[PATCH] [scaled-font] Guard against invalid matrices when creating the scaled font.

[Chris Wilson]

Check the user input for validity before passing the values on to the
backend. Currently the error is detected by the backend and the error is
propagated onto the font-face.
---
 src/cairo-scaled-font.c |   22 ++++++++++++++++++++--
 1 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/src/cairo-scaled-font.c b/src/cairo-scaled-font.c
index 57cfaa6..912dac5 100644
--- a/src/cairo-scaled-font.c
+++ b/src/cairo-scaled-font.c
@@ -38,9 +38,17 @@
  *      Chris Wilson <chris at chris-wilson.co.uk>
  */
 
+#define _GNU_SOURCE
+
 #include "cairoint.h"
 #include "cairo-scaled-font-private.h"
 
+#if _XOPEN_SOURCE >= 600 || defined (_ISOC99_SOURCE)
+#define ISFINITE(x) isfinite (x)
+#else
+#define ISFINITE(x) ((x) * (x) >= 0.) /* check for NaNs */
+#endif
+
 #define CAIRO_SCALED_GLYPH_PAGE_SHIFT 7
 #define CAIRO_SCALED_GLYPH_PAGE_SIZE (1 << CAIRO_SCALED_GLYPH_PAGE_SHIFT)
 #define CAIRO_SCALED_GLYPH_PAGE_INDEX(I) \
@@ -909,9 +917,19 @@ cairo_scaled_font_create (cairo_font_face_t          *font_face,
     cairo_status_t status;
     cairo_scaled_font_map_t *font_map;
     cairo_scaled_font_t key, *old = NULL, *scaled_font = NULL;
+    double det;
+
+    status = font_face->status;
+    if (unlikely (status))
+	return _cairo_scaled_font_create_in_error (status);
+
+    det = _cairo_matrix_compute_determinant (font_matrix);
+    if (! ISFINITE (det))
+	return _cairo_scaled_font_create_in_error (_cairo_error (CAIRO_STATUS_INVALID_MATRIX));
 
-    if (font_face->status)
-	return _cairo_scaled_font_create_in_error (font_face->status);
+    det = _cairo_matrix_compute_determinant (ctm);
+    if (! ISFINITE (det))
+	return _cairo_scaled_font_create_in_error (_cairo_error (CAIRO_STATUS_INVALID_MATRIX));
 
     status = cairo_font_options_status ((cairo_font_options_t *) options);
     if (unlikely (status))
-- 
1.6.0.4


--=-eOh/xoSIvGBTom+9YKG9
Content-Disposition: attachment; filename*0=0025--scaled-font-Differentiate-fatal-error-when-creatin.patc; filename*1=h
Content-Type: text/x-patch; name="0025--scaled-font-Differentiate-fatal-error-when-creatin.patch"; charset="UTF-8"
Content-Transfer-Encoding: 7bit