mirror of
https://github.com/MacPaw/XADMaster.git
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111 lines
2.7 KiB
Objective-C
111 lines
2.7 KiB
Objective-C
/*
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* XADPaddedBlockHandle.m
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*
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* Copyright (c) 2017-present, MacPaw Inc. All rights reserved.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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* MA 02110-1301 USA
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*/
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#import "XADPaddedBlockHandle.h"
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@implementation XADPaddedBlockHandle
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-(id)initWithHandle:(CSHandle *)handle startOffset:(off_t)start
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logicalBlockSize:(int)logical physicalBlockSize:(int)physical;
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{
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if((self=[super initWithParentHandle:handle]))
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{
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startoffset=start;
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logicalsize=logical;
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physicalsize=physical;
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}
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return self;
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}
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static inline off_t PhysicalToLogical(XADPaddedBlockHandle *self,off_t physical)
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{
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off_t block=(physical-self->startoffset)/self->physicalsize;
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int offset=(physical-self->startoffset)%self->physicalsize;
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if(offset>self->logicalsize) physical-=offset-self->logicalsize;
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return physical-self->startoffset-block*(self->physicalsize-self->logicalsize);
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}
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static inline off_t LogicalToPhysical(XADPaddedBlockHandle *self,off_t logical)
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{
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off_t block=logical/self->logicalsize;
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return logical+self->startoffset+block*(self->physicalsize-self->logicalsize);
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}
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-(off_t)fileSize
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{
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off_t size=[parent fileSize];
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if(size==CSHandleMaxLength) return CSHandleMaxLength;
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return PhysicalToLogical(self,size);
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}
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-(off_t)offsetInFile
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{
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return PhysicalToLogical(self,[parent offsetInFile]);
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}
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-(BOOL)atEndOfFile
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{
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return [parent atEndOfFile];
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}
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-(void)seekToFileOffset:(off_t)offs
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{
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if(offs<0) [self _raiseEOF];
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[parent seekToFileOffset:LogicalToPhysical(self,offs)];
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}
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-(void)seekToEndOfFile
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{
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[parent seekToEndOfFile];
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}
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-(int)readAtMost:(int)num toBuffer:(void *)buffer
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{
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if(!num) return 0;
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uint8_t *bytebuffer=(uint8_t *)buffer;
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off_t pos=[parent offsetInFile];
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int total=0;
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while(total<num)
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{
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int offset=(pos-startoffset)%physicalsize;
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if(offset>=logicalsize)
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{
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pos+=physicalsize-offset;
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offset=0;
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[parent seekToFileOffset:pos];
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}
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int numbytes=logicalsize-offset;
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if(numbytes>num-total) numbytes=num-total;
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int actual=[parent readAtMost:numbytes toBuffer:&bytebuffer[total]];
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if(actual==0) return total;
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total+=actual;
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pos+=actual;
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}
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return total;
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}
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@end
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