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81 lines
2.3 KiB
C
81 lines
2.3 KiB
C
/* Copyright (C) 1991-2025 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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/* Mark symbols hidden in static PIE for early self relocation to work. */
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#if BUILD_PIE_DEFAULT
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# pragma GCC visibility push(hidden)
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#endif
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#include <errno.h>
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#include <libc-internal.h>
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#include <stdbool.h>
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#include <stdint.h>
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#include <unistd.h>
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/* Defined in brk.c. */
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extern void *__curbrk;
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extern int __brk (void *addr);
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/* Extend the process's data space by INCREMENT.
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If INCREMENT is negative, shrink data space by - INCREMENT.
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Return start of new space allocated, or -1 for errors. */
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void *
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__sbrk (intptr_t increment)
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{
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/* Controls whether __brk (0) is called to read the brk value from
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the kernel. */
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bool update_brk = __curbrk == NULL;
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#if defined (SHARED) && ! IS_IN (rtld)
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if (!__libc_initial)
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{
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if (increment != 0)
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{
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/* Do not allow changing the brk from an inner libc because
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it cannot be synchronized with the outer libc's brk. */
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__set_errno (ENOMEM);
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return (void *) -1;
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}
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/* Querying the kernel's brk value from an inner namespace is
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fine. */
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update_brk = true;
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}
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#endif
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if (update_brk)
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if (__brk (NULL) < 0) /* Initialize the break. */
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return (void *) -1;
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if (increment == 0)
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return __curbrk;
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void *oldbrk = __curbrk;
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if (increment > 0
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? ((uintptr_t) oldbrk + (uintptr_t) increment < (uintptr_t) oldbrk)
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: ((uintptr_t) oldbrk < (uintptr_t) -increment))
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{
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__set_errno (ENOMEM);
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return (void *) -1;
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}
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if (__brk (oldbrk + increment) < 0)
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return (void *) -1;
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return oldbrk;
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}
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libc_hidden_def (__sbrk)
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weak_alias (__sbrk, sbrk)
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