webkitpy: Override TEMPDIR for Xvfb.

third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/port/linux.py

Index: third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/port/linux.py
diff --git a/third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/port/linux.py b/third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/port/linux.py
index d0c6bbd325e86c278c582898714ffe473bc9d302..3e76cea94628ed12b153328399943da099c89ffe 100644
--- a/third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/port/linux.py
+++ b/third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/port/linux.py
@@ -157,12 +157,24 @@ class LinuxPort(base.Port):
             _log.warn('Failed to find a free display to start Xvfb.')
             return
 
+        # Parts of Xvfb use a hard-coded "/tmp" for its temporary directory.
+        # This can cause a failure when those parts expect to hardlink against
+        # files that were created in "TEMPDIR" / "TMPDIR".
+        #
+        # Since altering this behavior requires an Xvfb patch or some deep
+        # surgery, we instead opt to use the system "TEMPDIR" for this specific
+        # process.

[mithro, 2017/05/03 01:58:34]

Don't need this second paragraph.

[dnj, 2017/05/03 03:36:36]

Done.

+        #
+        # See: crbug.com/715848

[mithro, 2017/05/03 01:58:34]

https://crbug.com/XXXXX

[dnj, 2017/05/03 03:36:36]

Done.

+        env = self.host.environ.copy()
+        env['TEMPDIR'] = env['TMPDIR'] = '/tmp'

[mithro, 2017/05/03 01:58:34]

Can you log a warning if 'TEMPDIR' is set in the environment and not equal to
'/tmp'

[iannucci, 2017/05/03 02:06:36]

Actually... Why set TEMPDIR? That's only used on windows.

[dnj, 2017/05/03 03:36:36]

I can - however, this will generally not be set on developer systems, and will
always be set to not "/tmp" on bots. I'll log a warning if it's set and not
"/tmp".

[dnj, 2017/05/03 03:36:36]

I was overriding everything I saw in the log vars, but good to know - I'll just
set TMPDIR.

+
         _log.info('Starting Xvfb with display "%s".', display)
         self._xvfb_stdout = tempfile.NamedTemporaryFile(delete=False)
         self._xvfb_stderr = tempfile.NamedTemporaryFile(delete=False)
         self._xvfb_process = self.host.executive.popen(
             ['Xvfb', display, '-screen', '0', '1280x800x24', '-ac', '-dpi', '96'],
-            stdout=self._xvfb_stdout, stderr=self._xvfb_stderr)
+            stdout=self._xvfb_stdout, stderr=self._xvfb_stderr, env=env)
 
         # By setting DISPLAY here, the individual worker processes will
         # get the right DISPLAY. Note, if this environment could be passed