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.\" @(#)sigreturn.2 6.5 (Berkeley) 3/10/91
.Fd #include <sys/signal.h>
.Fn sigreturn "struct sigcontext *scp"
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
when returning from a signal to the previously executing program.
This system call is not available in 4.2
hence it should not be used if backward compatibility is needed.
If successful, the system call does not return.
Otherwise, a value of -1 is returned and
is set to indicate the error.
will fail and the process context will remain unchanged
if one of the following occurs.
points to memory that is not a valid part of the process
The process status longword is invalid or would improperly
raise the privilege level of the process.
function call appeared in