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/* sigaltstack wrappers.
Copyright (C) 2019-2021 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/>. */
#include <support/xsignal.h>
#include <support/support.h>
#include <support/xunistd.h>
#include <support/check.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/param.h> /* roundup, MAX */
#ifndef MAP_NORESERVE
# define MAP_NORESERVE 0
#endif
#ifndef MAP_STACK
# define MAP_STACK 0
#endif
/* The "cookie" returned by xalloc_sigstack points to one of these
structures. */
struct sigstack_desc
{
struct support_stack stack;
stack_t alt_stack; /* The address and size of the stack itself. */
stack_t old_stack; /* The previous signal stack. */
};
void *
xalloc_sigstack (size_t size)
{
struct sigstack_desc *desc = xmalloc (sizeof (struct sigstack_desc));
desc->stack = support_stack_alloc (size);
desc->alt_stack.ss_sp = desc->stack.stack;
desc->alt_stack.ss_flags = 0;
desc->alt_stack.ss_size = desc->stack.size;
if (sigaltstack (&desc->alt_stack, &desc->old_stack))
FAIL_EXIT1 ("sigaltstack (new stack: sp=%p, size=%zu, flags=%u): %m\n",
desc->alt_stack.ss_sp, desc->alt_stack.ss_size,
desc->alt_stack.ss_flags);
return desc;
}
void
xfree_sigstack (void *stack)
{
struct sigstack_desc *desc = stack;
if (sigaltstack (&desc->old_stack, 0))
FAIL_EXIT1 ("sigaltstack (restore old stack: sp=%p, size=%zu, flags=%u): "
"%m\n", desc->old_stack.ss_sp, desc->old_stack.ss_size,
desc->old_stack.ss_flags);
support_stack_free (&desc->stack);
free (desc);
}
void
xget_sigstack_location (const void *stack, unsigned char **addrp, size_t *sizep)
{
const struct sigstack_desc *desc = stack;
*addrp = desc->alt_stack.ss_sp;
*sizep = desc->alt_stack.ss_size;
}
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