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/* Copyright (C) 2023-2024 Free Software Foundation, Inc.
This file is part of GNU Bash, the Bourne Again SHell.
Bash is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Bash is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with Bash. If not, see <http://www.gnu.org/licenses/>.
*/
#include <config.h>
#include <unistd.h>
#include <errno.h>
#if defined (HAVE_BRK) && !defined (HAVE_SBRK)
static void *initialbrk;
static void *curbrk;
static int
initbrk (void)
{
if (initialbrk == 0)
{
void *b;
b = brk (NULL);
if (b == (void *)-1)
return -1;
initialbrk = curbrk = b;
}
return (0);
}
/* sbrk(3) implementation in terms of brk(2). Good enough for malloc to use. */
void *
sbrk (intptr_t incr)
{
void *newbrk, *oldbrk;
if (initialbrk == 0 && initbrk () == -1)
{
errno = ENOMEM;
return (void *)-1;
}
if (incr == 0)
return curbrk;
/* bounds checking, overflow */
if ((incr > 0 && (uintptr_t) curbrk + incr < (uintptr_t) curbrk) ||
(incr < 0 && (uintptr_t) curbrk + incr > (uintptr_t) curbrk))
{
errno = ENOMEM;
return (void *)-1;
}
newbrk = curbrk + incr;
if (newbrk < initialbrk)
{
errno = EINVAL;
return (void *)-1;
}
if (brk (newbrk) == (void *)-1)
return (void *)-1; /* preserve errno */
oldbrk = curbrk;
curbrk = newbrk;
return (oldbrk);
}
#endif /* HAVE_BRK && !HAVE_SBRK */
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