SIGRETURN(2)                         BSD                          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;
     };

     sigreturn(scp);
     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 status
     longword are restored from the context.  Execution resumes at the
     specified program counter.  This system call is used by the trampoline
     code, and longjmp(3) when returning from a signal to the previously
     executing program.

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
     sigvec(2), setjmp(3)

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

NOTES
     This system call is not available in Domain/IX BSD4.2; hence, it should
     not be used if backward compatibility is needed.