CocoaDev

Hello,

When executing “writeToFile” below, my code consistently crashes (SIGSEGV), and I cannot figure out why. All I want to do is to pick some directory (e.g., “/tmp” in the code below) and gather information about all the files within that directory. Once that is completed, I want to save this information to file. I don’t understand, though, why this code would crash on me. What am I missing?

NSDirectoryEnumerator *enumerator = [[NSFileManager defaultManager] enumeratorAtPath:@"/tmp"];
NSMutableArray *array = [NSMutableArray arrayWithCapacity:50];
while ([enumerator nextObject]) {
	[array addObject:[enumerator fileAttributes]];
}

[array writeToFile:@"/tmp/experiment" atomically:YES]; // crashes right here

P.S.: I am using OS X Panther

What is the backtrace of the crash? What are the exact contents of array?

Thanks for the reply. The stack trace is as follows:

… [ repeat #12260 - #12258 until crash ] #12258 0x90a9041c in -[NSCFArray isEqual:] #12259 0x90ae7a68 in -[NSFileAttributes isEqual:] #12260 0x901c1eb0 in CFEqual #12261 0x90a9041c in -[NSCFArray isEqual:] #12262 0x90ae7a68 in -[NSFileAttributes isEqual:] #12263 0x901c1eb0 in CFEqual #12264 0x90a9041c in -[NSCFArray isEqual:] #12265 0x90ae7a68 in -[NSFileAttributes isEqual:] #12266 0x901c1eb0 in CFEqual #12267 0x901c7170 in __CFSetFindBuckets1 #12268 0x901d3904 in CFSetGetValueIfPresent #12269 0x90a2d210 in -[NSCFSet member:] #12270 0x90a321c4 in -[NSSet containsObject:] #12271 0x90a31b4c in _NSIsPList #12272 0x90a31be4 in _NSIsPList #12273 0x90aaa73c in -[NSArray writeToFile:atomically:] #12274 0x000d8e3c in main at main.m:12

The contents of the array is:

( { NSFileCreationDate = 2006-10-12 11:00:08 -0700; NSFileExtensionHidden = 0; NSFileGroupOwnerAccountID = 0; NSFileGroupOwnerAccountName = wheel; NSFileModificationDate = 2006-10-12 11:02:33 -0700; NSFileOwnerAccountID = 502; NSFileOwnerAccountName = xyz; NSFilePosixPermissions = 488; NSFileReferenceCount = 3; NSFileSize = 102; NSFileSystemFileNumber = 2481598; NSFileSystemNumber = 234881026; NSFileType = NSFileTypeDirectory; }, { NSFileCreationDate = 2006-10-12 11:02:33 -0700; NSFileExtensionHidden = 0; NSFileGroupOwnerAccountID = 0; NSFileGroupOwnerAccountName = wheel; NSFileModificationDate = 2006-10-12 11:06:32 -0700; NSFileOwnerAccountID = 502; NSFileOwnerAccountName = xyz; NSFilePosixPermissions = 488; NSFileReferenceCount = 3; NSFileSize = 102; NSFileSystemFileNumber = 2481628; NSFileSystemNumber = 234881026; NSFileType = NSFileTypeDirectory; }, { NSFileCreationDate = 2006-10-12 11:02:33 -0700; NSFileExtensionHidden = 0; NSFileGroupOwnerAccountID = 0; NSFileGroupOwnerAccountName = wheel; NSFileModificationDate = 2006-10-12 11:02:33 -0700; NSFileOwnerAccountID = 502; NSFileOwnerAccountName = xyz; NSFilePosixPermissions = 488; NSFileReferenceCount = 3; NSFileSize = 102; NSFileSystemFileNumber = 2481629; NSFileSystemNumber = 234881026; NSFileType = NSFileTypeDirectory; }, { NSFileCreationDate = 2006-10-12 11:02:33 -0700; NSFileExtensionHidden = 0; NSFileGroupOwnerAccountID = 0; NSFileGroupOwnerAccountName = wheel; NSFileModificationDate = 2006-10-12 11:02:33 -0700; NSFileOwnerAccountID = 502; NSFileOwnerAccountName = xyz; NSFilePosixPermissions = 488; NSFileReferenceCount = 2; NSFileSize = 68; NSFileSystemFileNumber = 2481630; NSFileSystemNumber = 234881026; NSFileType = NSFileTypeDirectory; }, { NSFileCreationDate = 2006-10-12 10:59:50 -0700; NSFileExtensionHidden = 0; NSFileGroupOwnerAccountID = 0; NSFileGroupOwnerAccountName = wheel; NSFileHFSCreatorCode = 0; NSFileHFSTypeCode = 0; NSFileModificationDate = 2006-10-12 10:59:50 -0700; NSFileOwnerAccountID = 0; NSFileOwnerAccountName = root; NSFilePosixPermissions = 420; NSFileReferenceCount = 1; NSFileSize = 745; NSFileSystemFileNumber = 2481588; NSFileSystemNumber = 234881026; NSFileType = NSFileTypeRegular; } )

It seems that the dictionary you get back is being uncooperative, and is a special subclass of NSDictionary. Try making normal NSDictionary objects from the array, something like this:

[array addObject:[NSDictionary dictionaryWithDictionary:[enumerator fileAttributes]]];

I’m not sure this is the problem but it’s worth a try.

Are you sure you have the right write rights on that path?

otherwise try this

NSString *storePath = [NSHomeDirectory() stringByAppendingPathComponent:@”/tmp/experiment”]; [arrayData writeToFile:storePath atomically:YES];

I did convert your given content into a plist, read that into a array and then wrote it to disk. No problems here, even in /tmp/.. ( if I have write rights ).

Thank you very much for the two suggestions! Creating normal NSDictionary objects did the trick.

I recommend filing a bug about this on http://bugreport.apple.com . The interface declares the return type as NSDictionary and so they ought to be directly serializable! Whip up a small test case to post with the report, they like that. —- Can you tell us what version of osx and xcode you did use? I did use this code in an older app to and want to be sure if I need to change it. Thanks

Re: 1) Good point. Just filed a bugreport. Re: 2) OS X 10.3.9 Build 7W98, XCode 1.2

So you haven’t tried 10.4?

No, all my machines are still running 10.3.