/**************************************************************************** * fs/vfs/fs_write.c * * Copyright (C) 2007-2009, 2012-2014, 2016-2017 Gregory Nutt. All rights * reserved. * Author: Gregory Nutt * * 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 #include #include #include #include #include #include #ifdef CONFIG_NET_TCP # include #endif #include #include #include "inode/inode.h" /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: file_write * * Description: * Equivalent to the standard write() function except that is accepts a * struct file instance instead of a file descriptor. It is functionally * equivalent to write() except that in addition to the differences in * input paramters: * * - It does not modify the errno variable, * - It is not a cancellation point, and * - It does not handle socket descriptors. * * Input Parameters: * filep - Instance of struct file to use with the write * buf - Data to write * nbytes - Length of data to write * * Returned Value: * On success, the number of bytes written are returned (zero indicates * nothing was written). On any failure, a negated errno value is returned * (see comments withwrite() for a description of the appropriate errno * values). * ****************************************************************************/ ssize_t file_write(FAR struct file *filep, FAR const void *buf, size_t nbytes) { FAR struct inode *inode; /* Was this file opened for write access? */ if ((filep->f_oflags & O_WROK) == 0) { return -EBADF; } /* Is a driver registered? Does it support the write method? */ inode = filep->f_inode; if (!inode || !inode->u.i_ops || !inode->u.i_ops->write) { return -EBADF; } /* Yes, then let the driver perform the write */ return inode->u.i_ops->write(filep, buf, nbytes); } /**************************************************************************** * Name: nx_write * * Description: * nx_write() writes up to nytes bytes to the file referenced by the file * descriptor fd from the buffer starting at buf. nx_write() is an * internal OS function. It is functionally equivalent to write() except * that: * * - It does not modify the errno variable, and * - It is not a cancellation point. * * Input Parameters: * fd - file descriptor (or socket descriptor) to write to * buf - Data to write * nbytes - Length of data to write * * Returned Value: * On success, the number of bytes written are returned (zero indicates * nothing was written). On any failure, a negated errno value is returned * (see comments withwrite() for a description of the appropriate errno * values). * ****************************************************************************/ ssize_t nx_write(int fd, FAR const void *buf, size_t nbytes) { FAR struct file *filep; ssize_t ret; if (buf == NULL) { return -EINVAL; } /* Did we get a valid file descriptor? */ if ((unsigned int)fd >= CONFIG_NFILE_DESCRIPTORS) { #ifdef CONFIG_NET_TCP /* Write to a socket descriptor is equivalent to send with flags == 0. */ ret = nx_send(fd, buf, nbytes, 0); #else ret = -EBADF; #endif } else { /* The descriptor is in the right range to be a file descriptor.. * write to the file. Note that fs_getfilep() will set the errno on * failure. */ ret = (ssize_t)fs_getfilep(fd, &filep); if (ret >= 0) { /* Perform the write operation using the file descriptor as an * index. Note that file_write() will set the errno on failure. */ ret = file_write(filep, buf, nbytes); } } return ret; } /**************************************************************************** * Name: write * * Description: * write() writes up to nytes bytes to the file referenced by the file * descriptor fd from the buffer starting at buf. * * Input Parameters: * fd - file descriptor (or socket descriptor) to write to * buf - Data to write * nbytes - Length of data to write * * Returned Value: * On success, the number of bytes written are returned (zero indicates * nothing was written). On error, -1 is returned, and errno is set appro- * priately: * * EAGAIN * Non-blocking I/O has been selected using O_NONBLOCK and the write * would block. * EBADF * fd is not a valid file descriptor or is not open for writing. * EFAULT * buf is outside your accessible address space. * EFBIG * An attempt was made to write a file that exceeds the implementation * defined maximum file size or the process' file size limit, or * to write at a position past the maximum allowed offset. * EINTR * The call was interrupted by a signal before any data was written. * EINVAL * fd is attached to an object which is unsuitable for writing; or * the file was opened with the O_DIRECT flag, and either the address * specified in buf, the value specified in count, or the current * file offset is not suitably aligned. * EIO * A low-level I/O error occurred while modifying the inode. * ENOSPC * The device containing the file referred to by fd has no room for * the data. * EPIPE * fd is connected to a pipe or socket whose reading end is closed. * When this happens the writing process will also receive a SIGPIPE * signal. (Thus, the write return value is seen only if the program * catches, blocks or ignores this signal.) * ****************************************************************************/ ssize_t write(int fd, FAR const void *buf, size_t nbytes) { ssize_t ret; /* write() is a cancellation point */ enter_cancellation_point(); /* Let nx_write() do all of the work */ ret = nx_write(fd, buf, nbytes); if (ret < 0) { set_errno(-ret); ret = ERROR; } leave_cancellation_point(); return ret; }