sigreturn(2) [opendarwin man page]

SIGRETURN(2)						      BSD System Calls Manual						      SIGRETURN(2)

NAME

     sigreturn -- return from signal

SYNOPSIS

     #include <signal.h>

     struct sigcontext {
	     int sc_onstack;
	     int sc_mask;
	     int sc_sp;
	     int sc_fp;
	     int sc_ap;
	     int sc_pc;
	     int sc_ps;
     };

     int
     sigreturn(struct sigcontext *scp);

DESCRIPTION

     Sigreturn() allows users to atomically unmask, switch stacks, and return from a signal context.  The processes signal mask and stack status
     are restored from the context.  The system call does not return; the users stack pointer, frame pointer, argument pointer, and processor sta-
     tus longword are restored from the context.  Execution resumes at the specified pc.  This system call is used by the trampoline code and
     longjmp(3) when returning from a signal to the previously executing program.

NOTES

     This system call is not available in 4.2 BSD hence it should not be used if backward compatibility is needed.

RETURN VALUES

     If successful, the system call does not return.  Otherwise, a value of -1 is returned and errno is set to indicate the error.

ERRORS

     Sigreturn() will fail and the process context will remain unchanged if one of the following occurs.

     [EFAULT]		Scp points to memory that is not a valid part of the process address space.

     [EINVAL]		The process status longword is invalid or would improperly raise the privilege level of the process.

SEE ALSO

     sigaction(2), setjmp(3)

HISTORY

     The sigreturn() function call appeared in 4.3BSD.

4.3 Berkeley Distribution					   June 4, 1993 					 4.3 Berkeley Distribution

sigreturn(2)							System Calls Manual						      sigreturn(2)

NAME

       sigreturn - Returns from signal

SYNOPSIS

       #include <signal.h>
       int sigreturn(	   struct sigcontext *scp) ;

PARAMETERS

       Points  to a sigcontext structure whose members contain the processor state to be restored. The contents of the sigcontext structure should
       have been previously obtained by entry to a signal handler or by the setjmp() or sigsetjmp() function.

DESCRIPTION

       The sigreturn() function restores the processor state of the calling process from a sigcontext structure. The sigcontext structure contains
       the  state  of all application-visible registers as well as the signal mask. The specific members of the sigcontext structure depend on the
       machine architecture. Each machine-dependent structure member is defined in the signal.h include file.

       The sigreturn() function is used internally by the system software to restore the processor state on return from a signal handler and  from
       a longjmp() function, to restore the state saved by a previous setjmp() or sigsetjmp() function.

NOTES

       An application should only use sigreturn() with great caution.

RETURN VALUES

       Upon  successful  completion, the sigreturn() function does not return.	Otherwise, a value of -1 is returned and errno may be set to indi-
       cate the error.

ERRORS

       If the sigreturn() function fails, the process context remains unchanged and errno is set to one of the following values: The scp parameter
       points  to  memory  space  that is not a valid part of the process address space.  The sigcontext structure contains unsupported or illegal
       values.

RELATED INFORMATION

       Functions: setjmp(3), sigaction(2), sigvec(2) delim off

																      sigreturn(2)