1/* Variable-sized buffer with on-stack default allocation.
2   Copyright (C) 2015-2022 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
27bool
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}
64libc_hidden_def (__libc_scratch_buffer_set_array_size)
65