trusty (3) posix_fallocate.3posix.gz

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NAME
       posix_fallocate - file space control (ADVANCED REALTIME)


SYNOPSIS
       #include <fcntl.h>

       int posix_fallocate(int fd, off_t offset, size_t len);


DESCRIPTION
       The  posix_fallocate()  function shall ensure that any required storage for regular file data starting at
       offset and continuing for len bytes is allocated on the file system storage media.  If  posix_fallocate()
       returns successfully, subsequent writes to the specified file data shall not fail due to the lack of free
       space on the file system storage media.

       If the offset+ len is beyond the current file size, then posix_fallocate() shall adjust the file size  to
       offset+ len. Otherwise, the file size shall not be changed.

       It is implementation-defined whether a previous posix_fadvise() call influences allocation strategy.

       Space  allocated  via  posix_fallocate()  shall  be  freed by a successful call to creat() or open() that
       truncates the size of the file. Space allocated via posix_fallocate() may be freed by a  successful  call
       to ftruncate() that reduces the file size to a size smaller than offset+ len.


RETURN VALUE
       Upon  successful  completion,  posix_fallocate()  shall  return zero; otherwise, an error number shall be
       returned to indicate the error.


ERRORS
       The posix_fallocate() function shall fail if:

       EBADF  The fd argument is not a valid file descriptor.

       EBADF  The fd argument references a file that was opened without write permission.

       EFBIG  The value of offset+ len is greater than the maximum file size.

       EINTR  A signal was caught during execution.

       EINVAL The len argument was zero or the offset argument was less than zero.

       EIO    An I/O error occurred while reading from or writing to a file system.

       ENODEV The fd argument does not refer to a regular file.

       ENOSPC There is insufficient free space remaining on the file system storage media.

       ESPIPE The fd argument is associated with a pipe or FIFO.

       The following sections are informative.


EXAMPLES
       None.


APPLICATION USAGE
       The posix_fallocate() function is part of the Advisory Information option and need not be provided on all
       implementations.


RATIONALE
       None.


FUTURE DIRECTIONS
       None.


SEE ALSO
       creat()  ,  ftruncate()  ,  open()  ,  unlink()  ,  the  Base Definitions volume of IEEE Std 1003.1-2001,
       <fcntl.h>


       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition,
       Standard  for  Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 6, Copyright (C) 2001-2003 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 .