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PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface
may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface
may not be implemented on Linux.
NAME
fsetpos — set current file position
SYNOPSIS
#include <stdio.h> int fsetpos(FILE *stream, const fpos_t *pos);
DESCRIPTION
The functionality described on this reference page is aligned with the ISO C standard. Any conflict
between the requirements described here and the ISO C standard is unintentional. This volume of
POSIX.1‐2008 defers to the ISO C standard.
The fsetpos() function shall set 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. If a read or write error occurs, the
error indicator for the stream shall be set and fsetpos() fails.
A successful call to the fsetpos() function shall clear the end-of-file indicator for the stream and undo
any effects of ungetc() on the same stream. After an fsetpos() call, the next operation on an update
stream may be either input or output.
The behavior of fsetpos() on devices which are incapable of seeking is implementation-defined. The value
of the file offset associated with such a device is undefined.
The fsetpos() function shall not change the setting of errno if successful.
RETURN VALUE
The fsetpos() function shall return 0 if it succeeds; otherwise, it shall return a non-zero value and set
errno to indicate the error.
ERRORS
The fsetpos() function shall fail if, either the stream is unbuffered or the stream's buffer needed to be
flushed, and the call to fsetpos() causes an underlying lseek() or write() to be invoked, and:
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.
EFBIG An attempt was made to write a file that exceeds the file size limit of the process.
EFBIG The file is a regular file and an attempt was made to write at or beyond the offset maximum
associated with the corresponding stream.
EINTR The write operation was terminated due to the receipt of a signal, and no data was transferred.
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 calling thread is
not blocking SIGTTOU, the process is not ignoring 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.
EPIPE An attempt was made to write to a pipe or FIFO that is not open for reading by any process; a
SIGPIPE signal shall also be sent to the thread.
ESPIPE The file descriptor underlying stream is associated with a pipe, FIFO, or socket.
The fsetpos() function may fail if:
ENXIO A request was made of a nonexistent device, or the request was outside the capabilities of the
device.
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
None.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
Section 2.5, Standard I/O Streams, fopen(), ftell(), lseek(), rewind(), ungetc(), write()
The Base Definitions volume of POSIX.1‐2008, <stdio.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition,
Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers, Inc
and The Open Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the event
of any discrepancy between this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at
http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are most likely to have been introduced
during the conversion of the source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .