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sigreturn(2)

NAME

     sigreturn -- return from signal

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <signal.h>

     int
     sigreturn(ucontext_t *scp);

DESCRIPTION

     The sigreturn() system call 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 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.

NOTES

     This system call is not available in 4.2BSD 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

     The sigreturn() system call will fail and the process 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

     sigvec(2), setjmp(3), ucontext(3)

HISTORY

     The sigreturn() system call appeared in 4.3BSD.

FreeBSD 5.4			 June 4, 1993			   FreeBSD 5.4

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