toolchain/gcc/newlib/libc/stdio64/ftello64.c

   1 /*
   2  * Copyright (c) 1990 The Regents of the University of California.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms are permitted
   6  * provided that the above copyright notice and this paragraph are
   7  * duplicated in all such forms and that any documentation,
   8  * advertising materials, and other materials related to such
   9  * distribution and use acknowledge that the software was developed
  10  * by the University of California, Berkeley.  The name of the
  11  * University may not be used to endorse or promote products derived
  12  * from this software without specific prior written permission.
  13  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  14  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  15  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  16  */
  17
  18 /*
  19 FUNCTION
  20 <<ftello64>>---return position in a stream or file
  21
  22 INDEX
  23         ftello64
  24 INDEX
  25         _ftello64_r
  26
  27 ANSI_SYNOPSIS
  28         #include <stdio.h>
  29         _off64_t ftello64(FILE *<[fp]>);
  30         _off64_t _ftello64_r(struct _reent *<[ptr]>, FILE *<[fp]>);
  31
  32 TRAD_SYNOPSIS
  33         #include <stdio.h>
  34         _off64_t ftello64(<[fp]>)
  35         FILE *<[fp]>;
  36
  37         _off64_t _ftello64_r(<[ptr]>, <[fp]>)
  38         struct _reent *<[ptr]>;
  39         FILE *<[fp]>;
  40
  41 DESCRIPTION
  42 Objects of type <<FILE>> can have a ``position'' that records how much
  43 of the file your program has already read.  Many of the <<stdio>> functions
  44 depend on this position, and many change it as a side effect.
  45
  46 The result of <<ftello64>> is the current position for a large file
  47 identified by <[fp]>.  If you record this result, you can later
  48 use it with <<fseeko64>> to return the file to this
  49 position.  The difference between <<ftello>> and <<ftello64>> is that
  50 <<ftello>> returns <<off_t>> and <<ftello64>> is designed to work
  51 for large files (>2GB) and returns <<_off64_t>>.
  52
  53 In the current implementation, <<ftello64>> simply uses a character
  54 count to represent the file position; this is the same number that
  55 would be recorded by <<fgetpos64>>.
  56
  57 The function exists only if the __LARGE64_FILES flag is defined.
  58 An error occurs if the <[fp]> was not opened via <<fopen64>>.
  59
  60 RETURNS
  61 <<ftello64>> returns the file position, if possible.  If it cannot do
  62 this, it returns <<-1>>.  Failure occurs on streams that do not support
  63 positioning or not opened via <<fopen64>>; the global <<errno>> indicates
  64 this condition with the value <<ESPIPE>>.
  65
  66 PORTABILITY
  67 <<ftello64>> is a glibc extension.
  68
  69 No supporting OS subroutines are required.
  70 */
  71
  72 #if defined(LIBC_SCCS) && !defined(lint)
  73 static char sccsid[] = "%W% (Berkeley) %G%";
  74 #endif /* LIBC_SCCS and not lint */
  75
  76 /*
  77  * ftello64: return current offset.
  78  */
  79
  80 #include <stdio.h>
  81 #include <errno.h>
  82
  83 #include "local64.h"
  84
  85 #ifdef __LARGE64_FILES
  86
  87 _off64_t
  88 _DEFUN (_ftello64_r, (ptr, fp),
  89         struct _reent *ptr _AND
  90         register FILE * fp)
  91 {
  92   _fpos64_t pos;
  93
  94   _flockfile(fp);
  95
  96   /* Ensure stdio is set up.  */
  97
  98   CHECK_INIT (fp);
  99
 100   if (fp->_seek64 == NULL)
 101     {
 102       ptr->_errno = ESPIPE;
 103       _funlockfile(fp);
 104       return -1L;
 105     }
 106
 107   /* Find offset of underlying I/O object, then
 108      adjust for buffered bytes.  */
 109   fflush(fp);           /* may adjust seek offset on append stream */
 110   if (fp->_flags & __SOFF)
 111     pos = fp->_offset;
 112   else
 113     {
 114       pos = (*fp->_seek64) (fp->_cookie, (_fpos64_t) 0, SEEK_CUR);
 115       if (pos == -1L)
 116         {
 117           _funlockfile(fp);
 118           return pos;
 119         }
 120     }
 121   if (fp->_flags & __SRD)
 122     {
 123       /*
 124        * Reading.  Any unread characters (including
 125        * those from ungetc) cause the position to be
 126        * smaller than that in the underlying object.
 127        */
 128       pos -= fp->_r;
 129       if (HASUB (fp))
 130         pos -= fp->_ur;
 131     }
 132   else if (fp->_flags & __SWR && fp->_p != NULL)
 133     {
 134       /*
 135        * Writing.  Any buffered characters cause the
 136        * position to be greater than that in the
 137        * underlying object.
 138        */
 139       pos += fp->_p - fp->_bf._base;
 140     }
 141
 142   _funlockfile(fp);
 143   return pos;
 144 }
 145
 146 #ifndef _REENT_ONLY
 147
 148 _off64_t
 149 _DEFUN (ftello64, (fp),
 150         register FILE * fp)
 151 {
 152   return _ftello64_r (_REENT, fp);
 153 }
 154
 155 #endif /* !_REENT_ONLY */
 156
 157 #endif /* __LARGE64_FILES */