30ad31e9d7
* Make readv/writev implementations update struct uio This can simplify partial result handling. * change the error number on the overflow from EOVERFLOW to EINVAL to match NetBSD * add a commented out uio_offset field. I used "#if 0" here as C comments can't nest. * add a few helper functions Note on uio_copyfrom/uio_copyto: although i'm not quite happy with the "offset" functionality, it's necessary to simplify the adaptation of some drivers like drivers/serial/serial.c, which (ab)uses the user-supplied buffer as a line-buffer.
175 lines
5.2 KiB
C
175 lines
5.2 KiB
C
/****************************************************************************
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* drivers/loop/loop.c
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <sys/types.h>
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#include <stdbool.h>
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#include <string.h>
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#include <errno.h>
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#include <nuttx/fs/fs.h>
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#include <nuttx/fs/loop.h>
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#ifdef CONFIG_DEV_LOOP
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/****************************************************************************
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* Private Function Prototypes
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****************************************************************************/
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static ssize_t loop_readv(FAR struct file *filep, FAR struct uio *uio);
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static ssize_t loop_writev(FAR struct file *filep, FAR struct uio *uio);
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static int loop_ioctl(FAR struct file *filep, int cmd,
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unsigned long arg);
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/****************************************************************************
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* Private Data
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****************************************************************************/
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static const struct file_operations g_loop_fops =
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{
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NULL, /* open */
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NULL, /* close */
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NULL, /* read */
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NULL, /* write */
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NULL, /* seek */
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loop_ioctl, /* ioctl */
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NULL, /* mmap */
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NULL, /* truncate */
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NULL, /* poll */
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loop_readv, /* readv */
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loop_writev /* writev */
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};
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: loop_readv
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****************************************************************************/
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static ssize_t loop_readv(FAR struct file *filep, FAR struct uio *uio)
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{
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return 0; /* Return EOF */
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}
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/****************************************************************************
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* Name: loop_writev
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****************************************************************************/
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static ssize_t loop_writev(FAR struct file *filep, FAR struct uio *uio)
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{
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/* Say that everything was written */
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size_t ret = uio->uio_resid;
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uio_advance(uio, ret);
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return ret;
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}
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/****************************************************************************
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* Name: loop_ioctl
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****************************************************************************/
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static int loop_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
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{
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int ret;
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switch (cmd)
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{
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/* Command: LOOPIOC_SETUP
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* Description: Setup the loop device
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* Argument: A pointer to a read-only instance of struct losetup_s.
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* Dependencies: The loop device must be enabled (CONFIG_DEV_LOOP=y)
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*/
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case LOOPIOC_SETUP:
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{
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FAR struct losetup_s *setup =
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(FAR struct losetup_s *)((uintptr_t)arg);
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if (setup == NULL)
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{
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ret = -EINVAL;
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}
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else
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{
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ret = losetup(setup->devname, setup->filename, setup->sectsize,
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setup->offset, setup->readonly);
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}
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}
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break;
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/* Command: LOOPIOC_TEARDOWN
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* Description: Teardown a loop device previously setup via
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LOOPIOC_SETUP
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* Argument: A read-able pointer to the path of the device to be
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* torn down
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* Dependencies: The loop device must be enabled (CONFIG_DEV_LOOP=y)
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*/
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case LOOPIOC_TEARDOWN:
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{
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FAR const char *devname = (FAR const char *)((uintptr_t)arg);
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if (devname == NULL)
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{
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ret = -EINVAL;
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}
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else
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{
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ret = loteardown(devname);
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}
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}
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break;
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default:
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ret = -ENOTTY;
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break;
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}
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return ret;
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: loop_register
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*
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* Description:
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* Register /dev/null
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*
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****************************************************************************/
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void loop_register(void)
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{
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register_driver("/dev/loop", &g_loop_fops, 0666, NULL);
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}
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#endif /* CONFIG_DEV_LOOP */
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