tty: vt: extract ascii handling to handle_ascii()

To make the do_con_trol() a bit more understandable, extract the ASCII
handling (the switch-case) to a separate function.

Other nested switch-cases will follow in the next patches.

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20240202065608.14019-12-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index 451a852..7cda1a9 100644 (file)
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -2197,28 +2197,26 @@ enum {
        ASCII_EXT_CSI           = 128 + ASCII_ESCAPE,
 };
 
-/* console_lock is held */
-static void do_con_trol(struct tty_struct *tty, struct vc_data *vc, u8 c)
+/*
+ * Handle ascii characters in control sequences and change states accordingly.
+ * E.g. ESC sets the state of vc to ESesc.
+ *
+ * Returns: true if @c handled.
+ */
+static bool handle_ascii(struct tty_struct *tty, struct vc_data *vc, u8 c)
 {
-       /*
-        *  Control characters can be used in the _middle_
-        *  of an escape sequence, aside from ANSI control strings.
-        */
-       if (ansi_control_string(vc->vc_state) && c >= ASCII_IGNORE_FIRST &&
-           c <= ASCII_IGNORE_LAST)
-               return;
        switch (c) {
        case ASCII_NULL:
-               return;
+               return true;
        case ASCII_BELL:
                if (ansi_control_string(vc->vc_state))
                        vc->vc_state = ESnormal;
                else if (vc->vc_bell_duration)
                        kd_mksound(vc->vc_bell_pitch, vc->vc_bell_duration);
-               return;
+               return true;
        case ASCII_BACKSPACE:
                bs(vc);
-               return;
+               return true;
        case ASCII_HTAB:
                vc->vc_pos -= (vc->state.x << 1);
 
@@ -2230,41 +2228,59 @@ static void do_con_trol(struct tty_struct *tty, struct vc_data *vc, u8 c)
 
                vc->vc_pos += (vc->state.x << 1);
                notify_write(vc, '\t');
-               return;
+               return true;
        case ASCII_LINEFEED:
        case ASCII_VTAB:
        case ASCII_FORMFEED:
                lf(vc);
                if (!is_kbd(vc, lnm))
-                       return;
+                       return true;
                fallthrough;
        case ASCII_CAR_RET:
                cr(vc);
-               return;
+               return true;
        case ASCII_SHIFTOUT:
                vc->state.charset = 1;
                vc->vc_translate = set_translate(vc->state.Gx_charset[1], vc);
                vc->vc_disp_ctrl = 1;
-               return;
+               return true;
        case ASCII_SHIFTIN:
                vc->state.charset = 0;
                vc->vc_translate = set_translate(vc->state.Gx_charset[0], vc);
                vc->vc_disp_ctrl = 0;
-               return;
+               return true;
        case ASCII_CANCEL:
        case ASCII_SUBSTITUTE:
                vc->vc_state = ESnormal;
-               return;
+               return true;
        case ASCII_ESCAPE:
                vc->vc_state = ESesc;
-               return;
+               return true;
        case ASCII_DEL:
                del(vc);
-               return;
+               return true;
        case ASCII_EXT_CSI:
                vc->vc_state = ESsquare;
-               return;
+               return true;
        }
+
+       return false;
+}
+
+/* console_lock is held */
+static void do_con_trol(struct tty_struct *tty, struct vc_data *vc, u8 c)
+{
+       /*
+        *  Control characters can be used in the _middle_
+        *  of an escape sequence, aside from ANSI control strings.
+        */
+       if (ansi_control_string(vc->vc_state) && c >= ASCII_IGNORE_FIRST &&
+           c <= ASCII_IGNORE_LAST)
+               return;
+
+       if (handle_ascii(tty, vc, c))
+               return;
+
        switch(vc->vc_state) {
        case ESesc:
                vc->vc_state = ESnormal;