[U-Boot] [PATCH v2 2/2] efi_loader: Fix possible starving in efi_cin_read_key

[matthias.bgg at kernel.org <matthias.bgg@kernel.org>]

From: Matthias Brugger <mbrugger@suse.com>

The function efi_cin_read_key can be affected by a loss of
a character which will make u-boot to wait forever.
Fix this by calling term_get_char instead.

Signed-off-by: Matthias Brugger <mbrugger@suse.com>
---

Changes in v2: None

 lib/efi_loader/efi_console.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/lib/efi_loader/efi_console.c b/lib/efi_loader/efi_console.c
index 1133674faf..558aaed109 100644
--- a/lib/efi_loader/efi_console.c
+++ b/lib/efi_loader/efi_console.c
@@ -493,13 +493,14 @@ static int analyze_modifiers(struct efi_key_state *key_state)
 {
 	int c, mod = 0, ret = 0;
 
-	c = getc();
+	if (!term_get_char(&c))
+		goto out;
 
 	if (c != ';') {
 		ret = c;
 		if (c == '~')
 			goto out;
-		c = getc();
+		term_get_char(&c);
 	}
 	for (;;) {
 		switch (c) {
@@ -508,7 +509,7 @@ static int analyze_modifiers(struct efi_key_state *key_state)
 			mod += c - '0';
 		/* fall through */
 		case ';':
-			c = getc();
+			term_get_char(&c);
 			break;
 		default:
 			goto out;
@@ -551,7 +552,9 @@ static efi_status_t efi_cin_read_key(struct efi_key_data *key)
 		 * Xterm Control Sequences
 		 * https://www.xfree86.org/4.8.0/ctlseqs.html
 		 */
-		ch = getc();
+		if (!term_get_char(&ch))
+			return EFI_NOT_READY;
+
 		switch (ch) {
 		case cESC: /* ESC */
 			pressed_key.scan_code = 23;
@@ -561,12 +564,15 @@ static efi_status_t efi_cin_read_key(struct efi_key_data *key)
 			/* consider modifiers */
 			if (ch < 'P') {
 				set_shift_mask(ch - '0', &key->key_state);
-				ch = getc();
+				if (!term_get_char(&ch))
+					return EFI_NOT_READY;
 			}
 			pressed_key.scan_code = ch - 'P' + 11;
 			break;
 		case '[':
-			ch = getc();
+			if (!term_get_char(&ch))
+				return EFI_NOT_READY;
+
 			switch (ch) {
 			case 'A'...'D': /* up, down right, left */
 				pressed_key.scan_code = ch - 'A' + 1;
-- 
2.20.1