Re: [cx-oracle-users] Using cx_Oracle 6.0rc1 on Windows

[Anthony T. <ant...@gm...>]

On Wed, Jul 5, 2017 at 8:21 AM, Anthony Tuininga <ant...@gm...
> wrote:

>
>
> On Wed, Jul 5, 2017 at 6:29 AM, Walter Dörwald <wa...@li...>
> wrote:
>
>> On 4 Jul 2017, at 16:35, Anthony Tuininga wrote:
>>
>> On Tue, Jul 4, 2017 at 3:18 AM, Walter Dörwald <wa...@li...>
>>> wrote:
>>>
>>> On 3 Jul 2017, at 15:59, Anthony Tuininga wrote:
>>>>
>>>> Hi Walter,
>>>>
>>>>>
>>>>> DPI_DEBUG_LEVEL=7 causes a bunch of output that tells me which public
>>>>> ODPI-C functions are being called. The fact that you are not getting
>>>>> any
>>>>> at
>>>>> all suggests something is going wrong even before cx_Oracle code is
>>>>> involved. Can you try a few more things?
>>>>>
>>>>> 1) Use python -v so you can see if the error is occurring prior to the
>>>>> actual import of cx_Oracle (it may not help but it might, too)
>>>>>
>>>>>
>>>> Here is the output of importing cx_Oracle in a verbose Python session:
>>>> [...]
>>>> Traceback (most recent call last):
>>>>   File "<stdin>", line 1, in <module>
>>>>   File "<frozen importlib._bootstrap>", line 961, in _find_and_load
>>>>   File "<frozen importlib._bootstrap>", line 950, in
>>>> _find_and_load_unlocked
>>>>   File "<frozen importlib._bootstrap>", line 648, in _load_unlocked
>>>>   File "<frozen importlib._bootstrap>", line 560, in module_from_spec
>>>>   File "<frozen importlib._bootstrap_external>", line 922, in
>>>> create_module
>>>>   File "<frozen importlib._bootstrap>", line 205, in
>>>> _call_with_frames_removed
>>>> UnicodeDecodeError: 'utf-8' codec can't decode byte 0xe4 in position 66:
>>>> invalid continuation byte
>>>>
>>>>
>>> Looks like it may have started running code in the module as the first
>>> thing it does is imports the datetime and decimal modules. If you're able
>>> to add some printf() statements at key positions in the
>>> Module_Initialize()
>>> function in src/cx_Oracle.c that would be helpful. In particular, at the
>>> very beginning (to confirm that it is running), after the imports, after
>>> the PyModule_Create() call, just prior to the dpiContext_create() call,
>>> just after it, and just at the end. I wish I could replicate this myself!
>>>
>>
>> We've found the spot where the error occurs with the following patch:
>>
>> ============================================================
>> ====================
>>
>> C:\checkouts\python-cx_Oracle\odpi>git diff
>> diff --git a/src/dpiOci.c b/src/dpiOci.c
>> index f881bed..e588b1c 100644
>> --- a/src/dpiOci.c
>> +++ b/src/dpiOci.c
>> @@ -1338,6 +1338,7 @@ static int dpiOci__loadLib(dpiError *error)
>>  #ifdef _WIN32
>>      DWORD length, errorNum;
>>  #endif
>> +    printf("Start dpiOci__loadLib()\n");
>>
>>      // dynamically load the OCI library
>>      for (i = 0; !dpiOciLibHandle; i++) {
>> @@ -1356,6 +1357,7 @@ static int dpiOci__loadLib(dpiError *error)
>>              if (length > 3)
>>                  loadError[length - 3] = '\0';
>>              else strcpy(loadError, "DLL load failed");
>> +            printf("loadError: %s\n",loadError);
>>          }
>>  #else
>>          dpiOciLibHandle = dlopen(libName, RTLD_LAZY);
>> @@ -1370,6 +1372,7 @@ static int dpiOci__loadLib(dpiError *error)
>>          return dpiError__set(error, "load library", DPI_ERR_LOAD_LIBRARY,
>>                  loadError);
>>
>> +    printf("After LoadLibrary()\n");
>>      // validate library
>>      if (dpiOci__loadLibValidate(error) < 0) {
>>  #ifdef _WIN32
>>
>> ============================================================
>> ====================
>>
>> With this patch, we get the following output:
>>
>> ============================================================
>> ====================
>>
>> import cx_Oracle
>>>>>
>>>> Start dpiOci__loadLib()
>> loadError: %1 ist keine zulõssige Win32-Anwendung
>> Traceback (most recent call last):
>>   File "<stdin>", line 1, in <module>
>>   File "<frozen importlib._bootstrap>", line 961, in _find_and_load
>>   File "<frozen importlib._bootstrap>", line 950, in
>> _find_and_load_unlocked
>>   File "<frozen importlib._bootstrap>", line 648, in _load_unlocked
>>   File "<frozen importlib._bootstrap>", line 560, in module_from_spec
>>   File "<frozen importlib._bootstrap_external>", line 922, in
>> create_module
>>   File "<frozen importlib._bootstrap>", line 205, in
>> _call_with_frames_removed
>> UnicodeDecodeError: 'utf-8' codec can't decode byte 0xe4 in position 66:
>> invalid continuation byte
>>
>> ============================================================
>> ====================
>>
>> "%1 ist keine zulõssige Win32-Anwendung" (which should read "%1 ist keine
>> zulässige Win32-Anwendung", i.e. the "ö" should be an "ä") means "%1 is not
>> an acceptable win32 application".
>>
>> So we don't see the real problem because cx_Oracle fails to create the
>> proper Unicode string from the OS error message.
>>
>> It's not clear what encoding this is (probable latin-1 or cp1252, but
>> definitely *not* UTF-8). A
>>
>>    grep 'xe4.*LATIN SMALL LETTER A WITH DIAERESIS' Lib/encodings/*.py
>>
>> in the Python source code returns 40 encodings that map the byte 0xE4 to
>> ä.
>>
>> If the correct encoding can't be determined from the environment it might
>> be best to use a less strict error handling (like e.g. backslashreplace)
>> when decoding the bytes of the error message.
>>
>
> Thanks, Walter. This is very helpful. We'll have to see what makes the
> most sense in this case. Do you see information in the event log regarding
> this error?
>

I have discovered the source of the problem. I was able to replicate the
issue thanks to this pointer and have corrected it in the source. If you
can do a new pull and compile you should get the correct error message now.
If you can confirm that would be helpful! Thanks.


>
>
>>
>> And of cause it would help if %1 was resolved to a useful filename.
>>
>
> Naturally. But that information isn't directly provided. I'll look into
> that, too.
>

This is a limitation of Windows and there isn't much that can be done about
it. Sorry!


>
>
>>
>> But now for the real error...
>>
>> [...]
>>>
>>>>
>>>> I also note that you are using VS 2017. Another person noted that
>>>>
>>>>> uninstalling VS 2017 and using an earlier version worked for him -- why
>>>>> that would be is an interesting question (!!?) but if you have a
>>>>> machine
>>>>> that doesn't have VS 2017 but an earlier version that would be worth
>>>>> testing, too.
>>>>>
>>>>>
>>>> We currently don't have a Windows 10 machine without VS 2017, but we're
>>>> going to
>>>> uninstall VS 2017 on this machine and retry with and an older version.
>>>>
>>>> Also, IIRC this exception means that the VS Redistributables are missing
>>>> or are
>>>> installed incorrectly.
>>>>
>>>> However I don't know how we can check this.
>>>>
>>>
>>>
>>> You can use this tool: http://www.dependencywalker.com/ which will tell
>>> you
>>> what dependencies the cx_Oracle.pyd file and all of their dependencies,
>>> too. Hopefully it helps.
>>>
>>
>> OK, we tried that. The output is here:
>>
>>    http://styx.livinglogic.de/~walter/cx_Oracle/cx_Oracle.cp36
>> -win_amd64.txt
>>
>> dependencywalker seem that have many problems with this DLL, but what
>> sticks out is VCRUNTIME140.dll. This seems to be part of the "Visual C++
>> Redistributable for Visual Studio 2015" which we downloaded from here:
>>
>>    https://www.microsoft.com/en-us/download/details.aspx?id=48145
>>
>> (we've downloaded vc_redist.x64.exe). When we install it, it complains
>> that another version is already installed. After we've uninstalled the 2017
>> Redistributables installation works, but the output of "import cx_Oracle"
>> remains the same.
>>
>
> So the problem isn't resolved by the change of VS redistributable. Can you
> take a look in the event log? Can you also provide a list of all of the VS
> redistributables you have installed? I am going to try to replicate this
> myself.
>
>
>>
>> [...]
>>>
>>
>> Servus,
>>    Walter
>>
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>
>