u-boot/common/cli_getch.c
Yurii Monakov 2dd86b9075 cli: Consume invalid escape sequences early
Unexpected 'Esc' key presses are accumulated internally, even if it is
already clear that the current escape sequence is invalid. This results
in weird behaviour. For example, the next character after 'Esc' key
simply disappears from input and 'Unknown command' is printed
after 'Enter'.

This commit fixes some issues with extra 'Esc' keys entered by user:

1. Sequence <Esc><Esc><Enter> right after autoboot stop gives:
=>
nknown command 'ry 'help'
=>
2. Sequence <Esc><p><r><i><Enter> gives:
=> ri
Unknown command 'ri' - try 'help'
=>
3. Extra 'Esc' key presses break backspace functionality.

Signed-off-by: Yurii Monakov <monakov.y@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
2023-10-24 16:34:45 -04:00

211 lines
4.5 KiB
C

// SPDX-License-Identifier: GPL-2.0+
/*
* (C) Copyright 2000
* Wolfgang Denk, DENX Software Engineering, wd@denx.de.
*
* Copyright 2022 Google LLC
*/
#include <common.h>
#include <cli.h>
/**
* enum cli_esc_state_t - indicates what to do with an escape character
*
* @ESC_REJECT: Invalid escape sequence, so the esc_save[] characters are
* returned from each subsequent call to cli_ch_esc()
* @ESC_SAVE: Character should be saved in esc_save until we have another one
* @ESC_CONVERTED: Escape sequence has been completed and the resulting
* character is available
*/
enum cli_esc_state_t {
ESC_REJECT,
ESC_SAVE,
ESC_CONVERTED
};
void cli_ch_init(struct cli_ch_state *cch)
{
memset(cch, '\0', sizeof(*cch));
}
/**
* cli_ch_esc() - Process a character in an ongoing escape sequence
*
* @cch: State information
* @ichar: Character to process
* @actp: Returns the action to take
* Returns: Output character if *actp is ESC_CONVERTED, else 0
*/
static int cli_ch_esc(struct cli_ch_state *cch, int ichar,
enum cli_esc_state_t *actp)
{
enum cli_esc_state_t act = ESC_REJECT;
switch (cch->esc_len) {
case 1:
if (ichar == '[' || ichar == 'O')
act = ESC_SAVE;
else
act = ESC_CONVERTED;
break;
case 2:
switch (ichar) {
case 'D': /* <- key */
ichar = CTL_CH('b');
act = ESC_CONVERTED;
break; /* pass off to ^B handler */
case 'C': /* -> key */
ichar = CTL_CH('f');
act = ESC_CONVERTED;
break; /* pass off to ^F handler */
case 'H': /* Home key */
ichar = CTL_CH('a');
act = ESC_CONVERTED;
break; /* pass off to ^A handler */
case 'F': /* End key */
ichar = CTL_CH('e');
act = ESC_CONVERTED;
break; /* pass off to ^E handler */
case 'A': /* up arrow */
ichar = CTL_CH('p');
act = ESC_CONVERTED;
break; /* pass off to ^P handler */
case 'B': /* down arrow */
ichar = CTL_CH('n');
act = ESC_CONVERTED;
break; /* pass off to ^N handler */
case '1':
case '2':
case '3':
case '4':
case '7':
case '8':
if (cch->esc_save[1] == '[') {
/* see if next character is ~ */
act = ESC_SAVE;
}
break;
}
break;
case 3:
switch (ichar) {
case '~':
switch (cch->esc_save[2]) {
case '3': /* Delete key */
ichar = CTL_CH('d');
act = ESC_CONVERTED;
break; /* pass to ^D handler */
case '1': /* Home key */
case '7':
ichar = CTL_CH('a');
act = ESC_CONVERTED;
break; /* pass to ^A handler */
case '4': /* End key */
case '8':
ichar = CTL_CH('e');
act = ESC_CONVERTED;
break; /* pass to ^E handler */
}
break;
case '0':
if (cch->esc_save[2] == '2')
act = ESC_SAVE;
break;
}
break;
case 4:
switch (ichar) {
case '0':
case '1':
act = ESC_SAVE;
break; /* bracketed paste */
}
break;
case 5:
if (ichar == '~') { /* bracketed paste */
ichar = 0;
act = ESC_CONVERTED;
}
}
*actp = act;
return ichar;
}
int cli_ch_process(struct cli_ch_state *cch, int ichar)
{
/*
* ichar=0x0 when error occurs in U-Boot getchar() or when the caller
* wants to check if there are more characters saved in the escape
* sequence
*/
if (!ichar) {
if (cch->emitting) {
if (cch->emit_upto < cch->esc_len)
return cch->esc_save[cch->emit_upto++];
cch->emit_upto = 0;
cch->emitting = false;
cch->esc_len = 0;
}
return 0;
} else if (ichar == -ETIMEDOUT) {
/*
* If we are in an escape sequence but nothing has followed the
* Escape character, then the user probably just pressed the
* Escape key. Return it and clear the sequence.
*/
if (cch->esc_len) {
cch->esc_len = 0;
return '\e';
}
/* Otherwise there is nothing to return */
return 0;
}
if (ichar == '\n' || ichar == '\r')
return '\n';
/* handle standard linux xterm esc sequences for arrow key, etc. */
if (cch->esc_len != 0) {
enum cli_esc_state_t act;
ichar = cli_ch_esc(cch, ichar, &act);
switch (act) {
case ESC_SAVE:
/* save this character and return nothing */
cch->esc_save[cch->esc_len++] = ichar;
ichar = 0;
break;
case ESC_REJECT:
/*
* invalid escape sequence, start returning the
* characters in it
*/
cch->esc_save[cch->esc_len++] = ichar;
ichar = cch->esc_save[cch->emit_upto++];
cch->emitting = true;
return ichar;
case ESC_CONVERTED:
/* valid escape sequence, return the resulting char */
cch->esc_len = 0;
break;
}
}
if (ichar == '\e') {
if (!cch->esc_len) {
cch->esc_save[cch->esc_len] = ichar;
cch->esc_len = 1;
} else {
puts("impossible condition #876\n");
cch->esc_len = 0;
}
return 0;
}
return ichar;
}