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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.18.0/] [newlib/] [libc/] [stdio64/] [ftello64.c] - Blame information for rev 258

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1 207 jeremybenn
/*
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 * Copyright (c) 1990 The Regents of the University of California.
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms are permitted
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 * provided that the above copyright notice and this paragraph are
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 * duplicated in all such forms and that any documentation,
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 * advertising materials, and other materials related to such
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 * distribution and use acknowledge that the software was developed
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 * by the University of California, Berkeley.  The name of the
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 * University may not be used to endorse or promote products derived
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 * from this software without specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
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 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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 */
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/*
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FUNCTION
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<<ftello64>>---return position in a stream or file
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INDEX
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        ftello64
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INDEX
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        _ftello64_r
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ANSI_SYNOPSIS
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        #include <stdio.h>
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        _off64_t ftello64(FILE *<[fp]>);
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        _off64_t _ftello64_r(struct _reent *<[ptr]>, FILE *<[fp]>);
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TRAD_SYNOPSIS
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        #include <stdio.h>
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        _off64_t ftello64(<[fp]>)
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        FILE *<[fp]>;
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        _off64_t _ftello64_r(<[ptr]>, <[fp]>)
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        struct _reent *<[ptr]>;
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        FILE *<[fp]>;
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DESCRIPTION
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Objects of type <<FILE>> can have a ``position'' that records how much
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of the file your program has already read.  Many of the <<stdio>> functions
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depend on this position, and many change it as a side effect.
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The result of <<ftello64>> is the current position for a large file
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identified by <[fp]>.  If you record this result, you can later
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use it with <<fseeko64>> to return the file to this
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position.  The difference between <<ftello>> and <<ftello64>> is that
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<<ftello>> returns <<off_t>> and <<ftello64>> is designed to work
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for large files (>2GB) and returns <<_off64_t>>.
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In the current implementation, <<ftello64>> simply uses a character
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count to represent the file position; this is the same number that
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would be recorded by <<fgetpos64>>.
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The function exists only if the __LARGE64_FILES flag is defined.
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An error occurs if the <[fp]> was not opened via <<fopen64>>.
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RETURNS
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<<ftello64>> returns the file position, if possible.  If it cannot do
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this, it returns <<-1>>.  Failure occurs on streams that do not support
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positioning or not opened via <<fopen64>>; the global <<errno>> indicates
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this condition with the value <<ESPIPE>>.
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PORTABILITY
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<<ftello64>> is a glibc extension.
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No supporting OS subroutines are required.
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*/
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#if defined(LIBC_SCCS) && !defined(lint)
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static char sccsid[] = "%W% (Berkeley) %G%";
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#endif /* LIBC_SCCS and not lint */
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/*
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 * ftello64: return current offset.
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 */
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#include <stdio.h>
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#include <errno.h>
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#include "local.h"
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#ifdef __LARGE64_FILES
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_off64_t
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_DEFUN (_ftello64_r, (ptr, fp),
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        struct _reent *ptr _AND
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        register FILE * fp)
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{
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  _fpos64_t pos;
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  /* Only do 64-bit tell on large file.  */
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  if (!(fp->_flags & __SL64))
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    return (_off64_t) _ftello_r (ptr, fp);
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  /* Ensure stdio is set up.  */
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  CHECK_INIT (ptr, fp);
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  _flockfile(fp);
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  if (fp->_seek64 == NULL)
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    {
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      ptr->_errno = ESPIPE;
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      _funlockfile(fp);
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      return -1L;
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    }
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  /* Find offset of underlying I/O object, then adjust for buffered
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     bytes.  Flush a write stream, since the offset may be altered if
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     the stream is appending.  Do not flush a read stream, since we
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     must not lose the ungetc buffer.  */
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  if (fp->_flags & __SWR)
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    _fflush_r (ptr, fp);
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  if (fp->_flags & __SOFF)
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    pos = fp->_offset;
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  else
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    {
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      pos = fp->_seek64 (ptr, fp->_cookie, (_fpos64_t) 0, SEEK_CUR);
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      if (pos == -1L)
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        {
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          _funlockfile(fp);
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          return pos;
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        }
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    }
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  if (fp->_flags & __SRD)
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    {
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      /*
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       * Reading.  Any unread characters (including
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       * those from ungetc) cause the position to be
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       * smaller than that in the underlying object.
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       */
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      pos -= fp->_r;
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      if (HASUB (fp))
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        pos -= fp->_ur;
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    }
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  else if (fp->_flags & __SWR && fp->_p != NULL)
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    {
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      /*
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       * Writing.  Any buffered characters cause the
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       * position to be greater than that in the
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       * underlying object.
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       */
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      pos += fp->_p - fp->_bf._base;
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    }
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  _funlockfile(fp);
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  return pos;
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}
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#ifndef _REENT_ONLY
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_off64_t
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_DEFUN (ftello64, (fp),
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        register FILE * fp)
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{
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  return _ftello64_r (_REENT, fp);
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}
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#endif /* !_REENT_ONLY */
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#endif /* __LARGE64_FILES */

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