POSIX_FADVISE(3C) Standard C Library Functions POSIX_FADVISE(3C)

NAME

posix_fadvise - file advisory information

SYNOPSIS

#include <fcntl.h>

int posix_fadvise(int fd, off_t offset, off_t len, int advice);

DESCRIPTION

The posix_fadvise() function advises the system on the expected behavior
of the application with respect to the data in the file associated with
the open file descriptor, fd, starting at offset and continuing for len
bytes. The specified range need not currently exist in the file. If len
is zero, all data following offset is specified. The system may use this
information to optimize handling of the specified data. The
posix_fadvise() function has no effect on the semantics of other
operations on the specified data, although it may affect the performance
of other operations.


The advice to be applied to the data is specified by the advice parameter
and may be one of the following values:

POSIX_FADV_NORMAL
Specifies that the application has no advice to
give on its behavior with respect to the
specified data. It is the default characteristic
if no advice is given for an open file.


POSIX_FADV_SEQUENTIAL
Specifies that the application expects to access
the specified data sequentially from lower
offsets to higher offsets.


POSIX_FADV_RANDOM
Specifies that the application expects to access
the specified data in a random order.


POSIX_FADV_WILLNEED
Specifies that the application expects to access
the specified data in the near future.


POSIX_FADV_DONTNEED
Specifies that the application expects that it
will not access the specified data in the near
future.


POSIX_FADV_NOREUSE
Specifies that the application expects to access
the specified data once and then not reuse it
thereafter.


These values are defined in <fcntl.h>

RETURN VALUES

Upon successful completion, posix_fadvise() returns zero. Otherwise, an
error number is returned to indicate the error.

ERRORS

The posix_fadvise() function will fail if:

EBADF
The fd argument is not a valid file descriptor.


EINVAL
The value of advice is invalid, or the value of len is less
than zero.


ESPIPE
The fd argument is associated with a pipe or FIFO.

USAGE

The posix_fadvise() function has a transitional interface for 64-bit file
offsets. See lf64(7).

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:


+--------------------+-------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-------------------+
|Interface Stability | Committed |
+--------------------+-------------------+
|MT-Level | MT-Safe |
+--------------------+-------------------+
|Standard | See standards(7). |
+--------------------+-------------------+

SEE ALSO

posix_madvise(3C), attributes(7), standards(7)


July 14, 2008 POSIX_FADVISE(3C)