1 /* Variable-sized buffer with on-stack default allocation.
2 Copyright (C) 2015-2023 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 <https://www.gnu.org/licenses/>. */
18
19 #ifndef _LIBC
20 # include <libc-config.h>
21 #endif
22
23 #include <scratch_buffer.h>
24 #include <errno.h>
25 #include <limits.h>
26
27 bool
28 __libc_scratch_buffer_set_array_size (struct scratch_buffer *buffer,
29 size_t nelem, size_t size)
30 {
31 size_t new_length = nelem * size;
32
33 /* Avoid overflow check if both values are small. */
34 if ((nelem | size) >> (sizeof (size_t) * CHAR_BIT / 2) != 0
35 && nelem != 0 && size != new_length / nelem)
36 {
37 /* Overflow. Discard the old buffer, but it must remain valid
38 to free. */
39 scratch_buffer_free (buffer);
40 scratch_buffer_init (buffer);
41 __set_errno (ENOMEM);
42 return false;
43 }
44
45 if (new_length <= buffer->length)
46 return true;
47
48 /* Discard old buffer. */
49 scratch_buffer_free (buffer);
50
51 char *new_ptr = malloc (new_length);
52 if (new_ptr == NULL)
53 {
54 /* Buffer must remain valid to free. */
55 scratch_buffer_init (buffer);
56 return false;
57 }
58
59 /* Install new heap-based buffer. */
60 buffer->data = new_ptr;
61 buffer->length = new_length;
62 return true;
63 }
64 libc_hidden_def (__libc_scratch_buffer_set_array_size)