Misleading error message when opening a file (on Windows XP SP 2)
Here an example of what I mean (Python 2.4.2, IDLE 1.1.2, Windows XP SP2, NTFS file system, 80 GByte large file): f = file('veryBigFile.dat','r') f = file('veryBigFile.dat','r+') 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? Claudio Grondi -- http://mail.python.org/mailman/listinfo/python-list
Re: Misleading error message when opening a file (on Windows XP SP 2)
In [EMAIL PROTECTED], Claudio Grondi wrote: Here an example of what I mean (Python 2.4.2, IDLE 1.1.2, Windows XP SP2, NTFS file system, 80 GByte large file): f = file('veryBigFile.dat','r') f = file('veryBigFile.dat','r+') You mention the file size and gave a speaking name to that file -- does the file size matter? 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? It's the error number Windows returns for that operation. Ciao, Marc 'BlackJack' Rintsch -- http://mail.python.org/mailman/listinfo/python-list
Re: Misleading error message when opening a file (on Windows XP SP 2)
Marc 'BlackJack' Rintsch wrote: In [EMAIL PROTECTED], Claudio Grondi wrote: Here an example of what I mean (Python 2.4.2, IDLE 1.1.2, Windows XP SP2, NTFS file system, 80 GByte large file): f = file('veryBigFile.dat','r') f = file('veryBigFile.dat','r+') You mention the file size and gave a speaking name to that file -- does the file size matter? Yes, it does. I haven't tested it yet, but I suppose 2 or 4 GByte threshold value. 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? It's the error number Windows returns for that operation. So you just try to say: it's not Python fault - it's just another bug of the damn Microsoft Windows operating system, right? Claudio Grondi -- http://mail.python.org/mailman/listinfo/python-list
Re: Misleading error message when opening a file (on Windows XP SP 2)
[Claudio Grondi] Here an example of what I mean (Python 2.4.2, IDLE 1.1.2, Windows XP SP2, NTFS file system, 80 GByte large file): f = file('veryBigFile.dat','r') f = file('veryBigFile.dat','r+') 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). -- http://mail.python.org/mailman/listinfo/python-list
Re: Misleading error message when opening a file (on Windows XP SP 2)
Tim Peters wrote: 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). dir bigfile.dat 2006-08-28 11:46 5 000 000 000 bigfile.dat f = file(bigfile.dat, r) f = file(bigfile.dat, r+) Traceback (most recent call last): File stdin, line 1, in module IOError: [Errno 2] No such file or directory: 'bigfile.dat' f = file(bigfile.dat, rb) f = file(bigfile.dat, r+b) (typing f.read() here is a nice way to lock up the machine ;-) /F -- http://mail.python.org/mailman/listinfo/python-list
Re: Misleading error message when opening a file (on Windows XP SP 2)
Tim Peters wrote: [Claudio Grondi] Here an example of what I mean (Python 2.4.2, IDLE 1.1.2, Windows XP SP2, NTFS file system, 80 GByte large file): f = file('veryBigFile.dat','r') f = file('veryBigFile.dat','r+') 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). I knew already that 'r+b' fixes it. Yes, you have won the bet :) . I suppose, like you do, that because there is a difference between text and binary files on Windows and the text files are e.g. opened being buffered using a 32-bit buffer pointer, this fails on too large NTFS files. I could also imagine that Python tries to buffer the text file and fails because it uses the wrong pointer size when asking Windows for the content. I have not yet looked into the C-code of Python - any hint which file I should take a closer look at? Just curious to see for myself, that the bug is on the Windows side. Claudio Grondi -- http://mail.python.org/mailman/listinfo/python-list
Re: Misleading error message when opening a file (on Windows XP SP 2)
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 -- http://mail.python.org/mailman/listinfo/python-list
Re: Misleading error message when opening a file (on Windows XP SP 2)
Fredrik Lundh wrote: 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 Using MSVC++ .NET 2003 compiler (if I did it all the right way): fstm = fopen(bigfile.dat,r+); if(fstm == 0) { printf( ErrNo: %i \n, errno ); } // ^-- prints : // on r+ with too large file: 22 (EINVAL-Invalid argument) // on non-existing file : 2 (ENOENT-no such file) // on bad mode string spec. : 0 (??? why not EINVAL ...) So there _is_ a way to distinguish the different problems occurred while opening the file. The error message comes from Python (errnomodule.c), not from Windows(errno.h). Concluding from this it becomes evident for me, that this misleading error message is Python fault (even if originated by misleading errno values set after fopen in the MSVC++ environment and Windows), right? Probably also in Python 2.5? Claudio Grondi -- http://mail.python.org/mailman/listinfo/python-list
Re: Misleading error message when opening a file (on Windows XP SP 2)
Claudio Grondi wrote: Tim Peters wrote: [Claudio Grondi] Here an example of what I mean (Python 2.4.2, IDLE 1.1.2, Windows XP SP2, NTFS file system, 80 GByte large file): f = file('veryBigFile.dat','r') f = file('veryBigFile.dat','r+') 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). I knew already that 'r+b' fixes it. Yes, you have won the bet :) . I suppose, like you do, that because there is a difference between text and binary files on Windows and the text files are e.g. opened being buffered using a 32-bit buffer pointer, this fails on too large NTFS files. I could also imagine that Python tries to buffer the text file and fails because it uses the wrong pointer size when asking Windows for the content. I have not yet looked into the C-code of Python - any hint which file I should take a closer look at? That would be Objects/fileobject.c. And no, on just open()ing the file, Python does nothing more than fopen() (or some Windows equivalent). Georg -- http://mail.python.org/mailman/listinfo/python-list