Gamma™ : Version 6.4
	OS APIs

`block_signal`, `unblock_signal`

block_signal, unblock_signal — delimit signal blocking.

Syntax

block_signal (signo)
unblock_signal (signo)

Arguments

signo: The integer signal number as defined by the operating system. Symbols such as SIGINT are defined to provide an operating-system independent method for specifying this number. (see signal)

Returns

t

Description

block_signal causes a particular signal to be blocked until a call to unblock_signal is made. If the signal actually occurred while it was blocked, it will occur immediately when unblock_signal is called. Multiple occurrences of the signal while it was blocked will cause the signal to be reported multiple times when unblock_signal is called on most operating systems. Code that blocks signals should be surrounded by a call to unwind_protect.

Example

Gamma> block_signal(14);
t
Gamma> kill(getpid(),14);
t
Gamma> unblock_signal(14);
Alarm clock

Gamma> block_signal (SIGINT);
t
Gamma> critical_function();
<function return>
Gamma> unblock_signal (SIGINT);
t


atexit		errno

block_signal, unblock_signal