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sigsetjmp(3)
NAME
  sigsetjmp, siglongjmp - Save and restores the current execution context

SYNOPSIS
  #include <setjmp.h>

  int sigsetjmp(
	  sigjmp_buf environment,
	  int savemask );

  void siglongjmp(
	  sigjmp_buf environment,
	  int value );

LIBRARY
  Standard C Library (libc)

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
  environment
      Specifies an address for a sigjmp_buf structure.

  savemask
      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.

  value
      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 savemask
  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.

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 contains 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.

CAUTION
  The results of the siglongjmp() function are undefined if one of the
  following is true:

    ·  The siglongjmp() function is called with an environment 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.

SEE ALSO
  Routines: setjmp(3)

  Standards: standards(5)

Index for Section 3

Alphabetical listing for S

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