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<base href="https://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW " title="NEW --- - #including files from /sys on Linux adds extra null characters" href="https://urldefense.proofpoint.com/v2/url?u=https-3A__llvm.org_bugs_show-5Fbug.cgi-3Fid-3D24168&d=AwMBaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=pF93YEPyB-J_PERP4DUZOJDzFVX5ZQ57vQk33wu0vio&m=l_wOxVKO8ZmU9r8bS6wx-ynR2eEmDTZ9ANJsH8FeBGg&s=BArdykvXbDLc7sV6I7ufnUf4WAdyXjjyS-XcPtNlVUs&e=">24168</a>
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<th>Summary</th>
<td>#including files from /sys on Linux adds extra null characters
</td>
</tr>
<tr>
<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>Linux
</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
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
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<th>Reporter</th>
<td>ncraun@gmail.com
</td>
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Hello,
I recently encountered a bug where #including files from /sys on Linux will
read extra null characters that are not originally in that file.
The bug can be reproduced by #including any file from /sys, for example:
bug.c:
#include "/sys/devices/system/cpu/cpu0/cache/index0/coherency_line_size"
This makes clang generate about several thousand warnings about null
characters:
/sys/devices/system/cpu/cpu0/cache/index0/coherency_line_size:2:1968: warning:
null character ignored [-Wnull-character
However, if you run something like cat
/sys/devices/system/cpu/cpu0/cache/index0/coherency_line_size you see that the
file does not have all these extra null characters. On my machine cat cat
/sys/devices/system/cpu/cpu0/cache/index0/coherency_line_size just prints out
"64".
So somehow the preprocessor is reading many more null characters than are
actually in the file. Now of course there's probably no practical reason to
#include files from /sys, but still it should read the file in correctly
without appending extra null bytes.
I think the preprocessor is not correctly reading the file from the sysfs
virtual file system on /sys.
I am running clang version 3.5.0 on Linux kernel 4.0.6.</pre>
</div>
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