From 3a98c7fae196fd149078af4553b966dc1c8d763b Mon Sep 17 00:00:00 2001
From: Ebrahim Byagowi <ebrahim@gnu.org>
Date: Thu, 6 Feb 2020 01:11:00 +0330
Subject: [PATCH] [glyf] Skip empty contours

As https://savannah.nongnu.org/bugs/index.php?57701
---
 src/hb-ot-glyf-table.hh     |   8 +++++
 test/api/fonts/Stroking.ttf | Bin 0 -> 3380 bytes
 test/api/test-draw.c        |  60 ++++++++++++++++++++++++++++++++++--
 3 files changed, 65 insertions(+), 3 deletions(-)
 create mode 100644 test/api/fonts/Stroking.ttf

diff --git a/src/hb-ot-glyf-table.hh b/src/hb-ot-glyf-table.hh
index a4b685e80..cb1a95c41 100644
--- a/src/hb-ot-glyf-table.hh
+++ b/src/hb-ot-glyf-table.hh
@@ -1098,6 +1098,14 @@ struct glyf
 	  if (points[i].is_end_point)
 	    break;
 	}
+
+	/* Skip contours with less than 2 points */
+	if (contour_length < 2)
+	{
+	  contour_start += contour_length;
+	  continue;
+	}
+
 	contour_point_t *curr = &points[contour_start + contour_length - 1];
 	contour_point_t *next = &points[contour_start];
 
diff --git a/test/api/fonts/Stroking.ttf b/test/api/fonts/Stroking.ttf
new file mode 100644
index 0000000000000000000000000000000000000000..b88c6fa03855e420d2a61d8e32e8d1ba82495321
GIT binary patch
literal 3380
zcmdT{O=uHQ5dPlgHT_F93Bf-^Up3VzR?}8JX;DOb5!4ncRJ4YeCZ$O?#t5x~D1y{K
z^rWCDiU=YiMSHM^UV0FVf`Wo2mw?ohUKB*ccH{Rpt(K}#dr<Sj?9O~M^Y+`<$#en%
zpbW?1fZEZtruOR6+xq|!Ai6)C2qmNav7NMgX~(1S?zZfa)*xVP0!oKtk<bBE((#VI
zdzAGt0`pPvi24Y{A4{aWRIIp%`4j}=W;o=z;akM~h1#D8btTb^J@l8*R-K_l<W#s~
zFW{O-`%BV1l(t@D2&nLBKQvcL?oP{a>+B7mQ0^uGWSULQ51HM!-h)pn?<;SlSpq|&
zT+GpkIOys_kD%Y)Deuc)9X8^@N}hvWI#bx#Caks*>FN^~QN+V)E3ad~#{9kbKAuUx
zPADq1<Mf5uN^`Z>&bF-wc)qIYsSBgzU~{uMO+-LJXlB~xosa$fharL-_3kc6?C0GF
zHxbEQ9-?0*)lqd)ovj+GdYa48tMI@^kErA7Odid>$?eK*&tA%&&z{bn%xueSwfAH2
zPs_*MeMsQ3SS-543nO5hFfxuh$2rGaSuZck_k36KmP2KC$)Omi^Hh4ODm|4wa`R||
zqh|DZ+1*dgJ*8LRAm!`!Uq--#6?~1L-|dA|et6vm{7M3DuXnwlnw;Y$W;i9i{$+-<
z<!j4;s2BZWgi=2+U=3Og)<Vjlbs^k4CaOhPq$$;7y<ytcOY53-j`DJ>x9H=?eB{8C
z9Y$~dE=6x4s__fPHHF3)g~zyXs)F^30PFbwE{Y%DyK%lK6uz^uT=xlfg=uvO1V!JJ
z@A$O4g#7FrnOU1K=1%Gpf6BO~&=`w?J7e*GoH6^vbn96BqoSBn$A7>W|DN&0OtJ3o
zG&k{KX59kD_bEvCis{$Hj62&*`x?2G;n?@NZ~<*nx348wFs>V%_?C?8lJoWi?zDAI
zsZ!6xYuUx~y5N7zz2mxpS)42LxSWJLwZ6qncBk5-v9t<=SE$-xZE%%pFwJN@(v(h_
z9qpab#z^#VJe0x~m`I`<DYPSs7}6Yg0|@hx3bhE@vWj{G<4i`x5kV89QnWgl(@Ct6
YSQLlp3lZna{|12d3Qz1e*4U)=4T6?$rT_o{

literal 0
HcmV?d00001

diff --git a/test/api/test-draw.c b/test/api/test-draw.c
index 086f4e710..51fdebee9 100644
--- a/test/api/test-draw.c
+++ b/test/api/test-draw.c
@@ -352,10 +352,9 @@ test_hb_glyph_ttf_parser_tests (void)
       g_assert_cmpmem (str, user_data.consumed, expected, sizeof (expected) - 1);
     }
     {
-      /* According to tests on tts-parser we should return an empty on single point but we aren't */
       user_data.consumed = 0;
       g_assert (hb_font_draw_glyph (font, 5, funcs, &user_data));
-      char expected[] = "M15,0Q15,0 15,0Z";
+      char expected[] = "";
       g_assert_cmpmem (str, user_data.consumed, expected, sizeof (expected) - 1);
     }
     {
@@ -365,7 +364,7 @@ test_hb_glyph_ttf_parser_tests (void)
 			"L29,509L123,539L123,570Q123,674 169,720Q215,765 297,765"
 			"L297,765Q329,765 356,760Q382,754 401,747L401,747L378,678"
 			"Q362,683 341,688Q320,693 298,693L298,693Q254,693 233,664"
-			"Q211,634 211,571L211,571L211,536L346,536ZM15,0Q15,0 15,0Z";
+			"Q211,634 211,571L211,571L211,536L346,536Z";
       g_assert_cmpmem (str, user_data.consumed, expected, sizeof (expected) - 1);
     }
 
@@ -760,6 +759,60 @@ test_hb_glyph_font_kit_variations_tests (void)
   }
 }
 
+static void
+test_hb_draw_stroking (void)
+{
+  /* https://skia-review.googlesource.com/c/skia/+/266945
+     https://savannah.nongnu.org/bugs/index.php?57701 */
+  char str[2048];
+  user_data_t user_data = {
+    .str = str,
+    .size = sizeof (str)
+  };
+  {
+    hb_face_t *face = hb_test_open_font_file ("fonts/Stroking.ttf");
+    hb_font_t *font = hb_font_create (face);
+    hb_face_destroy (face);
+
+    user_data.consumed = 0;
+    g_assert (hb_font_draw_glyph (font, 6, funcs, &user_data));
+    char expected[] = "M1626,1522Q1626,1522 1626,1522Q1626,1522 1626,1522ZM531,1985"
+		      "Q436,1764 436,1522Q436,1280 531,1060Q625,839 784,680Q943,521 1164,427"
+		      "Q1384,332 1626,332Q1868,332 2089,427Q2309,521 2468,680Q2627,839 2722,1060"
+		      "Q2816,1280 2816,1522Q2816,1764 2722,1985Q2627,2205 2468,2364"
+		      "Q2309,2523 2089,2618Q1868,2712 1626,2712Q1384,2712 1164,2618"
+		      "Q943,2523 784,2364Q625,2205 531,1985ZM306,1165Q256,1342 256,1528"
+		      "Q256,1714 306,1892Q355,2069 443,2220Q531,2370 658,2497"
+		      "Q784,2623 935,2711Q1085,2799 1263,2849Q1440,2898 1626,2898"
+		      "Q1812,2898 1990,2849Q2167,2799 2318,2711Q2468,2623 2595,2497"
+		      "Q2721,2370 2809,2220Q2897,2069 2947,1892Q2996,1714 2996,1528"
+		      "Q2996,1342 2947,1165Q2897,987 2809,837Q2721,686 2595,560"
+		      "Q2468,433 2318,345Q2167,257 1990,208Q1812,158 1626,158"
+		      "Q1440,158 1263,208Q1085,257 935,345Q784,433 658,560"
+		      "Q531,686 443,837Q355,987 306,1165Z";
+    g_assert_cmpmem (str, user_data.consumed, expected, sizeof (expected) - 1);
+
+    user_data.consumed = 0;
+    g_assert (hb_font_draw_glyph (font, 7, funcs, &user_data));
+    char expected2[] = "M531,1985Q436,1764 436,1522Q436,1280 531,1060Q625,839 784,680"
+		       "Q943,521 1164,427Q1384,332 1626,332Q1868,332 2089,427"
+		       "Q2309,521 2468,680Q2627,839 2722,1060Q2816,1280 2816,1522"
+		       "Q2816,1764 2722,1985Q2627,2205 2468,2364Q2309,2523 2089,2618"
+		       "Q1868,2712 1626,2712Q1384,2712 1164,2618Q943,2523 784,2364"
+		       "Q625,2205 531,1985ZM306,1165Q256,1342 256,1528Q256,1714 306,1892"
+		       "Q355,2069 443,2220Q531,2370 658,2497Q784,2623 935,2711"
+		       "Q1085,2799 1263,2849Q1440,2898 1626,2898Q1812,2898 1990,2849"
+		       "Q2167,2799 2318,2711Q2468,2623 2595,2497Q2721,2370 2809,2220"
+		       "Q2897,2069 2947,1892Q2996,1714 2996,1528Q2996,1342 2947,1165"
+		       "Q2897,987 2809,837Q2721,686 2595,560Q2468,433 2318,345"
+		       "Q2167,257 1990,208Q1812,158 1626,158Q1440,158 1263,208"
+		       "Q1085,257 935,345Q784,433 658,560Q531,686 443,837Q355,987 306,1165Z";
+    g_assert_cmpmem (str, user_data.consumed, expected2, sizeof (expected2) - 1);
+
+    hb_font_destroy (font);
+  }
+}
+
 int
 main (int argc, char **argv)
 {
@@ -786,6 +839,7 @@ main (int argc, char **argv)
   hb_test_add (test_hb_glyph_ttf_parser_tests);
   hb_test_add (test_hb_glyph_font_kit_glyphs_tests);
   hb_test_add (test_hb_glyph_font_kit_variations_tests);
+  hb_test_add (test_hb_draw_stroking);
   unsigned result = hb_test_run ();
 
   hb_draw_funcs_destroy (funcs);