SSIGNAL(S) UNIX System V SSIGNAL(S)
Name
ssignal, gsignal - software signals
Syntax
#include <signal.h>
int (*ssignal (sig, action))( )
int sig, (*action)( );
int gsignal (sig)
int sig;
Description
The ssignal and gsignal functions implement a software
facility similar to signal(S). This facility is used by the
Standard C Library to enable users to indicate the
disposition of error conditions, and is also made available
to users for their own purposes.
Software signals made available to users are associated with
integers in the inclusive range 1 through 16. A call to
ssignal associates a procedure, action, with the software
signal sig; the software signal, sig, is raised by a call to
gsignal. Raising a software signal causes the action
established for that signal to be taken.
The first argument to ssignal is a number identifying the
type of signal for which an action is to be established. The
second argument defines the action; it is either the name of
a (user-defined) action function or one of the manifest
constants SIG_DFL (default) or SIG_IGN (ignore). The
ssignal function returns the action previously established
for that signal type; if no action has been established or
the signal number is illegal, ssignal returns SIG_DFL.
The gsignal function raises the signal identified by its
argument, sig:
If an action function has been established for sig,
then that action is reset to SIG_DFL and the action
function is entered with argument sig. gsignal returns
the value returned to it by the action function.
If the action for sig is SIG_IGN, gsignal returns the
value 1 and takes no other action.
If the action for sig is SIG_DFL, gsignal returns the
value 0 and takes no other action.
If sig has an illegal value or no action was ever
specified for sig, gsignal returns the value 0 and
takes no other action.
See Also
signal(S), sigset(S)
Notes
There are some additional signals with numbers outside the
range 1 through 16 which are used by the Standard C Library
to indicate error conditions. Thus, some signal numbers
outside the range 1 through 16 are legal, although their use
may interfere with the operation of the Standard C Library.
Standards Conformance
gsignal and ssignal are conformant with:
AT&T SVID Issue 2, Select Code 307-127;
and The X/Open Portability Guide II of January 1987.
(printed 6/20/89)