1 | /* Variable-sized buffer with on-stack default allocation. |
2 | Copyright (C) 2015-2017 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 | |
23 | bool |
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 | } |
63 | libc_hidden_def (__libc_scratch_buffer_grow_preserve); |
64 | |