CocoaDev

I’ve got a little snippet of code, and it always seems to show a leak in MallocDebug whenever I run it. And of course, I can’t figure out what I’m doing wrong.

Here’s the code I’m using (I just throw it in the main method of a generic Cocoa App):

#import <Cocoa/Cocoa.h>

void makeLeak() { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

NSString *rtfPath = @"/Developer/Examples/DiscRecording/ObjectiveC/EnhancedDataBurn/ReadMe.rtfd";

[[[NSFileWrapper alloc] initWithPath:rtfPath] autorelease];

[pool release]; }

int main(int argc, const char *argv[]) { makeLeak(); return NSApplicationMain(argc, argv); }

And in MallocDebug I get this:

16 bytes in 1 node: 0x1 _dyld_start _start main makeLeak -[NSFileWrapper initWithPath:] +[NSFileAttributes attributesAtPath:traverseLink:] _NS_FSPathMakeRef _NSSoftLinkingGetFrameworkFuncPtr _NSSoftLinkingLoadFrameworkImage bytesInEncoding -[NSString(NSStringOtherEncodings) getBytes:maxLength:filledLength:encoding:allowLossyConversion:range:remainingRange:] __CFStringEncodeByteStream CFPreferencesGetAppBooleanValue CFPreferencesAppBooleanValue CFPreferencesCopyAppValue _CFStandardApplicationPreferences _CFApplicationPreferencesSetStandardSearchList _CFPreferencesIsManaged _CFGetUserName _CFUserName _CFUpdateUserInfo CFStringCreateWithCString __CFStringCreateImmutableFunnel3 _CFRuntimeCreateInstance NXZoneMalloc

Anyone want to slap me around a little bit and point out what I’m doing wrong? Or maybe verify this?

• GusMueller

An interesting problem, but I can’t duplicate it. I put basically the same code in my main() and could not find any leaks using leaks on the command line.

It looks to me like the leak comes when Cocoa tries to call FSPathMakeRef and has to load Carbon, or whatever framework has it. If you add a loop so that you make a bunch of file wrappers, do you get more leaks? If you only ever get one leak, then it’s not a big deal, and probably not your fault. It’s very strange, though; I can verify that the chain of functions you list is being called in the debugger (I didn’t verify all of them, but up to CFPreferencesGetAppBooleanValue it’s the same) but I don’t see the leak. I’m running OS X 10.3.1, maybe this is very version-specific. – MikeAsh

Ok, adding on a bit more info, since I don’t feel like editing the above. If I run my test app in the debugger with ZeroLink turned off and MallocStackLogging not set, I get a single 16-byte leak (even though I create 100 NSFileWrappers). I can’t duplicate the leak outside of the debugger or with MallocStackLogging set. Very strange.

Probably some one-shot allocation that is cached up in the internals and reused for the life of the program. I wouldn’t worry about it to much. —- Running it in a loop, I still only get 16 bytes leaked, so I guess it’s not a big deal. It is annoying though. – GusMueller