/**************************************************************************** * libs/libc/misc/lib_sendfile.c * * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. The * ASF licenses this file to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance with the * License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the * License for the specific language governing permissions and limitations * under the License. * ****************************************************************************/ /**************************************************************************** * Included Files ****************************************************************************/ #include #include #include #include #include #include #include #include "libc.h" /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: sendfile / lib_sendfile * * Description: * sendfile() copies data between one file descriptor and another. * sendfile() basically just wraps a sequence of reads() and writes() * to perform a copy. It serves a purpose in systems where there is * a penalty for copies to between user and kernal space, but really * nothing in NuttX but provide some Linux compatible (and adding * another 'almost standard' interface). * * 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 * ****************************************************************************/ #ifdef CONFIG_NET_SENDFILE ssize_t lib_sendfile(int outfd, int infd, off_t *offset, size_t count) #else ssize_t sendfile(int outfd, int infd, off_t *offset, size_t count) #endif { FAR uint8_t *iobuffer; FAR 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) { off_t newpos; /* Use lseek to get the current file position */ startpos = _NX_SEEK(infd, 0, SEEK_CUR); if (startpos < 0) { int errcode = _NX_GETERRNO(startpos); _NX_SETERRNO(errcode); return ERROR; } /* Use lseek again to set the new file position */ newpos = _NX_SEEK(infd, *offset, SEEK_SET); if (newpos < 0) { int errcode = _NX_GETERRNO(newpos); _NX_SETERRNO(errcode); return ERROR; } } /* Allocate an I/O buffer */ iobuffer = (FAR void *)lib_malloc(CONFIG_LIB_SENDFILE_BUFSIZE); if (!iobuffer) { set_errno(ENOMEM); return 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 = _NX_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 = _NX_GETERRNO(nbytesread); /* 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. */ _NX_SETERRNO(nbytesread); ntransferred = 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 = _NX_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 = _NX_GETERRNO(nbyteswritten); /* 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. */ _NX_SETERRNO(nbyteswritten); ntransferred = ERROR; endxfr = true; break; } } } while (nbytesread > 0); } } /* Release the I/O buffer */ lib_free(iobuffer); /* Return the current file position */ if (offset) { /* Use lseek to get the current file position */ off_t curpos = _NX_SEEK(infd, 0, SEEK_CUR); if (curpos < 0) { int errcode = _NX_GETERRNO(curpos); _NX_SETERRNO(errcode); return ERROR; } /* Return the current file position */ *offset = curpos; /* Use lseek again to restore the original file position */ startpos = _NX_SEEK(infd, startpos, SEEK_SET); if (startpos < 0) { int errcode = _NX_GETERRNO(startpos); _NX_SETERRNO(errcode); return ERROR; } } /* Finally return the number of bytes actually transferred (or ERROR * if any failure occurred). */ return ntransferred; }