Refactor dev_write prior to allowing it to take partial strings.

ServoBlaster/servoblaster.c

@@ -403,18 +403,21 @@ static ssize_t dev_read(struct file *filp,char *buf,size_t count,loff_t *f_pos)
 }
 
 static ssize_t dev_write(struct file *filp,const char *buf,size_t count,loff_t *f_pos)
+{
+	char str[32];
+
+	if (count > 31) count = 31;
+	if (copy_from_user(str, buf, count)) {
+		return -EFAULT;
+	}
+	str[count] = '\0';
+
+	// Process the complete user string.
 	{
 		int servo;
 		int cnt;
 		int n;
-	char str[32];
 		char dummy;
-
-	cnt = count < 32 ? count : 31;
-	if (copy_from_user(str, buf, cnt)) {
-		return -EFAULT;
-	}
-	str[cnt] = '\0';
 		n = sscanf(str, "%d=%d\n%c", &servo, &cnt, &dummy);
 		if (n != 2) {
 			printk(KERN_WARNING "ServoBlaster: Failed to parse command (n=%d)\n", n);
@@ -443,6 +446,7 @@ static ssize_t dev_write(struct file *filp,const char *buf,size_t count,loff_t *
 		}
 		written_data[servo] = cnt;	// Record data for use by dev_read
 		local_irq_enable();
+	}
 
 	return count;
 }