SSIGNAL(3C)SSIGNAL(3C)NAME
ssignal, gsignal - software signals
SYNOPSIS
#include <signal.h>
int (*ssignal(int sig, int (*action)(int))(int);
int gsignal(int sig);
DESCRIPTIONssignal and gsignal implement a software facility similar to signal(2).
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). ssignal
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.
Gsignal 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 ALSOsignal(2), sigset(2).
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SSIGNAL(3C)SSIGNAL(3C)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.
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