1 /*
2 * Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining
5 * a copy of this software and associated documentation files (the
6 * "Software"), to deal in the Software without restriction, including
7 * without limitation the rights to use, copy, modify, merge, publish,
8 * distribute, sublicense, and/or sell copies of the Software, and to
9 * permit persons to whom the Software is furnished to do so, subject to
10 * the following conditions:
11 *
12 * The above copyright notice and this permission notice shall be
13 * included in all copies or substantial portions of the Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
16 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
18 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
19 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
20 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
21 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22 * SOFTWARE.
23 */
24
25 #include "brssl.h"
26
27 /*
28 * Prepare a vector buffer for adding 'extra' elements.
29 * buf current buffer
30 * esize size of a vector element
31 * ptr pointer to the 'ptr' vector field
32 * len pointer to the 'len' vector field
33 * extra number of elements to add
34 *
35 * If the buffer must be enlarged, then this function allocates the new
36 * buffer and releases the old one. The new buffer address is then returned.
37 * If the buffer needs not be enlarged, then the buffer address is returned.
38 *
39 * In case of enlargement, the 'len' field is adjusted accordingly. The
40 * 'ptr' field is not modified.
41 */
42 void *
vector_expand(void * buf,size_t esize,size_t * ptr,size_t * len,size_t extra)43 vector_expand(void *buf,
44 size_t esize, size_t *ptr, size_t *len, size_t extra)
45 {
46 size_t nlen;
47 void *nbuf;
48
49 if (*len - *ptr >= extra) {
50 return buf;
51 }
52 nlen = (*len << 1);
53 if (nlen - *ptr < extra) {
54 nlen = extra + *ptr;
55 if (nlen < 8) {
56 nlen = 8;
57 }
58 }
59 nbuf = xmalloc(nlen * esize);
60 if (buf != NULL) {
61 memcpy(nbuf, buf, *len * esize);
62 xfree(buf);
63 }
64 *len = nlen;
65 return nbuf;
66 }
67