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util_varbuf.h
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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 * * 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 util_varbuf.h * @brief Apache resizable variable length buffer library * * @defgroup APACHE_CORE_VARBUF Variable length buffer library * @ingroup APACHE_CORE * * This set of functions provides resizable buffers. While the primary * usage is with NUL-terminated strings, most functions also work with * arbitrary binary data. * * @{ */ #ifndef AP_VARBUF_H #define AP_VARBUF_H #include "apr.h" #include "apr_allocator.h" #include "httpd.h" #ifdef __cplusplus extern "C" { #endif #define AP_VARBUF_UNKNOWN APR_SIZE_MAX 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 previously * 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 reallocations. * @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 cfp 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 #endif /* !AP_VARBUF_H */ /** @} */