| lh | 9ed821d | 2023-04-07 01:36:19 -0700 | [diff] [blame^] | 1 | /* Copyright (C) 1991-2015 Free Software Foundation, Inc. |
| 2 | This file is part of the GNU C Library. |
| 3 | |
| 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. |
| 8 | |
| 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. |
| 13 | |
| 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 | <http://www.gnu.org/licenses/>. */ |
| 17 | |
| 18 | #include <errno.h> |
| 19 | #include <stdint.h> |
| 20 | #include <unistd.h> |
| 21 | |
| 22 | /* Defined in brk.c. */ |
| 23 | extern void *__curbrk; |
| 24 | extern int __brk (void *addr); |
| 25 | |
| 26 | /* Defined in init-first.c. */ |
| 27 | extern int __libc_multiple_libcs attribute_hidden; |
| 28 | |
| 29 | /* Extend the process's data space by INCREMENT. |
| 30 | If INCREMENT is negative, shrink data space by - INCREMENT. |
| 31 | Return start of new space allocated, or -1 for errors. */ |
| 32 | void * |
| 33 | __sbrk (intptr_t increment) |
| 34 | { |
| 35 | void *oldbrk; |
| 36 | |
| 37 | /* If this is not part of the dynamic library or the library is used |
| 38 | via dynamic loading in a statically linked program update |
| 39 | __curbrk from the kernel's brk value. That way two separate |
| 40 | instances of __brk and __sbrk can share the heap, returning |
| 41 | interleaved pieces of it. */ |
| 42 | if (__curbrk == NULL || __libc_multiple_libcs) |
| 43 | if (__brk (0) < 0) /* Initialize the break. */ |
| 44 | return (void *) -1; |
| 45 | |
| 46 | if (increment == 0) |
| 47 | return __curbrk; |
| 48 | |
| 49 | oldbrk = __curbrk; |
| 50 | if (increment > 0 |
| 51 | ? ((uintptr_t) oldbrk + (uintptr_t) increment < (uintptr_t) oldbrk) |
| 52 | : ((uintptr_t) oldbrk < (uintptr_t) -increment)) |
| 53 | { |
| 54 | __set_errno (ENOMEM); |
| 55 | return (void *) -1; |
| 56 | } |
| 57 | |
| 58 | if (__brk (oldbrk + increment) < 0) |
| 59 | return (void *) -1; |
| 60 | |
| 61 | return oldbrk; |
| 62 | } |
| 63 | libc_hidden_def (__sbrk) |
| 64 | weak_alias (__sbrk, sbrk) |