Fix pango escaping and refactor escape_markup_text

Fixes #2674.

The cause of the issue was in get_pango_layout. When we call
pango_parse_markup, `text` is the escaped string, and the unescaped
string is then computed and written to `buf`. We were then passing the
unescaped string to pango_layout_set_markup, but this function needs the
escaped string. `buf` is not needed and has been removed.

The other part of this PR refactors escape_markup_text to remove the
dest_length argument and removes the -1 return value on error. It now
assumes that you've allocated dest to the correct length.

common/pango.c

@@ -7,66 +7,45 @@
 #include <stdlib.h>
 #include <string.h>
 #include "log.h"
+#include "stringop.h"
 
-int escape_markup_text(const char *src, char *dest, int dest_length) {
-	int length = 0;
+size_t escape_markup_text(const char *src, char *dest) {
+	size_t length = 0;
+	if (dest) {
+		dest[0] = '\0';
+	}
 
 	while (src[0]) {
 		switch (src[0]) {
 		case '&':
 			length += 5;
-			if (dest && dest_length - length >= 0) {
-				dest += sprintf(dest, "%s", "&amp;");
-			} else {
-				dest_length = -1;
-			}
+			lenient_strcat(dest, "&amp;");
 			break;
 		case '<':
 			length += 4;
-			if (dest && dest_length - length >= 0) {
-				dest += sprintf(dest, "%s", "&lt;");
-			} else {
-				dest_length = -1;
-			}
+			lenient_strcat(dest, "&lt;");
 			break;
 		case '>':
 			length += 4;
-			if (dest && dest_length - length >= 0) {
-				dest += sprintf(dest, "%s", "&gt;");
-			} else {
-				dest_length = -1;
-			}
+			lenient_strcat(dest, "&gt;");
 			break;
 		case '\'':
 			length += 6;
-			if (dest && dest_length - length >= 0) {
-				dest += sprintf(dest, "%s", "&apos;");
-			} else {
-				dest_length = -1;
-			}
+			lenient_strcat(dest, "&apos;");
 			break;
 		case '"':
 			length += 6;
-			if (dest && dest_length - length >= 0) {
-				dest += sprintf(dest, "%s", "&quot;");
-			} else {
-				dest_length = -1;
-			}
+			lenient_strcat(dest, "&quot;");
 			break;
 		default:
-			length += 1;
-			if (dest && dest_length - length >= 0) {
-				*(dest++) = *src;
-			} else {
-				dest_length = -1;
+			if (dest) {
+				dest[length] = *src;
+				dest[length + 1] = '\0';
 			}
+			length += 1;
 		}
 		src++;
 	}
-	// if we could not fit the escaped string in dest, return -1
-	if (dest && dest_length == -1) {
-		return -1;
-	}
 	return length;
 }
 
@@ -75,11 +54,9 @@ PangoLayout *get_pango_layout(cairo_t *cairo, const char *font,
 	PangoLayout *layout = pango_cairo_create_layout(cairo);
 	PangoAttrList *attrs;
 	if (markup) {
-		char *buf;
 		GError *error = NULL;
-		if (pango_parse_markup(text, -1, 0, &attrs, &buf, NULL, &error)) {
-			pango_layout_set_markup(layout, buf, -1);
-			free(buf);
+		if (pango_parse_markup(text, -1, 0, &attrs, NULL, NULL, &error)) {
+			pango_layout_set_markup(layout, text, -1);
 		} else {
 			wlr_log(WLR_ERROR, "pango_parse_markup '%s' -> error %s", text,
 					error->message);

include/pango.h

@@ -6,17 +6,13 @@
 #include <cairo/cairo.h>
 #include <pango/pangocairo.h>
 
-/* Utility function which escape characters a & < > ' ".
+/**
+ * Utility function which escape characters a & < > ' ".
  *
- * If the dest parameter is NULL, then the function returns the length of
- * of the escaped src string. The dest_length doesn't matter.
- *
- * If the dest parameter is not NULL then the fuction escapes the src string
- * an puts the escaped string in dest and returns the lenght of the escaped string.
- * The dest_length parameter is the size of dest array. If the size of dest is not
- * enough, then the function returns -1.
+ * The function returns the length of the escaped string, optionally writing the
+ * escaped string to dest if provided.
  */
-int escape_markup_text(const char *src, char *dest, int dest_length);
+size_t escape_markup_text(const char *src, char *dest);
 PangoLayout *get_pango_layout(cairo_t *cairo, const char *font,
 		const char *text, double scale, bool markup);
 void get_text_size(cairo_t *cairo, const char *font, int *width, int *height,

sway/tree/view.c

@@ -785,14 +785,9 @@ static size_t parse_title_format(struct sway_view *view, char *buffer) {
 }
 
 static char *escape_title(char *buffer) {
-	int length = escape_markup_text(buffer, NULL, 0);
+	size_t length = escape_markup_text(buffer, NULL);
 	char *escaped_title = calloc(length + 1, sizeof(char));
-	int result = escape_markup_text(buffer, escaped_title, length);
-	if (result != length) {
-		wlr_log(WLR_ERROR, "Could not escape title: %s", buffer);
-		free(escaped_title);
-		return buffer;
-	}
+	escape_markup_text(buffer, escaped_title);
 	free(buffer);
 	return escaped_title;
 }