Module `luaffifb`

Corona binding for luaffifb, a library for calling C functions and manipulating C types from Lua.

It is designed to be interface-compatible with the FFI library in LuaJIT (see here). It can parse C function declarations and struct definitions that have been directly copied out of C header files and into Lua source as a string.

This is a fork of luaffi.

Documentation

This library is designed to be source-compatible with LuaJIT's FFI extension. The documentation here describes the API and semantics.

Pointer Comparison

Use ffi.NULL instead of nil when checking for NULL pointers.

ffi.new('void *', 0) == ffi.NULL -- true

Known Issues

Comparing a ctype pointer to nil doesn't work the same as in LuaJIT (see above). This is unfixable with the current metamethod semantics.
Constant expressions can't handle non integer intermediate values (eg offsetof won't work because it manipulates pointers)
Not all metamethods work (e.g. char* + number). This is due to the way metamethods are looked up with mixed types in Lua 5.1. If you need this use boxed numbers (uint64_t and uintptr_t).
All bitfields are treated as unsigned (does anyone even use signed bitfields?). Note that "int s:8" is unsigned on Unix x86/x64, but signed on Windows.

Corona-specific changes

tonumber and type are left intact. For the FFI-aware behavior, stick to ffi.number and ffi.type.
To play nice with plugins, library loaders of the luaopen_* kind are rejected by ffi.cdef.

How it works

Types are represented by a struct ctype structure and an associated user value table. The table is shared between all related types for structs, unions, and functions. Its members have the types of struct members, function argument types, etc. The struct ctype structure then contains the modifications from the base type (e.g. number of pointers, array size, etc).

Types are pushed into Lua as a userdata containing the struct ctype with fenv set to the shared type table.

Boxed cdata types are pushed into Lua as a userdata containing the struct cdata structure (which contains the struct ctype of the data as its header) followed by the boxed data.

The functions in ffi.C provide the cdata and ctype metatables and ffi.* functions which manipulate these two types.

C functions (and function pointers) are pushed into Lua as a Lua C function with the function pointer cdata as the first upvalue. The actual code is JITed using dynasm (see call_x86.dasc). The JITed code does the following in order:

Calls the needed unpack functions in ffi.C placing each argument on the HW stack
Updates errno
Performs the C call
Retrieves errno
Pushes the result back into Lua from the HW register or stack

BSD License

For luaffifb software

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
Neither the name Facebook nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

This product contains portions of third party software provided under this license:

luaffi software

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Facebook provides this code under the BSD License above.

luaffifb

Modules