degesch: fix crash on invalid cp1252 characters

We don't even really need iconv here.

degesch.c

@@ -1973,7 +1973,6 @@ struct app_context
 
 	iconv_t term_to_utf8;               ///< Terminal encoding to UTF-8
 	iconv_t term_from_utf8;             ///< UTF-8 to terminal encoding
-	iconv_t latin1_to_utf8;             ///< ISO Latin 1 to UTF-8
 
 	struct input *input;                ///< User interface
 
@@ -2054,12 +2053,9 @@ app_context_init (struct app_context *self)
 	self->backlog_limit = 1000;
 	self->last_displayed_msg_time = time (NULL);
 
-	// Windows 1252 redefines several silly control characters as glyphs
 	char *native = nl_langinfo (CODESET);
 	if (!app_iconv_open (&self->term_from_utf8, native, "UTF-8")
-	 || !app_iconv_open (&self->term_to_utf8, "UTF-8", native)
+	 || !app_iconv_open (&self->term_to_utf8, "UTF-8", native))
-	 || (!app_iconv_open (&self->latin1_to_utf8, "UTF-8", "WINDOWS-1252")
-	  && !app_iconv_open (&self->latin1_to_utf8, "UTF-8", "ISO-8859-1")))
 		exit_fatal ("creating the UTF-8 conversion object failed: %s",
 			strerror (errno));
 
@@ -2100,7 +2096,6 @@ app_context_free (struct app_context *self)
 	str_map_free (&self->servers);
 	poller_free (&self->poller);
 
-	iconv_close (self->latin1_to_utf8);
 	iconv_close (self->term_from_utf8);
 	iconv_close (self->term_to_utf8);
 
@@ -2915,14 +2910,41 @@ irc_skip_statusmsg (struct server *s, const char *target)
 // As of 2015, everything should be in UTF-8.  And if it's not, we'll decode it
 // as ISO Latin 1.  This function should not be called on the whole message.
 static char *
-irc_to_utf8 (struct app_context *ctx, const char *text)
+irc_to_utf8 (const char *text)
 {
 	if (!text)
 		return NULL;
 	size_t len = strlen (text) + 1;
 	if (utf8_validate (text, len))
 		return xstrdup (text);
-	return iconv_xstrdup (ctx->latin1_to_utf8, (char *) text, len, NULL);
+
+	// Windows 1252 redefines several silly C1 control characters as glyphs
+	static const char *c1[32] =
+	{
+		"\xe2\x82\xac", "\xc2\x81",     "\xe2\x80\x9a", "\xc6\x92",
+		"\xe2\x80\x9e", "\xe2\x80\xa6", "\xe2\x80\xa0", "\xe2\x80\xa1",
+		"\xcb\x86",     "\xe2\x80\xb0", "\xc5\xa0",     "\xe2\x80\xb9",
+		"\xc5\x92",     "\xc2\x8d",     "\xc5\xbd",     "\xc2\x8f",
+		"\xc2\x90",     "\xe2\x80\x98", "\xe2\x80\x99", "\xe2\x80\x9c",
+		"\xe2\x80\x9d", "\xe2\x80\xa2", "\xe2\x80\x93", "\xe2\x80\x94",
+		"\xcb\x9c",     "\xe2\x84\xa2", "\xc5\xa1",     "\xe2\x80\xba",
+		"\xc5\x93",     "\xc2\x9d",     "\xc5\xbe",     "\xc5\xb8",
+	};
+
+	struct str s;
+	str_init (&s);
+	for (const char *p = text; *p; p++)
+	{
+		int c = *(unsigned char *) p;
+		if (c < 0x80)
+			str_append_c (&s, c);
+		else if (c < 0xA0)
+			str_append (&s, c1[c & 0x1f]);
+		else
+			str_append_data (&s,
+				(char[]) {0xc0 | (c >> 6), 0x80 | (c & 0x3f)}, 2);
+	}
+	return str_steal (&s);
 }
 
 // This function is used to output debugging IRC traffic to the terminal.
@@ -2931,7 +2953,7 @@ irc_to_utf8 (struct app_context *ctx, const char *text)
 static char *
 irc_to_term (struct app_context *ctx, const char *text)
 {
-	char *utf8 = irc_to_utf8 (ctx, text);
+	char *utf8 = irc_to_utf8 (text);
 	char *term = iconv_xstrdup (ctx->term_from_utf8, utf8, -1, NULL);
 	free (utf8);
 	return term;
@@ -3096,7 +3118,7 @@ formatter_parse_nick (struct formatter *self, char *s)
 	// which would also make us not cut off the userhost part, ever
 	if (irc_is_channel (self->s, irc_skip_statusmsg (self->s, s)))
 	{
-		char *tmp = irc_to_utf8 (self->ctx, s);
+		char *tmp = irc_to_utf8 (s);
 		FORMATTER_ADD_TEXT (self, tmp);
 		free (tmp);
 		return;
@@ -3120,7 +3142,7 @@ formatter_parse_nick (struct formatter *self, char *s)
 
 	FORMATTER_ADD_ITEM (self, FG_COLOR, .color = color);
 
-	char *x = irc_to_utf8 (self->ctx, nick);
+	char *x = irc_to_utf8 (nick);
 	free (nick);
 	FORMATTER_ADD_TEXT (self, x);
 	free (x);
@@ -3141,7 +3163,7 @@ formatter_parse_nick_full (struct formatter *self, char *s)
 	FORMATTER_ADD_TEXT (self, " (");
 	FORMATTER_ADD_ITEM (self, ATTR, .attribute = ATTR_USERHOST);
 
-	char *x = irc_to_utf8 (self->ctx, userhost);
+	char *x = irc_to_utf8 (userhost);
 	FORMATTER_ADD_TEXT (self, x);
 	free (x);
 
@@ -3181,12 +3203,12 @@ restart:
 		break;
 
 	case 'S':
-		tmp = irc_to_utf8 (self->ctx, (s = va_arg (*ap, char *)));
+		tmp = irc_to_utf8 ((s = va_arg (*ap, char *)));
 		str_append (buf, tmp);
 		free (tmp);
 		break;
 	case 'm':
-		tmp = irc_to_utf8 (self->ctx, (s = va_arg (*ap, char *)));
+		tmp = irc_to_utf8 ((s = va_arg (*ap, char *)));
 		formatter_parse_mirc (self, tmp);
 		free (tmp);
 		break;