NAME    [Toc]    [Back]

     sigreturn - return from signal

SYNOPSIS    [Toc]    [Back]

     #include <signal.h>

     int
     sigreturn(struct sigcontext *scp);

DESCRIPTION    [Toc]    [Back]

     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 status
     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.

     Note that sigcontext contains machine dependent information.

NOTES    [Toc]    [Back]

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

RETURN VALUES    [Toc]    [Back]

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

ERRORS    [Toc]    [Back]

     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    [Toc]    [Back]

     sigaction(2), setjmp(3)

HISTORY    [Toc]    [Back]

     The sigreturn() function call appeared in 4.3BSD.

OpenBSD      3.6                           June      4,      1993