NAME

       sysv_signal - signal handling with System V semantics

SYNOPSIS

       #define _GNU_SOURCE         /* See feature_test_macros(7) */
       #include <signal.h>

       typedef void (*sighandler_t)(int);

       sighandler_t sysv_signal(int signum, sighandler_t handler);

DESCRIPTION

       The  sysv_signal()  function  takes  the  same  arguments,  and performs the same task, as
       signal(2).

       However sysv_signal() provides the System V unreliable signal semantics, that is:  a)  the
       disposition of the signal is reset to the default when the handler is invoked; b) delivery
       of further instances of the signal is not blocked while the signal handler  is  executing;
       and  c) if the handler interrupts (certain) blocking system calls, then the system call is
       not automatically restarted.

RETURN VALUE

       The sysv_signal() function returns the previous value of the signal handler, or SIG_ERR on
       error.

ERRORS

       As for signal(2).

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       ┌──────────────┬───────────────┬─────────┐
       │Interface     │ Attribute     │ Value   │
       ├──────────────┼───────────────┼─────────┤
       │sysv_signal() │ Thread safety │ MT-Safe │
       └──────────────┴───────────────┴─────────┘

CONFORMING TO

       This function is nonstandard.

NOTES

       Use of sysv_signal() should be avoided; use sigaction(2) instead.

       On  older  Linux  systems,  sysv_signal()  and  signal(2)  were  equivalent.  But on newer
       systems, signal(2) provides reliable signal semantics; see signal(2) for details.

       The use of sighandler_t is a GNU extension; this type is defined only if  the  _GNU_SOURCE
       feature test macro is defined.

SEE ALSO

       sigaction(2), signal(2), bsd_signal(3), signal(7)

COLOPHON

       This  page  is  part of release 5.10 of the Linux man-pages project.  A description of the
       project, information about reporting bugs, and the latest version of  this  page,  can  be
       found at https://www.kernel.org/doc/man-pages/.

                                            2017-09-15                             SYSV_SIGNAL(3)