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<th>Priority</th>
<td>medium
</td>
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<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - OpenType weight between 0 and 100 could result in assertion in FcWeightFromOpenType"
href="https://bugs.freedesktop.org/show_bug.cgi?id=82228">82228</a>
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<th>Assignee</th>
<td>fontconfig-bugs@lists.freedesktop.org
</td>
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<th>Summary</th>
<td>OpenType weight between 0 and 100 could result in assertion in FcWeightFromOpenType
</td>
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<th>QA Contact</th>
<td>freedesktop@behdad.org
</td>
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<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr>
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<th>OS</th>
<td>All
</td>
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<th>Reporter</th>
<td>daphnediane@mac.com
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<th>Hardware</th>
<td>Other
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
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<th>Component</th>
<td>library
</td>
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<th>Product</th>
<td>fontconfig
</td>
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<p>
<div>
<pre>Calling FcWeightFromOpenType with ot_weight between 1 and 99 triggers an
assertion. lerp will get called with x = ot_weight, x1 = 0, x2 = 100, y1 = 0,
y2 = 0. It will then compute dy = y2 - y1 = 0. Which will cause assert ( dx > 0
&& dy > 0 && x1 <= x && x <= x2 ) to fail as dy is 0. Seems like if dy == 0,
then it should return y1.
Possible patch
diff --git a/src/fcweight.c b/src/fcweight.c
index 87bbe67..4def775 100644
--- a/src/fcweight.c
+++ b/src/fcweight.c
@@ -45,6 +45,7 @@ static int lerp(int x, int x1, int x2, int y1, int y2)
{
int dx = x2 - x1;
int dy = y2 - y1;
+ if (dy == 0 && x1 <= x && x <= x2) return y1;
assert (dx > 0 && dy > 0 && x1 <= x && x <= x2);
return y1 + (dy*(x-x1) + dx/2) / dx;
}</pre>
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