1/* Variable-sized buffer with on-stack default allocation.
2 Copyright (C) 2015-2016 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <http://www.gnu.org/licenses/>. */
18
19#include <scratch_buffer.h>
20#include <errno.h>
21
22bool
23__libc_scratch_buffer_set_array_size (struct scratch_buffer *buffer,
24 size_t nelem, size_t size)
25{
26 size_t new_length = nelem * size;
27
28 /* Avoid overflow check if both values are small. */
29 if ((nelem | size) >> (sizeof (size_t) * CHAR_BIT / 2) != 0
30 && nelem != 0 && size != new_length / nelem)
31 {
32 /* Overflow. Discard the old buffer, but it must remain valid
33 to free. */
34 scratch_buffer_free (buffer);
35 scratch_buffer_init (buffer);
36 __set_errno (ENOMEM);
37 return false;
38 }
39
40 if (new_length <= buffer->length)
41 return true;
42
43 /* Discard old buffer. */
44 scratch_buffer_free (buffer);
45
46 char *new_ptr = malloc (new_length);
47 if (new_ptr == NULL)
48 {
49 /* Buffer must remain valid to free. */
50 scratch_buffer_init (buffer);
51 return false;
52 }
53
54 /* Install new heap-based buffer. */
55 buffer->data = new_ptr;
56 buffer->length = new_length;
57 return true;
58}
59libc_hidden_def (__libc_scratch_buffer_set_array_size);
60