201 lines
6.7 KiB
C
201 lines
6.7 KiB
C
/****************************************************************************
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* fs/vfs/fs_truncate.c
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*
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* Copyright (C) 2018 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 <unistd.h>
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#include <fcntl.h>
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#include <errno.h>
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#include <assert.h>
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#include <nuttx/fs/fs.h>
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#include "inode/inode.h"
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#ifndef CONFIG_DISABLE_MOUNTPOINT
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: file_truncate
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*
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* Description:
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* Equivalent to the standard ftruncate() function except that is accepts
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* a struct file instance instead of a file descriptor and it does not set
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* the errno variable.
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*
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****************************************************************************/
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int file_truncate(FAR struct file *filep, off_t length)
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{
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struct inode *inode;
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/* Was this file opened for write access? */
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if ((filep->f_oflags & O_WROK) == 0)
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{
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fwarn("WARNING: Cannot truncate a file opened read-only\n");
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return -EBADF;
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}
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/* Is this inode a registered mountpoint? Does it support the
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* truncate operations may be relevant to device drivers but only
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* the mountpoint operations vtable contains a truncate method.
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*/
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inode = filep->f_inode;
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if (inode == NULL || !INODE_IS_MOUNTPT(inode) || inode->u.i_mops == NULL)
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{
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fwarn("WARNING: Not a (regular) file on a mounted file system.\n");
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return -EINVAL;
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}
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/* A NULL write() method is an indicator of a read-only file system (but
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* possible not the only indicator -- sufficient, but not necessary")
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*/
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if (inode->u.i_mops->write == NULL)
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{
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fwarn("WARNING: File system is read-only\n");
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return -EROFS;
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}
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/* Does the file system support the truncate method? It should if it is
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* a write-able file system.
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*/
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if (inode->u.i_mops->truncate == NULL)
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{
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fwarn("WARNING: File system does not support the truncate() method\n");
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return -ENOSYS;
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}
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/* Yes, then tell the file system to truncate this file */
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return inode->u.i_mops->truncate(filep, length);
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}
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/****************************************************************************
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* Name: ftruncate
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*
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* Description:
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* The ftruncate() function causes the regular file referenced by fd to
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* have a size of length bytes.
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*
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* If the file previously was larger than length, the extra data is
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* discarded. If it was previously shorter than length, it is unspecified
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* whether the file is changed or its size increased. If the file is
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* extended, the extended area appears as if it were zero-filled. If fd
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* references a shared memory object, ftruncate() sets the size of the
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* shared memory object to length. If the file is not a regular file or
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* a shared memory object, the result is unspecified.
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* With ftruncate(), the file must be open for writing; for truncate(),
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* the process must have write permission for the file.
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*
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* ftruncate() does not modify the file offset for any open file
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* descriptions associated with the file.
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*
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* Input Parameters:
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* fd - A reference to an open, regular file or shared memory object
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* to be truncated.
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* length - The new length of the file or shared memory object.
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*
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* Returned Value:
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* Upon successful completion, ftruncate() return 0s. Otherwise a -1 is
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* returned, and errno is set to indicate the error.
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*
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* EINTR
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* - A signal was caught during execution.
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* EINVAL
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* - The length argument was less than 0.
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* EFBIG or EINVAL
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* - The length argument was greater than the maximum file size.
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* EIO
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* - An I/O error occurred while reading from or writing to a file
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* system.
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* EBADF or EINVAL
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* - the fd argument is not a file descriptor open for writing.
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* EFBIG
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* - The file is a regular file and length is greater than the offset
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* maximum established in the open file description associated with
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* fd.
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* EINVAL
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* - The fd argument references a file that was opened without write
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* permission.
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* EROFS
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* - The named file resides on a read-only file system.
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*
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****************************************************************************/
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int ftruncate(int fd, off_t length)
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{
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FAR struct file *filep;
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int ret;
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/* Get the file structure corresponding to the file descriptor. */
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ret = fs_getfilep(fd, &filep);
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if (ret < 0)
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{
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ferr("ERROR: Could no get file structure: %d\n", ret);
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goto errout;
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}
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DEBUGASSERT(filep != NULL);
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/* Perform the truncate operation */
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ret = file_truncate(filep, length);
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if (ret >= 0)
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{
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return 0;
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}
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fwarn("WARNING: file_truncate() failed: %d\n", ret);
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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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#endif /* !CONFIG_DISABLE_MOUNTPOINT */
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