[Python-bugs-list] [ python-Bugs-781891 ] file.write() incorrectly tests remaining space

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Bugs item #781891, was opened at 2003-08-02 08:51
Message generated for change (Settings changed) made by uselpa
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=781891&group_id=5470

Category: Python Library
Group: Not a Bug
>Status: Open
Resolution: Invalid
Priority: 5
Submitted By: Patrick Useldinger (uselpa)
Assigned to: Nobody/Anonymous (nobody)
Summary: file.write() incorrectly tests remaining space

Initial Comment:
It seems as if before writing each block, a check was
done in order to verifiy that there is enough space
left for the whole* file, not for the *remaining* data
to be written.
It happens both under 2.3 and 2.2.3.

===== Python 2.3 ======
I:\My Programs\dfc>b2

start dfc.py [v.0.19.final (July 31st, 2003)] @
2003-08-01 00:21:48
Python 2.3.final running on win32
reading configuration file dfcCfgBackupCd
instantiating processor(s) .
paths & includes/excludes taken from configuration file
creating initial reference point
i:\dfc\ref\dfcRefBackupCd.dfc
..copying  i:\dfc\arc\dfcArchive cheetah
20030731-234648 F.zip to
f:\dfcArchive cheetah 20030731-234648 F.zip
Traceback (most recent call last):
  File "I:\My Programs\dfc\dfc.py", line 199, in ?
    dfc.doProcess(cfgFile.DFCProcTags)
  File "I:\My Programs\dfc\dfc.py", line 144, in doProcess
    newStat=self.newStat.get(fileName,None)) == None:
  File "I:\My Programs\dfc\dfc.py", line 129, in process
    return
self.pubSub.publishMessage(self.pubSubProcess,kwargs,checkRet=True)
  File "I:\My Programs\dfc\PubSub.py", line 170, in
publishMessage
    retVal.append(subscriber(**dict(args)))
  File "I:\My Programs\dfc\dfcProcCopy.py", line 20, in
process
    shutil.copyfile(fileName,toFile)
  File "C:\Python23\lib\shutil.py", line 39, in copyfile
    copyfileobj(fsrc, fdst)
  File "C:\Python23\lib\shutil.py", line 24, in copyfileobj
    fdst.write(buf)
IOError: [Errno 28] No space left on device

I:\My Programs\dfc>dir f:
 Volume in drive F is Backup 01
 Volume Serial Number is E2CB-1650

 Directory of F:\

18/05/2002  15:39       <DIR>          .
18/05/2002  15:39       <DIR>          ..
01/08/2003  00:25          299.630.592 dfcArchive cheetah
20030731-234648 F.zip
               1 File(s)    299.630.592 bytes
               2 Dir(s)     299.636.736 bytes free

===== Python 2.2.3 =======

I:\My Programs\dfc>i:\py222\python.exe dfc.py
dfcCfgBackupCd

start dfc.py [v.0.19.final (July 31st, 2003)] @
2003-08-01 00:29:08
Python 2.2.3.final running on win32
reading configuration file dfcCfgBackupCd
instantiating processor(s) .
paths & includes/excludes taken from configuration file
creating initial reference point
i:\dfc\ref\dfcRefBackupCd.dfc
..copying  i:\dfc\arc\dfcArchive cheetah
20030731-234648 F.zip to
f:\dfcArchive cheetah 20030731-234648 F.zip
Traceback (most recent call last):
  File "dfc.py", line 199, in ?
    dfc.doProcess(cfgFile.DFCProcTags)
  File "dfc.py", line 144, in doProcess
    newStat=self.newStat.get(fileName,None)) == None:
  File "dfc.py", line 129, in process
    return
self.pubSub.publishMessage(self.pubSubProcess,kwargs,checkRet=True)
  File "PubSub.py", line 170, in publishMessage
    retVal.append(subscriber(**dict(args)))
  File "dfcProcCopy.py", line 20, in process
    shutil.copyfile(fileName,toFile)
  File "i:\py222\lib\shutil.py", line 30, in copyfile
    copyfileobj(fsrc, fdst)
  File "i:\py222\lib\shutil.py", line 20, in copyfileobj
    fdst.write(buf)
IOError: [Errno 28] No space left on device
========================================================================

----------------------------------------------------------------------

Comment By: Patrick Useldinger (uselpa)
Date: 2003-08-02 20:22

Message:
Logged In: YES 
user_id=835987

As already explained on c.l.python, a manual copy via
Explorer *does* work. I've just repeated the same with a
copy /b, and again that's OK. 

----------------------------------------------------------------------

Comment By: Tim Peters (tim_one)
Date: 2003-08-02 12:32

Message:
Logged In: YES 
user_id=31435

Python has no idea how much space you have left.  Write the 
code in raw C, and the same thing will happen (Python raises 
an exception because C's I/O returned an error code).

It looks like you in fact don't have enough disk space to 
complete the write.  That's why C is complaining.  As 
someone already explained on comp.lang.python, filesystems 
have hidden overheads, and hoping you can fill it to the last 
byte with usable data is futile.

Experiment:  since you're on Windows, try making a copy of 
the file from a DOS box with "copy /b".  That should fail too.

----------------------------------------------------------------------

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=781891&group_id=5470