newlib/libc/stdio64/fsetpos64.c

   1 /*
   2 FUNCTION
   3 <<fsetpos64>>---restore position of a large stream or file
   4
   5 INDEX
   6         fsetpos64
   7 INDEX
   8         _fsetpos64_r
   9
  10 SYNOPSIS
  11         #include <stdio.h>
  12         int fsetpos64(FILE *<[fp]>, const _fpos64_t *<[pos]>);
  13         int _fsetpos64_r(struct _reent *<[ptr]>, FILE *<[fp]>,
  14                          const _fpos64_t *<[pos]>);
  15
  16 DESCRIPTION
  17 Objects of type <<FILE>> can have a ``position'' that records how much
  18 of the file your program has already read.  Many of the <<stdio>> functions
  19 depend on this position, and many change it as a side effect.
  20
  21 You can use <<fsetpos64>> to return the large file identified by <[fp]> to a
  22 previous position <<*<[pos]>>> (after first recording it with <<fgetpos64>>).
  23
  24 See <<fseeko64>> for a similar facility.
  25
  26 RETURNS
  27 <<fgetpos64>> returns <<0>> when successful.  If <<fgetpos64>> fails, the
  28 result is <<1>>.  The reason for failure is indicated in <<errno>>:
  29 either <<ESPIPE>> (the stream identified by <[fp]> doesn't support
  30 64-bit repositioning) or <<EINVAL>> (invalid file position).
  31
  32 PORTABILITY
  33 <<fsetpos64>> is a glibc extension.
  34
  35 Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
  36 <<lseek64>>, <<read>>, <<sbrk>>, <<write>>.
  37 */
  38
  39 #include <stdio.h>
  40
  41 #ifdef __LARGE64_FILES
  42
  43 int
  44 _fsetpos64_r (struct _reent *ptr,
  45         FILE * iop,
  46         const _fpos64_t * pos)
  47 {
  48   int x = _fseeko64_r (ptr, iop, (_off64_t)(*pos), SEEK_SET);
  49
  50   if (x != 0)
  51     return 1;
  52   return 0;
  53 }
  54
  55 #ifndef _REENT_ONLY
  56
  57 int
  58 fsetpos64 (FILE * iop,
  59         const _fpos64_t * pos)
  60 {
  61   return _fsetpos64_r (_REENT, iop, pos);
  62 }
  63
  64 #endif /* !_REENT_ONLY */
  65
  66 #endif /* __LARGE64_FILES */