SETJMP(3) Library Functions Manual SETJMP(3)
setjmp, longjmp - non-local goto
These routines are useful for dealing with errors and interrupts
encountered in a low-level subroutine of a program.
Setjmp saves its stack environment in env for later use by longjmp. It
returns value 0.
Longjmp restores the environment saved by the last call of setjmp. It
then returns in such a way that execution continues as if the call of
setjmp had just returned the value val to the function that invoked
setjmp, which must not itself have returned in the interim. All acces-
sible data have values as of the time longjmp was called.