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9c2866d7 | 25 | .\" |
4b8c67d9 | 26 | .TH SIGVEC 3 2017-09-15 "Linux" "Linux Programmer's Manual" |
9c2866d7 MK |
27 | .SH NAME |
28 | sigvec, sigblock, sigsetmask, siggetmask, sigmask \- BSD signal API | |
29 | .SH SYNOPSIS | |
9c2866d7 | 30 | .B #include <signal.h> |
68e4db0a | 31 | .PP |
7accd937 | 32 | .BI "int sigvec(int " sig ", const struct sigvec *" vec ", struct sigvec *" ovec ); |
68e4db0a | 33 | .PP |
9c2866d7 | 34 | .BI "int sigmask(int " signum ); |
68e4db0a | 35 | .PP |
9c2866d7 | 36 | .BI "int sigblock(int " mask ); |
68e4db0a | 37 | .PP |
9c2866d7 | 38 | .BI "int sigsetmask(int " mask ); |
68e4db0a | 39 | .PP |
9c2866d7 | 40 | .B int siggetmask(void); |
68e4db0a | 41 | .PP |
cc4615cc MK |
42 | .in -4n |
43 | Feature Test Macro Requirements for glibc (see | |
44 | .BR feature_test_macros (7)): | |
45 | .in | |
68e4db0a | 46 | .PP |
cfc2d88d | 47 | All functions shown above: |
51c612fb MK |
48 | Since glibc 2.19: |
49 | _DEFAULT_SOURCE | |
50 | Glibc 2.19 and earlier: | |
51 | _BSD_SOURCE | |
9c2866d7 MK |
52 | .SH DESCRIPTION |
53 | These functions are provided in glibc as a compatibility interface | |
54 | for programs that make use of the historical BSD signal API. | |
c13182ef MK |
55 | This API is obsolete: new applications should use the POSIX signal API |
56 | .RB ( sigaction (2), | |
9c2866d7 | 57 | .BR sigprocmask (2), |
1bea464c | 58 | etc.). |
847e0d88 | 59 | .PP |
9c2866d7 MK |
60 | The |
61 | .BR sigvec () | |
62 | function sets and/or gets the disposition of the signal | |
c13182ef | 63 | .I sig |
9c2866d7 MK |
64 | (like the POSIX |
65 | .BR sigaction (2)). | |
c13182ef | 66 | If |
9c2866d7 MK |
67 | .I vec |
68 | is not NULL, it points to a | |
69 | .I sigvec | |
c13182ef | 70 | structure that defines the new disposition for |
9c2866d7 MK |
71 | .IR sig . |
72 | If | |
73 | .I ovec | |
c13182ef | 74 | is not NULL, it points to a |
9c2866d7 MK |
75 | .I sigvec |
76 | structure that is used to return the previous disposition of | |
77 | .IR sig . | |
c13182ef | 78 | To obtain the current disposition of |
9c2866d7 MK |
79 | .I sig |
80 | without changing it, specify NULL for | |
c13182ef | 81 | .IR vec , |
b437fdd9 | 82 | and a non-null pointer for |
9c2866d7 | 83 | .IR ovec . |
847e0d88 | 84 | .PP |
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85 | The dispositions for |
86 | .B SIGKILL | |
c13182ef | 87 | and |
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88 | .B SIGSTOP |
89 | cannot be changed. | |
847e0d88 | 90 | .PP |
9c2866d7 MK |
91 | The |
92 | .I sigvec | |
93 | structure has the following form: | |
e646a1ba | 94 | .PP |
088a639b | 95 | .in +4n |
e646a1ba | 96 | .EX |
9c2866d7 | 97 | struct sigvec { |
559a2b66 MK |
98 | void (*sv_handler)(int); /* Signal disposition */ |
99 | int sv_mask; /* Signals to be blocked in handler */ | |
100 | int sv_flags; /* Flags */ | |
9c2866d7 | 101 | }; |
e646a1ba | 102 | .EE |
d4f3dcff | 103 | .in |
e646a1ba | 104 | .PP |
9c2866d7 MK |
105 | The |
106 | .I sv_handler | |
107 | field specifies the disposition of the signal, and is either: | |
4eaa04c5 | 108 | the address of a signal handler function; |
1bea464c | 109 | .BR SIG_DFL , |
9c2866d7 | 110 | meaning the default disposition applies for the signal; or |
1bea464c | 111 | .BR SIG_IGN , |
9c2866d7 | 112 | meaning that the signal is ignored. |
847e0d88 | 113 | .PP |
9c2866d7 MK |
114 | If |
115 | .I sv_handler | |
116 | specifies the address of a signal handler, then | |
117 | .I sv_mask | |
c13182ef | 118 | specifies a mask of signals that are to be blocked while |
9c2866d7 | 119 | the handler is executing. |
c13182ef | 120 | In addition, the signal for which the handler is invoked is |
e191c685 | 121 | also blocked. |
9c2866d7 MK |
122 | Attempts to block |
123 | .B SIGKILL | |
c13182ef | 124 | or |
9c2866d7 MK |
125 | .B SIGSTOP |
126 | are silently ignored. | |
847e0d88 | 127 | .PP |
9c2866d7 MK |
128 | If |
129 | .I sv_handler | |
130 | specifies the address of a signal handler, then the | |
131 | .I sv_flags | |
132 | field specifies flags controlling what happens when the handler is called. | |
133 | This field may contain zero or more of the following flags: | |
134 | .TP | |
135 | .B SV_INTERRUPT | |
136 | If the signal handler interrupts a blocking system call, | |
a23d8efa MK |
137 | then upon return from the handler the system call s not be restarted: |
138 | instead it fails with the error | |
7b2b5ea4 | 139 | .BR EINTR . |
c13182ef | 140 | If this flag is not specified, then system calls are restarted |
9c2866d7 MK |
141 | by default. |
142 | .TP | |
143 | .B SV_RESETHAND | |
c13182ef | 144 | Reset the disposition of the signal to the default |
9c2866d7 MK |
145 | before calling the signal handler. |
146 | If this flag is not specified, then the handler remains established | |
c13182ef | 147 | until explicitly removed by a later call to |
9c2866d7 MK |
148 | .BR sigvec () |
149 | or until the process performs an | |
150 | .BR execve (2). | |
151 | .TP | |
152 | .B SV_ONSTACK | |
c13182ef MK |
153 | Handle the signal on the alternate signal stack |
154 | (historically established under BSD using the obsolete | |
9c2866d7 | 155 | .BR sigstack () |
c13182ef | 156 | function; the POSIX replacement is |
fb186734 | 157 | .BR sigaltstack (2)). |
9c2866d7 | 158 | .PP |
c13182ef | 159 | The |
9c2866d7 | 160 | .BR sigmask () |
c1729f52 | 161 | macro constructs and returns a "signal mask" for |
9c2866d7 | 162 | .IR signum . |
d9bfdb9c | 163 | For example, we can initialize the |
c13182ef MK |
164 | .I vec.sv_mask |
165 | field given to | |
9c2866d7 MK |
166 | .BR sigvec () |
167 | using code such as the following: | |
207050fa MK |
168 | .PP |
169 | .in +4n | |
170 | .EX | |
171 | vec.sv_mask = sigmask(SIGQUIT) | sigmask(SIGABRT); | |
172 | /* Block SIGQUIT and SIGABRT during | |
173 | handler execution */ | |
174 | .EE | |
175 | .in | |
9c2866d7 MK |
176 | .PP |
177 | The | |
178 | .BR sigblock () | |
179 | function adds the signals in | |
180 | .I mask | |
181 | to the process's signal mask | |
c13182ef | 182 | (like POSIX |
9c2866d7 MK |
183 | .IR sigprocmask(SIG_BLOCK) ), |
184 | and returns the process's previous signal mask. | |
185 | Attempts to block | |
186 | .B SIGKILL | |
c13182ef | 187 | or |
9c2866d7 MK |
188 | .B SIGSTOP |
189 | are silently ignored. | |
190 | .PP | |
c13182ef | 191 | The |
9c2866d7 MK |
192 | .BR sigsetmask () |
193 | function sets the process's signal mask to the value given in | |
c13182ef MK |
194 | .I mask |
195 | (like POSIX | |
9c2866d7 MK |
196 | .IR sigprocmask(SIG_SETMASK) ), |
197 | and returns the process's previous signal mask. | |
198 | .PP | |
199 | The | |
200 | .BR siggetmask () | |
201 | function returns the process's current signal mask. | |
202 | This call is equivalent to | |
203 | .IR sigblock(0) . | |
204 | .SH RETURN VALUE | |
c13182ef | 205 | The |
9c2866d7 MK |
206 | .BR sigvec () |
207 | function returns 0 on success; on error, it returns \-1 and sets | |
c13182ef | 208 | .I errno |
9c2866d7 | 209 | to indicate the error. |
847e0d88 | 210 | .PP |
9c2866d7 MK |
211 | The |
212 | .BR sigblock () | |
213 | and | |
214 | .BR sigsetmask () | |
215 | functions return the previous signal mask. | |
847e0d88 | 216 | .PP |
9c2866d7 MK |
217 | The |
218 | .BR sigmask () | |
c1729f52 | 219 | macro returns the signal mask for |
9c2866d7 MK |
220 | .IR signum . |
221 | .SH ERRORS | |
222 | See the ERRORS under | |
223 | .BR sigaction (2) | |
224 | and | |
225 | .BR sigprocmask (2). | |
84f6b067 MK |
226 | .SH VERSIONS |
227 | Starting with version 2.21, the GNU C library no longer exports the | |
228 | .BR sigvec () | |
229 | function as part of the ABI. | |
230 | (To ensure backward compatibility, | |
231 | the glibc symbol versioning scheme continues to export the interface | |
232 | to binaries linked against older versions of the library.) | |
74fe2018 | 233 | .SH ATTRIBUTES |
3c180819 PH |
234 | For an explanation of the terms used in this section, see |
235 | .BR attributes (7). | |
236 | .TS | |
237 | allbox; | |
238 | lbw32 lb lb | |
239 | l l l. | |
240 | Interface Attribute Value | |
241 | T{ | |
74fe2018 | 242 | .BR sigvec (), |
3c180819 | 243 | .BR sigmask (), |
74fe2018 PH |
244 | .BR sigblock (), |
245 | .BR sigsetmask (), | |
74fe2018 | 246 | .BR siggetmask () |
3c180819 PH |
247 | T} Thread safety MT-Safe |
248 | .TE | |
47297adb | 249 | .SH CONFORMING TO |
2b2581ee MK |
250 | All of these functions were in |
251 | 4.3BSD, except | |
252 | .BR siggetmask (), | |
253 | whose origin is unclear. | |
254 | These functions are obsolete: do not use them in new programs. | |
9c2866d7 MK |
255 | .SH NOTES |
256 | On 4.3BSD, the | |
257 | .BR signal () | |
c13182ef | 258 | function provided reliable semantics (as when calling |
9c2866d7 MK |
259 | .BR sigvec () |
260 | with | |
261 | .I vec.sv_mask | |
262 | equal to 0). | |
263 | On System V, | |
264 | .BR signal () | |
265 | provides unreliable semantics. | |
9041febd | 266 | POSIX.1 leaves these aspects of |
9c2866d7 MK |
267 | .BR signal () |
268 | unspecified. | |
c13182ef | 269 | See |
9c2866d7 MK |
270 | .BR signal (2) |
271 | for further details. | |
847e0d88 | 272 | .PP |
9c2866d7 MK |
273 | In order to wait for a signal, |
274 | BSD and System V both provided a function named | |
7a056410 | 275 | .BR sigpause (3), |
9c2866d7 MK |
276 | but this function has a different argument on the two systems. |
277 | See | |
278 | .BR sigpause (3) | |
279 | for details. | |
47297adb | 280 | .SH SEE ALSO |
9c2866d7 MK |
281 | .BR kill (2), |
282 | .BR pause (2), | |
9c2866d7 MK |
283 | .BR sigaction (2), |
284 | .BR signal (2), | |
285 | .BR sigprocmask (2), | |
9fe51d8d | 286 | .BR raise (3), |
46c721e7 MK |
287 | .BR sigpause (3), |
288 | .BR sigset (3), | |
9c2866d7 | 289 | .BR signal (7) |