NAME

     sigreturn — return from signal

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <signal.h>

     int
     sigreturn(const ucontext_t *scp);

DESCRIPTION

     The sigreturn() system call allows users to atomically unmask, switch stacks, and return
     from a signal context.  The thread's signal mask and stack status are restored from the
     context structure pointed to by scp.  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.

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

     The sigreturn() system call will fail and the thread context will remain unchanged if one of
     the following occurs.

     [EFAULT]           The scp argument 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), ucontext(3)

HISTORY

     The sigreturn() system call appeared in 4.3BSD.