NAME    [Toc]    [Back]

     sigreturn - return from signal

LIBRARY    [Toc]    [Back]

     Standard C Library (libc, -lc)

SYNOPSIS    [Toc]    [Back]

     #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    [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.

NOTES    [Toc]    [Back]

     This system call is not available in 4.2BSD 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), signal(7)

HISTORY    [Toc]    [Back]

     The sigreturn() function call appeared in 4.3BSD.

BSD                              June 4, 1993                              BSD