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SETJMP(3)                BSD Library Functions Manual                SETJMP(3)

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

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <setjmp.h>

     void
     _longjmp(jmp_buf env, int val);

     int
     _setjmp(jmp_buf env);

     void
     longjmp(jmp_buf env, int val);

     void
     longjmperror(void);

     int
     setjmp(jmp_buf env);

     void
     siglongjmp(sigjmp_buf env, int val);

     int
     sigsetjmp(sigjmp_buf env, int savemask);

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 corresponding
     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 invocation
     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 environment
     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'').

BSD                              June 4, 1993                              BSD