NSFileManager destroying target of symlink at changefileattributes

FROM : thomas bauer
DATE : Sun Nov 18 20:39:29 2007

dear list,

following code is executed as root in a test foundation tool.
it simply copies the localtime symlink (/etc/localtime) to another 
partition and then tries to clone
its fileattributes. if a copy of the source fileattributes dictionary 
is used
instead of the original one, the changefileattributes call damages the 
target
of the symlink replacing it with a broken symlink.

(ie /usr/share/zoneinfo/yourzone will be damaged, destroying your 
timezone setting.
make a copy before testing this!)

if the original dict is used, everything is fine.
i nslogged both dicts and both are identical.

(only in this example code i use a trivial copy of the attributes 
dict. the original code has to use
a mutable copy to alter the permission flags between source and 
target. since this modification
is not related to the issue i have altered the testcode to just use a 
trivial copy)

thanks and regards
thomas bauer - freeridecoding


#import <Foundation/Foundation.h>

int main (int argc, const char * argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

   NSFileManager *fm = [NSFileManager defaultManager];    
   [fm copyPath:@"/private/etc/localtime" toPath:@"/Volumes/tigerclone/
localtime" handler:nil];

   NSDictionary *sourceAttributes = [fm fileAttributesAtPath:@"/private/
etc/localtime" traverseLink:NO];
   NSDictionary *copyattrs= [NSDictionary 
dictionaryWithDictionary:sourceAttributes];
   
   // [fm changeFileAttributes:copyattrs atPath:@"/Volumes/tigerclone/
localtime"];    // THIS BREAKS TARGET OF SOURCE SYMLINK
   [fm changeFileAttributes:sourceAttributes atPath:@"/Volumes/
tigerclone/localtime"];    //THIS IS OK

   [pool release];
    return 0;
}

d