Allocate minimum size necessary in pango text functions. (#3473)

* Allocate minimum size necessary in pango text functions.

* Handle malloc failure.

1 files changed, 22 insertions, 12 deletions

diff --git a/common/pango.c b/common/pango.c
index db8413f7..7e164043 100644
--- a/common/pango.c
+++ b/common/pango.c
@@ -10,10 +10,6 @@
 #include "log.h"
 #include "stringop.h"
 
-#define MAX_CHARS 16384
-
-static const char overflow[] = "[buffer overflow]";
-
 size_t escape_markup_text(const char *src, char *dest) {
         size_t length = 0;
         if (dest) {
@@ -88,13 +84,19 @@ PangoLayout *get_pango_layout(cairo_t *cairo, const char *font,
 
 void get_text_size(cairo_t *cairo, const char *font, int *width, int *height,
                 int *baseline, double scale, bool markup, const char *fmt, ...) {
-        char buf[MAX_CHARS];
-
         va_list args;
         va_start(args, fmt);
-        if (vsnprintf(buf, sizeof(buf), fmt, args) >= MAX_CHARS) {
-                strcpy(&buf[sizeof(buf) - sizeof(overflow)], overflow);
+        // Add one since vsnprintf excludes null terminator.
+        int length = vsnprintf(NULL, 0, fmt, args) + 1;
+        va_end(args);
+
+        char *buf = malloc(length);
+        if (buf == NULL) {
+                wlr_log(WLR_ERROR, "Failed to allocate memory");
+                return;
         }
+        va_start(args, fmt);
+        vsnprintf(buf, length, fmt, args);
         va_end(args);
 
         PangoLayout *layout = get_pango_layout(cairo, font, buf, scale, markup);
@@ -104,17 +106,24 @@ void get_text_size(cairo_t *cairo, const char *font, int *width, int *height,
                 *baseline = pango_layout_get_baseline(layout) / PANGO_SCALE;
         }
         g_object_unref(layout);
+        free(buf);
 }
 
 void pango_printf(cairo_t *cairo, const char *font,
                 double scale, bool markup, const char *fmt, ...) {
-        char buf[MAX_CHARS];
-
         va_list args;
         va_start(args, fmt);
-        if (vsnprintf(buf, sizeof(buf), fmt, args) >= MAX_CHARS) {
-                strcpy(&buf[sizeof(buf) - sizeof(overflow)], overflow);
+        // Add one since vsnprintf excludes null terminator.
+        int length = vsnprintf(NULL, 0, fmt, args) + 1;
+        va_end(args);
+
+        char *buf = malloc(length);
+        if (buf == NULL) {
+                wlr_log(WLR_ERROR, "Failed to allocate memory");
+                return;
         }
+        va_start(args, fmt);
+        vsnprintf(buf, length, fmt, args);
         va_end(args);
 
         PangoLayout *layout = get_pango_layout(cairo, font, buf, scale, markup);
@@ -125,4 +134,5 @@ void pango_printf(cairo_t *cairo, const char *font,
         pango_cairo_update_layout(cairo, layout);
         pango_cairo_show_layout(cairo, layout);
         g_object_unref(layout);
+        free(buf);
 }