Re: [Qemu-devel] [PATCH v2 2/4] tests/qemu-iotests/group: Remove some more tests from the "auto" group

[Thomas Huth]

On 16/07/2019 18.12, Max Reitz wrote:
> On 16.07.19 18:09, Eric Blake wrote:
>> On 7/16/19 10:58 AM, Max Reitz wrote:
[...]
>>>> Is there any way to create our sockets somewhere under /tmp instead of
>>>> inside tests/qemu-iotests, so that we have a shorter filename for
>>>> sockets no matter how deep in the file hierarchy the tests themselves live?
>>>>
>>>> Also, at one point, we tossed around the idea of
>>>> s/qemu-iotests/iotests/, to shave off 5 characters that don't really add
>>>> anything.
>>>
>>> I’d personally rather just skip the iotests if we detect such a silly
>>> OS, but maybe that’s just me.
>>
>> It's a rather unfortunate limit, but it's not all that silly (the limit
>> is based on the fact that struct sockaddr has to fit inside a nice
>> power-of-2 structure somewhere in the kernel, and enough else is used
>> that you really are left with just 104/108 bytes, or even 92 bytes if
>> you use HP-UX 11).  POSIX does not place a minimum length on sun_path,
>> but I know of no system that does not allow at least 92 bytes, if you
>> are aiming for a portably-small name.
> 
> It does come to me as a surprise that the sockaddr is a path instead of,
> say, an inode number.
> 
> But shaving off the “qemu-” seems like the wrong approach to me still.

Anyway, it would be great if someone who's familiar with the code could
find a proper fix for this problem. FWIW, it also happens on Linux:

mkdir 
/tmp/0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789
cd 
/tmp/0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789/
~/path/to/qemu/configure --target-list=x86_64-softmmu
make -j8
cd tests/qemu-iotests/
./check -g quick -qcow2
...
058      fail       [09:29:33] [09:29:34]                    output mismatch 
(see 058.out.bad)
--- /home/thuth/devel/qemu/tests/qemu-iotests/058.out   2019-04-23 
16:43:12.000000000 +0200
+++ 
/tmp/0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789/tests/qemu-iotests/058.out.bad
    2019-07-18 09:29:34.305070819 +0200
@@ -17,18 +17,22 @@
 4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 4096/4096 bytes at offset 8192
 4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-nbd: UNIX socket path 
'/tmp/0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789/tests/qemu-iotests/scratch/qemu-nbd.sock'
 is too long
+Path must be less than 108 bytes
...
065      fail       [09:29:38] [09:29:38]                    output mismatch 
(see 065.out.bad)
--- /home/thuth/devel/qemu/tests/qemu-iotests/065.out   2019-04-23 
16:43:12.000000000 +0200
+++ 
/tmp/0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789/tests/qemu-iotests/065.out.bad
    2019-07-18 09:29:38.568118520 +0200
@@ -1,5 +1,41 @@
-........
+....E..E
+======================================================================
+ERROR: test_qmp (__main__.TestQCow3LazyQMP)
+----------------------------------------------------------------------
+Traceback (most recent call last):
+  File "065", line 75, in setUp
+    self.vm.launch()
+  File 
"/home/thuth/devel/qemu/tests/qemu-iotests/../../python/qemu/machine.py", line 
294, in launch
+    self._launch()
+  File 
"/home/thuth/devel/qemu/tests/qemu-iotests/../../python/qemu/machine.py", line 
311, in _launch
+    self._pre_launch()
+  File "/home/thuth/devel/qemu/tests/qemu-iotests/../../python/qemu/qtest.py", 
line 103, in _pre_launch
+    super(QEMUQtestMachine, self)._pre_launch()
+  File 
"/home/thuth/devel/qemu/tests/qemu-iotests/../../python/qemu/machine.py", line 
262, in _pre_launch
+    server=True)
+  File "/home/thuth/devel/qemu/tests/qemu-iotests/../../python/qemu/qmp.py", 
line 60, in __init__
+    self.__sock.bind(self.__address)
+OSError: AF_UNIX path too long
...

 Thomas

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