Reference a binary-component to js-ctypes

Question

I have registered a binary component in my chrome.manifest:

binary-component components/linux/myLib.so abi=Linux_x86-gcc3

Now I want to pass its path to ctypes.open(). My question is: how do I reference the binary component so I can pass it to ctypes.open()?

Answer 1

The binary components listed in chrome.manifest should be XPCOM components. Yours on the other hand is a regular library, no need to list it in the manifest - it is a very "manual" approach instead. Your code needs to check nsIXULRuntime.XPCOMABI (see https://developer.mozilla.org/En/NsIXULRuntime) to see whether the platform is compatible. Then you need to get the location of your library file, something like this:

Components.utils.import("resource://gre/modules/AddonManager.jsm");
AddonManager.getAddonByID("[email protected]", function(addon)
{
    var uri = addon.getResourceURI("components/linux/myLib.so");
    if (uri instanceof Components.interfaces.nsIFileURL)
    {
        ctypes.open(uri.file.path);
        ...
    }
});

The first parameter to getAddonByID() needs to be replaced by the ID of your add-on of course. And the assumption here is that your add-on is installed unpacked (<em:unpack>true</em:unpack> specified in install.rdf) because otherwise there won't be a file on disk to be loaded.

Answer 2

You could use "resource" to reference the normal binary file in your addon: add this to your manifest:

resource YOUR-ADDON-LIB path/to/libaddon.so ABI=Linux_x86-gcc3
resource YOUR-ADDON-LIB path/to/addon.dll ABI=WINNT_x86-msvc

The "ABI" directive will give your right lib path under different platform.

In your javascript file, your could reference the lib path like this:

const ioService = Cc["@mozilla.org/network/io-service;1"].getService(Ci.nsIIOService);
var uri = ioService.newURI('resource://YOUR-ADDON-LIB', null, null);
if (uri instanceof Components.interfaces.nsIFileURL)
{
    var lib = ctypes.open(uri.file.path);
    /// ...
}