UKXattrMetadataStore.m

//
//  UKXattrMetadataStore.m
//  BubbleBrowser
//
//  Created by Uli Kusterer on 12.03.06.
//  Copyright 2006 Uli Kusterer.
//	
//	This software is provided 'as-is', without any express or implied
//	warranty. In no event will the authors be held liable for any damages
//	arising from the use of this software.
//
//	Permission is granted to anyone to use this software for any purpose,
//	including commercial applications, and to alter it and redistribute it
//	freely, subject to the following restrictions:
//
//	   1. The origin of this software must not be misrepresented; you must not
//	   claim that you wrote the original software. If you use this software
//	   in a product, an acknowledgment in the product documentation would be
//	   appreciated but is not required.
//
//	   2. Altered source versions must be plainly marked as such, and must not be
//	   misrepresented as being the original software.
//
//	   3. This notice may not be removed or altered from any source
//	   distribution.
//

#if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_4
// -----------------------------------------------------------------------------
//	Headers:
// -----------------------------------------------------------------------------

#import "UKXattrMetadataStore.h"
#import <sys/xattr.h>


@implementation UKXattrMetadataStore

// -----------------------------------------------------------------------------
//	allKeysAtPath:traverseLink:
//		Return an NSArray of NSStrings containing all xattr names currently set
//		for the file at the specified path.
//		If travLnk == YES, it follows symlinks.
// -----------------------------------------------------------------------------

+(NSArray*)		allKeysAtPath: (NSString*)path traverseLink:(BOOL)travLnk
{
	NSMutableArray*	allKeys = [NSMutableArray array];
	size_t dataSize = listxattr( [path fileSystemRepresentation],
								NULL, ULONG_MAX,
								(travLnk ? 0 : XATTR_NOFOLLOW) );
	if( dataSize == ULONG_MAX )
		return allKeys;	// Empty list.
	NSMutableData*	listBuffer = [NSMutableData dataWithLength: dataSize];
	dataSize = listxattr( [path fileSystemRepresentation],
							[listBuffer mutableBytes], [listBuffer length],
							(travLnk ? 0 : XATTR_NOFOLLOW) );
	char*	nameStart = [listBuffer mutableBytes];
	int x;
	for( x = 0; x < dataSize; x++ )
	{
		if( ((char*)[listBuffer mutableBytes])[x] == 0 )	// End of string.
		{
			NSString*	str = [NSString stringWithUTF8String: nameStart];
			nameStart = [listBuffer mutableBytes] +x +1;
			[allKeys addObject: str];
		}
	}
	
	return allKeys;
}


// -----------------------------------------------------------------------------
//	setData:forKey:atPath:traverseLink:
//		Set the xattr with name key to a block of raw binary data.
//		path is the file whose xattr you want to set.
//		If travLnk == YES, it follows symlinks.
// -----------------------------------------------------------------------------

+(void)				setData: (NSData*)data forKey: (NSString*)key atPath: (NSString*)path traverseLink:(BOOL)travLnk
{
	setxattr( [path fileSystemRepresentation], [key UTF8String],
				[data bytes], [data length],
				0, (travLnk ? 0 : XATTR_NOFOLLOW) );
}


// -----------------------------------------------------------------------------
//	setObject:forKey:atPath:traverseLink:
//		Set the xattr with name key to an XML property list representation of
//		the specified object (or object graph).
//		path is the file whose xattr you want to set.
//		If travLnk == YES, it follows symlinks.
// -----------------------------------------------------------------------------

+(void)	setObject: (id)obj forKey: (NSString*)key atPath: (NSString*)path traverseLink:(BOOL)travLnk
{
	// Serialize our objects into a property list XML string:
	NSString*	errMsg = nil;
	NSData*		plistData = [NSPropertyListSerialization dataFromPropertyList: obj
								format: NSPropertyListXMLFormat_v1_0
								errorDescription: &errMsg];
	if( errMsg )
	{
		[errMsg autorelease];
		[NSException raise: @"UKXattrMetastoreCantSerialize" format: @"%@", errMsg];
	}
	else
		[[self class] setData: plistData forKey: key atPath: path traverseLink: travLnk];
}


// -----------------------------------------------------------------------------
//	setString:forKey:atPath:traverseLink:
//		Set the xattr with name key to an XML property list representation of
//		the specified object (or object graph).
//		path is the file whose xattr you want to set.
//		If travLnk == YES, it follows symlinks.
// -----------------------------------------------------------------------------

+(void)	setString: (NSString*)str forKey: (NSString*)key atPath: (NSString*)path traverseLink:(BOOL)travLnk
{
	NSData*		data = [str dataUsingEncoding: NSUTF8StringEncoding];
	
	if( !data )
		[NSException raise: NSCharacterConversionException format: @"Couldn't convert string to UTF8 for xattr storage."];
	
	[[self class] setData: data forKey: key atPath: path traverseLink: travLnk];
}


// -----------------------------------------------------------------------------
//	dataForKey:atPath:traverseLink:
//		Retrieve the xattr with name key as a raw block of data.
//		path is the file whose xattr you want to set.
//		If travLnk == YES, it follows symlinks.
// -----------------------------------------------------------------------------

+(NSMutableData*)	dataForKey: (NSString*)key atPath: (NSString*)path traverseLink:(BOOL)travLnk
{
	size_t		dataSize = getxattr( [path fileSystemRepresentation], [key UTF8String],
										NULL, ULONG_MAX, 0, (travLnk ? 0 : XATTR_NOFOLLOW) );
	if( dataSize == ULONG_MAX )
		return nil;
	NSMutableData*	data = [NSMutableData dataWithLength: dataSize];
	getxattr( [path fileSystemRepresentation], [key UTF8String],
				[data mutableBytes], [data length], 0, (travLnk ? 0 : XATTR_NOFOLLOW) );
	
	return data;
}


// -----------------------------------------------------------------------------
//	objectForKey:atPath:traverseLink:
//		Retrieve the xattr with name key, which is an XML property list
//		and unserialize it back into an object or object graph.
//		path is the file whose xattr you want to set.
//		If travLnk == YES, it follows symlinks.
// -----------------------------------------------------------------------------

+(id)	objectForKey: (NSString*)key atPath: (NSString*)path traverseLink:(BOOL)travLnk
{
	NSString*				errMsg = nil;
	NSMutableData*			data = [[self class] dataForKey: key atPath: path traverseLink: travLnk];
	if( !data )
		return nil;
	NSPropertyListFormat	outFormat = NSPropertyListXMLFormat_v1_0;
	id obj = [NSPropertyListSerialization propertyListFromData: data
					mutabilityOption: NSPropertyListImmutable
					format: &outFormat
					errorDescription: &errMsg];
	if( errMsg )
	{
		[errMsg autorelease];
		[NSException raise: @"UKXattrMetastoreCantUnserialize" format: @"%@", errMsg];
	}
	
	return obj;
}


// -----------------------------------------------------------------------------
//	stringForKey:atPath:traverseLink:
//		Retrieve the xattr with name key, which is an XML property list
//		and unserialize it back into an object or object graph.
//		path is the file whose xattr you want to set.
//		If travLnk == YES, it follows symlinks.
// -----------------------------------------------------------------------------

+(id)	stringForKey: (NSString*)key atPath: (NSString*)path traverseLink:(BOOL)travLnk
{
	NSMutableData*			data = [[self class] dataForKey: key atPath: path traverseLink: travLnk];
	
	if( !data )
		return nil;
	
	return [[[NSString alloc] initWithData: data encoding: NSUTF8StringEncoding] autorelease];
}


@end

#endif /*MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_4*/