sigsetjmp(3)						     Library Functions Manual						      sigsetjmp(3)

NAME

       sigsetjmp, siglongjmp - Saves and restores the current execution context

LIBRARY

       Standard C Library  (libc.a, libc.so)

SYNOPSIS

       #include <setjmp.h>

       int sigsetjmp(
	       sigjmp_buf environment ,
	       int savemask);

       void siglongjmp(
	       sigjmp_buf environment,
	       int value);

STANDARDS

       Interfaces documented on this reference page conform to industry standards as follows:

       siglongjmp(), sigsetjmp(): XPG4, XPG4-UNIX

       Refer to the standards(5) reference page for more information about industry standards and associated tags.

PARAMETERS

       Specifies  an address for a sigjmp_buf structure.  Specifies whether the current signal mask should be saved.  If this parameter contains a
       0 (zero) value, sigsetjmp() does not save the signal mask.  Otherwise, the function saves the signal mask.  Specifies the  value  you  want
       written to the execution context as the return value of the sigsetjmp() function.  If you specify 0 (zero) in this parameter, the execution
       context contains a value of 1 as the sigsetjmp() return value.  See the RETURN VALUES section for more information.

DESCRIPTION

       The sigsetjmp() and siglongjmp() functions are useful when handling errors and interrupts encountered in low-level functions of a program.

       The sigsetjmp() function saves the current stack context in the buffer specified by the environment parameter.  If the value of	the  save-
       mask parameter is not 0 (zero), the sigsetjmp() function also saves the process' current signal mask as part of the calling environment.

       You use the buffer specified by the environment parameter in a later call to the siglongjmp() function.	The siglongjmp() function restores
       the stack context and (optionally) signal mask that were saved by the sigsetjmp() function.

       After the siglongjmp() function runs, program execution continues as if the  corresponding  call  to  the  sigsetjmp()  function  had  just
       returned  the  value of the value parameter. The function that called the sigsetjmp() function must not have returned before the completion
       of the siglongjmp() function.

       Because it bypasses the usual function call and return mechanisms, the siglongjmp() function executes correctly in contexts of  interrupts,
       signals,  and  any  of their associated functions.  However, if the siglongjmp() function is invoked from a nested signal handler (that is,
       from a function invoked as a result of a signal raised during the handling of another signal), the behavior is undefined.

CAUTION

       The results of the siglongjmp() function are undefined if one of the following is true: The siglongjmp() function is called with  an  envi-
       ronment	parameter that was not previously set by the sigsetjmp() function The function that made the corresponding call to the sigsetjmp()
       function has already returned.

       If the siglongjmp() function detects one of these conditions, it calls the longjmperror() function.  If longjmperror() returns, the program
       is  aborted.   The  default version of longjmperror() displays an error message to standard error and returns.  If you want your program to
       exit more gracefully, you can write your own version of the longjmperror() program.

RETURN VALUES

       After the siglongjmp() function is finished executing, program execution continues as if the corresponding call of the sigsetjmp() function
       just  returned.	 In other words, the execution context saved by the corresponding sigsetjmp() function is in place and execution continues
       at the statement immediately following the call to the sigsetjmp() function.

       Part of that execution context is the return value from the sigsetjmp() function.  When the sigsetjmp() function actually  returns  (before
       the  call to the siglongjmp() function), that return value is 0 (zero).	When the siglongjmp() function returns, the execution context con-
       tains a non-zero value as the return value from the sigsetjmp() function.

       The value you specify in the value parameter to the siglongjmp() function is written to the execution context as the return value  for  the
       sigsetjmp() function.  You cannot cause the execution context to contain a 0 (zero) value for the sigsetjmp() return value.  If you specify
       0 in the value parameter, the execution context contains a 1 as the sigsetjmp() return value.

RELATED INFORMATION

       Routines: setjmp(3)

       Standards: standards(5) delim off

																      sigsetjmp(3)