Protect against possible division by zeros (#316468, Steve Grubb)

2005-11-23  Behdad Esfahbod  <behdad@gnome.org>

        Protect against possible division by zeros (#316468, Steve Grubb)

        * pango/pango-context.c (update_metrics_from_items),
        pango/pango-fontset.c (pango_fontset_real_get_metrics): If count is
        zero, do not alter approximate_{char,digit}_width.

        * pango/opentype/disasm.c: Err on invalid DeltaFormat.

4 files changed, 38 insertions, 14 deletions

diff --git a/ChangeLog b/ChangeLog
index 05afa81b..1e44c6dc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,15 @@
 2005-11-23  Behdad Esfahbod  <behdad@gnome.org>
 
+	Protect against possible division by zeros (#316468, Steve Grubb)
+
+	* pango/pango-context.c (update_metrics_from_items),
+	pango/pango-fontset.c (pango_fontset_real_get_metrics): If count is
+	zero, do not alter approximate_{char,digit}_width.
+
+	* pango/opentype/disasm.c: Err on invalid DeltaFormat.
+
+2005-11-23  Behdad Esfahbod  <behdad@gnome.org>
+
 	* pango/fonts.c (pango_font_description_get_absolute_size): Remove
 	excess "the" in docs. (#319175, Masao Mutoh)
 
diff --git a/pango/opentype/disasm.c b/pango/opentype/disasm.c
index a49aa3f8..544baa27 100644
--- a/pango/opentype/disasm.c
+++ b/pango/opentype/disasm.c
@@ -447,18 +447,26 @@ Dump_Device (TTO_Device *Device, FILE *stream, int indent, FT_Bool is_gsub)
       break;
     }
 
-  n_per = 16 / bits;
-  mask = (1 << bits) - 1;
-  mask = mask << (16 - bits);
-
   DUMP ("<DeltaValue>");
-  for (i = Device->StartSize; i <= Device->EndSize ; i++)
+  if (!bits)
+    {
+
+      fprintf(stderr, "invalid DeltaFormat!!!!!\n");
+    }
+  else
     {
-      FT_UShort val = Device->DeltaValue[i / n_per];
-      FT_Short signed_val = ((val << ((i % n_per) * bits)) & mask);
-      dump (stream, indent, "%d", signed_val >> (16 - bits));
-      if (i != Device->EndSize)
-	DUMP (", ");
+      n_per = 16 / bits;
+      mask = (1 << bits) - 1;
+      mask = mask << (16 - bits);
+
+      for (i = Device->StartSize; i <= Device->EndSize ; i++)
+	{
+	  FT_UShort val = Device->DeltaValue[i / n_per];
+	  FT_Short signed_val = ((val << ((i % n_per) * bits)) & mask);
+	  dump (stream, indent, "%d", signed_val >> (16 - bits));
+	  if (i != Device->EndSize)
+	    DUMP (", ");
+	}
     }
   DUMP ("</DeltaValue>\n");
 }
diff --git a/pango/pango-context.c b/pango/pango-context.c
index cc2dee6a..58fd3eaf 100644
--- a/pango/pango-context.c
+++ b/pango/pango-context.c
@@ -1338,8 +1338,11 @@ update_metrics_from_items (PangoFontMetrics *metrics,
   
   g_hash_table_destroy (fonts_seen);
   
-  metrics->approximate_char_width /= count;
-  metrics->approximate_digit_width /= count;
+  if (count)
+    {
+      metrics->approximate_char_width /= count;
+      metrics->approximate_digit_width /= count;
+    }
 }
 
 /**
diff --git a/pango/pango-fontset.c b/pango/pango-fontset.c
index 261b6d70..d0feb62c 100644
--- a/pango/pango-fontset.c
+++ b/pango/pango-fontset.c
@@ -182,8 +182,11 @@ pango_fontset_real_get_metrics (PangoFontset  *fontset)
 
   g_hash_table_destroy (fonts_seen);
   
-  metrics->approximate_char_width /= count;
-  metrics->approximate_digit_width /= count;
+  if (count)
+    {
+      metrics->approximate_char_width /= count;
+      metrics->approximate_digit_width /= count;
+    }
 
   return metrics;
 }