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#include <string.h>
22
23bool
24__libc_scratch_buffer_grow_preserve (struct scratch_buffer *buffer)
25{
26 size_t new_length = 2 * buffer->length;
27 void *new_ptr;
28
29 if (buffer->data == buffer->__space)
30 {
31 /* Move buffer to the heap. No overflow is possible because
32 buffer->length describes a small buffer on the stack. */
33 new_ptr = malloc (new_length);
34 if (new_ptr == NULL)
35 return false;
36 memcpy (new_ptr, buffer->__space, buffer->length);
37 }
38 else
39 {
40 /* Buffer was already on the heap. Check for overflow. */
41 if (__glibc_likely (new_length >= buffer->length))
42 new_ptr = realloc (buffer->data, new_length);
43 else
44 {
45 __set_errno (ENOMEM);
46 new_ptr = NULL;
47 }
48
49 if (__glibc_unlikely (new_ptr == NULL))
50 {
51 /* Deallocate, but buffer must remain valid to free. */
52 free (buffer->data);
53 scratch_buffer_init (buffer);
54 return false;
55 }
56 }
57
58 /* Install new heap-based buffer. */
59 buffer->data = new_ptr;
60 buffer->length = new_length;
61 return true;
62}
63libc_hidden_def (__libc_scratch_buffer_grow_preserve);
64