source: branches/samba-3.5.x/source4/ntvfs/posix/pvfs_read.c

/* 
   Unix SMB/CIFS implementation.

   POSIX NTVFS backend - read

   Copyright (C) Andrew Tridgell 2004

   This program 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 of the License, or
   (at your option) any later version.
   
   This program 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, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"
#include "vfs_posix.h"
#include "lib/events/events.h"

/*
  read from a file
*/
NTSTATUS pvfs_read(struct ntvfs_module_context *ntvfs,
                   struct ntvfs_request *req, union smb_read *rd)
{
        struct pvfs_state *pvfs = talloc_get_type(ntvfs->private_data,
                                  struct pvfs_state);
        ssize_t ret;
        struct pvfs_file *f;
        NTSTATUS status;
        uint32_t maxcnt;
        uint32_t mask;

        if (rd->generic.level != RAW_READ_READX) {
                return ntvfs_map_read(ntvfs, req, rd);
        }

        f = pvfs_find_fd(pvfs, req, rd->readx.in.file.ntvfs);
        if (!f) {
                return NT_STATUS_INVALID_HANDLE;
        }

        if (f->handle->fd == -1) {
                return NT_STATUS_INVALID_DEVICE_REQUEST;
        }

        mask = SEC_FILE_READ_DATA;
        if (rd->readx.in.read_for_execute) {
                mask |= SEC_FILE_EXECUTE;
        }
        if (!(f->access_mask & mask)) {
                return NT_STATUS_ACCESS_DENIED;
        }

        maxcnt = rd->readx.in.maxcnt;
        if (maxcnt > 2*UINT16_MAX && req->ctx->protocol < PROTOCOL_SMB2) {
                return NT_STATUS_INVALID_PARAMETER;
        }

        status = pvfs_check_lock(pvfs, f, req->smbpid, 
                                 rd->readx.in.offset,
                                 maxcnt,
                                 READ_LOCK);
        if (!NT_STATUS_IS_OK(status)) {
                return status;
        }

        if (f->handle->name->stream_name) {
                ret = pvfs_stream_read(pvfs, f->handle, 
                                       rd->readx.out.data, maxcnt, rd->readx.in.offset);
        } else {
#if HAVE_LINUX_AIO
                /* possibly try an aio read */
                if ((req->async_states->state & NTVFS_ASYNC_STATE_MAY_ASYNC) &&
                    (pvfs->flags & PVFS_FLAG_LINUX_AIO)) {
                        status = pvfs_aio_pread(req, rd, f, maxcnt);
                        if (NT_STATUS_IS_OK(status)) {
                                return NT_STATUS_OK;
                        }
                }
#endif
                ret = pread(f->handle->fd, 
                            rd->readx.out.data, 
                            maxcnt,
                            rd->readx.in.offset);
        }
        if (ret == -1) {
                return pvfs_map_errno(pvfs, errno);
        }

        /* only SMB2 honors mincnt */
        if (req->ctx->protocol == PROTOCOL_SMB2) {
                if (rd->readx.in.mincnt > ret ||
                    (ret == 0 && maxcnt > 0)) {
                        return NT_STATUS_END_OF_FILE;
                }
        }

        f->handle->position = f->handle->seek_offset = rd->readx.in.offset + ret;

        rd->readx.out.nread = ret;
        rd->readx.out.remaining = 0xFFFF;
        rd->readx.out.compaction_mode = 0; 

        return NT_STATUS_OK;
}