If you use gets() and enter any of the arrow keys, you will get into a hang
condition. The root cause appears to be in da_ConRead, in daConsole.c.
Arrow keys (and various others listed in table 88 of the UEFI specification)
return ScanCode != 0 and UnicodeChar == 0 (except ESC, which I'll mention
later). This causes the code to go to:
if(iswcntrl(Key.UnicodeChar)) { // If a control character, or a scan code
break;
}
Since UnicodeChar is 0 for arrow keys, and iswcntrl returns TRUE for 0, this
will cause a break. By causing a break, no key will be placed in the output
buffer, which will give a read length of 0. Upper levels of the read code in
StdLib will interpret this as an EOF condition. So if you used code like:
char *x;
while ((x = gets(mybuffer)) != NULL) {
..process string...
}
You will hang. It tested under other environments and the arrow keys are
ignored. I suggest removing this section of code above
But this leaves other strange behavior with regard to control characters. Try
typing CTRL-C. Rather than ignoring it, it tries to print it. I added the
following code after NumEcho = 0;
if(Key.ScanCode == SCAN_NULL) {
NumEcho = 0;
if (iswcntrl (Key.UnicodeChar) &&
Key.UnicodeChar != CHAR_CARRIAGE_RETURN &&
Key.UnicodeChar != CHAR_BACKSPACE &&
Key.UnicodeChar != CHAR_TAB) {
Stream->UnGetKey.UnicodeChar = CHAR_NULL;
Stream->UnGetKey.ScanCode = SCAN_NULL;
continue;
}
This may not be the right way to handle this. In particular, there still seems
to be an issue with backspace. In implementations I tested (other than the
shell) backspace at the beginning of the line did nothing. But in the shell it
continues. Any help here?
Tim
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