| /**************************************************************************** |
| * libs/libc/stdio/lib_ftello.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 <nuttx/config.h> |
| |
| #include <sys/types.h> |
| #include <stdio.h> |
| #include <unistd.h> |
| #include <fcntl.h> |
| #include <errno.h> |
| |
| #include "libc.h" |
| |
| /**************************************************************************** |
| * Private Functions |
| ****************************************************************************/ |
| |
| /**************************************************************************** |
| * Name: lib_getoffset |
| * |
| * Description: |
| * It is insufficient to simply use the file offset; we must also account |
| * for the data offset in the any buffered data. This function calculates |
| * that offset. |
| * |
| * Returned Value: |
| * The file position offset due to buffered data. |
| * |
| ****************************************************************************/ |
| |
| #ifndef CONFIG_STDIO_DISABLE_BUFFERING |
| static off_t lib_getoffset(FAR FILE *stream) |
| { |
| off_t offset = 0; |
| flockfile(stream); |
| |
| if (stream->fs_bufstart != |
| NULL && stream->fs_bufread != |
| stream->fs_bufstart) |
| { |
| #if CONFIG_NUNGET_CHARS > 0 |
| offset = stream->fs_bufread - stream->fs_bufpos + |
| stream->fs_nungotten; |
| #else |
| offset = stream->fs_bufread - stream->fs_bufpos; |
| #endif |
| } |
| else |
| { |
| offset = -(stream->fs_bufpos - stream->fs_bufstart); |
| } |
| |
| funlockfile(stream); |
| return offset; |
| } |
| #else |
| # define lib_getoffset(stream) (0) |
| #endif |
| |
| /**************************************************************************** |
| * Public Functions |
| ****************************************************************************/ |
| |
| /**************************************************************************** |
| * Name: ftello |
| * |
| * Description: |
| * ftello() returns the current value of the file position indicator for |
| * the stream pointed to by stream. |
| * |
| * Returned Value: |
| * Zero on success; -1 on failure with errno set appropriately. |
| * |
| ****************************************************************************/ |
| |
| off_t ftello(FAR FILE *stream) |
| { |
| off_t position; |
| off_t offset = 0; |
| |
| /* Verify that we were provided with a stream */ |
| |
| if (!stream) |
| { |
| set_errno(EBADF); |
| return ERROR; |
| } |
| |
| /* Perform the lseek to the current position. This will not move the |
| * file pointer, but will return its current setting |
| */ |
| |
| if (stream->fs_iofunc.seek != NULL) |
| { |
| position = stream->fs_iofunc.seek(stream->fs_cookie, &offset, |
| SEEK_CUR); |
| } |
| else |
| { |
| position = lseek((int)(intptr_t)stream->fs_cookie, 0, SEEK_CUR); |
| } |
| |
| if (position != (off_t)-1) |
| { |
| return position - lib_getoffset(stream); |
| } |
| else |
| { |
| return ERROR; |
| } |
| } |