1 /* Convenience function to catch expected signals during an operation.
2 Copyright (C) 1996-2023 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 <hurd/signal.h>
20 #include <hurd/sigpreempt.h>
21 #include <string.h>
22 #include <assert.h>
23
24 error_t
25 __hurd_catch_signal (sigset_t sigset,
26 unsigned long int first, unsigned long int last,
27 error_t (*operate) (struct hurd_signal_preemptor *),
28 sighandler_t handler)
29 {
30 /* We need to restore the signal mask, because otherwise the
31 signal-handling code will have blocked the caught signal and for
32 instance calling hurd_catch_signal again would then dump core. */
33 sigjmp_buf buf;
34 void throw (int signo, long int sigcode, struct sigcontext *scp)
35 { siglongjmp (buf, scp->sc_error ?: EGRATUITOUS); }
36
37 struct hurd_signal_preemptor preemptor =
38 {
39 sigset, first, last,
40 NULL, handler == SIG_ERR ? (sighandler_t) &throw : handler,
41 };
42
43 struct hurd_sigstate *const ss = _hurd_self_sigstate ();
44 error_t error;
45
46 if (handler != SIG_ERR)
47 /* Not our handler; don't bother saving state. */
48 error = 0;
49 else
50 /* This returns again with nonzero value when we preempt a signal. */
51 error = sigsetjmp (buf, 1);
52
53 if (error == 0)
54 {
55 /* Install a signal preemptor for the thread. */
56 __spin_lock (&ss->lock);
57 preemptor.next = ss->preemptors;
58 ss->preemptors = &preemptor;
59 __spin_unlock (&ss->lock);
60
61 /* Try the operation that might crash. */
62 (*operate) (&preemptor);
63 }
64
65 /* Either FUNCTION completed happily and ERROR is still zero, or it hit
66 an expected signal and `throw' made setjmp return the signal error
67 code in ERROR. Now we can remove the preemptor and return. */
68
69 __spin_lock (&ss->lock);
70 assert (ss->preemptors == &preemptor);
71 ss->preemptors = preemptor.next;
72 __spin_unlock (&ss->lock);
73
74 return error;
75 }
76 strong_alias (__hurd_catch_signal, hurd_catch_signal)
77
78
79 error_t
80 hurd_safe_memset (void *dest, int byte, size_t nbytes)
81 {
82 error_t operate (struct hurd_signal_preemptor *preemptor)
83 {
84 memset (dest, byte, nbytes);
85 return 0;
86 }
87 return __hurd_catch_signal (__sigmask (SIGBUS) | __sigmask (SIGSEGV),
88 (vm_address_t) dest, (vm_address_t) dest + nbytes,
89 &operate, SIG_ERR);
90 }
91
92
93 error_t
94 hurd_safe_copyout (void *dest, const void *src, size_t nbytes)
95 {
96 error_t operate (struct hurd_signal_preemptor *preemptor)
97 {
98 memcpy (dest, src, nbytes);
99 return 0;
100 }
101 return __hurd_catch_signal (__sigmask (SIGBUS) | __sigmask (SIGSEGV),
102 (vm_address_t) dest, (vm_address_t) dest + nbytes,
103 &operate, SIG_ERR);
104 }
105
106 error_t
107 hurd_safe_copyin (void *dest, const void *src, size_t nbytes)
108 {
109 error_t operate (struct hurd_signal_preemptor *preemptor)
110 {
111 memcpy (dest, src, nbytes);
112 return 0;
113 }
114 return __hurd_catch_signal (__sigmask (SIGBUS) | __sigmask (SIGSEGV),
115 (vm_address_t) src, (vm_address_t) src + nbytes,
116 &operate, SIG_ERR);
117 }
118
119 error_t
120 hurd_safe_memmove (void *dest, const void *src, size_t nbytes)
121 {
122 jmp_buf buf;
123 void throw (int signo, long int sigcode, struct sigcontext *scp)
124 { longjmp (buf, scp->sc_error ?: EGRATUITOUS); }
125
126 struct hurd_signal_preemptor src_preemptor =
127 {
128 __sigmask (SIGBUS) | __sigmask (SIGSEGV),
129 (vm_address_t) src, (vm_address_t) src + nbytes,
130 NULL, (sighandler_t) &throw,
131 };
132 struct hurd_signal_preemptor dest_preemptor =
133 {
134 __sigmask (SIGBUS) | __sigmask (SIGSEGV),
135 (vm_address_t) dest, (vm_address_t) dest + nbytes,
136 NULL, (sighandler_t) &throw,
137 &src_preemptor
138 };
139
140 struct hurd_sigstate *const ss = _hurd_self_sigstate ();
141 error_t error;
142
143 /* This returns again with nonzero value when we preempt a signal. */
144 error = setjmp (buf);
145
146 if (error == 0)
147 {
148 /* Install a signal preemptor for the thread. */
149 __spin_lock (&ss->lock);
150 src_preemptor.next = ss->preemptors;
151 ss->preemptors = &dest_preemptor;
152 __spin_unlock (&ss->lock);
153
154 /* Do the copy; it might fault. */
155 memmove (dest, src, nbytes);
156 }
157
158 /* Either memmove completed happily and ERROR is still zero, or it hit
159 an expected signal and `throw' made setjmp return the signal error
160 code in ERROR. Now we can remove the preemptor and return. */
161
162 __spin_lock (&ss->lock);
163 assert (ss->preemptors == &dest_preemptor);
164 ss->preemptors = src_preemptor.next;
165 __spin_unlock (&ss->lock);
166
167 return error;
168 }