FSETPOS(3)                 POSIX Programmer's Manual                FSETPOS(3)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.

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.1-2017
       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.1-2017, <stdio.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  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.opengroup.org/unix/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 .



IEEE/The Open Group                  2017                           FSETPOS(3)
