291 lines
7.8 KiB
C
291 lines
7.8 KiB
C
/*
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* This file Copyright (C) 2007-2008 Charles Kerr <charles@rebelbase.com>
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*
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* This file is licensed by the GPL version 2. Works owned by the
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* Transmission project are granted a special exemption to clause 2(b)
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* so that the bulk of its code can remain under the MIT license.
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* This exemption does not extend to derived works not owned by
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* the Transmission project.
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*
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* $Id$
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*/
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#include <assert.h>
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#include <errno.h>
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#include <stdlib.h> /* realloc */
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#include <string.h> /* memcmp */
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include <openssl/sha.h>
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#include "transmission.h"
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#include "crypto.h"
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#include "fdlimit.h"
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#include "inout.h"
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#include "platform.h"
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#include "stats.h"
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#include "torrent.h"
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#include "utils.h"
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/****
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***** Low-level IO functions
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****/
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#ifdef WIN32
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#define lseek _lseeki64
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#if defined(read)
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#undef read
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#endif
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#define read _read
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#if defined(write)
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#undef write
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#endif
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#define write _write
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#endif
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enum { TR_IO_READ, TR_IO_WRITE };
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/* returns 0 on success, or an errno on failure */
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static int
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readOrWriteBytes( const tr_torrent * tor,
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int ioMode,
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tr_file_index_t fileIndex,
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uint64_t fileOffset,
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void * buf,
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size_t buflen )
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{
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const tr_info * info = &tor->info;
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const tr_file * file = &info->files[fileIndex];
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typedef size_t ( *iofunc )( int, void *, size_t );
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iofunc func = ioMode ==
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TR_IO_READ ? (iofunc)read : (iofunc)write;
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char * path;
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struct stat sb;
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int fd = -1;
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int err;
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int fileExists;
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assert( fileIndex < info->fileCount );
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assert( !file->length || ( fileOffset < file->length ) );
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assert( fileOffset + buflen <= file->length );
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path = tr_buildPath( tor->downloadDir, file->name, NULL );
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fileExists = !stat( path, &sb );
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tr_free( path );
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if( !file->length )
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return 0;
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if( ( ioMode == TR_IO_READ ) && !fileExists ) /* does file exist? */
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err = errno;
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else if( ( fd = tr_fdFileCheckout ( tor->downloadDir, file->name, ioMode == TR_IO_WRITE, !file->dnd, file->length ) ) < 0 )
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err = errno;
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else if( lseek( fd, (off_t)fileOffset, SEEK_SET ) == ( (off_t)-1 ) )
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err = errno;
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else if( func( fd, buf, buflen ) != buflen )
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err = errno;
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else
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err = 0;
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if( ( !err ) && ( !fileExists ) && ( ioMode == TR_IO_WRITE ) )
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tr_statsFileCreated( tor->session );
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if( fd >= 0 )
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tr_fdFileReturn( fd );
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return err;
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}
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static int
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compareOffsetToFile( const void * a,
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const void * b )
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{
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const uint64_t offset = *(const uint64_t*)a;
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const tr_file * file = b;
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if( offset < file->offset ) return -1;
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if( offset >= file->offset + file->length ) return 1;
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return 0;
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}
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void
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tr_ioFindFileLocation( const tr_torrent * tor,
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tr_piece_index_t pieceIndex,
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uint32_t pieceOffset,
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tr_file_index_t * fileIndex,
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uint64_t * fileOffset )
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{
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const uint64_t offset = tr_pieceOffset( tor, pieceIndex, pieceOffset,
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0 );
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const tr_file * file;
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file = bsearch( &offset,
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tor->info.files, tor->info.fileCount, sizeof( tr_file ),
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compareOffsetToFile );
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*fileIndex = file - tor->info.files;
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*fileOffset = offset - file->offset;
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assert( *fileIndex < tor->info.fileCount );
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assert( *fileOffset < file->length );
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assert( tor->info.files[*fileIndex].offset + *fileOffset == offset );
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}
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#ifdef WIN32
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/* return 0 on success, or an errno on failure */
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static int
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ensureMinimumFileSize( const tr_torrent * tor,
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tr_file_index_t fileIndex,
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uint64_t minBytes )
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{
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int fd;
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int err;
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struct stat sb;
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const tr_file * file = &tor->info.files[fileIndex];
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assert( 0 <= fileIndex && fileIndex < tor->info.fileCount );
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assert( minBytes <= file->length );
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fd = tr_fdFileCheckout( tor->downloadDir,
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file->name, TRUE, !file->dnd, file->length );
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if( fd < 0 ) /* bad fd */
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err = errno;
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else if( fstat ( fd, &sb ) ) /* how big is the file? */
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err = errno;
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else if( sb.st_size >= (off_t)minBytes ) /* already big enough */
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err = 0;
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else if( !ftruncate( fd, minBytes ) ) /* grow it */
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err = 0;
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else /* couldn't grow it */
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err = errno;
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if( fd >= 0 )
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tr_fdFileReturn( fd );
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return err;
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}
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#endif
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/* returns 0 on success, or an errno on failure */
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static int
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readOrWritePiece( const tr_torrent * tor,
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int ioMode,
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tr_piece_index_t pieceIndex,
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uint32_t pieceOffset,
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uint8_t * buf,
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size_t buflen )
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{
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int err = 0;
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tr_file_index_t fileIndex;
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uint64_t fileOffset;
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const tr_info * info = &tor->info;
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if( pieceIndex >= tor->info.pieceCount )
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return EINVAL;
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if( pieceOffset + buflen > tr_torPieceCountBytes( tor, pieceIndex ) )
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return EINVAL;
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tr_ioFindFileLocation( tor, pieceIndex, pieceOffset,
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&fileIndex, &fileOffset );
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while( buflen && !err )
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{
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const tr_file * file = &info->files[fileIndex];
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const uint64_t bytesThisPass = MIN( buflen,
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file->length - fileOffset );
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#ifdef WIN32
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if( ioMode == TR_IO_WRITE )
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err = ensureMinimumFileSize( tor, fileIndex,
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fileOffset + bytesThisPass );
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if( !err )
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#endif
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err = readOrWriteBytes( tor, ioMode,
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fileIndex, fileOffset, buf, bytesThisPass );
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buf += bytesThisPass;
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buflen -= bytesThisPass;
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++fileIndex;
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fileOffset = 0;
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}
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return err;
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}
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int
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tr_ioRead( const tr_torrent * tor,
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tr_piece_index_t pieceIndex,
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uint32_t begin,
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uint32_t len,
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uint8_t * buf )
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{
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return readOrWritePiece( tor, TR_IO_READ, pieceIndex, begin, buf, len );
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}
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int
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tr_ioWrite( const tr_torrent * tor,
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tr_piece_index_t pieceIndex,
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uint32_t begin,
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uint32_t len,
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const uint8_t * buf )
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{
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return readOrWritePiece( tor, TR_IO_WRITE, pieceIndex, begin,
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(uint8_t*)buf,
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len );
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}
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/****
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*****
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****/
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static int
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recalculateHash( const tr_torrent * tor,
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tr_piece_index_t pieceIndex,
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uint8_t * setme )
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{
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size_t bytesLeft;
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uint32_t offset = 0;
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int success = TRUE;
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SHA_CTX sha;
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assert( tor );
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assert( setme );
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assert( pieceIndex < tor->info.pieceCount );
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SHA1_Init( &sha );
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bytesLeft = tr_torPieceCountBytes( tor, pieceIndex );
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while( bytesLeft )
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{
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uint8_t buf[8192];
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const int len = MIN( bytesLeft, sizeof( buf ) );
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success = !tr_ioRead( tor, pieceIndex, offset, len, buf );
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if( !success )
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break;
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SHA1_Update( &sha, buf, len );
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offset += len;
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bytesLeft -= len;
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}
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if( success )
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SHA1_Final( setme, &sha );
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return success;
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}
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int
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tr_ioTestPiece( const tr_torrent * tor,
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int pieceIndex )
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{
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uint8_t hash[SHA_DIGEST_LENGTH];
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const int recalculated = recalculateHash( tor, pieceIndex, hash );
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return recalculated && !memcmp( hash, tor->info.pieces[pieceIndex].hash, SHA_DIGEST_LENGTH );
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}
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