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transmission/libtransmission/inout.c

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/*
* This file Copyright (C) 2007-2008 Charles Kerr <charles@rebelbase.com>
*
* 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 <assert.h>
#include <errno.h>
#include <stdlib.h> /* realloc */
#include <string.h> /* memcmp */
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#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
#endif
enum { TR_IO_READ, TR_IO_WRITE };
static tr_errno
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[MAX_PATH_LENGTH];
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 );
tr_buildPath ( path, sizeof(path), tor->destination, file->name, NULL );
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;
if( ( err==TR_OK ) && ( !fileExists ) && ( ioMode == TR_IO_WRITE) )
tr_statsFileCreated( tor->handle );
if( fd >= 0 )
tr_fdFileReturn( fd );
return err;
}
static void
findFileLocation( const tr_torrent * tor,
tr_piece_index_t pieceIndex,
uint32_t pieceOffset,
tr_file_index_t * fileIndex,
uint64_t * fileOffset )
{
size_t len;
tr_file_index_t first, last;
const tr_info * inf = &tor->info;
uint64_t offset = tr_pieceOffset( tor, pieceIndex, pieceOffset, 0 );
assert( pieceIndex < inf->pieceCount );
assert( pieceOffset < tr_torPieceCountBytes( tor, pieceIndex ) );
assert( offset < inf->totalSize );
/* use a lower-bound bsearch to find the file that matches */
first = 0;
last = inf->fileCount;
len = last - first;
while( len > 0 ) {
size_t half = len / 2;
size_t middle = first + half;
if( inf->files[middle].offset + inf->files[middle].length < offset )
{
first = middle;
++first;
len = len - half - 1;
}
else len = half;
}
*fileIndex = first;
*fileOffset = offset - inf->files[first].offset;
assert( inf->files[first].offset <= offset );
if( offset >= inf->files[first].offset + inf->files[first].length ) {
fprintf( stderr, "piece index is %lu\n", (unsigned long)pieceIndex );
fprintf( stderr, "piece offset is %lu\n", (unsigned long)pieceOffset );
fprintf( stderr, "piece size is %lu\n", (unsigned long)inf->pieceSize );
fprintf( stderr, "inf->totalSize is %"PRIu64"\n", inf->totalSize );
fprintf( stderr, "offset is %"PRIu64"\n", offset );
fprintf( stderr, "first is is %"PRIu64"\n", (uint64_t)first );
fprintf( stderr, "inf->fileCount is %"PRIu64"\n", (uint64_t)inf->fileCount );
fprintf( stderr, "inf->fileCount is %d\n", (int)inf->fileCount );
fprintf( stderr, "inf->files[first].offset is %"PRIu64"\n", inf->files[first].offset );
fprintf( stderr, "inf->files[first].length is %"PRIu64"\n", inf->files[first].length );
assert( offset < inf->files[first].offset + inf->files[first].length );
}
assert( *fileIndex < inf->fileCount );
assert( *fileOffset < inf->files[first].length );
}
#ifdef WIN32
static tr_errno
ensureMinimumFileSize( const tr_torrent * tor,
tr_file_index_t fileIndex,
uint64_t minBytes )
{
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
static tr_errno
readOrWritePiece( const tr_torrent * tor,
int ioMode,
tr_piece_index_t pieceIndex,
uint32_t pieceOffset,
uint8_t * buf,
size_t buflen )
{
tr_errno err = 0;
tr_file_index_t fileIndex;
uint64_t fileOffset;
const tr_info * info = &tor->info;
if( pieceIndex >= tor->info.pieceCount )
return TR_ERROR_ASSERT;
if( pieceOffset + buflen > tr_torPieceCountBytes( tor, pieceIndex ) )
return TR_ERROR_ASSERT;
findFileLocation ( 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;
}
tr_errno
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 );
}
tr_errno
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 tr_errno
recalculateHash( const tr_torrent * tor,
tr_piece_index_t pieceIndex,
uint8_t * setme )
{
static uint8_t * buf = NULL;
static int buflen = 0;
static tr_lock * lock = NULL;
int n;
tr_errno err;
const tr_info * info;
/* only check one block at a time to prevent disk thrashing.
* this also lets us reuse the same buffer each time. */
if( lock == NULL )
lock = tr_lockNew( );
tr_lockLock( lock );
assert( tor != NULL );
assert( setme != NULL );
assert( pieceIndex < tor->info.pieceCount );
info = &tor->info;
n = tr_torPieceCountBytes( tor, pieceIndex );
if( buflen < n ) {
buflen = n;
buf = tr_renew( uint8_t, buf, buflen );
}
err = tr_ioRead( tor, pieceIndex, 0, n, buf );
if( !err )
tr_sha1( setme, buf, n, NULL );
tr_lockUnlock( lock );
return err;
}
tr_errno
tr_ioTestPiece( const tr_torrent * tor, int pieceIndex )
{
int err;
uint8_t hash[SHA_DIGEST_LENGTH];
err = recalculateHash( tor, pieceIndex, hash );
if( !err && memcmp( hash, tor->info.pieces[pieceIndex].hash,
SHA_DIGEST_LENGTH ) )
err = TR_ERROR_IO_CHECKSUM;
tr_tordbg (tor, "piece %d hash check: %s",
pieceIndex, ( err ? "FAILED" : "OK" ));
return err;
}
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