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/* Early memory allocation for the dynamic loader. Generic version.
Copyright (C) 2022 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
/* Mark symbols hidden in static PIE for early self relocation to work. */
#if BUILD_PIE_DEFAULT
# pragma GCC visibility push(hidden)
#endif
#include <startup.h>
#include <ldsodefs.h>
#include <stddef.h>
#include <string.h>
#include <sysdep.h>
#include <unistd.h>
#include <brk_call.h>
#include <mmap_call.h>
/* Defined in brk.c. */
extern void *__curbrk;
void *
_dl_early_allocate (size_t size)
{
void *result;
if (__curbrk != NULL)
/* If the break has been initialized, brk must have run before,
so just call it once more. */
{
result = __sbrk (size);
if (result == (void *) -1)
result = NULL;
}
else
{
/* If brk has not been invoked, there is no need to update
__curbrk. The first call to brk will take care of that. */
void *previous = __brk_call (0);
result = __brk_call (previous + size);
if (result == previous)
result = NULL;
else
result = previous;
}
/* If brk fails, fall back to mmap. This can happen due to
unfortunate ASLR layout decisions and kernel bugs, particularly
for static PIE. */
if (result == NULL)
{
intptr_t ret;
int prot = PROT_READ | PROT_WRITE;
int flags = MAP_PRIVATE | MAP_ANONYMOUS;
#ifdef __NR_mmap2
ret = MMAP_CALL_INTERNAL (mmap2, 0, size, prot, flags, -1, 0);
#else
ret = MMAP_CALL_INTERNAL (mmap, 0, size, prot, flags, -1, 0);
#endif
if (INTERNAL_SYSCALL_ERROR_P (ret))
result = NULL;
else
result = (void *) ret;
}
return result;
}
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