SIGNAL(3) NEWLIB SIGNAL(3)NAME
8.2 `signal'--specify handler subroutine for a signalSYNOPSIS
#include <signal.h>
void (*signal(int SIG, void(*FUNC)(int))) (int);
void (*_signal_r(void *REENT, int SIG, void(*FUNC)(int))) (int);
DESCRIPTION
`signal' provides a simple signal-handling implementation for embedded
targets.
`signal' allows you to request changed treatment for a particular
signal SIG. You can use one of the predefined macros `SIG_DFL' (select
system default handling) or `SIG_IGN' (ignore this signal) as the value
of FUNC; otherwise, FUNC is a function pointer that identifies a sub‐
routine in your program as the handler for this signal.
Some of the execution environment for signal handlers is unpre‐
dictable; notably, the only library function required to work correctly
from within a signal handler is `signal' itself, and only when used to
redefine the handler for the current signal value.
Static storage is likewise unreliable for signal handlers, with one
exception: if you declare a static storage location as ``volatile
sig_atomic_t'', then you may use that location in a signal handler to
store signal values.
If your signal handler terminates using `return' (or implicit
return), your program's execution continues at the point where it was
when the signal was raised (whether by your program itself, or by an
external event). Signal handlers can also use functions such as `exit'
and `abort' to avoid returning.
The alternate function `_signal_r' is the reentrant version. The
extra argument REENT is a pointer to a reentrancy structure.
RETURNS
If your request for a signal handler cannot be honored, the result is
`SIG_ERR'; a specific error number is also recorded in `errno'.
Otherwise, the result is the previous handler (a function pointer or
one of the predefined macros).
PORTABILITY
ANSI C requires `signal'.
No supporting OS subroutines are required to link with `signal', but
it will not have any useful effects, except for software generated sig‐
nals, without an operating system that can actually raise exceptions.
SEE ALSOsignal is part of the library. The full documentation for is main‐
tained as a Texinfo manual. If info and are properly installed at your
site, the command
info
will give you access to the complete manual.
NEWLIB April 2010 SIGNAL(3)
