UTF-8 cleanup of the function pappend():

Use the standard function mbrtowc(3) to distinguish valid, incomplete,
and invalid multibyte characters, getting rid of five calls to functions
and macros that we want to phase out, and of one goto.  Add comments.
OK millert@.

1 files changed, 42 insertions, 42 deletions

diff --git a/usr.bin/less/line.c b/usr.bin/less/line.c
index 78bbda7b927..8b811d700e5 100644
--- a/usr.bin/less/line.c
+++ b/usr.bin/less/line.c
@@ -64,7 +64,6 @@ extern off_t start_attnpos;
 extern off_t end_attnpos;
 
 static char mbc_buf[MAX_UTF_CHAR_LEN];
-static int mbc_buf_len = 0;
 static int mbc_buf_index = 0;
 static off_t mbc_pos;
 
@@ -129,7 +128,6 @@ prewind(void)
 	column = 0;
 	cshift = 0;
 	overstrike = 0;
-	mbc_buf_len = 0;
 	is_null_line = 0;
 	pendc = '\0';
 	lmargin = 0;
@@ -683,6 +681,9 @@ flush_mbc_buf(off_t pos)
 int
 pappend(char c, off_t pos)
 {
+	mbstate_t mbs;
+	size_t sz;
+	wchar_t ch;
 	int r;
 
 	if (pendc) {
@@ -696,13 +697,12 @@ pappend(char c, off_t pos)
 	}
 
 	if (c == '\r' && bs_mode == BS_SPECIAL) {
-		if (mbc_buf_len > 0)  /* utf_mode must be on. */ {
+		if (mbc_buf_index > 0)  /* utf_mode must be on. */ {
 			/* Flush incomplete (truncated) sequence. */
 			r = flush_mbc_buf(mbc_pos);
-			mbc_buf_index = r + 1;
-			mbc_buf_len = 0;
+			mbc_buf_index = 0;
 			if (r)
-				return (mbc_buf_index);
+				return (r + 1);
 		}
 
 		/*
@@ -718,40 +718,43 @@ pappend(char c, off_t pos)
 	if (!utf_mode) {
 		r = do_append((LWCHAR) c, NULL, pos);
 	} else {
-		/* Perform strict validation in all possible cases. */
-		if (mbc_buf_len == 0) {
-retry:
-			mbc_buf_index = 1;
-			*mbc_buf = c;
-			if (IS_ASCII_OCTET(c)) {
-				r = do_append((LWCHAR) c, NULL, pos);
-			} else if (IS_UTF8_LEAD(c)) {
-				mbc_buf_len = utf_len(c);
+		for (;;) {
+			if (mbc_buf_index == 0)
 				mbc_pos = pos;
-				return (0);
-			} else {
-				/* UTF8_INVALID or stray UTF8_TRAIL */
-				r = flush_mbc_buf(pos);
-			}
-		} else if (IS_UTF8_TRAIL(c)) {
 			mbc_buf[mbc_buf_index++] = c;
-			if (mbc_buf_index < mbc_buf_len)
+			memset(&mbs, 0, sizeof(mbs));
+			sz = mbrtowc(&ch, mbc_buf, mbc_buf_index, &mbs);
+			
+			/* Incomplete UTF-8: wait for more bytes. */
+			if (sz == (size_t)-2)
 				return (0);
-			if (is_utf8_well_formed(mbc_buf))
-				r = do_append(get_wchar(mbc_buf), mbc_buf,
-				    mbc_pos);
+
+			/* Valid UTF-8: use the character. */
+			if (sz != (size_t)-1) {
+				r = do_append(ch, mbc_buf, mbc_pos) ?
+				    mbc_buf_index : 0;
+				break;
+			}
+
+			/* Invalid start byte: encode it. */
+			if (mbc_buf_index == 1) {
+				r = store_prchar(c, pos);
+				break;
+			}
+
+			/*
+			 * Invalid continuation.
+			 * Encode the preceding bytes.
+			 * If they fit, handle the interrupting byte.
+			 * Otherwise, tell the caller to back up
+			 * by the  number of bytes that do not fit,
+			 * plus one for the new byte.
+			 */
+			mbc_buf_index--;
+			if ((r = flush_mbc_buf(mbc_pos) + 1) == 1)
+				mbc_buf_index = 0;
 			else
-				/* Complete, but not shortest form, sequence. */
-				mbc_buf_index = r = flush_mbc_buf(mbc_pos);
-			mbc_buf_len = 0;
-		} else {
-			/* Flush incomplete (truncated) sequence.  */
-			r = flush_mbc_buf(mbc_pos);
-			mbc_buf_index = r + 1;
-			mbc_buf_len = 0;
-			/* Handle new char.  */
-			if (!r)
-				goto retry;
+				break;
 		}
 	}
 
@@ -765,10 +768,7 @@ retry:
 		linebuf[curr] = '\0';
 		pshift(hshift - cshift);
 	}
-	if (r) {
-		/* How many chars should caller back up? */
-		r = (!utf_mode) ? 1 : mbc_buf_index;
-	}
+	mbc_buf_index = 0;
 	return (r);
 }
 
@@ -913,10 +913,10 @@ pflushmbc(void)
 {
 	int r = 0;
 
-	if (mbc_buf_len > 0) {
+	if (mbc_buf_index > 0) {
 		/* Flush incomplete (truncated) sequence.  */
 		r = flush_mbc_buf(mbc_pos);
-		mbc_buf_len = 0;
+		mbc_buf_index = 0;
 	}
 	return (r);
 }