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/*
This file is part of gnunet-fuse.
(C) 2012 Christian Grothoff (and other contributing authors)
gnunet-fuse is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published
by the Free Software Foundation; either version 3, or (at your
option) any later version.
gnunet-fuse is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
* read.c - FUSE read function
*
* Created on: Mar 14, 2012
* Author: mg
*
* Read data from an open file
*
* Read should return exactly the number of bytes requested except
* on EOF or error, otherwise the rest of the data will be
* substituted with zeroes. An exception to this is when the
* 'direct_io' mount option is specified, in which case the return
* value of the read system call will reflect the return value of
* this operation.
*
* Changed in version 2.2
*/
/**
* @file fuse/read.c
* @brief reading files
* @author Christian Grothoff
*/
#include "gnunet-fuse.h"
#include "gfs_download.h"
int
gn_read (const char *path, char *buf, size_t size, off_t offset,
struct fuse_file_info *fi)
{
struct GNUNET_FUSE_PathInfo *path_info;
uint64_t fsize;
struct GNUNET_DISK_FileHandle *fh;
int eno;
path_info = GNUNET_FUSE_path_info_get (path, &eno);
if (NULL == path_info)
return - eno;
fsize = GNUNET_FS_uri_chk_get_file_size (path_info->uri);
if (offset > fsize)
{
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"No data available at offset %llu of file `%s'\n",
(unsigned long long) offset,
path);
return 0;
}
if (offset + size > fsize)
size = fsize - offset;
if (NULL == path_info->tmpfile)
{
/* store to temporary file */
path_info->tmpfile = GNUNET_DISK_mktemp ("gnunet-fuse-tempfile");
if (GNUNET_OK != GNUNET_FUSE_download_file (path_info,
offset,
size))
{
UNLINK (path_info->tmpfile);
GNUNET_free (path_info->tmpfile);
path_info->tmpfile = NULL;
GNUNET_FUSE_path_info_done (path_info);
return - EIO; /* low level IO error */
}
}
else
{
if ( (offset < path_info->download_start) ||
(size + offset > path_info->download_end) )
{
/* need to download some more... */
if (GNUNET_OK != GNUNET_FUSE_download_file (path_info,
offset,
size))
{
UNLINK (path_info->tmpfile);
GNUNET_free (path_info->tmpfile);
path_info->tmpfile = NULL;
GNUNET_FUSE_path_info_done (path_info);
return - EIO; /* low level IO error */
}
}
}
/* combine ranges */
if (path_info->download_start == path_info->download_end)
{
/* first range */
path_info->download_start = offset;
path_info->download_end = offset + size;
}
else
{
/* only combine ranges if the resulting range would
be contiguous... */
if ( (offset >= path_info->download_start) &&
(offset <= path_info->download_end) &&
(offset + size > path_info->download_end) )
path_info->download_end = offset + size;
if ( (offset + size >= path_info->download_start) &&
(offset + size <= path_info->download_end) &&
(offset < path_info->download_start) )
path_info->download_start = offset;
}
fh = GNUNET_DISK_file_open (path_info->tmpfile,
GNUNET_DISK_OPEN_READ,
GNUNET_DISK_PERM_NONE);
if (NULL == fh)
{
GNUNET_FUSE_path_info_done (path_info);
return - EBADF;
}
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Trying to read bytes %llu-%llu/%llu of file `%s'\n",
(unsigned long long) offset,
(unsigned long long) offset + size,
(unsigned long long) fsize,
path);
if (offset != GNUNET_DISK_file_seek (fh, offset, GNUNET_DISK_SEEK_SET))
{
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"No data available at offset %llu of file `%s'\n",
(unsigned long long) offset,
path);
GNUNET_DISK_file_close (fh);
GNUNET_FUSE_path_info_done (path_info);
return 0;
}
size = GNUNET_MIN (size, fsize - offset);
if (GNUNET_SYSERR == (size = GNUNET_DISK_file_read (fh, buf, size)))
{
int eno = errno;
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Error reading from file `%s': %s\n",
path,
STRERROR (errno));
GNUNET_DISK_file_close (fh);
GNUNET_FUSE_path_info_done (path_info);
return - eno;
}
GNUNET_DISK_file_close (fh);
GNUNET_FUSE_path_info_done (path_info);
return size;
}
/* end of read.c */
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