posix_fallocate(3p) [centos man 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 correspond-
       ing 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, 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>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- 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 .

IEEE
/The Open Group						       2003						       POSIX_FALLOCATE(3P)

Check Out this Related Man Page

POSIX_FALLOCATE(2)					      BSD System Calls Manual						POSIX_FALLOCATE(2)

NAME

     posix_fallocate -- pre-allocate storage for a range in a file

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <fcntl.h>

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

DESCRIPTION

     Required storage for the range offset to offset + len in the file referenced by fd is guaranteed to be allocated upon successful return.
     That is, if posix_fallocate() returns successfully, subsequent writes to the specified file data will not fail due to lack of free space on
     the file system storage media.  Any existing file data in the specified range is unmodified.  If offset + len is beyond the current file
     size, then posix_fallocate() will adjust the file size to offset + len.  Otherwise, the file size will not be changed.

     Space allocated by posix_fallocate() will be freed by a successful call to creat(2) or open(2) that truncates the size of the file.  Space
     allocated via posix_fallocate() may be freed by a successful call to ftruncate(2) that reduces the file size to a size smaller than offset +
     len.

RETURN VALUES

     If successful, posix_fallocate() returns zero.  It returns an error on failure, without setting errno.

ERRORS

     Possible failure conditions:

     [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 less than or equal to 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.

SEE ALSO

     creat(2), ftruncate(2), open(2), unlink(2)

STANDARDS

     The posix_fallocate() system call conforms to IEEE Std 1003.1-2004 (``POSIX.1'').

HISTORY

     The posix_fallocate() function appeared in FreeBSD 9.0.

AUTHORS

     posix_fallocate() and this manual page were initially written by Matthew Fleming <mdf@FreeBSD.org>.

BSD
								 January 23, 2014							       BSD

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posix_fallocate(3p) [centos man page]

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