XADMaster/XADGzipParser.m

/*
 * XADGzipParser.m
 *
 * Copyright (c) 2017-present, MacPaw Inc. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301  USA
 */
#import "XADGzipParser.h"
#import "CSZlibHandle.h"
#import "CRC.h"
#import "Progress.h"
#import "Scanning.h"



@implementation XADGzipParser

+(int)requiredHeaderSize { return 3; }

+(BOOL)recognizeFileWithHandle:(CSHandle *)handle firstBytes:(NSData *)data name:(NSString *)name;
{
	const uint8_t *bytes=[data bytes];
	int length=[data length];

	if(length<3) return NO;
	if(bytes[0]==0x1f)
	{
		if((bytes[1]==0x8b||bytes[1]==0x9e) && bytes[2]==8) return YES;
		if(bytes[1]==0xa1) return YES; /* BSD-compress variant */
	}
	return NO;
}

-(void)parse
{
	CSHandle *handle=[self handle];

	uint16_t headid=[handle readUInt16BE];
	uint8_t method=[handle readUInt8];
	uint8_t flags=[handle readUInt8];
	uint32_t time=[handle readUInt32LE];
	uint8_t extraflags=[handle readUInt8];
	uint8_t os=[handle readUInt8];

	if(method!=8) [XADException raiseIllegalDataException];

	NSMutableData *filename=nil,*comment=nil;

    if(headid!=0x1fa1)
    {
		if(flags&0x04) // FEXTRA: extra fields
		{
			uint16_t len=[handle readUInt16LE];
			[handle skipBytes:len];
		}
		if(flags&0x08) // FNAME: filename
		{
			filename=[NSMutableData data];
			uint8_t chr;
			while((chr=[handle readUInt8])) [filename appendBytes:&chr length:1];
		}
		if(flags&0x10) // FCOMMENT: comment
		{
			comment=[NSMutableData data];
			uint8_t chr;
			while((chr=[handle readUInt8])) [comment appendBytes:&chr length:1];
		}
		if(flags&0x02) // FHCRC: header crc
		{
			[handle skipBytes:2];
		}
    }

	NSString *name=[self name];
	NSString *extension=[[name pathExtension] lowercaseString];
	NSString *contentname;
	if([extension isEqual:@"tgz"]) contentname=[[name stringByDeletingPathExtension] stringByAppendingPathExtension:@"tar"];
	else if([extension isEqual:@"adz"]) contentname=[[name stringByDeletingPathExtension] stringByAppendingPathExtension:@"adf"];
	else if([extension isEqual:@"cpgz"]) contentname=[[name stringByDeletingPathExtension] stringByAppendingPathExtension:@"cpio"];
	else contentname=[name stringByDeletingPathExtension];

	// TODO: set no filename flag
	NSMutableDictionary *dict=[NSMutableDictionary dictionaryWithObjectsAndKeys:
		[self XADPathWithUnseparatedString:contentname],XADFileNameKey,
		[self XADStringWithString:@"Deflate"],XADCompressionNameKey,
		[NSNumber numberWithUnsignedInt:extraflags],@"GzipExtraFlags",
		[NSNumber numberWithUnsignedInt:os],@"GzipOS",
	nil];

	if(time) [dict setObject:[NSDate dateWithTimeIntervalSince1970:time] forKey:XADLastModificationDateKey];

	if([contentname matchedByPattern:@"\\.(tar|cpio|pax|warc)$" options:REG_ICASE])
	[dict setObject:[NSNumber numberWithBool:YES] forKey:XADIsArchiveKey];

	off_t filesize=[handle fileSize];
	if(filesize!=CSHandleMaxLength)
	[dict setObject:[NSNumber numberWithLongLong:filesize] forKey:XADCompressedSizeKey];

	if(filename)
	[dict setObject:[self XADStringWithData:filename] forKey:@"GzipFilename"];

	if(comment)
	[dict setObject:[self XADStringWithData:comment] forKey:XADCommentKey];

	[self addEntryWithDictionary:dict];
}

-(CSHandle *)handleForEntryWithDictionary:(NSDictionary *)dictionary wantChecksum:(BOOL)checksum
{
	CSHandle *handle=[self handle];
	[handle seekToFileOffset:0];
	return [[[XADGzipHandle alloc] initWithHandle:handle] autorelease];
}

-(NSString *)formatName { return @"Gzip"; }

@end




@implementation XADGzipSFXParser

+(int)requiredHeaderSize { return 5000; }

+(BOOL)recognizeFileWithHandle:(CSHandle *)handle firstBytes:(NSData *)data
name:(NSString *)name propertiesToAdd:(NSMutableDictionary *)props
{
	const uint8_t *bytes=[data bytes];
	int length=[data length];

	if(length<5) return NO;
	if(length>5000) length=5000;

	if(bytes[0]!='#'||bytes[1]!='!') return NO;

	for(int i=2;i<length-3;i++)
	{
		if(bytes[i]==0x1f&&(bytes[i+1]==0x8b||bytes[i+1]==0x9e)&&bytes[i+2]==8)
		{
			[props setObject:[NSNumber numberWithInt:i] forKey:@"GzipSFXOffset"];
			return YES;
		}
    }

	return NO;
}

-(void)parse
{
	off_t offs=[[[self properties] objectForKey:@"GzipSFXOffset"] longLongValue];
	[[self handle] seekToFileOffset:offs];

	[super parse];
}

-(NSString *)formatName { return @"Gzip (Self-extracting)"; }

@end




#define HeaderState 0
#define DataState 1
#define FooterState 2
#define EndState 10

@implementation XADGzipHandle

-(id)initWithHandle:(CSHandle *)handle
{
	if(self=[super initWithParentHandle:handle])
	{
		startoffs=[parent offsetInFile];
		currhandle=nil;
	}
	return self;
}

-(void)dealloc
{
	[currhandle release];
	[super dealloc];
}

-(void)resetStream
{
	[parent seekToFileOffset:startoffs];
	state=HeaderState;
	checksumscorrect=YES;
}

-(int)streamAtMost:(int)num toBuffer:(void *)buffer
{
	int bytesread=0;
	uint8_t *bytebuf=buffer;

	while(bytesread<num && state!=EndState) switch(state)
	{
		case HeaderState:
		{
			uint16_t headid=[parent readUInt16BE];
			uint8_t method=[parent readUInt8];
			uint8_t flags=[parent readUInt8];
			/*uint32_t time=[parent readUInt32LE];
			uint8_t extraflags=[parent readUInt8];
			uint8_t os=[parent readUInt8];*/
			[parent skipBytes:6];

			if(method!=8) [XADException raiseIllegalDataException];

			if(headid!=0x1fa1)
			{
				if(flags&0x04) // FEXTRA: extra fields
				{
					uint16_t len=[parent readUInt16LE];
					[parent skipBytes:len];
				}
				if(flags&0x08) // FNAME: filename
				{
					while([parent readUInt8]);
				}
				if(flags&0x10) // FCOMMENT: comment
				{
					while([parent readUInt8]);
				}
				if(flags&0x02) // FHCRC: header crc
				{
					[parent skipBytes:2];
				}
			}

			CSZlibHandle *zh=[CSZlibHandle deflateHandleWithHandle:parent];
			[zh setSeekBackAtEOF:YES];

			[currhandle release];
			currhandle=[zh retain];

			crc=0xffffffff;

			state=DataState;
		}
		break;

		case DataState:
		{
			int actual=[currhandle readAtMost:num-bytesread toBuffer:&bytebuf[bytesread]];
			crc=XADCalculateCRCFast(crc,&bytebuf[bytesread],actual,XADCRCTable_sliced16_edb88320);

			bytesread+=actual;

			if([currhandle atEndOfFile]) state=FooterState;
		}
		break;

		case FooterState:
		{
			@try
			{
				uint32_t correctcrc=[parent readUInt32LE];
				/*uint32_t len=[parent readUInt32LE];*/
				[parent skipBytes:4];
				if((crc^0xffffffff)!=correctcrc) checksumscorrect=NO;
			}
			@catch(id e)
			{
				checksumscorrect=NO;
				state=EndState;
				break;
			}

			if([parent atEndOfFile]) state=EndState;
			else state=HeaderState;
		}
		break;
	}

	if(state==EndState)
	{
		[self endStream];
		[currhandle release];
		currhandle=nil;
	}

	return bytesread;
}

-(BOOL)hasChecksum
{
	return YES;
}

-(BOOL)isChecksumCorrect
{
	if(currhandle) return NO;
	return checksumscorrect;
}

-(double)estimatedProgress { return [parent estimatedProgress]; } // TODO: better estimation using buffer?

@end