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POSIX_FALLOCATE(2)	  FreeBSD 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 refer-
     enced by fd is guarateed 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	allo-
     cated 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	-1 on failure,
     and sets errno to indicate	the error.

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 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>.

FreeBSD	10.1			April 13, 2011			  FreeBSD 10.1

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | STANDARDS | HISTORY | AUTHORS

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