_ Git - BearSSL/blob - vector.c

   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 *
  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 }