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efi_loader: cursor positioning

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When backspacing in column 0 do no set the column index to ULONG_MAX.
Ensure that the row number is not set to ULONG_MAX even if the row count is
advertised as 0.
Ignore control characters other the 0x08, 0x0a, 0x0d when updating the
column.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
This commit is contained in:
Heinrich Schuchardt 2019-09-04 21:13:45 +02:00
parent d41f99e179
commit 97ea0690f4
1 changed files with 13 additions and 5 deletions
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18
lib/efi_loader/efi_console.c
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@ -156,13 +156,14 @@ static efi_status_t EFIAPI efi_cout_output_string(
* Update the cursor position.
*
* The UEFI spec provides advance rules for U+0000, U+0008, U+000A,
* and U000D. All other characters, including control characters
* U+0007 (BEL) and U+0009 (TAB), have to increase the column by one.
* and U000D. All other control characters are ignored. Any non-control
* character increase the column by one.
*/
for (p = string; *p; ++p) {
switch (*p) {
case '\b': /* U+0008, backspace */
con->cursor_column = max(0, con->cursor_column - 1);
if (con->cursor_column)
con->cursor_column--;
break;
case '\n': /* U+000A, newline */
con->cursor_column = 0;
@ -178,14 +179,21 @@ static efi_status_t EFIAPI efi_cout_output_string(
*/
break;
default:
con->cursor_column++;
/* Exclude control codes */
if (*p > 0x1f)
con->cursor_column++;
break;
}
if (con->cursor_column >= mode->columns) {
con->cursor_column = 0;
con->cursor_row++;
}
con->cursor_row = min(con->cursor_row, (s32)mode->rows - 1);
/*
* When we exceed the row count the terminal will scroll up one
* line. We have to adjust the cursor position.
*/
if (con->cursor_row >= mode->rows && con->cursor_row)
con->cursor_row--;
}
out: