From 8e62854265eea86eb0d9d01d3421d168f1777e62 Mon Sep 17 00:00:00 2001
From: Andriy Gapon <avg@FreeBSD.org>
Date: Sat, 17 Dec 2011 15:16:54 +0000
Subject: [PATCH] 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
---
 sys/kern/kern_cons.c | 49 ++++++++++++++++++++++++++++++++++++++++++++
 sys/sys/cons.h       |  1 +
 2 files changed, 50 insertions(+)

diff --git a/sys/kern/kern_cons.c b/sys/kern/kern_cons.c
index b5df465bebde..01254e376f67 100644
--- a/sys/kern/kern_cons.c
+++ b/sys/kern/kern_cons.c
@@ -407,6 +407,55 @@ cncheckc(void)
 	return (-1);
 }
 
+void
+cngets(char *cp, size_t size, int visible)
+{
+	char *lp, *end;
+	int c;
+
+	cngrab();
+
+	lp = cp;
+	end = cp + size - 1;
+	for (;;) {
+		c = cngetc() & 0177;
+		switch (c) {
+		case '\n':
+		case '\r':
+			cnputc(c);
+			*lp = '\0';
+			cnungrab();
+			return;
+		case '\b':
+		case '\177':
+			if (lp > cp) {
+				if (visible) {
+					cnputc(c);
+					cnputs(" \b");
+				}
+				lp--;
+			}
+			continue;
+		case '\0':
+			continue;
+		default:
+			if (lp < end) {
+				switch (visible) {
+				case GETS_NOECHO:
+					break;
+				case GETS_ECHOPASS:
+					cnputc('*');
+					break;
+				default:
+					cnputc(c);
+					break;
+				}
+				*lp++ = c;
+			}
+		}
+	}
+}
+
 void
 cnputc(int c)
 {
diff --git a/sys/sys/cons.h b/sys/sys/cons.h
index bd599c095092..79e2574895fc 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);