tty: vt: separate ESesc state handling into handle_esc()

Similar to the ASCII handling, the ESC handling can be easily moved away
from do_con_trol(). So create a new handle_esc() for that.

And add a comment with an example.

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20240202065608.14019-13-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 7cda1a958c5e745bb41049a8e83b46a135df43bb..3dddb7128234a88d436c8fbedda0842938f23e84 100644 (file)
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -2267,6 +2267,77 @@ static bool handle_ascii(struct tty_struct *tty, struct vc_data *vc, u8 c)
        return false;
 }
 
+/*
+ * Handle a character (@c) following an ESC (when @vc is in the ESesc state).
+ * E.g. previous ESC with @c == '[' here yields the ESsquare state (that is:
+ * CSI).
+ */
+static void handle_esc(struct tty_struct *tty, struct vc_data *vc, u8 c)
+{
+       vc->vc_state = ESnormal;
+       switch (c) {
+       case '[':
+               vc->vc_state = ESsquare;
+               break;
+       case ']':
+               vc->vc_state = ESnonstd;
+               break;
+       case '_':
+               vc->vc_state = ESapc;
+               break;
+       case '^':
+               vc->vc_state = ESpm;
+               break;
+       case '%':
+               vc->vc_state = ESpercent;
+               break;
+       case 'E':
+               cr(vc);
+               lf(vc);
+               break;
+       case 'M':
+               ri(vc);
+               break;
+       case 'D':
+               lf(vc);
+               break;
+       case 'H':
+               if (vc->state.x < VC_TABSTOPS_COUNT)
+                       set_bit(vc->state.x, vc->vc_tab_stop);
+               break;
+       case 'P':
+               vc->vc_state = ESdcs;
+               break;
+       case 'Z':
+               respond_ID(tty);
+               break;
+       case '7':
+               save_cur(vc);
+               break;
+       case '8':
+               restore_cur(vc);
+               break;
+       case '(':
+               vc->vc_state = ESsetG0;
+               break;
+       case ')':
+               vc->vc_state = ESsetG1;
+               break;
+       case '#':
+               vc->vc_state = EShash;
+               break;
+       case 'c':
+               reset_terminal(vc, 1);
+               break;
+       case '>':  /* Numeric keypad */
+               clr_kbd(vc, kbdapplic);
+               break;
+       case '=':  /* Appl. keypad */
+               set_kbd(vc, kbdapplic);
+               break;
+       }
+}
+
 /* console_lock is held */
 static void do_con_trol(struct tty_struct *tty, struct vc_data *vc, u8 c)
 {
@@ -2283,68 +2354,7 @@ static void do_con_trol(struct tty_struct *tty, struct vc_data *vc, u8 c)
 
        switch(vc->vc_state) {
        case ESesc:
-               vc->vc_state = ESnormal;
-               switch (c) {
-               case '[':
-                       vc->vc_state = ESsquare;
-                       return;
-               case ']':
-                       vc->vc_state = ESnonstd;
-                       return;
-               case '_':
-                       vc->vc_state = ESapc;
-                       return;
-               case '^':
-                       vc->vc_state = ESpm;
-                       return;
-               case '%':
-                       vc->vc_state = ESpercent;
-                       return;
-               case 'E':
-                       cr(vc);
-                       lf(vc);
-                       return;
-               case 'M':
-                       ri(vc);
-                       return;
-               case 'D':
-                       lf(vc);
-                       return;
-               case 'H':
-                       if (vc->state.x < VC_TABSTOPS_COUNT)
-                               set_bit(vc->state.x, vc->vc_tab_stop);
-                       return;
-               case 'P':
-                       vc->vc_state = ESdcs;
-                       return;
-               case 'Z':
-                       respond_ID(tty);
-                       return;
-               case '7':
-                       save_cur(vc);
-                       return;
-               case '8':
-                       restore_cur(vc);
-                       return;
-               case '(':
-                       vc->vc_state = ESsetG0;
-                       return;
-               case ')':
-                       vc->vc_state = ESsetG1;
-                       return;
-               case '#':
-                       vc->vc_state = EShash;
-                       return;
-               case 'c':
-                       reset_terminal(vc, 1);
-                       return;
-               case '>':  /* Numeric keypad */
-                       clr_kbd(vc, kbdapplic);
-                       return;
-               case '=':  /* Appl. keypad */
-                       set_kbd(vc, kbdapplic);
-                       return;
-               }
+               handle_esc(tty, vc, c);
                return;
        case ESnonstd:
                if (c=='P') {   /* palette escape sequence */