Re: Defaults being destroyed

[Alexey I. Froloff]

On Tue, Aug 27, 2002 at 08:14:55AM +0100, Richard Frith-Macdonald wrote:
> >On Tue, Aug 27, 2002 at 07:15:07AM +0100, Stefan Urbanek wrote:
> >[/dev/null]
> >>It seems, that if a program does not see some domain in
> >>database at program startup, it will not write it back. It
> >>may be a problem in -[NSUserDefaults synchronize] I think,
> >>but I am not sure.
> >-[NSUserDefaults synchronize] uses NSLock than works between
> >threads but not processes. Writinig defaults database is not
> >atomic operation.
> Actually, it uses writeToFile:atomically: with the second argument
> set to YES ... so it *IS* an atomic operation.
This is *NOT* atomic operation.

NSData.m:

- (BOOL) writeToFile: (NSString*)path atomically: (BOOL)useAuxiliaryFile
{
[/dev/null]
  if (useAuxiliaryFile)
    {
      NSFileManager             *mgr = [NSFileManager defaultManager];
      NSMutableDictionary       *att = nil;

      if ([mgr fileExistsAtPath: path])
        {
          att = [[mgr fileAttributesAtPath: path
                              traverseLink: YES] mutableCopy];
          IF_NO_GC(TEST_AUTORELEASE(att));
          [mgr removeFileAtPath: path handler: nil];
        }
/* In this moment file does not exist. */
      c = rename(thePath, theRealPath);

> You would only need filesystem locking if the user defaults
> database was split across multiple files.

-- 
Regards, Sir Raorn.
AIF5-RIPN, AIF5-RIPE, Binec System Administrator.

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