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Message-Id: <20200615074910.19267-13-jslaby@suse.cz>
Date: Mon, 15 Jun 2020 09:48:45 +0200
From: Jiri Slaby <jslaby@...e.cz>
To: gregkh@...uxfoundation.org
Cc: linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 13/38] vt: rearrange vc_translate_unicode
The code was too overcomplicated. Extract vc_sanitize_unicode to a
separate function and flatten the code. I believe the code is
straightforward now.
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
drivers/tty/vt/vt.c | 121 +++++++++++++++++++++++---------------------
1 file changed, 64 insertions(+), 57 deletions(-)
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index caaad820413a..5004242d601b 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -2572,6 +2572,19 @@ static inline int vc_translate_ascii(const struct vc_data *vc, int c)
return c;
}
+
+/**
+ * vc_sanitize_unicode -- Replace invalid Unicode code points with U+FFFD
+ * @c: the received character, or U+FFFD for invalid sequences.
+ */
+static inline int vc_sanitize_unicode(const int c)
+{
+ if ((c >= 0xd800 && c <= 0xdfff) || c == 0xfffe || c == 0xffff)
+ return 0xfffd;
+
+ return c;
+}
+
/**
* vc_translate_unicode -- Combine UTF-8 into Unicode in @vc_utf_char
*
@@ -2586,69 +2599,63 @@ static int vc_translate_unicode(struct vc_data *vc, int c, bool *rescan)
0x001fffff, 0x03ffffff, 0x7fffffff
};
+ /* Continuation byte received */
if ((c & 0xc0) == 0x80) {
- /* Continuation byte received */
- if (vc->vc_utf_count) {
- vc->vc_utf_char = (vc->vc_utf_char << 6) | (c & 0x3f);
- vc->vc_npar++;
- if (--vc->vc_utf_count) {
- /* Still need some bytes */
- return -1;
- }
- /* Got a whole character */
- c = vc->vc_utf_char;
- /* Reject overlong sequences */
- if (c <= utf8_length_changes[vc->vc_npar - 1] ||
- c > utf8_length_changes[vc->vc_npar])
- return 0xfffd;
- } else {
- /* Unexpected continuation byte */
- vc->vc_utf_count = 0;
+ /* Unexpected continuation byte? */
+ if (!vc->vc_utf_count)
return 0xfffd;
- }
- } else {
- /* Single ASCII byte or first byte of a sequence received */
- if (vc->vc_utf_count) {
- /* Continuation byte expected */
- *rescan = true;
- vc->vc_utf_count = 0;
+
+ vc->vc_utf_char = (vc->vc_utf_char << 6) | (c & 0x3f);
+ vc->vc_npar++;
+ if (--vc->vc_utf_count)
+ goto need_more_bytes;
+
+ /* Got a whole character */
+ c = vc->vc_utf_char;
+ /* Reject overlong sequences */
+ if (c <= utf8_length_changes[vc->vc_npar - 1] ||
+ c > utf8_length_changes[vc->vc_npar])
return 0xfffd;
- } else if (c > 0x7f) {
- /* First byte of a multibyte sequence received */
- vc->vc_npar = 0;
- if ((c & 0xe0) == 0xc0) {
- vc->vc_utf_count = 1;
- vc->vc_utf_char = (c & 0x1f);
- } else if ((c & 0xf0) == 0xe0) {
- vc->vc_utf_count = 2;
- vc->vc_utf_char = (c & 0x0f);
- } else if ((c & 0xf8) == 0xf0) {
- vc->vc_utf_count = 3;
- vc->vc_utf_char = (c & 0x07);
- } else if ((c & 0xfc) == 0xf8) {
- vc->vc_utf_count = 4;
- vc->vc_utf_char = (c & 0x03);
- } else if ((c & 0xfe) == 0xfc) {
- vc->vc_utf_count = 5;
- vc->vc_utf_char = (c & 0x01);
- } else {
- /* 254 and 255 are invalid */
- return 0xfffd;
- }
- if (vc->vc_utf_count) {
- /* Still need some bytes */
- return -1;
- }
- }
- /* Nothing to do if an ASCII byte was received */
+
+ return vc_sanitize_unicode(c);
}
- /* End of UTF-8 decoding. */
- /* c is the received character, or U+FFFD for invalid sequences. */
- /* Replace invalid Unicode code points with U+FFFD too */
- if ((c >= 0xd800 && c <= 0xdfff) || c == 0xfffe || c == 0xffff)
+
+ /* Single ASCII byte or first byte of a sequence received */
+ if (vc->vc_utf_count) {
+ /* Continuation byte expected */
+ *rescan = true;
+ vc->vc_utf_count = 0;
return 0xfffd;
+ }
- return c;
+ /* Nothing to do if an ASCII byte was received */
+ if (c <= 0x7f)
+ return c;
+
+ /* First byte of a multibyte sequence received */
+ vc->vc_npar = 0;
+ if ((c & 0xe0) == 0xc0) {
+ vc->vc_utf_count = 1;
+ vc->vc_utf_char = (c & 0x1f);
+ } else if ((c & 0xf0) == 0xe0) {
+ vc->vc_utf_count = 2;
+ vc->vc_utf_char = (c & 0x0f);
+ } else if ((c & 0xf8) == 0xf0) {
+ vc->vc_utf_count = 3;
+ vc->vc_utf_char = (c & 0x07);
+ } else if ((c & 0xfc) == 0xf8) {
+ vc->vc_utf_count = 4;
+ vc->vc_utf_char = (c & 0x03);
+ } else if ((c & 0xfe) == 0xfc) {
+ vc->vc_utf_count = 5;
+ vc->vc_utf_char = (c & 0x01);
+ } else {
+ /* 254 and 255 are invalid */
+ return 0xfffd;
+ }
+
+need_more_bytes:
+ return -1;
}
/* acquires console_lock */
--
2.27.0
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