Envoyé par C89
4.7.1.1 The signal function
Synopsis
#include <signal.h> void (*signal(int sig, void (*func)(int)))(int);
Description
The signal function chooses one of three ways in which receipt of the signal number sig is to be subsequently handled. If the value of func is SIG_DFL , default handling for that signal will occur. If the value of func is SIG_IGN , the signal will be ignored. Otherwise, func shall point to a function to be called when that signal occurs. Such a function is called a signal handler .
When a signal occurs, if func points to a function, first the equivalent of signal(sig, SIG_DFL); is executed or an implementation-defined blocking of the signal is performed. (If the value of sig is SIGILL, whether the reset to SIG_DFL occurs is implementation-defined.) Next the equivalent of (*func)(sig); is executed. The function func may terminate by executing a return statement or by calling the abort , exit , or longjmp function. If func executes a return statement and the value of sig was SIGFPE or any other implementation-defined value corresponding to a computational exception, the behavior is undefined. Otherwise, the program will resume execution at the point it was interrupted.
If the signal occurs other than as the result of calling the abort or raise function, the behavior is undefined if the signal handler calls any function in the standard library other than the signal function itself or refers to any object with static storage duration other than by assigning a value to a static storage duration variable of type volatile sig_atomic_t . Furthermore, if such a call to the signal function results in a SIG_ERR return, the value of errno is indeterminate.
At program startup, the equivalent of
signal(sig, SIG_IGN);
may be executed for some signals selected in an implementation-defined manner; the equivalent of
signal(sig, SIG_DFL);
is executed for all other signals defined by the implementation.
The implementation shall behave as if no library function calls the signal function.
Returns
If the request can be honored, the signal function returns the value of func for the most recent call to signal for the specified signal sig . Otherwise, a value of SIG_ERR is returned and a positive value is stored in errno .
Forward references: the abort function (4.10.4.1).
