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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - clang trunk r261461+ fails to compile on some platforms (including Snow Leopard) due to strnlen usage"
href="https://llvm.org/bugs/show_bug.cgi?id=27714">27714</a>
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<th>Summary</th>
<td>clang trunk r261461+ fails to compile on some platforms (including Snow Leopard) due to strnlen usage
</td>
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<th>Product</th>
<td>clang
</td>
</tr>
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<th>Version</th>
<td>unspecified
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>-New Bugs
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>jeremyhu@apple.com
</td>
</tr>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>strnlen() is used unconditionally, but it is not available on all supported
platforms.
trunk/tools/clang/lib/Lex/HeaderMap.cpp:158:18: error: use of undeclared
identifier 'strnlen'
unsigned Len = strnlen(Data, MaxLen);
^
1 error generated.
---
Regression introduced by:
commit 839cd13b65d802f06276ff88d234419c38a44199
Author: Duncan P. N. Exon Smith <<a href="mailto:dexonsmith@apple.com">dexonsmith@apple.com</a>>
Date: Sun Feb 21 00:14:36 2016 +0000
Lex: Never overflow the file in HeaderMap::lookupFilename()
If a header map file is corrupt, the strings in the string table may not
be null-terminated. The logic here previously relied on `MemoryBuffer`
always being null-terminated, but this isn't actually guaranteed by the
class AFAICT. Moreover, we're seeing a lot of crash traces at calls to
`strlen()` inside of `lookupFilename()`, so something is going wrong
there.
Instead, use `strnlen()` to get the length, and check for corruption.
Also remove code paths that could call `StringRef(nullptr)`. r261459
made these rather obvious (although they'd been there all along).
git-svn-id: <a href="https://llvm.org/svn/llvm-project/cfe/trunk@261461">https://llvm.org/svn/llvm-project/cfe/trunk@261461</a>
91177308-0d34-0410-b5e6-96231b3b80d8</pre>
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</p>
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