1POSIX_FALLOCATE(P)         POSIX Programmer's Manual        POSIX_FALLOCATE(P)
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NAME

6       posix_fallocate - file space control (ADVANCED REALTIME)
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SYNOPSIS

9       #include <fcntl.h>
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11       int posix_fallocate(int fd, off_t offset, size_t len);
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DESCRIPTION

15       The  posix_fallocate()  function shall ensure that any required storage
16       for regular file data starting at offset and continuing for  len  bytes
17       is  allocated  on  the  file system storage media. If posix_fallocate()
18       returns successfully, subsequent writes  to  the  specified  file  data
19       shall not fail due to the lack of free space on the file system storage
20       media.
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22       If the offset+ len is beyond the current file size,  then  posix_fallo‐
23       cate()  shall  adjust the file size to offset+ len. Otherwise, the file
24       size shall not be changed.
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26       It is implementation-defined whether a  previous  posix_fadvise()  call
27       influences allocation strategy.
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29       Space  allocated  via  posix_fallocate() shall be freed by a successful
30       call to creat() or open() that truncates the size of  the  file.  Space
31       allocated  via  posix_fallocate()  may be freed by a successful call to
32       ftruncate() that reduces the file size to a size smaller  than  offset+
33       len.
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RETURN VALUE

36       Upon successful completion, posix_fallocate() shall return zero; other‐
37       wise, an error number shall be returned to indicate the error.
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ERRORS

40       The posix_fallocate() function shall fail if:
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42       EBADF  The fd argument is not a valid file descriptor.
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44       EBADF  The fd argument references a file that was opened without  write
45              permission.
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47       EFBIG  The value of offset+ len is greater than the maximum file size.
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49       EINTR  A signal was caught during execution.
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51       EINVAL The  len  argument was zero or the offset argument was less than
52              zero.
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54       EIO    An I/O error occurred while reading from or writing  to  a  file
55              system.
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57       ENODEV The fd argument does not refer to a regular file.
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59       ENOSPC There  is  insufficient  free space remaining on the file system
60              storage media.
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62       ESPIPE The fd argument is associated with a pipe or FIFO.
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65       The following sections are informative.
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EXAMPLES

68       None.
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APPLICATION USAGE

71       The posix_fallocate() function is  part  of  the  Advisory  Information
72       option and need not be provided on all implementations.
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RATIONALE

75       None.
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FUTURE DIRECTIONS

78       None.
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SEE ALSO

81       creat() , ftruncate() , open() , unlink() , the Base Definitions volume
82       of IEEE Std 1003.1-2001, <fcntl.h>
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85       Portions of this text are reprinted and reproduced in  electronic  form
86       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
87       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
88       Specifications  Issue  6,  Copyright  (C) 2001-2003 by the Institute of
89       Electrical and Electronics Engineers, Inc and The Open  Group.  In  the
90       event of any discrepancy between this version and the original IEEE and
91       The Open Group Standard, the original IEEE and The Open Group  Standard
92       is  the  referee document. The original Standard can be obtained online
93       at http://www.opengroup.org/unix/online.html .
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97IEEE/The Open Group                  2003                   POSIX_FALLOCATE(P)
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