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    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW --- - Recursive #include overruns MAX_PATH due to lack of path canonization"
   href="http://llvm.org/bugs/show_bug.cgi?id=20440">20440</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Recursive #include overruns MAX_PATH due to lack of path canonization
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>clang
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>3.4
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>PC
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>Windows XP
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>normal
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>Frontend
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>unassignedclangbugs@nondot.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>ilya.konstantinov@gmail.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvmbugs@cs.uiuc.edu
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Created <span class=""><a href="attachment.cgi?id=12821" name="attach_12821" title="Simple testcase">attachment 12821</a> <a href="attachment.cgi?id=12821&action=edit" title="Simple testcase">[details]</a></span>
Simple testcase

When #include "..." is relative to the including file's directory, clang
performs simple path concatenation.

FOR EXAMPLE, if foo/foo.h includes "../bar/bar.h", clang will ask the OS to
open "foo/../bar/bar.h" -- i.e. it will not canonize the path to "bar/bar.h".

Normally, the OS handles this under the hood. However, Win32 CreateFile only
accepts up to 260 (a.k.a MAX_PATH) characters.

With sufficiently long and contrived chains of relative #includes, which
actually occurred in a real-life project of mine, it can overrun MAX_PATH and
result in erroneous "File not found".

TESTCASE

I'm attaching a reproducing testcase. Microsoft Visual C++ handles it well.
(gcc fails similarly.)

Curiously, merely recursively including the same file does not reproduce it,
probably due to directory caching of some sort in HeaderSearch::LookupFile.</pre>
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