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List: kde-frameworks-devel
Subject: Re: Review Request 129259: Fix the buffersize in certain situations.
From: taro yamada <archer_ame () yahoo ! co ! jp>
Date: 2016-10-27 5:00:59
Message-ID: 20161027050059.9507.67007 () mimi ! kde ! org
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> On Oct. 26, 2016, 5:58 a.m., Jonathan Doman wrote:
> > src/ioslaves/file/file.cpp, line 790
> > <https://git.reviewboard.kde.org/r/129259/diff/2/?file=482957#file482957line790>
> >
> > I don't think we should use buff.st_size at all. We now know that on "virtual" \
> > filesystems, the link's reported size is basically useless for this purpose. In \
> > the case I reported in the bug, we are allocating 2 GiB just to read a measly \
> > file path.
> > We should just always start with a small constant (maybe 1024 is fine), and then \
> > increase as necessary.
Added initialiLimit.
Thanks!
- taro
-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://git.reviewboard.kde.org/r/129259/#review100282
-----------------------------------------------------------
On Oct. 27, 2016, 4:58 a.m., taro yamada wrote:
>
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://git.reviewboard.kde.org/r/129259/
> -----------------------------------------------------------
>
> (Updated Oct. 27, 2016, 4:58 a.m.)
>
>
> Review request for KDE Frameworks.
>
>
> Bugs: 369275
> https://bugs.kde.org/show_bug.cgi?id=369275
>
>
> Repository: kio
>
>
> Description
> -------
>
> Currently, KIO uses lstat to get the buffersize for readlink.
> But in certain situations, it returns inappropriate value.
>
> For example, "/proc/self" or "/sys/bus/cpu/devices/*" returns its size is 0 , and \
> then readlink fails with EINVAL.(so link won't be shown in kde application.) TMSU \
> seems it returns its target's actual filesize insted of the link's filesize itself. \
> This patch changes the buffersize to 1024 bytes if it is 0.
> And later truncate it to actual size.
>
>
> Diffs
> -----
>
> src/ioslaves/file/file.cpp 8b17d31
>
> Diff: https://git.reviewboard.kde.org/r/129259/diff/
>
>
> Testing
> -------
>
>
> Thanks,
>
> taro yamada
>
>
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This is an automatically generated e-mail. To reply, visit:
<a href="https://git.reviewboard.kde.org/r/129259/">https://git.reviewboard.kde.org/r/129259/</a>
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<br />
<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: \
10px;"> <p style="margin-top: 0;">On October 26th, 2016, 5:58 a.m. UTC, <b>Jonathan \
Doman</b> wrote:</p> <blockquote style="margin-left: 1em; border-left: 2px solid \
#d0d0d0; padding-left: 10px;">
<table width="100%" border="0" bgcolor="white" style="border: 1px solid #C0C0C0; \
border-collapse: collapse; margin: 2px padding: 2px;"> <thead>
<tr>
<th colspan="4" bgcolor="#F0F0F0" style="border-bottom: 1px solid #C0C0C0; \
font-size: 9pt; padding: 4px 8px; text-align: left;"> <a \
href="https://git.reviewboard.kde.org/r/129259/diff/2/?file=482957#file482957line790" \
style="color: black; font-weight: bold; text-decoration: \
underline;">src/ioslaves/file/file.cpp</a> <span style="font-weight: normal;">
(Diff revision 2)
</span>
</th>
</tr>
</thead>
<tbody>
<tr>
<th bgcolor="#e9eaa8" style="border-right: 1px solid #C0C0C0;" \
align="right"><font size="2">790</font></th> <td bgcolor="#fdfebc" width="50%"><pre \
style="font-size: 8pt; line-height: 140%; margin: 0; "> <span \
class="n"><span class="hl">linkTargetB</span>uffer</span><span class="p"><span \
class="hl">.</span></span><span class="n"><span class="hl">res</span>ize</span><span \
class="p">(</span><span class="n">buff</span><span class="p">.</span><span \
class="n">st_size</span><span class="p"><span class="hl">)</span>;</span></pre></td> \
<th bgcolor="#e9eaa8" style="border-left: 1px solid #C0C0C0; border-right: 1px solid \
#C0C0C0;" align="right"><font size="2">790</font></th> <td bgcolor="#fdfebc" \
width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "> \
<span class="kt"><span class="hl">size_t</span></span><span class="hl"> </span><span \
class="n"><span class="hl">b</span>uffer<span class="hl">S</span>ize</span><span \
class="hl"> </span><span class="o"><span class="hl">=</span></span><span class="hl"> \
</span><span class="p">(</span><span class="n">buff</span><span \
class="p">.</span><span class="n">st_size</span><span class="hl"> </span><span \
class="o"><span class="hl">==</span></span><span class="hl"> </span><span \
class="mi"><span class="hl">0</span></span><span class="p"><span \
class="hl">)</span></span><span class="hl"> </span><span class="o"><span \
class="hl">?</span></span><span class="hl"> </span><span class="mi"><span \
class="hl">1024</span></span><span class="hl"> </span><span class="o"><span \
class="hl">:</span></span><span class="hl"> </span><span class="n"><span \
class="hl">buff</span></span><span class="p"><span class="h l">.</span></span><span \
class="n"><span class="hl">st_size</span></span><span class="hl"> </span><span \
class="p">;</span></pre></td> </tr>
</tbody>
</table>
<pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">I \
don't think we should use buff.st_size at all. We now know that on "virtual" \
filesystems, the link's reported size is basically useless for this purpose. In the \
case I reported in the bug, we are allocating 2 GiB just to read a measly file \
path.</p> <p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">We should just always start with a small constant \
(maybe 1024 is fine), and then increase as necessary.</p></pre> </blockquote>
</blockquote>
<pre style="margin-left: 1em; white-space: pre-wrap; white-space: -moz-pre-wrap; \
white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p \
style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
inherit;">Added initialiLimit. Thanks!</p></pre>
<br />
<p>- taro</p>
<br />
<p>On October 27th, 2016, 4:58 a.m. UTC, taro yamada wrote:</p>
<table bgcolor="#fefadf" width="100%" cellspacing="0" cellpadding="12" style="border: \
1px #888a85 solid; border-radius: 6px; -moz-border-radius: 6px; \
-webkit-border-radius: 6px;"> <tr>
<td>
<div>Review request for KDE Frameworks.</div>
<div>By taro yamada.</div>
<p style="color: grey;"><i>Updated Oct. 27, 2016, 4:58 a.m.</i></p>
<div style="margin-top: 1.5em;">
<b style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Bugs: </b>
<a href="https://bugs.kde.org/show_bug.cgi?id=369275">369275</a>
</div>
<div style="margin-top: 1.5em;">
<b style="color: #575012; font-size: 10pt;">Repository: </b>
kio
</div>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Description </h1>
<table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" \
style="border: 1px solid #b8b5a0"> <tr>
<td>
<pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">Currently, KIO uses lstat to get the buffersize for \
readlink. But in certain situations, it returns inappropriate value.</p>
<p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">For example, "/proc/self" or "/sys/bus/cpu/devices/*" \
returns its size is 0 , and then readlink fails with EINVAL.(so link won't be shown \
in kde application.) TMSU seems it returns its target's actual filesize insted of the \
link's filesize itself.</p> <p style="padding: 0;text-rendering: inherit;margin: \
0;line-height: inherit;white-space: inherit;">This patch changes the buffersize to \
1024 bytes if it is 0. And later truncate it to actual size.</p></pre>
</td>
</tr>
</table>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> </h1>
<ul style="margin-left: 3em; padding-left: 0;">
<li>src/ioslaves/file/file.cpp <span style="color: grey">(8b17d31)</span></li>
</ul>
<p><a href="https://git.reviewboard.kde.org/r/129259/diff/" style="margin-left: \
3em;">View Diff</a></p>
</td>
</tr>
</table>
</div>
</body>
</html>
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