mirror of
https://github.com/transmission/transmission
synced 2024-12-27 01:57:52 +00:00
315 lines
8.2 KiB
C
315 lines
8.2 KiB
C
/*
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* This file Copyright (C) 2007-2014 Mnemosyne LLC
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*
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* It may be used under the GNU GPL versions 2 or 3
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* or any future license endorsed by Mnemosyne LLC.
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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 "log.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
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{
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TR_IO_READ,
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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_logAddTorErr (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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{
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const int rc = tr_pread (fd, buf, buflen, fileOffset);
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if (rc < 0)
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{
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err = errno;
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tr_logAddTorErr (tor, "read failed for \"%s\": %s", file->name, tr_strerror (err));
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}
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}
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else if (ioMode == TR_IO_WRITE)
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{
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const int rc = tr_pwrite (fd, buf, buflen, fileOffset);
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if (rc < 0)
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{
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err = errno;
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tr_logAddTorErr (tor, "write failed for \"%s\": %s", file->name, tr_strerror (err));
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}
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}
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else if (ioMode == TR_IO_PREFETCH)
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{
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tr_prefetch (fd, fileOffset, buflen);
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}
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else
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{
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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)
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return -1;
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if (offset >= file->offset + file->length)
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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, 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, (uint8_t*)buf, 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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