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SETJMP(3)		    Library Functions Manual		     SETJMP(3)

NAME
       sigsetjmp, siglongjmp, setjmp, longjmp, _setjmp,	_longjmp, longjmperror
       -- non-local jumps

LIBRARY
       Standard	C Library (libc, -lc)

SYNOPSIS
       #include	<setjmp.h>

       int
       sigsetjmp(sigjmp_buf env, int savemask);

       void
       siglongjmp(sigjmp_buf env, int val);

       int
       setjmp(jmp_buf env);

       void
       longjmp(jmp_buf env, int	val);

       int
       _setjmp(jmp_buf env);

       void
       _longjmp(jmp_buf	env, int val);

       void
       longjmperror(void);

DESCRIPTION
       The  sigsetjmp(),  setjmp(), and	_setjmp() functions save their calling
       environment in env.  Each of these functions returns 0.

       The corresponding longjmp() functions restore the environment saved  by
       their  most  recent  respective	invocations  of	the setjmp() function.
       They then return	so that	program	execution continues as if  the	corre-
       sponding	 invocation  of	 the setjmp() call had just returned the value
       specified by val, instead of 0.

       Pairs  of  calls	 may  be  intermixed,  i.e.,  both   sigsetjmp()   and
       siglongjmp() and	setjmp() and longjmp() combinations may	be used	in the
       same  program, however, individual calls	may not, e.g. the env argument
       to setjmp() may not be passed to	siglongjmp().

       The longjmp() routines may not be called	after the routine which	called
       the setjmp() routines returns.

       All accessible objects have values as of	the time longjmp() routine was
       called, except that the values of objects of automatic storage  invoca-
       tion  duration that do not have the volatile type and have been changed
       between the setjmp() invocation and longjmp() call are indeterminate.

       The setjmp()/longjmp() pairs save and restore  the  signal  mask	 while
       _setjmp()/_longjmp()  pairs  save and restore only the register set and
       the stack.  (See	sigprocmask(2).)

       The sigsetjmp()/siglongjmp() function pairs save	and restore the	signal
       mask if the argument savemask is	non-zero, otherwise only the  register
       set and the stack are saved.

ERRORS
       If  the contents	of the env are corrupted, or correspond	to an environ-
       ment that has already returned, the longjmp() routine calls the routine
       longjmperror(3).	 If longjmperror() returns the program is aborted (see
       abort(3)).  The default version of longjmperror()  prints  the  message
       "longjmp	 botch"	 to standard error and returns.	 User programs wishing
       to  exit	 more  gracefully  should  write   their   own	 versions   of
       longjmperror().

SEE ALSO
       sigaction(2), sigaltstack(2), signal(3)

STANDARDS
       The  setjmp()  and  longjmp()  functions	 conform  to ISO/IEC 9899:1990
       ("ISO C90").  The sigsetjmp() and  siglongjmp()	functions  conform  to
       IEEE Std	1003.1-1988 ("POSIX.1").

HISTORY
       The setjmp() and	longjmp() functions first appeared in the Programmer's
       Workbench (PWB/UNIX).

FreeBSD	14.3			 April 2, 2022			     SETJMP(3)

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