stagit-gopher

commit 554a9fe2e9d12defd9d6253871d8261d3f3ef3c6
parent 7b93d02cd8f26ab9a25d967c72c359a22c91eb74
Author: Hiltjo Posthuma <hiltjo@codemadness.org>
Date:   Sat,  9 Jan 2021 14:56:51 +0100

utf8pad: improve padded printing and printing invalid unicode characters

- Use unicode replacement character (codepoint 0xfffd) when a codepoint is
  invalid and proceed printing the rest of the characters.

- When a codepoint is invalid reset the internal state of mbtowc(3), from the
  OpenBSD man page:

  "  If a call to mbtowc() resulted in an undefined internal state, mbtowc()
     must be called with s set to NULL to reset the internal state before it
     can safely be used again."

- Make the function return 0 when `len` is 0 (this should not be not an error).

Diffstat:
M
stagit-gopher-index.c
 | 
59
++++++++++++++++++++++++++++++++++++++++++-----------------
M
stagit-gopher.c
 | 
58
+++++++++++++++++++++++++++++++++++++++++-----------------

2 files changed, 83 insertions(+), 34 deletions(-)
diff --git a/stagit-gopher-index.c b/stagit-gopher-index.c
@@ -10,6 +10,9 @@
 
 #include <git2.h>
 
+#define PAD_TRUNCATE_SYMBOL    "\xe2\x80\xa6" /* symbol: "ellipsis" */
+#define UTF_INVALID_SYMBOL     "\xef\xbf\xbd" /* symbol: "replacement" */
+
 static git_repository *repo;
 
 static const char *relpath = "";
@@ -17,40 +20,62 @@ static const char *relpath = "";
 static char description[255] = "Repositories";
 static char *name = "";
 
-/* format `len' columns of characters. If string is shorter pad the rest
+/* Format `len' columns of characters. If string is shorter pad the rest
  * with characters `pad`. */
 int
 utf8pad(char *buf, size_t bufsiz, const char *s, size_t len, int pad)
 {
 	wchar_t wc;
 	size_t col = 0, i, slen, siz = 0;
-	int rl, w;
+	int inc, rl, w;
 
-	if (!len)
+	if (!bufsiz)
 		return -1;
+	if (!len) {
+		buf[0] = '\0';
+		return 0;
+	}
 
 	slen = strlen(s);
-	for (i = 0; i < slen; i += rl) {
-		if ((rl = mbtowc(&wc, &s[i], slen - i < 4 ? slen - i : 4)) <= 0)
-			break;
-		if ((w = wcwidth(wc)) == -1)
+	for (i = 0; i < slen; i += inc) {
+		inc = 1;
+		if ((unsigned char)s[i] < 32)
 			continue;
-		if (col + w > len || (col + w == len && s[i + rl])) {
+
+		rl = mbtowc(&wc, &s[i], slen - i < 4 ? slen - i : 4);
+		if (rl < 0) {
+			mbtowc(NULL, NULL, 0); /* reset state */
+			inc = 1; /* next byte */
+			w = 1; /* replacement char is one width */
+		} else if ((w = wcwidth(wc)) == -1) {
+			continue;
+		} else {
+			inc = rl;
+		}
+
+		if (col + w > len || (col + w == len && s[i + inc])) {
 			if (siz + 4 >= bufsiz)
 				return -1;
-			memcpy(&buf[siz], "\xe2\x80\xa6", 3);
-			siz += 3;
-			if (col + w == len && w > 1)
-				buf[siz++] = pad;
+			memcpy(&buf[siz], PAD_TRUNCATE_SYMBOL, sizeof(PAD_TRUNCATE_SYMBOL) - 1);
+			siz += sizeof(PAD_TRUNCATE_SYMBOL) - 1;
 			buf[siz] = '\0';
-			return 0;
+			col++;
+			break;
+		} else if (rl < 0) {
+			if (siz + 4 >= bufsiz)
+				return -1;
+			memcpy(&buf[siz], UTF_INVALID_SYMBOL, sizeof(UTF_INVALID_SYMBOL) - 1);
+			siz += sizeof(UTF_INVALID_SYMBOL) - 1;
+			buf[siz] = '\0';
+			col++;
+			continue;
 		}
-		if (siz + rl + 1 >= bufsiz)
+		if (siz + inc + 1 >= bufsiz)
 			return -1;
-		memcpy(&buf[siz], &s[i], rl);
-		col += w;
-		siz += rl;
+		memcpy(&buf[siz], &s[i], inc);
+		siz += inc;
 		buf[siz] = '\0';
+		col += w;
 	}
 
 	len -= col;
diff --git a/stagit-gopher.c b/stagit-gopher.c
@@ -19,6 +19,8 @@
 #include "compat.h"
 
 #define LEN(s)    (sizeof(s)/sizeof(*s))
+#define PAD_TRUNCATE_SYMBOL    "\xe2\x80\xa6" /* symbol: "ellipsis" */
+#define UTF_INVALID_SYMBOL     "\xef\xbf\xbd" /* symbol: "replacement" */
 
 struct deltainfo {
 	git_patch *patch;
@@ -80,40 +82,62 @@ static char lastoidstr[GIT_OID_HEXSZ + 2]; /* id + newline + NUL byte */
 static FILE *rcachefp, *wcachefp;
 static const char *cachefile;
 
-/* format `len' columns of characters. If string is shorter pad the rest
+/* Format `len' columns of characters. If string is shorter pad the rest
  * with characters `pad`. */
 int
 utf8pad(char *buf, size_t bufsiz, const char *s, size_t len, int pad)
 {
 	wchar_t wc;
 	size_t col = 0, i, slen, siz = 0;
-	int rl, w;
+	int inc, rl, w;
 
-	if (!len)
+	if (!bufsiz)
 		return -1;
+	if (!len) {
+		buf[0] = '\0';
+		return 0;
+	}
 
 	slen = strlen(s);
-	for (i = 0; i < slen; i += rl) {
-		if ((rl = mbtowc(&wc, &s[i], slen - i < 4 ? slen - i : 4)) <= 0)
-			break;
-		if ((w = wcwidth(wc)) == -1)
+	for (i = 0; i < slen; i += inc) {
+		inc = 1;
+		if ((unsigned char)s[i] < 32)
+			continue;
+
+		rl = mbtowc(&wc, &s[i], slen - i < 4 ? slen - i : 4);
+		if (rl < 0) {
+			mbtowc(NULL, NULL, 0); /* reset state */
+			inc = 1; /* next byte */
+			w = 1; /* replacement char is one width */
+		} else if ((w = wcwidth(wc)) == -1) {
 			continue;
-		if (col + w > len || (col + w == len && s[i + rl])) {
+		} else {
+			inc = rl;
+		}
+
+		if (col + w > len || (col + w == len && s[i + inc])) {
 			if (siz + 4 >= bufsiz)
 				return -1;
-			memcpy(&buf[siz], "\xe2\x80\xa6", 3);
-			siz += 3;
-			if (col + w == len && w > 1)
-				buf[siz++] = pad;
+			memcpy(&buf[siz], PAD_TRUNCATE_SYMBOL, sizeof(PAD_TRUNCATE_SYMBOL) - 1);
+			siz += sizeof(PAD_TRUNCATE_SYMBOL) - 1;
 			buf[siz] = '\0';
-			return 0;
+			col++;
+			break;
+		} else if (rl < 0) {
+			if (siz + 4 >= bufsiz)
+				return -1;
+			memcpy(&buf[siz], UTF_INVALID_SYMBOL, sizeof(UTF_INVALID_SYMBOL) - 1);
+			siz += sizeof(UTF_INVALID_SYMBOL) - 1;
+			buf[siz] = '\0';
+			col++;
+			continue;
 		}
-		if (siz + rl + 1 >= bufsiz)
+		if (siz + inc + 1 >= bufsiz)
 			return -1;
-		memcpy(&buf[siz], &s[i], rl);
-		col += w;
-		siz += rl;
+		memcpy(&buf[siz], &s[i], inc);
+		siz += inc;
 		buf[siz] = '\0';
+		col += w;
 	}
 
 	len -= col;