NAME
fgetpos(), fsetpos() — save and restore a file position indicator for a stream
SYNOPSIS
#include <stdio.h>
int fgetpos(FILE *__restrict stream, fpos_t *__restrict pos);
int fsetpos(FILE *stream, const fpos_t *pos);
DESCRIPTION
- fgetpos()
Store the current value of the file position indicator
for the stream pointed to by
stream
in the object pointed to by
pos.
The value stored contains information usable by
fsetpos()
for repositioning the stream to its position at the time of the call to
fgetpos().
- fsetpos()
Set the file position indicator for the stream pointed to by
stream
according to the value of the object pointed to by
pos,
which must be a value set by an earlier call to
fgetpos()
on the same stream.
A successful call to
fsetpos()
clears the end-of-file indicator for the stream and undoes any effects of
ungetc(3S)
on the same stream.
After a
fsetpos()
call, the next operation on a update stream can be either input or output.
RETURN VALUE
If successful, these functions return zero; otherwise non-zero.
ERRORS
If
fgetpos()
fails,
errno
is set to one of the following values.
- [EINVAL]
The current value of the file position cannot be represented correctly
in an object of size
fpos_t
in this environment.
Additional
errno
values may be set by the underlying
ftell()
function (see
fseek(3S)).
WARNINGS
Failure can occur if these functions are used
on a file that has not been opened via
fopen().
In particular, they must not be used on a terminal
or on a file opened via
popen(3S).
fsetpos()
has no effect on streams that are open for append (see
fopen(3S)).
STANDARDS CONFORMANCE
fgetpos(): AES, SVID3, XPG4, ANSI C
fsetpos(): AES, SVID3, XPG4, ANSI C
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