posix_fallocate(3p) — Linux manual page

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(3p), ftruncate(3p), open(3p), unlink(3p)

       The Base Definitions volume of POSIX.1‐2017, fcntl.h(0p)

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)

Pages that refer to this page: fcntl.h(0p)

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