1/* sigaltstack wrappers.
2 Copyright (C) 2019-2023 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <support/xsignal.h>
20#include <support/support.h>
21#include <support/xunistd.h>
22#include <support/check.h>
23
24#include <stdlib.h>
25#include <string.h>
26#include <sys/mman.h>
27#include <sys/param.h> /* roundup, MAX */
28
29#ifndef MAP_NORESERVE
30# define MAP_NORESERVE 0
31#endif
32#ifndef MAP_STACK
33# define MAP_STACK 0
34#endif
35
36/* The "cookie" returned by xalloc_sigstack points to one of these
37 structures. */
38struct sigstack_desc
39{
40 struct support_stack stack;
41 stack_t alt_stack; /* The address and size of the stack itself. */
42 stack_t old_stack; /* The previous signal stack. */
43};
44
45void *
46xalloc_sigstack (size_t size)
47{
48 struct sigstack_desc *desc = xmalloc (sizeof (struct sigstack_desc));
49 desc->stack = support_stack_alloc (size);
50 desc->alt_stack.ss_sp = desc->stack.stack;
51 desc->alt_stack.ss_flags = 0;
52 desc->alt_stack.ss_size = desc->stack.size;
53
54 if (sigaltstack (&desc->alt_stack, &desc->old_stack))
55 FAIL_EXIT1 ("sigaltstack (new stack: sp=%p, size=%zu, flags=%u): %m\n",
56 desc->alt_stack.ss_sp, desc->alt_stack.ss_size,
57 desc->alt_stack.ss_flags);
58
59 return desc;
60}
61
62void
63xfree_sigstack (void *stack)
64{
65 struct sigstack_desc *desc = stack;
66
67 if (sigaltstack (&desc->old_stack, 0))
68 FAIL_EXIT1 ("sigaltstack (restore old stack: sp=%p, size=%zu, flags=%u): "
69 "%m\n", desc->old_stack.ss_sp, desc->old_stack.ss_size,
70 desc->old_stack.ss_flags);
71 support_stack_free (&desc->stack);
72 free (desc);
73}
74
75void
76xget_sigstack_location (const void *stack, unsigned char **addrp, size_t *sizep)
77{
78 const struct sigstack_desc *desc = stack;
79 *addrp = desc->alt_stack.ss_sp;
80 *sizep = desc->alt_stack.ss_size;
81}
82