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, the offset argument was less than
                          zero, or the operation is not supported by the file system.

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

       [EINTEGRITY]       Corrupted data was detected while reading from the 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.

       [ENOTCAPABLE]      The file descriptor fd has insufficient rights.

       [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>.

Debian                                           March 30, 2020                               POSIX_FALLOCATE(2)