Problem with os.chdir()

[Tim Golden]

venutaurus539 at gmail.com wrote:
> On Mar 11, 7:17 pm, Tim Golden <m... at timgolden.me.uk> wrote:
>> venutaurus... at gmail.com wrote:
>>> On Mar 11, 6:41 pm, Tim Golden <m... at timgolden.me.uk> wrote:
>>>> venutaurus... at gmail.com wrote:
>>>>> On Mar 11, 5:19 pm, Tim Golden <m... at timgolden.me.uk> wrote:
>>>>>>> Here is my code snippet which you will be interested in:
>>>>>> Indeed.
>>>>>>> file = ur'\\?\C:\\TestDataSet\DeepPaths
>>>>>>> \DeepPathLevel01\DeepPathLevel02\DeepPathLevel03\DeepPathLevel04\DeepPathLe vel05\DeepPathLevel06\DeepPathLevel07\DeepPathLevel08\DeepPathLevel09\DeepP athLevel10\DeepPathLevel11\DeepPathLevel12\DeepPathLevel13\DeepPathLevel14\ DeepPathLevel15\DeepPathLevel16\DeepPathLevel172.txt'
>>>>>> And what happens if you remove that second double-backslash,
>>>>>> the one between C: and TestDataSet?
>>>>>> TJG
>>>>> --------------------------------------------------------------------------- -------------
>>>>> Even if I give the file path as below
>>>>> file = ur'\\?\C:\TestDataSet\DeepPaths
>>>>> \DeepPathLevel01\DeepPathLevel02\DeepPathLevel03\DeepPathLevel04\DeepPathLe vel05\DeepPathLevel06\DeepPathLevel07\DeepPathLevel08\DeepPathLevel09\DeepP athLevel10\DeepPathLevel11\DeepPathLevel12\DeepPathLevel13\DeepPathLevel14\ DeepPathLevel15\DeepPathLevel16\DeepPathLevel172.txt'
>>>>> I am still getting the exception:
>>>>> Traceback (most recent call last):
>>>>>   File "C:\JPDump\test.py", line 29, in <module>
>>>>>     renameStubs(file)
>>>>>   File "C:\JPDump\test.py", line 12, in renameStubs
>>>>>     os.chdir (path)
>>>>> WindowsError: [Error 206] The filename or extension is too long: u'\\\
>>>>> \?\\C:\\TestDataSet\\DeepPaths\\DeepPathLevel01\\DeepPathLevel02\
>>>>> \DeepPathLevel03\\DeepPathLevel04\\DeepPathLevel05\\DeepPathLevel06\
>>>>> \DeepPathLevel07\\DeepPathLevel08\\DeepPathLevel09\\DeepPathLevel10\
>>>>> \DeepPathLevel11\\DeepPathLevel12\\DeepPathLevel13\\DeepPathLevel14\
>>>>> \DeepPathLevel15\\DeepPathLevel16\\'
>>>> Well, the source for os.chdir under Windows uses the Win32
>>>> SetCurrentDirectoryW API as expected. What is not expected
>>>> is that the MS docs for that function:
>>>>  http://msdn.microsoft.com/en-us/library/aa365530(VS.85).aspx
>>>> still seem to suggest that you can't exceed MAX_PATH (ie 260)
>>>> characters. And indeed, attempting to do a mkdir at the command
>>>> line of something longer than that will also fail.
>>>> Hmmm.. maybe the usual advice for naming files \\?\... doesn't
>>>> apply to directory paths?
>>>> Do you have an already existing full pathname that long?
>>>> TJG
>>> Yes Sir,
>>>       My application demands me to create deep paths of (1023) long.
>>> I've cross checked it and the folder actually exists.
>> Well, a little bit of experimentation shows that you can
>> *create* paths this deep (say, with os.mkdir). But you
>> can't actually set the current directory to it. So the
>> next question is: do you actually need to be *in* that
>> directory, rather than simply to reference it?
>>
>> In other words, you can do this (assuming you have a c:\temp):
>>
>> <code>
>> import os
>> for i in range (1, 15):
>>   os.mkdir (ur"\\?\c:\temp\%s" % "\\".join (100 * "c" for j in range (i)))
>>
>> </code>
>>
>> But you can't then os.chdir to it. You're hitting the limits of
>> the OS. Try accessing files directly within the structure
>> you're using. (ie without chdir-ing there first).
>>
>> TJG
> 
> Sir,
>    My application has to rename a file in that folder.For that I had
> to do a os.chdir() to that folder. Otherwise if I do a os.rename
> (deeppath\file1,file2), it is creating a new file in the current
> working directory with the new name and leaving the original file as
> it is which is not intended :-(. So, can you suggest me any work
> around for this?

Jus
t rename from and to with a full pathname (using the \\?\ bit):

os.rename (ur"\\?\c:\long\path\to\file.txt", ur"\\?\c:\long\path\to\newfile.txt")

TJG