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sigstack(2)
NAME
  sigstack - Set and get the signal stack context

SYNOPSIS
  #include <signal.h>

  int sigstack(
	  struct sigstack *instack,
	  struct sigstack *outstack );

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

  sigstack():  XSH4.0, XSH4.2, XSH5.0

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

PARAMETERS
  instack Points to the structure describing the new signal stack.

  outstack
	  Points to the structure where the current signal stack state is
	  stored.

DESCRIPTION
  The sigstack() function defines an alternate stack on which signals are to
  be processed.

  If the value of the instack parameter is nonzero, it points to a sigstack
  structure, which has the following members:

	struct sigstack{
	       caddr_t	ss_sp;
	       int	ss_onstack; }

  The value of instack->ss_sp specifies the stack pointer of the new signal
  stack. The value of instack->ss_onstack should be set to 1 if the process
  is currently running on that stack; otherwise, it should be 0 (zero).

  If the value of the instack parameter is 0 (that is, a null pointer), the
  signal stack state is not set.

  If the value of the outstack parameter is nonzero, it points to a sigstack
  structure into which the sigstack() function stores the current signal
  stack state. If the value of the outstack parameter is 0 (zero), the
  previous signal stack state is not reported.

  When a signal occurs and its handler is to run on the signal stack, the
  system checks to see if the process is already running on that stack.	 If
  so, the process continues to run on that stack even after the handler
  returns.  If not, the signal handler runs on the signal stack, and the
  original stack is restored when the handler returns.

  Use the sigaction() function to specify whether a given signal handler
  routine is to run on the signal stack.

NOTES
  A signal stack does not automatically increase in size as a normal stack
  does. If the stack overflows, unpredictable results can occur.

  The sigstack() function is defined as a LEGACY function by the XSH
  specification. XSH recommends that sigaltstack() rather than sigstack() be
  used when creating or rewriting portable applications.

RETURN VALUES
  Upon successful completion, a value of 0 (zero) is returned. Otherwise, a
  value of -1 is returned and errno is set to indicate the error.

ERRORS
  The sigstack() function sets errno to the specified value for the following
  conditions:

  [EFAULT]
	  [Tru64 UNIX]	The instack or outstack parameter points outside of
	  the address space of the process.

  [EPERM] An attempt was made to modify an active stack.

SEE ALSO
  Functions: sigaction(2), sigvec(2), setjmp(3)

  Standards: standards(5)

Index for Section 2

Alphabetical listing for S

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