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git.ipfire.org Git - thirdparty/glibc.git/blob - misc/sbrk.c
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1 /* Copyright (C) 1991-2021 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
19 #include <libc-internal.h>
24 /* Defined in brk.c. */
25 extern void *__curbrk
;
26 extern int __brk (void *addr
);
28 /* Extend the process's data space by INCREMENT.
29 If INCREMENT is negative, shrink data space by - INCREMENT.
30 Return start of new space allocated, or -1 for errors. */
32 __sbrk (intptr_t increment
)
34 /* Controls whether __brk (0) is called to read the brk value from
36 bool update_brk
= __curbrk
== NULL
;
38 #if defined (SHARED) && ! IS_IN (rtld)
43 /* Do not allow changing the brk from an inner libc because
44 it cannot be synchronized with the outer libc's brk. */
48 /* Querying the kernel's brk value from an inner namespace is
55 if (__brk (0) < 0) /* Initialize the break. */
61 void *oldbrk
= __curbrk
;
63 ? ((uintptr_t) oldbrk
+ (uintptr_t) increment
< (uintptr_t) oldbrk
)
64 : ((uintptr_t) oldbrk
< (uintptr_t) -increment
))
70 if (__brk (oldbrk
+ increment
) < 0)
75 libc_hidden_def (__sbrk
)
76 weak_alias (__sbrk
, sbrk
)