Multiple ways to calculate the size of a file's resource fork

filesize.m

/*
 *	filesize.m
 *	Description: Multiple ways to calculate the size of a file's resource fork
 * 	Author: Chad Armstrong
 *	Date: 14 April 2018 (Updated 28 October 2022)
 *	To compile: gcc -w -framework Cocoa filesize.m -o filesize
 *	To run: ./filesize path/to/file
 */
 
/*	References:
 *	https://stackoverflow.com/questions/32003590/check-for-resource-fork-in-objective-c
 *	https://github.com/bcpierce00/unison/blob/master/src/osxsupport.c
 *	https://svn.python.org/projects/external/tcl-8.5.11.x/macosx/tclMacOSXFCmd.c
 *	https://stackoverflow.com/questions/19400043/how-to-open-and-read-resource-forks-in-obj-c
 *	http://xahlee.info/UnixResource_dir/macosx.html
 *	http://www.cocoabuilder.com/archive/cocoa/14625-carbon-only.html
 *	https://stackoverflow.com/questions/586928/how-should-i-print-types-like-off-t-and-size-t
 */

#import <Cocoa/Cocoa.h>

#include <sys/attr.h>
#include <sys/xattr.h> // getxattr
#include "errno.h"

#pragma mark -

struct filesizebuf {
	u_int32_t length;
	off_t dataForkSize;
	off_t rsrcForkSize;
	off_t rsrcForkAllocSize;
};

/*
struct {
	unsigned long length;
	char          finderInfo [32];
	off_t         rsrcLength;
} attrBuf;
*/

int main (int argc, const char * argv[]) 
{
	NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
	
	if (argc < 2) {
		printf("Usage: %s <path_to_file>\n", argv[0]);
		return EXIT_FAILURE;
	}
	
	const char *path             = argv[1];
	NSString *pathToFile         = [NSString stringWithFormat:@"%s", path];
	NSString *pathToResourceFork = [pathToFile stringByAppendingPathComponent: @"..namedfork/rsrc"];
	NSFileManager *fm            = [NSFileManager defaultManager];
	NSError *error               = nil;
	
	if ([fm fileExistsAtPath: pathToFile] == NO) {
		NSLog(@"Error: The file %@ does not exist.", pathToFile);
		return EXIT_FAILURE;
	}
	
#pragma mark - getxattr
	// Retrieving extended attributes 
	printf("\n--- getxattr ---\n");
	
	if (getxattr(path, "com.apple.ResourceFork", NULL, 0, 0, 0) != -1) {
		ssize_t resourceForkSize = getxattr(path, "com.apple.ResourceFork", NULL, 0, 0, 0);
		printf("resourceForkSize:: %zu\n", resourceForkSize);
	} else {
		printf("The path %s does not contain a resource fork.\n", path);
	}
	
#pragma mark - NSFileManager
	printf("\n--- NSFileManager ---\n");
	// Using NSFileManager and iterating to the resource fork
	if ([fm fileExistsAtPath: pathToResourceFork] == YES) {
		NSLog(@"Yes, the path %@ exists", pathToResourceFork);
		// In older versions of Mac OS X, the path to the resource fork is just /rsrc, not ..namedfork/rsrc
		NSDictionary *fileAttr = [fm attributesOfItemAtPath: pathToResourceFork error: &error];
		if (error != nil) {
			NSLog(@"Error: %@", [error localizedDescription]);
		} else {
			NSNumber *fileSize = [fileAttr objectForKey: NSFileSize];
			NSLog(@"resource fork fileSize: %@", fileSize);
		}
	} else {
		NSLog(@"Cannot find the path %@", pathToResourceFork);
	}
	
	
#pragma mark - getattrlist	
	// http://www.cocoabuilder.com/archive/cocoa/14625-carbon-only.html
	printf("\n--- getattrlist ---\n");
	
	// Not working example
	printf("\n--- Not working example:\n");
	int retcode = -1;
	struct attrlist attrList;
	struct filesizebuf fsize;
	unsigned long options = FSOPT_NOFOLLOW | FSOPT_REPORT_FULLSIZE; //0;
	
	memset(&attrList, 0, sizeof(attrList)); // some examples show using bzero, instead
	
	attrList.bitmapcount = ATTR_BIT_MAP_COUNT;
	attrList.reserved    = 0;
	attrList.commonattr  = 0;	// ATTR_CMN_FNDRINFO;
	attrList.volattr     = 0;	/* volume attribute group */
	attrList.dirattr     = 0;	/* directory attribute group */
	attrList.fileattr    = ATTR_FILE_DATALENGTH | ATTR_FILE_RSRCLENGTH | ATTR_FILE_RSRCALLOCSIZE;    /* file attribute group */
	attrList.forkattr    = 0;	/* fork attribute group */

	retcode = getattrlist(path, &attrList, &fsize, sizeof(fsize), options);

	if (retcode == -1) {
		perror("getattrlist");
	} else {
		// https://stackoverflow.com/questions/586928/how-should-i-print-types-like-off-t-and-size-t
		printf("        Data fork length: %20qu (0x%016qX) bytes\n", fsize.dataForkSize, fsize.dataForkSize);
  		printf("    Resource fork length: %20qu (0x%016qX) bytes\n", fsize.rsrcForkSize, fsize.rsrcForkSize);
  		printf("Resource fork alloc size: %20qu\n", fsize.rsrcForkAllocSize);
	}
	
	// Working example
	printf("\n--- Working example:\n");
	// https://stackoverflow.com/questions/32003590/check-for-resource-fork-in-objective-c
	struct attrlist attrlist = {0};
	attrlist.bitmapcount = ATTR_BIT_MAP_COUNT;
	attrlist.fileattr    = ATTR_FILE_DATALENGTH | ATTR_FILE_RSRCLENGTH;
	typedef struct __attribute__((__packed__)) {
		uint32_t size;
		off_t dataSize;
		off_t forkSize;
	} result_t;
	result_t result = {0};
	
	if (getattrlist (path, &attrlist, &result, sizeof(result), 0) == 0) {
		assert(sizeof(result)==result.size); // makes sure we got the struct right
		// now we find the rsrc fork size in result.forkSize
		printf("    Data fork size: %20qu\n", result.dataSize);
		printf("Resource fork size: %20qu\n", result.forkSize);
	}
	
#pragma mark - FSGetCatalogInfo
	printf("\n--- FSGetCatalogInfo ---\n");
	// Note: A number of these methods (CFURLGetFSRefer, FSGetCatalogInfo) have been deprecated
	unsigned long long totalSize = 0;
	FSRef fileRef;
	NSURL *fileURL = [NSURL fileURLWithPath: pathToFile];

	// WARNING: 'CFURLGetFSRef' is deprecated: first deprecated in macOS 10.9
    if (!CFURLGetFSRef( (CFURLRef)fileURL, &fileRef )) {
        NSLog( @"Failed to create FSRef." );
    } else {
    
		FSCatalogInfo fsInfo;

		// WARNING: 'FSGetCatalogInfo' is deprecated: first deprecated in macOS 10.8
		if (FSGetCatalogInfo(&fileRef, kFSCatInfoDataSizes | kFSCatInfoRsrcSizes, &fsInfo, NULL, NULL, NULL) == noErr)
		{
			if (fsInfo.rsrcLogicalSize > 0)
			{
				totalSize += (fsInfo.dataLogicalSize + fsInfo.rsrcLogicalSize);
			}
			else
			{
				totalSize += (fsInfo.dataLogicalSize);
			}
		}
		
		NSLog(@"resource fork size: %llu | dataSize: %llu |  totalSize: %llu", fsInfo.rsrcLogicalSize, fsInfo.dataLogicalSize, totalSize);
	}
	
#pragma mark - NSURL
	printf("\n--- NSURL --\n");

	NSNumber *fileSizeBytes;
	NSNumber *totalFileSizeBytes;
	
	[fileURL getResourceValue:&fileSizeBytes forKey:NSURLFileSizeKey error:&error];
	[fileURL getResourceValue:&totalFileSizeBytes forKey:NSURLTotalFileSizeKey error:&error];

	NSLog(@"NSURLFileSizeKey %@", fileSizeBytes); // Returns only the data size
	NSLog(@"NSURLTotalFileSizeKey %@", totalFileSizeBytes); // Returns data + resource size
	
	[pool drain];
	return 0;
}