Use realpath() to find the path to the extension unpack dir on posix systems.

Use realpath() to find the path to the extension unpack dir on posix systems.

Extensions are unpacked by a sandboxed utility process.  The sandbox forbids file access outside the directory the extension will be unpacked in.  If the path to that directory contains a symbolic link, then unpacking will fail because following the link will cause file system access outside the sandbox path.  Use realpath() to get a symlink free path to the directory where the extension will be unpacked.

A similar issue exists on windows, with junctions instead of symlinks.  This will be fixed in another change.

BUG=13044, 35198
TEST=FileUtilTest.RealPath

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=47032

[Sam Kerner (Chrome), 2010-05-11 21:21:48]

This patch is intended to fix the "could not create directory for unzipping"
error for mac (and possibly linux) users.  A fix for windows is harder because
windows has no API call like realpath() in POSIX.  A fix for windows will come
in another CL.

[tkent, 2010-05-12 01:21:54]

The code seems ok.
Could write the reason why we use realpath() for this purpose in the description
please?

[Sam Kerner (Chrome), 2010-05-12 01:39:04]

On 2010/05/12 01:21:54, Kent Tamura wrote:
> The code seems ok.
> Could write the reason why we use realpath() for this purpose in the
description
> please?

I added a detailed description.

[tkent, 2010-05-12 01:40:48]

LGTM

[Timur Iskhodzhanov, 2010-05-12 18:08:20]

Looks like FileUtilTest.RealPath is not working on Mac/Valgrind bots:
http://build.chromium.org/buildbot/memory/builders/Chromium%20Mac%20(valgrind...

[Timur Iskhodzhanov, 2010-05-12 18:12:06]

This looks like a bug in Valgrind
http://code.google.com/p/chromium/issues/detail?id=44001

On 2010/05/12 18:08:20, Timur Iskhodzhanov wrote:
> Looks like FileUtilTest.RealPath is not working on Mac/Valgrind bots:
>
http://build.chromium.org/buildbot/memory/builders/Chromium%2520Mac%2520%28va...

[Lei Zhang, 2010-05-12 18:53:31]

http://codereview.chromium.org/2001013/diff/1/3
File base/file_util_posix.cc (right):

http://codereview.chromium.org/2001013/diff/1/3#newcode17
base/file_util_posix.cc:17: #include <sys/param.h>
nit: My Linux man page says this should be <limits.h> ?

[Sam Kerner (Chrome), 2010-05-12 20:02:57]

http://codereview.chromium.org/2001013/diff/1/3
File base/file_util_posix.cc (right):

http://codereview.chromium.org/2001013/diff/1/3#newcode17
base/file_util_posix.cc:17: #include <sys/param.h>
On 2010/05/12 18:53:32, Lei Zhang wrote:
> nit: My Linux man page says this should be <limits.h> ?

I used the mac man page, then tested on linux...  Will send you a CL with an
update shortly.