NAME

fgetpos, fsetpos – reposition a file pointer in a stream

SYNOPSIS

#include <stdio.h>

int fgetpos(FILE *stream, fpos_t *pos);

int fsetpos(FILE *stream, const fpos_t *pos);

DESCRIPTION

The fgetpos() function stores the current values of the parse state (if any) and file position indicator for the stream pointed to by stream in the object pointed to by pos. The value stored contains unspecified information usable by fsetpos() for repositioning the stream to its position at the time of the call to fgetpos().

The fsetpos() function sets the file position and state indicators for the stream pointed to by stream according to the value of the object pointed to by pos, which the application shall ensure is a value obtained from an earlier call to fgetpos() on the same stream.

RETURN VALUES

The functions return 0 if it succeeds; otherwise, it shall return a non-zero value and set errno to indicate the error.

ERRORS

These functions are members of Unison’s STDIO implementation. The STDIO implementation rests on top of IOLIB and inherits IOLIB’s dependency on each specific server to report an appropriate error code for its usage.

For an exact list of error codes returned by a particular server, refer to that server’s documentation in the Unison Programmer’s Guide for each specific platform.

Servers may implement these errors codes in response to this function.

For fgetpos():

[EBADF]

The file descriptor underlying stream is not an open file descriptor.

For fsetpos():

[EAGAIN]

The O_NONBLOCK flag is set for the file descriptor and the thread would be delayed in the write operation.

[EBADF]

The file descriptor underlying the stream file is not open for writing or the stream’s buffer needed to be flushed and the file is not open.

[EFBIG]

An attempt was made to write a file that exceeds the maximum file size.

[EINVAL]

The whence argument is invalid. The resulting file-position indicator would be set to a negative value.

[EIO]

A physical I/O error has occurred, or the process is a member of a background process group attempting to perform a write() to its controlling terminal, TOSTOP is set, the process is neither ignoring nor blocking SIGTTOU, and the process group of the process is orphaned. This error may also be returned under implementation-defined conditions.

[ENOSPC]

There was no free space remaining on the device containing the file.

[ENXIO]

A request was made of a nonexistent device, or the request was outside the capabilities of the device.

SEE ALSO

lseek(), write(), fopen(), ungetc()