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/*
FUNCTION
<<fgetpos>>---record position in a stream or file
INDEX
fgetpos
ANSI_SYNOPSIS
#include <stdio.h>
int fgetpos(FILE *<[fp]>, fpos_t *<[pos]>);
TRAD_SYNOPSIS
#include <stdio.h>
int fgetpos(<[fp]>, <[pos]>)
FILE *<[fp]>;
fpos_t *<[pos]>;
DESCRIPTION
Objects of type <<FILE>> can have a ``position'' that records how much
of the file your program has already read. Many of the <<stdio>> functions
depend on this position, and many change it as a side effect.
You can use <<fgetpos>> to report on the current position for a file
identified by <[fp]>; <<fgetpos>> will write a value
representing that position at <<*<[pos]>>>. Later, you can
use this value with <<fsetpos>> to return the file to this
position.
In the current implementation, <<fgetpos>> simply uses a character
count to represent the file position; this is the same number that
would be returned by <<ftell>>.
RETURNS
<<fgetpos>> returns <<0>> when successful. If <<fgetpos>> fails, the
result is <<1>>. Failure occurs on streams that do not support
positioning; the global <<errno>> indicates this condition with the
value <<ESPIPE>>.
PORTABILITY
<<fgetpos>> is required by the ANSI C standard, but the meaning of the
value it records is not specified beyond requiring that it be
acceptable as an argument to <<fsetpos>>. In particular, other
conforming C implementations may return a different result from
<<ftell>> than what <<fgetpos>> writes at <<*<[pos]>>>.
No supporting OS subroutines are required.
*/
#include <stdio.h>
int
_DEFUN (fgetpos, (fp, pos),
FILE * fp _AND
fpos_t * pos)
{
_flockfile(fp);
*pos = ftell (fp);
if (*pos != -1)
{
_funlockfile(fp);
return 0;
}
_funlockfile(fp);
return 1;
}
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