1SIGVEC(3) Linux Programmer's Manual SIGVEC(3)
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6 sigvec, sigblock, sigsetmask, siggetmask, sigmask - BSD signal API
7
9 #include <signal.h>
10 int sigvec(int sig, const struct sigvec *vec, struct sigvec *ovec);
12 int sigmask(int signum);
14 int sigblock(int mask);
16 int sigsetmask(int mask);
18 int siggetmask(void);
20 Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
22 All functions shown above:
24 Since glibc 2.19:
25 _DEFAULT_SOURCE
26 Glibc 2.19 and earlier:
27 _BSD_SOURCE
28
30 These functions are provided in glibc as a compatibility interface for
31 programs that make use of the historical BSD signal API. This API is
32 obsolete: new applications should use the POSIX signal API (sigac‐
33 tion(2), sigprocmask(2), etc.).
34 The sigvec() function sets and/or gets the disposition of the signal
36 sig (like the POSIX sigaction(2)). If vec is not NULL, it points to a
37 sigvec structure that defines the new disposition for sig. If ovec is
38 not NULL, it points to a sigvec structure that is used to return the
39 previous disposition of sig. To obtain the current disposition of sig
40 without changing it, specify NULL for vec, and a non-null pointer for
41 ovec.
42 The dispositions for SIGKILL and SIGSTOP cannot be changed.
44 The sigvec structure has the following form:
46 struct sigvec {
48 void (*sv_handler)(int); /* Signal disposition */
49 int sv_mask; /* Signals to be blocked in handler */
50 int sv_flags; /* Flags */
51 };
52 The sv_handler field specifies the disposition of the signal, and is
54 either: the address of a signal handler function; SIG_DFL, meaning the
55 default disposition applies for the signal; or SIG_IGN, meaning that
56 the signal is ignored.
57 If sv_handler specifies the address of a signal handler, then sv_mask
59 specifies a mask of signals that are to be blocked while the handler is
60 executing. In addition, the signal for which the handler is invoked is
61 also blocked. Attempts to block SIGKILL or SIGSTOP are silently ig‐
62 nored.
63 If sv_handler specifies the address of a signal handler, then the
65 sv_flags field specifies flags controlling what happens when the han‐
66 dler is called. This field may contain zero or more of the following
67 flags:
68 SV_INTERRUPT
70 If the signal handler interrupts a blocking system call, then
71 upon return from the handler the system call s not be restarted:
72 instead it fails with the error EINTR. If this flag is not
73 specified, then system calls are restarted by default.
74 SV_RESETHAND
76 Reset the disposition of the signal to the default before call‐
77 ing the signal handler. If this flag is not specified, then the
78 handler remains established until explicitly removed by a later
79 call to sigvec() or until the process performs an execve(2).
80 SV_ONSTACK
82 Handle the signal on the alternate signal stack (historically
83 established under BSD using the obsolete sigstack() function;
84 the POSIX replacement is sigaltstack(2)).
85 The sigmask() macro constructs and returns a "signal mask" for signum.
87 For example, we can initialize the vec.sv_mask field given to sigvec()
88 using code such as the following:
89 vec.sv_mask = sigmask(SIGQUIT) | sigmask(SIGABRT);
91 /* Block SIGQUIT and SIGABRT during
92 handler execution */
93 The sigblock() function adds the signals in mask to the process's sig‐
95 nal mask (like POSIX sigprocmask(SIG_BLOCK)), and returns the process's
96 previous signal mask. Attempts to block SIGKILL or SIGSTOP are
97 silently ignored.
98 The sigsetmask() function sets the process's signal mask to the value
100 given in mask (like POSIX sigprocmask(SIG_SETMASK)), and returns the
101 process's previous signal mask.
102 The siggetmask() function returns the process's current signal mask.
104 This call is equivalent to sigblock(0).
105
107 The sigvec() function returns 0 on success; on error, it returns -1 and
108 sets errno to indicate the error.
109 The sigblock() and sigsetmask() functions return the previous signal
111 mask.
112 The sigmask() macro returns the signal mask for signum.
114
116 See the ERRORS under sigaction(2) and sigprocmask(2).
117
119 Starting with version 2.21, the GNU C library no longer exports the
120 sigvec() function as part of the ABI. (To ensure backward compatibil‐
121 ity, the glibc symbol versioning scheme continues to export the inter‐
122 face to binaries linked against older versions of the library.)
123
125 For an explanation of the terms used in this section, see at‐
126 tributes(7).
127 ┌─────────────────────────────────┬───────────────┬─────────┐
129 │Interface │ Attribute │ Value │
130 ├─────────────────────────────────┼───────────────┼─────────┤
131 │sigvec(), sigmask(), sigblock(), │ Thread safety │ MT-Safe │
132 │sigsetmask(), siggetmask() │ │ │
133 └─────────────────────────────────┴───────────────┴─────────┘
135 All of these functions were in 4.3BSD, except siggetmask(), whose ori‐
136 gin is unclear. These functions are obsolete: do not use them in new
137 programs.
138
140 On 4.3BSD, the signal() function provided reliable semantics (as when
141 calling sigvec() with vec.sv_mask equal to 0). On System V, signal()
142 provides unreliable semantics. POSIX.1 leaves these aspects of sig‐
143 nal() unspecified. See signal(2) for further details.
144 In order to wait for a signal, BSD and System V both provided a func‐
146 tion named sigpause(3), but this function has a different argument on
147 the two systems. See sigpause(3) for details.
148
150 kill(2), pause(2), sigaction(2), signal(2), sigprocmask(2), raise(3),
151 sigpause(3), sigset(3), signal(7)
152
154 This page is part of release 5.10 of the Linux man-pages project. A
155 description of the project, information about reporting bugs, and the
156 latest version of this page, can be found at
157 https://www.kernel.org/doc/man-pages/.
158Linux 2020-08-13 SIGVEC(3)