9os

commit 01df3e6dcb31efe1959d9debeaca6013512df849
parent a18a0a49e712bc4f95b5e5ff80cd804f74fadb28
Author: Roberto E. Vargas Caballero <k0ga@shike2.com>
Date:   Tue,  8 Sep 2020 10:04:59 +0200

devcons: Improve quality of the code

Change-Id: I12385387724257babdba5c2be1bdd917922417e7

Diffstat:
M
src/kernel/dev/devcons.c
 | 
107
++++++++++++++++++++++++++++++++++++++-----------------------------------------

1 file changed, 52 insertions(+), 55 deletions(-)
diff --git a/src/kernel/dev/devcons.c b/src/kernel/dev/devcons.c
@@ -15,6 +15,7 @@
 #define CONSSTATUS   128
 
 #define CTRL(x) ((x) & 0x1f)
+#define DEL 127
 
 enum Orootqid {
 	Qconsfs,
@@ -118,14 +119,6 @@ conswriteraw(char *buf, int n)
 }
 
 static int
-echo(void *buf, int n)
-{
-	if (!echof)
-		return n;
-	return conswriteraw(buf, n);
-}
-
-static int
 consaddin(struct conscmd *cmd, char *s)
 {
 	if (in) {
@@ -238,85 +231,92 @@ conswrite(Chan *c, void *buf, int n)
 	}
 }
 
+static int
+echo(char *buf, int n)
+{
+	if (echof) {
+		if (conswriteraw(buf, n) < 0)
+			return -1;
+	}
+	return buf[n-1];
+}
+
 static void
 erase(int n)
 {
 	int i;
-	char editingchar;
+	char ch;
 
-	if (head + 1 < n)
-		n = head + 1;
+	if (head < n)
+		n = head;
 
-	editingchar = '\b';
+	ch = '\b';
 	for (i = 0; i < n; i++)
-		echo(&editingchar, 1);
-	editingchar = ' ';
+		echo(&ch, 1);
+	ch = ' ';
 	for (i = 0; i < n; i++)
-		echo(&editingchar, 1);
-	editingchar = '\b';
+		echo(&ch, 1);
+	ch = '\b';
 	for (i = 0; i < n; i++)
-		echo(&editingchar, 1);
+		echo(&ch, 1);
+
+	head -= n;
 }
 
 static int
-consreadediting(Chan *c)
+wordsize(void)
 {
-	int i;
-	char ch;
+	int i = 1;
+
+	while (head - i > 0 && buffer[head - i] == ' ')
+		i++;
+	while (head - i > 0 && buffer[head - i] != ' ')
+		i++;
+
+	return 1;
+}
 
+static int
+edit(char key)
+{
+	char ch;
 
-	if (!cookedf)
-		return echo(&buffer[head], 1);
+	if (!cookedf) {
+		buffer[head++] = key;
+		return echo(&key, 1);
+	}
 
-	/*
-	 * it relies on the fact that head is incremented in the
-	 * calling function after exiting this one. For example, head is
-	 * briefly equal to -1 when backspace is hit on an empty line.
-	 */
-	switch (buffer[head]) {
+	switch (key) {
 	case '\0':
-		return -1;
+		return 0;
 	case '\b':
-	case 127:                /* DEL */
-		head--;
+	case DEL:
 		erase(1);
-		head -= head >= 0;
 		return 0;
 	case CTRL('L'):
 		ch = '\r';
 		echo(&ch, 1);
-		echo(buffer, head);
-		head--;
+		echo(buffer, head-1);
 		return 0;
 	case CTRL('U'):
 		ch = '\r';
 		echo(&ch, 1);
-		ch = ' ';
-		for (i = 0; i < head; i++)
-			echo(&ch, 1);
-		ch = '\r';
+		erase(head);
 		echo(&ch, 1);
-		head = -1;
 		return 0;
 	case CTRL('W'):
-		i = 0;
-		head--;
-		while (head - i >= 0 && buffer[head - i] == ' ')
-			i++;
-		while (head - i >= 0 && buffer[head - i] != ' ')
-			i++;
-		erase(i);
-		head -= i;
+		erase(wordsize());
 		return 0;
 	case '\r':
-		buffer[head] = '\n';
+		key = '\n';
 	default:
-		return echo(&buffer[head], 1);
+		buffer[head++] = key;
+		return echo(&key, 1);
 	}
 }
 
 static int
-fillbuffer(Chan *c)
+fillbuffer(void)
 {
 	char ch;
 
@@ -325,16 +325,13 @@ fillbuffer(Chan *c)
 			ch = EOF;
 			break;
 		}
-		buffer[head] = ch;
-		consreadediting(c);
-		if (buffer[head++] == '\n')
+		if (edit(ch) == '\n')
 			break;
 	}
 	if (ch == EOF && head == 0) {
 		errno = EIO;
 		return -1;
 	}
-	buffer[head] = '\0';
 
 	return 0;
 }
@@ -368,7 +365,7 @@ consread(Chan *c, void *buf, int n)
 			return -1;
 		}
 		if (head == 0) {
-			if (fillbuffer(c) < 0)
+			if (fillbuffer() < 0)
 				return -1;
 		}