summaryrefslogtreecommitdiff
path: root/include/util_varbuf.h
blob: 8e45578e04faf2d9801f857f83c24c2f2a1c0ba7 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
/* 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 */
/** @} */