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138 lines
5.3 KiB
138 lines
5.3 KiB
/**************************************************************************** |
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* libc/stdio/lib_fseek.c |
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* |
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* Copyright (C) 2007, 2008, 2011 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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* Compilation Switches |
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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 <sys/types.h> |
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#include <stdio.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 "lib_internal.h" |
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/**************************************************************************** |
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* Definitions |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Type Declarations |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Function Prototypes |
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****************************************************************************/ |
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/**************************************************************************** |
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* Global Constant Data |
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****************************************************************************/ |
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/**************************************************************************** |
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* Global Variables |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Constant Data |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Variables |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Functions |
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****************************************************************************/ |
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/**************************************************************************** |
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* Public Functions |
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****************************************************************************/ |
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/**************************************************************************** |
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* Name: fseek |
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* |
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* Description: |
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* The fseek() function sets the file position indicator for the stream |
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* pointed to by stream. The new position, measured in bytes, is obtained |
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* by adding offset bytes to the position specified by whence. If whence is |
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* set to SEEK_SET, SEEK_CUR, or SEEK_END, the offset is relative to the |
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* start of the file, the current position indicator, or end-of-file, |
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* respectively. A successful call to the fseek() function clears the |
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* end-of-file indicator for the stream and undoes any effects of the ungetc(3) |
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* function on the same stream. |
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* |
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* Returned Value: |
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* Zero on succes; -1 on failure with errno set appropriately. |
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* |
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****************************************************************************/ |
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int fseek(FAR FILE *stream, long int offset, int whence) |
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{ |
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#if CONFIG_STDIO_BUFFER_SIZE > 0 |
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/* Flush any valid read/write data in the buffer (also verifies stream) */ |
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if (lib_rdflush(stream) < 0 || lib_wrflush(stream) < 0) |
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{ |
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return ERROR; |
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} |
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#else |
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/* Verify that we were provided with a stream */ |
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if (!stream) |
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{ |
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set_errno(EBADF); |
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return ERROR; |
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} |
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#endif |
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/* On success or failure, discard any characters saved by ungetc() */ |
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#if CONFIG_NUNGET_CHARS > 0 |
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stream->fs_nungotten = 0; |
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#endif |
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/* Perform the fseek on the underlying file descriptor */ |
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return lseek(stream->fs_filedes, offset, whence) == (off_t)-1 ? ERROR : OK; |
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} |
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