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	utf8pad: improve padded printing and printing invalid unicode characters - sfee…
	git clone git://git.codemadness.org/sfeed_curses
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	---
	commit 7f13213a355aba904f12a595b322909ce630fbe1
	parent 1c4116d1fa7db2ddf540d05df381cbf58e932981
	Author: Hiltjo Posthuma <[email protected]>
	Date: Sat, 9 Jan 2021 14:57:57 +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 sfeed_curses.c \| 76 +++++++++++++++++++++++------…

	1 file changed, 56 insertions(+), 20 deletions(-)
	---
	diff --git a/sfeed_curses.c b/sfeed_curses.c
	@@ -30,6 +30,7 @@
	#define PAD_TRUNCATE_SYMBOL "\xe2\x80\xa6" /* symbol: "ellipsis" */
	#define SCROLLBAR_SYMBOL_BAR "\xe2\x94\x82" /* symbol: "light vertical" */
	#define SCROLLBAR_SYMBOL_TICK " "
	+#define UTF_INVALID_SYMBOL "\xef\xbf\xbd" /* symbol: "replacement" */

	/* color-theme */
	#ifndef SFEED_THEME
	@@ -310,15 +311,28 @@ colw(const char *s)
	{
	wchar_t wc;
	size_t col = 0, i, slen;
	- int rl, w;
	+ int inc, rl, w;

	slen = strlen(s);
	- for (i = 0; i < slen; i += rl) {
	- if ((rl = mbtowc(&wc, &s[i], slen - i < 4 ? slen - i : 4)) <= …
	- break;
	- if ((w = wcwidth(wc)) == -1)
	+ for (i = 0; i < slen; i += inc) {
	+ inc = 1;
	+ if ((unsigned char)s[i] < 32) {
	continue;
	- col += w;
	+ } else if ((unsigned char)s[i] >= 127) {
	+ 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;
	+ }
	+ col += w;
	+ } else {
	+ col++;
	+ }
	}
	return col;
	}
	@@ -330,33 +344,55 @@ utf8pad(char buf, size_t bufsiz, const char s, size_t l…
	{
	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)) <= …
	- 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], PAD_TRUNCATE_SYMBOL, sizeof(PAD_TRUN…
	siz += sizeof(PAD_TRUNCATE_SYMBOL) - 1;
	- if (col + w == len && w > 1)
	- buf[siz++] = pad;
	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_INVAL…
	+ 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;