transmission/libtransmission/inout.c

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/*
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* This file Copyright (C) 2007-2008 Charles Kerr <charles@rebelbase.com>
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*
* 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.
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*
* $Id$
*/
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#include <assert.h>
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#include <errno.h>
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#include <string.h> /* memcmp */
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#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <openssl/sha.h>
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#include "transmission.h"
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#include "fdlimit.h"
#include "inout.h"
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#include "stats.h"
#include "torrent.h"
#include "utils.h"
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/****
***** Low-level IO functions
****/
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#ifdef WIN32
#define lseek _lseeki64
#endif
enum { TR_IO_READ, TR_IO_WRITE };
static tr_errno
readOrWriteBytes( const tr_torrent * tor,
int ioMode,
int 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[MAX_PATH_LENGTH];
struct stat sb;
int fd = -1;
int err;
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int fileExists;
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assert( 0<=fileIndex && fileIndex<info->fileCount );
assert( !file->length || (fileOffset < file->length));
assert( fileOffset + buflen <= file->length );
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tr_buildPath ( path, sizeof(path), tor->destination, file->name, NULL );
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fileExists = !stat( path, &sb );
if( !file->length )
return TR_OK;
if ((ioMode==TR_IO_READ) && !fileExists ) /* does file exist? */
err = tr_ioErrorFromErrno( errno );
else if ((fd = tr_fdFileCheckout ( tor->destination, file->name, ioMode==TR_IO_WRITE )) < 0)
err = fd;
else if( lseek( fd, (off_t)fileOffset, SEEK_SET ) == ((off_t)-1) )
err = tr_ioErrorFromErrno( errno );
else if( func( fd, buf, buflen ) != buflen )
err = tr_ioErrorFromErrno( errno );
else
err = TR_OK;
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if( ( err==TR_OK ) && ( !fileExists ) && ( ioMode == TR_IO_WRITE) )
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tr_statsFileCreated( tor->handle );
if( fd >= 0 )
tr_fdFileReturn( fd );
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return err;
}
static tr_errno
findFileLocation( const tr_torrent * tor,
int pieceIndex,
int pieceOffset,
int * fileIndex,
uint64_t * fileOffset )
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{
const tr_info * info = &tor->info;
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int i;
uint64_t piecePos = ((uint64_t)pieceIndex * info->pieceSize) + pieceOffset;
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if( pieceIndex < 0 || pieceIndex >= info->pieceCount )
return TR_ERROR_ASSERT;
if( pieceOffset >= tr_torPieceCountBytes( tor, pieceIndex ) )
return TR_ERROR_ASSERT;
if( piecePos >= info->totalSize )
return TR_ERROR_ASSERT;
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for( i=0; info->files[i].length<=piecePos; ++i )
piecePos -= info->files[i].length;
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*fileIndex = i;
*fileOffset = piecePos;
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assert( 0<=*fileIndex && *fileIndex<info->fileCount );
assert( *fileOffset < info->files[i].length );
return 0;
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}
#ifdef WIN32
static tr_errno
ensureMinimumFileSize( const tr_torrent * tor,
int fileIndex,
uint64_t minBytes )
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{
int fd;
tr_errno 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->destination, file->name, TRUE );
if( fd < 0 ) /* bad fd */
err = fd;
else if (fstat (fd, &sb) ) /* how big is the file? */
err = tr_ioErrorFromErrno( errno );
else if (sb.st_size >= (off_t)minBytes) /* already big enough */
err = TR_OK;
else if ( !ftruncate( fd, minBytes ) ) /* grow it */
err = TR_OK;
else /* couldn't grow it */
err = tr_ioErrorFromErrno( errno );
if( fd >= 0 )
tr_fdFileReturn( fd );
return err;
}
#endif
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static tr_errno
readOrWritePiece( tr_torrent * tor,
int ioMode,
int pieceIndex,
int pieceOffset,
uint8_t * buf,
size_t buflen )
{
tr_errno err = 0;
int fileIndex;
uint64_t fileOffset;
const tr_info * info = &tor->info;
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if( pieceIndex < 0 || pieceIndex >= tor->info.pieceCount )
err = TR_ERROR_ASSERT;
else if( buflen > ( size_t ) tr_torPieceCountBytes( tor, pieceIndex ) )
err = TR_ERROR_ASSERT;
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if( !err )
err = findFileLocation ( tor, pieceIndex, pieceOffset, &fileIndex, &fileOffset );
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while( buflen && !err )
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{
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;
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}
return err;
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}
tr_errno
tr_ioRead( const tr_torrent * tor,
int pieceIndex,
int begin,
int len,
uint8_t * buf )
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{
return readOrWritePiece( (tr_torrent*)tor, TR_IO_READ, pieceIndex, begin, buf, len );
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}
tr_errno
tr_ioWrite( tr_torrent * tor,
int pieceIndex,
int begin,
int len,
const uint8_t * buf )
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{
return readOrWritePiece( tor, TR_IO_WRITE, pieceIndex, begin, (uint8_t*)buf, len );
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}
/****
*****
****/
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static tr_errno
tr_ioRecalculateHash( const tr_torrent * tor,
int pieceIndex,
uint8_t * setme )
{
int offset;
int bytesLeft;
uint8_t buf[4096];
const tr_info * info;
SHA_CTX sha;
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assert( tor != NULL );
assert( setme != NULL );
assert( 0<=pieceIndex && pieceIndex<tor->info.pieceCount );
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info = &tor->info;
offset = 0;
bytesLeft = tr_torPieceCountBytes( tor, pieceIndex );
SHA1_Init( &sha );
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while( bytesLeft > 0 )
{
const int bytesThisPass = MIN( bytesLeft, (int)sizeof(buf) );
tr_errno err = tr_ioRead( tor, pieceIndex, offset, bytesThisPass, buf );
if( err )
return err;
SHA1_Update( &sha, buf, bytesThisPass );
bytesLeft -= bytesThisPass;
offset += bytesThisPass;
}
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SHA1_Final( setme, &sha );
return 0;
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}
tr_errno
tr_ioTestPiece( const tr_torrent * tor, int pieceIndex )
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{
int err;
uint8_t hash[SHA_DIGEST_LENGTH];
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err = tr_ioRecalculateHash( tor, pieceIndex, hash );
if( !err && memcmp( hash, tor->info.pieces[pieceIndex].hash, SHA_DIGEST_LENGTH ) )
err = TR_ERROR;
tr_dbg ("torrent [%s] piece %d hash check: %s",
tor->info.name, pieceIndex, ( err ? "FAILED" : "OK" ));
return err;
}