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This chapter describes the most common NSPR types, enumerations, and
structures used with the functions described in `I/O
Functions <I%2f%2fO_Functions>`__ and `Network
Addresses <Network_Addresses>`__. These include the types used for
system access, normal file I/O, and socket (network) I/O.
Types unique to a particular function are described with the function
itself.
For sample code that illustrates basic I/O operations, see `Introduction
to NSPR <Introduction_to_NSPR>`__.
- `Directory Type <#Directory_Type>`__
- `File Descriptor Types <#File_Descriptor_Types>`__
- `File Info Types <#File_Info_Types>`__
- `Network Address Types <#Network_Address_Types>`__
- `Types Used with Socket Options
Functions <#Types_Used_with_Socket_Options_Functions>`__
- `Type Used with Memory-Mapped
I/O <#Type_Used_with_Memory-Mapped_I/O>`__
- `Offset Interpretation for Seek
Functions <#Offset_Interpretation_for_Seek_Functions>`__
.. _Directory_Type:
Directory Type
--------------
- :ref:`PRDir`
.. _File_Descriptor_Types:
File Descriptor Types
---------------------
NSPR represents I/O objects, such as open files and sockets, by file
descriptors of type :ref:`PRFileDesc`. This section introduces
:ref:`PRFileDesc` and related types.
- :ref:`PRFileDesc`
- :ref:`PRIOMethods`
- :ref:`PRFilePrivate`
- :ref:`PRDescIdentity`
Note that the NSPR documentation follows the Unix convention of using
the term\ *files* to refer to many kinds of I/O objects. To refer
specifically to the files in a file system (that is, disk files), this
documentation uses the term\ *normal files*.
:ref:`PRFileDesc` has an object-oriented flavor. An I/O function on a
:ref:`PRFileDesc` structure is carried out by invoking the corresponding
"method" in the I/O methods table (a structure of type :ref:`PRIOMethods`)
of the :ref:`PRFileDesc` structure (the "object"). Different kinds of I/O
objects (such as files and sockets) have different I/O methods tables,
thus implementing different behavior in response to the same I/O
function call.
NSPR supports the implementation of layered I/O. Each layer is
represented by a :ref:`PRFileDesc` structure, and the :ref:`PRFileDesc`
structures for the layers are chained together. Each :ref:`PRFileDesc`
structure has a field (of type :ref:`PRDescIdentity`) to identify itself in
the layers. For example, the Netscape implementation of the Secure
Sockets Layer (SSL) protocol is implemented as an I/O layer on top of
NSPR's socket layer.
.. _File_Info_Types:
File Info Types
---------------
- :ref:`PRFileInfo`
- :ref:`PRFileInfo64`
- :ref:`PRFileType`
.. _Network_Address_Types:
Network Address Types
---------------------
- :ref:`PRNetAddr`
- :ref:`PRIPv6Addr`
.. _Types_Used_with_Socket_Options_Functions:
Types Used with Socket Options Functions
----------------------------------------
- :ref:`PRSocketOptionData`
- :ref:`PRSockOption`
- :ref:`PRLinger`
- :ref:`PRMcastRequest`
.. _Type_Used_with_Memory-Mapped_I.2FO:
Type Used with Memory-Mapped I/O
--------------------------------
- :ref:`PRFileMap`
.. _Offset_Interpretation_for_Seek_Functions:
Offset Interpretation for Seek Functions
----------------------------------------
- :ref:`PRSeekWhence`
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