/**************************************************************************** * fs/vfs/fs_sendfile.c * * Copyright (C) 2007, 2009, 2011, 2013, 2017-2018 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 "vfs_config.h" #include #include #include #include #include #ifndef CONFIG_LIB_SENDFILE_BUFSIZE # define CONFIG_LIB_SENDFILE_BUFSIZE 512 #endif /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: sendfile * * Description: * sendfile() copies data between one file descriptor and another. * Used with file descriptors it basically just wraps a sequence of * reads() and writes() to perform a copy. * * If the destination descriptor is a socket, it gives a better * performance than simple reds() and writes(). The data is read directly * into the net buffer and the whole tcp window is filled if possible. * * NOTE: This interface is *not* specified in POSIX.1-2001, or other * standards. The implementation here is very similar to the Linux * sendfile interface. Other UNIX systems implement sendfile() with * different semantics and prototypes. sendfile() should not be used * in portable programs. * * Input Parameters: * infd - A file (or socket) descriptor opened for reading * outfd - A descriptor opened for writing. * offset - If 'offset' is not NULL, then it points to a variable * holding the file offset from which sendfile() will start * reading data from 'infd'. When sendfile() returns, this * variable will be set to the offset of the byte following * the last byte that was read. If 'offset' is not NULL, * then sendfile() does not modify the current file offset of * 'infd'; otherwise the current file offset is adjusted to * reflect the number of bytes read from 'infd.' * * If 'offset' is NULL, then data will be read from 'infd' * starting at the current file offset, and the file offset * will be updated by the call. * count - The number of bytes to copy between the file descriptors. * * Returned Value: * If the transfer was successful, the number of bytes written to outfd is * returned. On error, -1 is returned, and errno is set appropriately. * There error values are those returned by read() or write() plus: * * EINVAL - Bad input parameters. * ENOMEM - Could not allocated an I/O buffer * ****************************************************************************/ ssize_t sendfile(int outfd, int infd, off_t *offset, size_t count) { uint8_t *iobuffer; uint8_t *wrbuffer; off_t startpos = 0; ssize_t nbytesread; ssize_t nbyteswritten; size_t ntransferred; bool endxfr; /* Get the current file position. */ if (offset) { /* Use lseek to get the current file position */ startpos = lseek(infd, 0, SEEK_CUR); if (startpos == (off_t)-1) { return VFS_ERROR; } /* Use lseek again to set the new file position */ if (lseek(infd, *offset, SEEK_SET) == (off_t)-1) { return VFS_ERROR; } } /* Allocate an I/O buffer */ iobuffer = (void *)malloc(CONFIG_LIB_SENDFILE_BUFSIZE); if (!iobuffer) { set_errno(ENOMEM); return VFS_ERROR; } /* Now transfer 'count' bytes from the infd to the outfd */ for (ntransferred = 0, endxfr = false; ntransferred < count && !endxfr; ) { /* Loop until the read side of the transfer comes to some conclusion */ do { /* Read a buffer of data from the infd */ nbytesread = read(infd, iobuffer, CONFIG_LIB_SENDFILE_BUFSIZE); /* Check for end of file */ if (nbytesread == 0) { /* End of file. Break out and return current number of bytes * transferred. */ endxfr = true; break; } /* Check for a read ERROR. EINTR is a special case. This function * should break out and return an error if EINTR is returned and * no data has been transferred. But what should it do if some * data has been transferred? I suppose just continue? */ else if (nbytesread < 0) { int errcode = get_errno(); /* EINTR is not an error (but will still stop the copy) */ if (errcode != EINTR || ntransferred == 0) { /* Read error. Break out and return the error condition. */ set_errno(errcode); ntransferred = VFS_ERROR; endxfr = true; break; } } } while (nbytesread < 0); /* Was anything read? */ if (!endxfr) { /* Yes.. Loop until the read side of the transfer comes to some * conclusion. */ wrbuffer = iobuffer; do { /* Write the buffer of data to the outfd */ nbyteswritten = write(outfd, wrbuffer, nbytesread); /* Check for a complete (or parial) write. write() should not * return zero. */ if (nbyteswritten >= 0) { /* Advance the buffer pointer and decrement the number of bytes * remaining in the iobuffer. Typically, nbytesread will now * be zero. */ wrbuffer += nbyteswritten; nbytesread -= nbyteswritten; /* Increment the total number of bytes successfully transferred. */ ntransferred += nbyteswritten; } /* Otherwise an error occurred */ else { int errcode = get_errno(); /* Check for a read ERROR. EINTR is a special case. This * function should break out and return an error if EINTR * is returned and no data has been transferred. But what * should it do if some data has been transferred? I * suppose just continue? */ if (errcode != EINTR || ntransferred == 0) { /* Write error. Break out and return the error * condition. */ set_errno(errcode); ntransferred = VFS_ERROR; endxfr = true; break; } } } while (nbytesread > 0); } } /* Release the I/O buffer */ free(iobuffer); /* Return the current file position */ if (offset) { /* Use lseek to get the current file position */ off_t curpos = lseek(infd, 0, SEEK_CUR); if (curpos == (off_t)-1) { return VFS_ERROR; } /* Return the current file position */ *offset = curpos; /* Use lseek again to restore the original file position */ if (lseek(infd, startpos, SEEK_SET) == (off_t)-1) { return VFS_ERROR; } } /* Finally return the number of bytes actually transferred (or VFS_ERROR * if any failure occurred). */ return ntransferred; }