Move the control characters detection to a separate function dubbed
vc_is_control. It makes the 14 subexpressions a "bit" more readable. And
also simplifies next patches.
It moves also CTRL_ACTION and CTRL_ALWAYS to this new function, as they
are used exclusively here. While at it, these are converted to static
const variables.
And we use "& BIT()" instead of ">>" and "& 1".
Checked using symbolic execution (klee), that the old and new
behaviors are the same.
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
drivers/tty/vt/vt.c | 71 ++++++++++++++++++++++++++++-----------------
1 file changed, 45 insertions(+), 26 deletions(-)
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index 0c663054ab79..45d32844e61b 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -127,14 +127,6 @@ struct con_driver {
static struct con_driver registered_con_driver[MAX_NR_CON_DRIVER];
const struct consw *conswitchp;
-/* A bitmap for codes <32. A bit of 1 indicates that the code
- * corresponding to that bit number invokes some special action
- * (such as cursor movement) and should not be displayed as a
- * glyph unless the disp_ctrl mode is explicitly enabled.
- */
-#define CTRL_ACTION 0x0d00ff81
-#define CTRL_ALWAYS 0x0800f501 /* Cannot be overridden by disp_ctrl */
-
/*
* Here is the default bell parameters: 750HZ, 1/8th of a second
*/
@@ -2691,13 +2683,56 @@ static inline unsigned char vc_invert_attr(const struct vc_data *vc)
((vc->vc_attr & 0x07) << 4);
}
+static bool vc_is_control(struct vc_data *vc, int tc, int c)
+{
+ /*
+ * A bitmap for codes <32. A bit of 1 indicates that the code
+ * corresponding to that bit number invokes some special action (such
+ * as cursor movement) and should not be displayed as a glyph unless
+ * the disp_ctrl mode is explicitly enabled.
+ */
+ static const u32 CTRL_ACTION = 0x0d00ff81;
+ /* Cannot be overridden by disp_ctrl */
+ static const u32 CTRL_ALWAYS = 0x0800f501;
+
+ if (vc->vc_state != ESnormal)
+ return true;
+
+ if (!tc)
+ return true;
+
+ /*
+ * If the original code was a control character we only allow a glyph
+ * to be displayed if the code is not normally used (such as for cursor
+ * movement) or if the disp_ctrl mode has been explicitly enabled.
+ * Certain characters (as given by the CTRL_ALWAYS bitmap) are always
+ * displayed as control characters, as the console would be pretty
+ * useless without them; to display an arbitrary font position use the
+ * direct-to-font zone in UTF-8 mode.
+ */
+ if (c < 32) {
+ if (vc->vc_disp_ctrl)
+ return CTRL_ALWAYS & BIT(c);
+ else
+ return vc->vc_utf || (CTRL_ACTION & BIT(c));
+ }
+
+ if (c == 127 && !vc->vc_disp_ctrl)
+ return true;
+
+ if (c == 128 + 27)
+ return true;
+
+ return false;
+}
+
/* acquires console_lock */
static int do_con_write(struct tty_struct *tty, const unsigned char *buf, int count)
{
struct vc_draw_region draw = {
.x = -1,
};
- int c, next_c, tc, ok, n = 0;
+ int c, next_c, tc, n = 0;
unsigned int currcons;
struct vc_data *vc;
unsigned char vc_attr;
@@ -2755,23 +2790,7 @@ static int do_con_write(struct tty_struct *tty, const unsigned char *buf, int co
¶m) == NOTIFY_STOP)
continue;
- /* If the original code was a control character we
- * only allow a glyph to be displayed if the code is
- * not normally used (such as for cursor movement) or
- * if the disp_ctrl mode has been explicitly enabled.
- * Certain characters (as given by the CTRL_ALWAYS
- * bitmap) are always displayed as control characters,
- * as the console would be pretty useless without
- * them; to display an arbitrary font position use the
- * direct-to-font zone in UTF-8 mode.
- */
- ok = tc && (c >= 32 ||
- !(vc->vc_disp_ctrl ? (CTRL_ALWAYS >> c) & 1 :
- vc->vc_utf || ((CTRL_ACTION >> c) & 1)))
- && (c != 127 || vc->vc_disp_ctrl)
- && (c != 128+27);
-
- if (vc->vc_state == ESnormal && ok) {
+ if (!vc_is_control(vc, tc, c)) {
if (vc->vc_utf && !vc->vc_disp_ctrl) {
if (is_double_width(c))
width = 2;
--
2.27.0
