Misleading error message when opening a file (on Windows XP SP 2)

[Fredrik Lundh]

Tim Peters wrote:

>> Traceback (most recent call last):
>>    File "<pyshell#1>", line 1, in -toplevel-
>>      f = file('veryBigFile.dat','r+')
>> IOError: [Errno 2] No such file or directory: 'veryBigFile.dat'
>>
>> Is it a BUG or a FEATURE?
>
> Assuming the file exists and isn't read-only, I bet it's a Windows
> bug, and that if you open in binary mode ("r+b") instead I bet it goes
> away (this wouldn't be the first large-file text-mode Windows bug).

however, if you use the C level API, you get EINVAL (which presumably means
that the CRT cannot open this file in text mode), not ENOENT.   this is also true
for older versions of Python:

Python 2.1.1 (#20, Aug 23 2001, 11:27:17) [MSC 32 bit (Intel)] on win32
>>> f = open("bigfile.dat")
>>> f = open("bigfile.dat", "r+")
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
IOError: [Errno 22] Invalid argument: 'bigfile.dat'

which probably means that this fix

    http://www.python.org/sf/538827

is partially responsible for the misleading error message.

(the cause of this seems to be that when you open a text file for updating, the
CRT check if there's a chr(26) at the end of the file, but the 32-bit lseek API
doesn't support seeking to positions larger than 2^31-2)

</F>