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