The GNU C Library - Non-Local Exits and Signals

Non-Local Exits and Signals

In BSD Unix systems, setjmp and longjmp also save and restore the set of blocked signals; see Blocking Signals. However, the POSIX.1 standard requires setjmp and longjmp not to change the set of blocked signals, and provides an additional pair of functions (sigsetjmp and sigsetjmp ) to get the BSD behavior.

The behavior of setjmp and longjmp in the GNU library is controlled by feature test macros; see Feature Test Macros. The default in the GNU system is the POSIX.1 behavior rather than the BSD behavior.

The facilities in this section are declared in the header file `setjmp.h'.

Data Type sigjmp_buf

This is similar to jmp_buf , except that it can also store state information about the set of blocked signals.

Function int sigsetjmp (sigjmp_buf state, int savesigs)

This is similar to setjmp . If savesigs is nonzero, the set of blocked signals is saved in state and will be restored if a siglongjmp is later performed with this state.

Function void siglongjmp (sigjmp_buf state, int value)

This is similar to longjmp except for the type of its state argument. If the sigsetjmp call that set this state used a nonzero savesigs flag, siglongjmp also restores the set of blocked signals.