mirror of
https://github.com/transmission/transmission
synced 2024-12-27 01:57:52 +00:00
306 lines
8.8 KiB
C
306 lines
8.8 KiB
C
/*
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* This file Copyright (C) Mnemosyne LLC
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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> /* bsearch() */
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#include <string.h> /* memcmp() */
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#include <openssl/sha.h>
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#include "transmission.h"
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#include "cache.h" /* tr_cacheReadBlock() */
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#include "fdlimit.h"
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#include "inout.h"
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#include "peer-common.h" /* MAX_BLOCK_SIZE */
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#include "stats.h" /* tr_statsFileCreated() */
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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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enum { TR_IO_READ, TR_IO_PREFETCH,
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/* Any operations that require write access must follow TR_IO_WRITE. */
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TR_IO_WRITE
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};
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/* returns 0 on success, or an errno on failure */
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static int
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readOrWriteBytes( tr_session * session,
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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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int fd;
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int err = 0;
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const bool doWrite = ioMode >= TR_IO_WRITE;
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const tr_info * const info = &tor->info;
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const tr_file * const file = &info->files[fileIndex];
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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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if( !file->length )
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return 0;
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/***
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**** Find the fd
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***/
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fd = tr_fdFileGetCached( session, tr_torrentId( tor ), fileIndex, doWrite );
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if( fd < 0 )
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{
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/* it's not cached, so open/create it now */
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char * subpath;
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const char * base;
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/* see if the file exists... */
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if( !tr_torrentFindFile2( tor, fileIndex, &base, &subpath, NULL ) )
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{
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/* we can't read a file that doesn't exist... */
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if( !doWrite )
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err = ENOENT;
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/* figure out where the file should go, so we can create it */
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base = tr_torrentGetCurrentDir( tor );
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subpath = tr_sessionIsIncompleteFileNamingEnabled( tor->session )
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? tr_torrentBuildPartial( tor, fileIndex )
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: tr_strdup( file->name );
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}
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if( !err )
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{
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/* open (and maybe create) the file */
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char * filename = tr_buildPath( base, subpath, NULL );
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const int prealloc = file->dnd || !doWrite
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? TR_PREALLOCATE_NONE
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: tor->session->preallocationMode;
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if((( fd = tr_fdFileCheckout( session, tor->uniqueId, fileIndex,
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filename, doWrite,
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prealloc, file->length ))) < 0 )
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{
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err = errno;
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tr_torerr( tor, "tr_fdFileCheckout failed for \"%s\": %s",
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filename, tr_strerror( err ) );
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}
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else if( doWrite )
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{
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/* make a note that we just created a file */
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tr_statsFileCreated( tor->session );
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}
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tr_free( filename );
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}
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tr_free( subpath );
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}
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/***
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**** Use the fd
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***/
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if( !err )
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{
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if( ioMode == TR_IO_READ ) {
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const int rc = tr_pread( fd, buf, buflen, fileOffset );
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if( rc < 0 ) {
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err = errno;
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tr_torerr( tor, "read failed for \"%s\": %s",
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file->name, tr_strerror( err ) );
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}
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} else if( ioMode == TR_IO_WRITE ) {
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const int rc = tr_pwrite( fd, buf, buflen, fileOffset );
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if( rc < 0 ) {
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err = errno;
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tr_torerr( tor, "write failed for \"%s\": %s",
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file->name, tr_strerror( err ) );
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}
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} else if( ioMode == TR_IO_PREFETCH ) {
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tr_prefetch( fd, fileOffset, buflen );
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} else {
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abort();
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}
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}
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return err;
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}
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static int
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compareOffsetToFile( const void * a, 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, 0 );
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const tr_file * file;
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assert( tr_isTorrent( tor ) );
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assert( offset < tor->info.totalSize );
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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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assert( file != NULL );
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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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/* returns 0 on success, or an errno on failure */
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static int
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readOrWritePiece( 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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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, file->length - fileOffset );
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err = readOrWriteBytes( tor->session, tor, ioMode, 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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if( ( err != 0 ) && (ioMode == TR_IO_WRITE ) && ( tor->error != TR_STAT_LOCAL_ERROR ) )
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{
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char * path = tr_buildPath( tor->downloadDir, file->name, NULL );
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tr_torrentSetLocalError( tor, "%s (%s)", tr_strerror( err ), path );
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tr_free( path );
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}
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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( 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_ioPrefetch( 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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{
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return readOrWritePiece( tor, TR_IO_PREFETCH, pieceIndex, begin,
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NULL, len );
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}
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int
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tr_ioWrite( 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 bool
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recalculateHash( tr_torrent * tor, tr_piece_index_t pieceIndex, 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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bool success = true;
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const size_t buflen = tor->blockSize;
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void * buffer = tr_valloc( buflen );
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SHA_CTX sha;
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assert( tor != NULL );
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assert( pieceIndex < tor->info.pieceCount );
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assert( buffer != NULL );
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assert( buflen > 0 );
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assert( setme != NULL );
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SHA1_Init( &sha );
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bytesLeft = tr_torPieceCountBytes( tor, pieceIndex );
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tr_ioPrefetch( tor, pieceIndex, offset, bytesLeft );
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while( bytesLeft )
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{
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const int len = MIN( bytesLeft, buflen );
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success = !tr_cacheReadBlock( tor->session->cache, tor, pieceIndex, offset, len, buffer );
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if( !success )
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break;
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SHA1_Update( &sha, buffer, 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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tr_free( buffer );
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return success;
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}
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bool
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tr_ioTestPiece( tr_torrent * tor, tr_piece_index_t piece )
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{
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uint8_t hash[SHA_DIGEST_LENGTH];
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return recalculateHash( tor, piece, hash )
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&& !memcmp( hash, tor->info.pieces[piece].hash, SHA_DIGEST_LENGTH );
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}
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