t max_len);
#ifdef __cplusplus
#endif /* !AP_VARBUF_H */
/** @} */
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