398 lines
11 KiB
C
398 lines
11 KiB
C
/****************************************************************************
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* fs/vfs/fs_stat.c
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*
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* Copyright (C) 2007-2009, 2012, 2017 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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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/stat.h>
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#include <stdbool.h>
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#include <string.h>
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#include <sched.h>
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#include <errno.h>
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#include "inode/inode.h"
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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#ifdef CONFIG_PSEUDOFS_SOFTLINKS
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/* Reset, preserving the number of symbolic links encountered so far */
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# define RESET_BUF(b) \
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{ \
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uint16_t save = (b)->st_count; \
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memset((b), 0, sizeof(struct stat)); \
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(b)->st_count = save; \
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}
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#else
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/* Reset everything */
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# define RESET_BUF(b) memset((b), 0, sizeof(struct stat));
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#endif
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/****************************************************************************
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* Private Function Prototypes
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****************************************************************************/
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static inline int statroot(FAR struct stat *buf);
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int stat_recursive(FAR const char *path, FAR struct stat *buf);
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: statroot
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****************************************************************************/
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static inline int statroot(FAR struct stat *buf)
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{
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/* There is no inode associated with the fake root directory */
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RESET_BUF(buf);
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buf->st_mode = S_IFDIR | S_IROTH | S_IRGRP | S_IRUSR;
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return OK;
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}
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/****************************************************************************
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* Name: stat_recursive
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*
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* Returned Value:
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* Zero on success; -1 on failure with errno set:
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*
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* EACCES Search permission is denied for one of the directories in the
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* path prefix of path.
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* EFAULT Bad address.
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* ENOENT A component of the path path does not exist, or the path is an
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* empty string.
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* ENOMEM Out of memory
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* ENOTDIR A component of the path is not a directory.
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*
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****************************************************************************/
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int stat_recursive(FAR const char *path, FAR struct stat *buf)
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{
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struct inode_search_s desc;
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FAR struct inode *inode;
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int ret;
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/* Get an inode for this path */
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SETUP_SEARCH(&desc, path, true);
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ret = inode_find(&desc);
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if (ret < 0)
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{
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/* This name does not refer to an inode in the pseudo file system and
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* there is no mountpoint that includes in this path.
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*/
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ret = -ret;
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goto errout_with_search;
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}
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/* Get the search results */
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inode = desc.node;
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DEBUGASSERT(inode != NULL);
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/* The way we handle the stat depends on the type of inode that we
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* are dealing with.
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*/
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#ifndef CONFIG_DISABLE_MOUNTPOINT
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if (INODE_IS_MOUNTPT(inode))
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{
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/* The node is a file system mointpoint. Verify that the mountpoint
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* supports the stat() method
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*/
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if (inode->u.i_mops && inode->u.i_mops->stat)
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{
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/* Perform the stat() operation */
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ret = inode->u.i_mops->stat(inode, desc.relpath, buf);
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}
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}
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else
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#endif
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{
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/* The node is part of the root pseudo file system. This path may
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* recurse if soft links are supported in the pseudo file system.
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*/
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ret = inode_stat(inode, buf);
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}
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/* Check if the stat operation was successful */
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if (ret < 0)
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{
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ret = -ret;
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goto errout_with_inode;
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}
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/* Successfully stat'ed the file */
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inode_release(inode);
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RELEASE_SEARCH(&desc);
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return OK;
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/* Failure conditions always set the errno appropriately */
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errout_with_inode:
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inode_release(inode);
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errout_with_search:
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RELEASE_SEARCH(&desc);
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set_errno(ret);
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return ERROR;
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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: stat
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*
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* Returned Value:
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* Zero on success; -1 on failure with errno set:
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*
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* EACCES Search permission is denied for one of the directories in the
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* path prefix of path.
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* EFAULT Bad address.
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* ENOENT A component of the path path does not exist, or the path is an
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* empty string.
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* ENOMEM Out of memory
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* ENOTDIR A component of the path is not a directory.
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*
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****************************************************************************/
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int stat(FAR const char *path, FAR struct stat *buf)
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{
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int ret;
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/* Sanity checks */
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if (path == NULL || buf == NULL)
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{
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ret = EFAULT;
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goto errout;
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}
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if (*path == '\0')
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{
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ret = ENOENT;
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goto errout;
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}
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/* Check for the fake root directory (which has no inode) */
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if (strcmp(path, "/") == 0)
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{
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return statroot(buf);
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}
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/* The perform the stat() operation on the path. This is potentially
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* recursive if soft link support is enabled.
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*/
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#ifdef CONFIG_PSEUDOFS_SOFTLINKS
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buf->st_count = 0;
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#endif
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return stat_recursive(path, buf);
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errout:
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set_errno(ret);
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return ERROR;
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}
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/****************************************************************************
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* Name: inode_stat
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*
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* Description:
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* The inode_stat() function will obtain information about an 'inode' in
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* the pseudo file system and will write it to the area pointed to by 'buf'.
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*
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* The 'buf' argument is a pointer to a stat structure, as defined in
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* <sys/stat.h>, into which information is placed concerning the file.
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*
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* Input Parameters:
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* inode - The indoe of interest
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* buf - The caller provide location in which to return information about
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* the inode.
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*
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* Returned Value:
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* Zero (OK) returned on success. Otherwise, a negated errno value is
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* returned to indicate the nature of the failure.
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*
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****************************************************************************/
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int inode_stat(FAR struct inode *inode, FAR struct stat *buf)
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{
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DEBUGASSERT(inode != NULL && buf != NULL);
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/* Most of the stat entries just do not apply */
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RESET_BUF(buf);
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if (INODE_IS_SPECIAL(inode))
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{
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#if defined(CONFIG_FS_NAMED_SEMAPHORES)
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if (INODE_IS_NAMEDSEM(inode))
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{
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buf->st_mode = S_IFSEM;
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}
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else
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#endif
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#if !defined(CONFIG_DISABLE_MQUEUE)
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if (INODE_IS_MQUEUE(inode))
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{
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buf->st_mode = S_IFMQ;
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}
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else
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#endif
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#if defined(CONFIG_FS_SHM)
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if (INODE_IS_SHM(inode))
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{
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buf->st_mode = S_IFSHM;
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}
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else
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#endif
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#ifdef CONFIG_PSEUDOFS_SOFTLINKS
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/* Handle softlinks differently. Just call stat() recursively on the
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* target of the softlink.
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*
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* REVISIT: This has the possibility of an infinite loop!
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*/
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if (INODE_IS_SOFTLINK(inode))
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{
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int ret;
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/* Increment the link counter. This is necesssary to avoid
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* infinite recursion if loops are encountered in the traversal.
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* If we encounter more SYMLOOP_MAX symbolic links at any time
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* during the travrsal, error out.
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*
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* NOTE: That inode_search() will automatically skip over
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* consecutive, intermediate symbolic links. Those numbers will
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* not be included in the total.
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*/
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if (++buf->st_count > SYMLOOP_MAX)
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{
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return -ELOOP;
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}
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DEBUGASSERT(buf->st_count > 0); /* Check for unsigned integer overflow */
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/* stat() the target of the soft link. */
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ret = stat_recursive((FAR const char *)inode->u.i_link, buf);
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/* If stat() fails, then there is a problem with the target of the
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* symbolic link, but not with the symbolic link itself. We should
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* still report success, just with less information.
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*/
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if (ret < 0)
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{
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RESET_BUF(buf);
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}
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/* Make sure that the caller knows that this really a symbolic link. */
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buf->st_mode |= S_IFLNK;
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}
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else
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#endif
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{
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}
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}
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else if (inode->u.i_ops != NULL)
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{
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/* Determine read/write privileges based on the existence of read
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* and write methods.
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*/
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if (inode->u.i_ops->read)
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{
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buf->st_mode = S_IROTH | S_IRGRP | S_IRUSR;
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}
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if (inode->u.i_ops->write)
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{
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buf->st_mode |= S_IWOTH | S_IWGRP | S_IWUSR;
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}
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/* Determine the type of the inode */
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if (INODE_IS_MOUNTPT(inode))
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{
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buf->st_mode |= S_IFDIR;
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}
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else if (INODE_IS_BLOCK(inode))
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{
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/* What is if also has child inodes? */
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buf->st_mode |= S_IFBLK;
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}
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else /* if (INODE_IS_DRIVER(inode)) */
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{
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/* What is it if it also has child inodes? */
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buf->st_mode |= S_IFCHR;
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}
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}
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else
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{
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/* If it has no operations, then it must just be a intermediate
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* node in the inode tree. It is something like a directory.
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* We'll say that all pseudo-directories are read-able but not
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* write-able.
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*/
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buf->st_mode |= S_IFDIR | S_IROTH | S_IRGRP | S_IRUSR;
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}
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return OK;
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}
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