introduce cngets, a method for kernel to read a string from console

This is intended as a replacement for libkern's gets and mostly borrows
its implementation.  It uses cngrab/cnungrab to delimit kernel's access
to console input.

Note: libkern's gets obviously doesn't share any bits of implementation
iwth libc's gets.  They also have different APIs and the former doesn't
have the overflow problems of the latter.

Inspired by:	bde
MFC after:	2 months

1 files changed, 1 insertions, 0 deletions

diff --git a/sys/sys/cons.h b/sys/sys/cons.h
index bd599c0..79e2574 100644
--- a/sys/sys/cons.h
+++ b/sys/sys/cons.h
@@ -121,6 +121,7 @@ void	cngrab(void);
 void	cnungrab(void);
 int	cncheckc(void);
 int	cngetc(void);
+void	cngets(char *, size_t, int);
 void	cnputc(int);
 void	cnputs(char *);
 int	cnunavailable(void);