NSFileManager contentsEqualAtPath

FROM : Gerriet M. Denkmann
DATE : Mon Aug 14 22:57:39 2006

Computer A has mounted via Finder some home directory of computer B.

A program does on A:

NSFileManager *fileManager = [ NSFileManager defaultManager ] ;
NSString *localPath = @"/Users/userid/Desktop/Test1/a"; <-- on 
computer A
NSString *distantPath = @"/Volumes/userid/Desktop/Test1/b"; <-- on 
computer B
BOOL ok = [ fileManager copyPath: localPath  toPath: distantPath 
handler: nil ];
// ok

Then the user deletes the last line (2 bytes + \n) of file b on 
computer B .

Now the program does on A:
BOOL same = [ fileManager contentsEqualAtPath: distantPath andPath: 
localPath ];
// same <-- strange

but the other way round:
BOOL sam2 = [ fileManager contentsEqualAtPath: localPath andPath: 
distantPath ];
// not same <-- strange

the user does on computer A:
ls -l /Users/userid/Desktop/Test1/a --> 53 bytes
ls -l /Volumes/userid/Desktop/Test1/b --> 53 bytes <-- strange

the user does on computer B:
ls -l /Users/userid/Desktop/Test1/b --> 50 bytes

the user opens distantPath  on computer A in a hex editor and sees 50 
bytes as expected, followed by 3 zero bytes.

What is my program doing wrong that it gets such strange and 
unexpected results?
(both computers 10.4.7 ppc)

Gerriet.