--- General Information.
module "nixio.README"

--- General error handling information.
-- <ul>
-- <li> Most of the functions available in this library may fail. If any error
-- occurs the function returns <strong>nil or false</strong>, an error code
-- (usually errno) and an additional error message text (if avaialable).</li>
-- <li>At the moment false is only returned when a non-blocking I/O function
-- fails with EAGAIN, EWOULDBLOCK or WSAEWOULDBLOCK for any others nil is
-- returned as first parameter. Therefore you can use false to write portable
-- non-blocking I/O applications.</li>
-- <li>Note that the function documentation does only mention the return values
-- in case of a successful operation.</li> 
-- <li>You can find a table of common error numbers and other useful constants
-- like signal numbers in <strong>nixio.const</strong> e.g. nixio.const.EINVAL,
-- nixio.const.SIGTERM, etc. For portability there is a second error constant
-- table <strong>nixio.const_sock</strong> for socket error codes. This might
-- be important if you are dealing with Windows applications, on POSIX however
-- const_sock is just an alias for const.</li>
-- <li>With some exceptions - which are explicitely stated in the function
-- documentation - all blocking functions are signal-protected and will not fail
-- with EINTR.</li>
-- <li>On POSIX the SIGPIPE signal will be set to ignore upon initialization.
-- You should restore the default behaviour or set a custom signal handler
-- in your program after loading nixio if you need this behaviour.</li>
-- </ul>
-- @class table
-- @name Errorhandling
-- @return !

--- Function conventions.
-- <br />In general all functions are namend and behave like their POSIX API
-- counterparts - where applicable - applying the following rules:
-- <ul>
-- <li>Functions should be named like the underlying POSIX API function omitting
-- prefixes or suffixes - especially when placed in an object-context (
-- lockf -> File:lock, fsync -> File:sync, dup2 -> dup, ...)</li>
-- <li>If you are unclear about the behaviour of a function you should consult
-- your OS API documentation (e.g. the manpages).</li>
-- <li>If the name is significantly different from the POSIX-function, the
-- underlying function(s) are stated in the documentation.</li>
-- <li>Parameters should reflect those of the C-API, buffer length arguments and 
-- by-reference parameters should be omitted for practical purposes.</li>
-- <li>If a C function accepts a bitfield as parameter, it should be translated
-- into lower case string flags representing the flags if the bitfield is the 
-- last parameter and also omitting prefixes or suffixes. (e.g.  waitpid
-- (pid, &s, WNOHANG | WUNTRACED) -> waitpid(pid, "nohang", "untraced"), 
-- getsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)) ->
-- Socket:getopt("socket", "reuseaddr"), etc.) </li>
-- <li>If it is not applicable to provide a string representation of the
-- bitfield a bitfield generator helper is provided. It is named FUNCTION_flags.
-- (open("/tmp/test", O_RDONLY | O_NONBLOCK) -> open("/tmp/test", open_flags(
-- "rdonly", "nonblock")))</li>  
-- </ul>
-- @class table
-- @name Functions
-- @return !

--- Platform information.
-- <ul>
-- <li>The minimum platform requirements are a decent POSIX 2001 support.
-- Builds are more or less tested on Linux, Solaris and FreeBSD. Builds for
-- Windows XP SP1 and later can be compiled with MinGW either from Windows
-- itself or using the MinGW cross-compiler. Earlier versions of Windows are not
-- supported.</li>
-- <li>In general all functions which don't have any remarks 
-- in their documentation are available on all platforms.</li>
-- <li>Functions with a (POSIX), (Linux) or similar prefix are only available
-- on these specific platforms. Same appplies to parameters of functions
-- with a similar suffix.</li>
-- <li>Some functions might have limitations on some platforms. This should
-- be stated in the documentation. Please also consult your OS API 
-- documentation.</li>   
-- </ul>
-- @usage Tes
-- @class table
-- @name Platforms
-- @return !

--- Cryptography and TLS libraries.
-- <ul>
-- <li>Currently 3 underlying cryptography libraries are supported: openssl,
-- cyassl and axTLS. The name of the library in use is written to 
-- <strong>nixio.tls_provider</strong></li>
-- <li>You should whenever possible use openssl or cyassl as axTLS has only 
-- limited support. It does not provide support for non-blocking sockets and
-- is probably less audited than the other ones.</li>
-- <li>As the supported Windows versions are not suitable for embedded devices
-- axTLS is at the moment not supported on Windows.</li>  
-- </ul>
-- @usage Tes
-- @class table
-- @name TLS-Crypto
-- @return !