posix_fallocate

POSIX_FALLOCATE(3P)         POSIX Programmer's Manual        POSIX_FALLOCATE(3P)



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
       posix_fallocate — file space control (ADVANCED REALTIME)

SYNOPSIS
       #include <fcntl.h>

       int posix_fallocate(int fd, off_t offset, off_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 is less than zero, or the offset argument is less
              than zero, or the underlying file system does not support this
              operation.

       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 posix_fallocate() function may fail if:

       EINVAL The len argument is zero.

       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 POSIX.1‐2017, <fcntl.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                   POSIX_FALLOCATE(3P)