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transmission/libtransmission/fastresume.c

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/******************************************************************************
* $Id:$
*
* Copyright (c) 2005-2007 Transmission authors and contributors
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*****************************************************************************/
/***********************************************************************
* Fast resume
***********************************************************************
* The format of the resume file is a 4 byte format version (currently 1),
* followed by several variable-sized blocks of data. Each block is
* preceded by a 1 byte ID and a 4 byte length. The currently recognized
* IDs are defined below by the FR_ID_* macros. The length does not include
* the 5 bytes for the ID and length.
*
* The name of the resume file is "resume.<hash>-<tag>", although
* older files with a name of "resume.<hash>" will be recognized if
* the former doesn't exist.
*
* All values are stored in the native endianness. Moving a
* libtransmission resume file from an architecture to another will not
* work, although it will not hurt either (the version will be wrong,
* so the resume file will not be read).
**********************************************************************/
#include "transmission.h"
#include "fastresume.h"
/* time_t can be 32 or 64 bits... for consistency we'll hardwire 64 */
typedef uint64_t tr_time_t;
/* deprecated */
#define FR_ID_PROGRESS_SLOTS 0x01
/* number of bytes downloaded */
#define FR_ID_DOWNLOADED 0x02
/* number of bytes uploaded */
#define FR_ID_UPLOADED 0x03
/* IPs and ports of connectable peers */
#define FR_ID_PEERS 0x04
/* progress data:
* - 4 bytes * number of files: mtimes of files
* - 1 bit * number of blocks: whether we have the block or not
*/
#define FR_ID_PROGRESS 0x05
/* macros for the length of various pieces of the progress data */
#define FR_MTIME_LEN( t ) \
( sizeof(tr_time_t) * (t)->info.fileCount )
#define FR_BLOCK_BITFIELD_LEN( t ) \
( ( (t)->blockCount + 7 ) / 8 )
#define FR_PROGRESS_LEN( t ) \
( FR_MTIME_LEN( t ) + FR_BLOCK_BITFIELD_LEN( t ) )
static void
fastResumeFileName( char * buf, size_t buflen, const tr_torrent_t * tor, int tag )
{
const char * cacheDir = tr_getCacheDirectory ();
const char * hash = tor->info.hashString;
if( !tag )
{
tr_buildPath( buf, buflen, cacheDir, hash, NULL );
}
else
{
char base[1024];
snprintf( base, sizeof(base), "%s-%s", hash, tor->handle->tag );
tr_buildPath( buf, buflen, cacheDir, base, NULL );
}
}
static tr_time_t*
getMTimes( const tr_torrent_t * tor, int * setme_n )
{
int i;
const int n = tor->info.fileCount;
tr_time_t * m = calloc( n, sizeof(tr_time_t) );
for( i=0; i<n; ++i ) {
char fname[MAX_PATH_LENGTH];
struct stat sb;
tr_buildPath( fname, sizeof(fname),
tor->destination, tor->info.files[i].name, NULL );
if ( !stat( fname, &sb ) && S_ISREG( sb.st_mode ) ) {
#ifdef SYS_DARWIN
m[i] = sb.st_mtimespec.tv_sec;
#else
m[i] = sb.st_mtime;
#endif
}
}
*setme_n = n;
return m;
}
static inline void fastResumeWriteData( uint8_t id, void * data, uint32_t size,
uint32_t count, FILE * file )
{
uint32_t datalen = size * count;
fwrite( &id, 1, 1, file );
fwrite( &datalen, 4, 1, file );
fwrite( data, size, count, file );
}
void fastResumeSave( const tr_torrent_t * tor )
{
char path[MAX_PATH_LENGTH];
FILE * file;
const int version = 1;
uint64_t total;
fastResumeFileName( path, sizeof path, tor, 1 );
file = fopen( path, "w" );
if( NULL == file ) {
tr_err( "Couldn't open '%s' for writing", path );
return;
}
/* Write format version */
fwrite( &version, 4, 1, file );
/* Write progress data */
if (1) {
int n;
tr_time_t * mtimes;
uint8_t * buf = malloc( FR_PROGRESS_LEN( tor ) );
uint8_t * walk = buf;
const tr_bitfield_t * bitfield;
/* mtimes */
mtimes = getMTimes( tor, &n );
memcpy( walk, mtimes, n*sizeof(tr_time_t) );
walk += n * sizeof(tr_time_t);
/* completion bitfield */
bitfield = tr_cpBlockBitfield( tor->completion );
assert( (unsigned)FR_BLOCK_BITFIELD_LEN( tor ) == bitfield->len );
memcpy( walk, bitfield->bits, bitfield->len );
walk += bitfield->len;
/* write it */
assert( walk-buf == (int)FR_PROGRESS_LEN( tor ) );
fastResumeWriteData( FR_ID_PROGRESS, buf, 1, walk-buf, file );
/* cleanup */
free( mtimes );
free( buf );
}
/* Write download and upload totals */
total = tor->downloadedCur + tor->downloadedPrev;
fastResumeWriteData( FR_ID_DOWNLOADED, &total, 8, 1, file );
total = tor->uploadedCur + tor->uploadedPrev;
fastResumeWriteData( FR_ID_UPLOADED, &total, 8, 1, file );
if( !( TR_FLAG_PRIVATE & tor->info.flags ) )
{
/* Write IPs and ports of connectable peers, if any */
int size;
uint8_t * buf = NULL;
if( ( size = tr_peerGetConnectable( tor, &buf ) ) > 0 )
{
fastResumeWriteData( FR_ID_PEERS, buf, size, 1, file );
free( buf );
}
}
fclose( file );
tr_dbg( "Resume file '%s' written", path );
}
static int
fastResumeLoadProgress( const tr_torrent_t * tor,
tr_bitfield_t * uncheckedPieces,
FILE * file )
{
const size_t len = FR_PROGRESS_LEN( tor );
uint8_t * buf = calloc( len, 1 );
uint8_t * walk = buf;
if( len != fread( buf, 1, len, file ) ) {
tr_inf( "Couldn't read from resume file" );
free( buf );
return TR_ERROR_IO_OTHER;
}
/* compare file mtimes */
if (1) {
int i, n;
tr_time_t * curMTimes = getMTimes( tor, &n );
const tr_time_t * oldMTimes = (const tr_time_t *) walk;
for( i=0; i<n; ++i ) {
if ( curMTimes[i]!=oldMTimes[i] ) {
const tr_file_t * file = &tor->info.files[i];
tr_dbg( "File '%s' mtimes differ-- flagging pieces [%d..%d] for recheck",
file->name, file->firstPiece, file->lastPiece);
tr_bitfieldAddRange( uncheckedPieces,
file->firstPiece, file->lastPiece );
}
}
free( curMTimes );
walk += n * sizeof(tr_time_t);
}
/* get the completion bitfield */
if (1) {
tr_bitfield_t bitfield;
memset( &bitfield, 0, sizeof bitfield );
bitfield.len = FR_BLOCK_BITFIELD_LEN( tor );
bitfield.bits = walk;
tr_cpBlockBitfieldSet( tor->completion, &bitfield );
}
free( buf );
return TR_OK;
}
static int
fastResumeLoadOld( tr_torrent_t * tor,
tr_bitfield_t * uncheckedPieces,
FILE * file )
{
/* Check the size */
const int size = 4 + FR_PROGRESS_LEN( tor );
fseek( file, 0, SEEK_END );
if( ftell( file ) != size )
{
tr_inf( "Wrong size for resume file (%d bytes, %d expected)",
(int)ftell( file ), size );
fclose( file );
return 1;
}
/* load progress information */
fseek( file, 4, SEEK_SET );
if( fastResumeLoadProgress( tor, uncheckedPieces, file ) )
{
fclose( file );
return 1;
}
fclose( file );
tr_inf( "Fast resuming successful (version 0)" );
return 0;
}
int
fastResumeLoad( tr_torrent_t * tor,
tr_bitfield_t * uncheckedPieces )
{
char path[MAX_PATH_LENGTH];
FILE * file;
int version = 0;
uint8_t id;
uint32_t len;
int ret;
assert( tor != NULL );
assert( uncheckedPieces != NULL );
/* Open resume file */
fastResumeFileName( path, sizeof path, tor, 1 );
file = fopen( path, "r" );
if( NULL == file )
{
if( ENOENT == errno )
{
fastResumeFileName( path, sizeof path, tor, 0 );
file = fopen( path, "r" );
if( NULL != file )
{
goto good;
}
fastResumeFileName( path, sizeof path, tor, 1 );
}
tr_inf( "Could not open '%s' for reading", path );
return 1;
}
good:
tr_dbg( "Resume file '%s' loaded", path );
/* Check format version */
fread( &version, 4, 1, file );
if( 0 == version )
{
return fastResumeLoadOld( tor, uncheckedPieces, file );
}
if( 1 != version )
{
tr_inf( "Resume file has version %d, not supported", version );
fclose( file );
return 1;
}
ret = 1;
/* read each block of data */
while( 1 == fread( &id, 1, 1, file ) && 1 == fread( &len, 4, 1, file ) )
{
switch( id )
{
case FR_ID_PROGRESS:
/* read progress data */
if( (uint32_t)FR_PROGRESS_LEN( tor ) == len )
{
if( fastResumeLoadProgress( tor, uncheckedPieces, file ) )
{
if( feof( file ) || ferror( file ) )
{
fclose( file );
return 1;
}
}
else
{
ret = 0;
}
continue;
}
break;
case FR_ID_DOWNLOADED:
/* read download total */
if( 8 == len)
{
if( 1 != fread( &tor->downloadedPrev, 8, 1, file ) )
{
fclose( file );
return 1;
}
continue;
}
break;
case FR_ID_UPLOADED:
/* read upload total */
if( 8 == len)
{
if( 1 != fread( &tor->uploadedPrev, 8, 1, file ) )
{
fclose( file );
return 1;
}
continue;
}
break;
case FR_ID_PEERS:
if( !( TR_FLAG_PRIVATE & tor->info.flags ) )
{
int used;
uint8_t * buf = malloc( len );
if( 1 != fread( buf, len, 1, file ) )
{
free( buf );
fclose( file );
return 1;
}
used = tr_torrentAddCompact( tor, TR_PEER_FROM_CACHE,
buf, len / 6 );
tr_dbg( "found %i peers in resume file, used %i",
len / 6, used );
free( buf );
}
continue;
default:
break;
}
/* if we didn't read the data, seek past it */
tr_inf( "Skipping resume data type %02x, %u bytes", id, len );
fseek( file, len, SEEK_CUR );
}
fclose( file );
if( !ret )
{
tr_inf( "Fast resuming successful" );
}
return ret;
}
void
fastResumeRemove( tr_torrent_t * tor )
{
char file[MAX_PATH_LENGTH];
fastResumeFileName( file, sizeof file, tor, NULL != tor->handle->tag );
if ( unlink( file ) )
{
tr_inf( "Removing fast resume file failed" );
}
}
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