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- /****************************************************************************
- * fs/vfs/fs_read.c
- *
- * Copyright (C) 2007-2009, 2012-2014, 2016-2017 Gregory Nutt. All rights
- * reserved.
- * Author: Gregory Nutt <gnutt@nuttx.org>
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the
- * distribution.
- * 3. Neither the name NuttX nor the names of its contributors may be
- * used to endorse or promote products derived from this software
- * without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
- * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
- * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
- * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- *
- ****************************************************************************/
- /****************************************************************************
- * Included Files
- ****************************************************************************/
- #include <nuttx/config.h>
- #include <sys/types.h>
- #include <sys/socket.h>
- #include <unistd.h>
- #include <fcntl.h>
- #include <sched.h>
- #include <errno.h>
- #include <nuttx/cancelpt.h>
- #include <nuttx/net/net.h>
- #include "inode/inode.h"
- /****************************************************************************
- * Public Functions
- ****************************************************************************/
- /****************************************************************************
- * Name: file_read
- *
- * Description:
- * file_read() is an interanl OS interface. It is functionally similar to
- * the standard read() interface except:
- *
- * - It does not modify the errno variable,
- * - It is not a cancellation point,
- * - It does not handle socket descriptors, and
- * - It accepts a file structure instance instead of file descriptor.
- *
- * Input Parameters:
- * filep - File structure instance
- * buf - User-provided to save the data
- * nbytes - The maximum size of the user-provided buffer
- *
- * Returned Value:
- * The positive non-zero number of bytes read on success, 0 on if an
- * end-of-file condition, or a negated errno value on any failure.
- *
- ****************************************************************************/
- ssize_t file_read(FAR struct file *filep, FAR void *buf, size_t nbytes)
- {
- FAR struct inode *inode;
- int ret = -EBADF;
- DEBUGASSERT(filep);
- inode = filep->f_inode;
- /* Was this file opened for read access? */
- if ((filep->f_oflags & O_RDOK) == 0)
- {
- /* No.. File is not read-able */
- ret = -EACCES;
- }
- /* Is a driver or mountpoint registered? If so, does it support the read
- * method?
- */
- else if (inode != NULL && inode->u.i_ops && inode->u.i_ops->read)
- {
- /* Yes.. then let it perform the read. NOTE that for the case of the
- * mountpoint, we depend on the read methods being identical in
- * signature and position in the operations vtable.
- */
- ret = (int)inode->u.i_ops->read(filep, (FAR char *)buf, (size_t)nbytes);
- }
- /* Return the number of bytes read (or possibly an error code) */
- return ret;
- }
- /****************************************************************************
- * Name: nx_read
- *
- * Description:
- * nx_read() is an internal OS interface. It is functionally similar to
- * the standard read() interface except:
- *
- * - It does not modify the errno variable, and
- * - It is not a cancellation point.
- *
- * Input Parameters:
- * fd - File descriptor to read from
- * buf - User-provided to save the data
- * nbytes - The maximum size of the user-provided buffer
- *
- * Returned Value:
- * The positive non-zero number of bytes read on success, 0 on if an
- * end-of-file condition, or a negated errno value on any failure.
- *
- ****************************************************************************/
- ssize_t nx_read(int fd, FAR void *buf, size_t nbytes)
- {
- /* Did we get a valid file descriptor? */
- if ((unsigned int)fd >= CONFIG_NFILE_DESCRIPTORS)
- {
- #ifdef CONFIG_NET
- /* No.. If networking is enabled, read() is the same as recv() with
- * the flags parameter set to zero.
- */
- return nx_recv(fd, buf, nbytes, 0);
- #else
- /* No networking... it is a bad descriptor in any event */
- return -EBADF;
- #endif
- }
- else
- {
- FAR struct file *filep;
- ssize_t ret;
- /* The descriptor is in a valid range to file descriptor... do the
- * read. First, get the file structure. Note that on failure,
- * fs_getfilep() will set the errno variable.
- */
- ret = (ssize_t)fs_getfilep(fd, &filep);
- if (ret < 0)
- {
- return ret;
- }
- /* Then let file_read do all of the work. */
- return file_read(filep, buf, nbytes);
- }
- }
- /****************************************************************************
- * Name: read
- *
- * Description:
- * The standard, POSIX read interface.
- *
- * Input Parameters:
- * fd - File descriptor to read from
- * buf - User-provided to save the data
- * nbytes - The maximum size of the user-provided buffer
- *
- * Returned Value:
- * The positive non-zero number of bytes read on success, 0 on if an
- * end-of-file condition, or -1 on failure with errno set appropriately.
- *
- ****************************************************************************/
- ssize_t read(int fd, FAR void *buf, size_t nbytes)
- {
- ssize_t ret;
- /* read() is a cancellation point */
- (void)enter_cancellation_point();
- /* Let nx_read() do the real work */
- ret = nx_read(fd, buf, nbytes);
- if (ret < 0)
- {
- set_errno(-ret);
- ret = ERROR;
- }
- leave_cancellation_point();
- return ret;
- }
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