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1 | /* Convenience function to catch expected signals during an operation. | |
2 | Copyright (C) 1996-2024 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 | } |