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)