I have a module compiled in a shared object (I followed the library part of this article https://chsasank.github.io/lua-c-wrapping.html) and I want to load it from C not from the interpreter.
Is it possible ? If so how to do it ?
Yes, it's possible, as require is a function stored in a global environment. Lua does the same in standalone interpreter when it needs to process the -l option, see the dolibrary function.
You do this the same way as with any other global function - in simplest case calling lua_getglobal(), then pushing the name of the file to require, and calling lua_call/lua_pcall/whatever.
I know that I am late, but someone else may struggle with this right now (like I just did).
This is a simple way of doing "require" from C:
int reqRes = luaL_dostring(L, "local t=require('myLib') return (t~=nil)");
if (reqRes==0)
//success
else
//failed
Unfortunately, right now, I'm using Lua 5.1 and "dolibrary" function doesn't exist, I >tried to take some part of the code and it crashes :\ So, for now, I use luaL_dostring(L, >"require 'libMyWrappings'"); libMyWrappings must be in the same directory as the c >program, and I can't use a path to indicate the lib. – Aminos Jan 22 at 11:45
I just ran into the same issue, it has to do when the package library is loaded
{LUA_LOADLIBNAME, luaopen_package}
needs to happen before you try and call it
Related
What's the best way to open a file in the default application from Vala?
A bit like how xdg-open works.
I found some existing code in another application, but later on I also found this
GLib.AppInfo.launch_default_for_uri method.
A simple example:
var file = File.new_for_path (file_path);
if (file.query_exists ()) {
try {
AppInfo.launch_default_for_uri (file.get_uri (), null);
} catch (Error e) {
warning ("Unable to launch %s", file_path);
}
}
If you're using GTK, then you've also got Gtk.gtk_show_uri_on_window(), which uses the GLib stuff under the hood.
As far as I know there is only one implementation of the relevant freedesktop.org standards.
That is the reference implementation in xdg-utils:
https://www.freedesktop.org/wiki/Software/xdg-utils/
The tools are written in shell script, for example here is the source code for xdg-open:
https://cgit.freedesktop.org/xdg/xdg-utils/tree/scripts/xdg-open.in
So by far the easiest way is to just call the xdg-open script via Process.spawn_async and friends.
If you insist on using a library function you would have to implement a standard conforming library yourself.
Update:
There are quite a few libraries in various languages that implement some of the freedesktop.org standards, for example here is a list on GitHub:
https://github.com/topics/xdg
For example here is a similar tool to xdg-open written in D:
https://github.com/FreeSlave/mimeapps/blob/master/source/mimeapps.d
What I didn't find so far is a Vala / GLib or plain C library that could easily be used from a Vala application.
Update 2:
Actually it turns out there is something for that purpose in GLib (or more precisely in Gio):
https://valadoc.org/gio-2.0/GLib.AppInfo.launch_default_for_uri_async.html
https://developer.gnome.org/gio/stable/GAppInfo.html
So you should be able to use the GLib.AppInfo.launch_default_for_uri_async method.
In a mozille extension I run:
SecSess.Logger.info("ctypes test");
Components.utils.import("resource://gre/modules/ctypes.jsm");
SecSess.Logger.info("1");
this.lib = ctypes.open("libcrypto.so");
SecSess.Logger.info("2");
var a = new Uint8Array(1<<10);
SecSess.Logger.info("3");
var ptr = new ctypes.uint8_t.ptr(a.buffer);
SecSess.Logger.info("4");
Why this ugly logging after each step you might ask? Well this code fails without showing me an error. (or at least I can't find the error message)
This is printed:
ctypes test
1
2
3
So the 5th log message is never printed which means the following statement never completes:
var ptr = new ctypes.uint8_t.ptr(a.buffer);
This is a simplified version of some old code I have to work with and which I also found online as being valid. However it doesn't work. This add-on wasn't developped using the new SDK with jpm. Quite frankly I don't know how and when it was developped but I need to run some tests on it. It comes with a few source files ordered in a components and a modules directory and a chrome.manifest and install.rdf in the root. I copied these files to the extension directory of Mozilla in order for it to work. The extension executes but there seems to be a problem with ctypes. Aren't ctypes fully supported anymore or are these old style add-on no longer valid for the modern Firefox?
Regards,
Roel
I think they landed a a patch to disallow making a pointer from buffers. I'll double check.
Edit:
Ah per this: https://developer.mozilla.org/en-US/docs/Mozilla/js-ctypes/Using_js-ctypes/Working_with_ArrayBuffers, you don't have to wrap it with a ctypes.uint8_t.ptr just pass it like a.buffer to wherever you need it. :)
So i got a new keyboard wit hG-keys. (hotkeys) And i'm not familiar with lua...
So could anybody give me a very simple command that sets my pc to sleep? please?
if gkey == 7 and mkey == 1 then
if event == "G_PRESSED" then
end
end
gkeys
so gkey is the key that is pressed, and mkey is the set it uses. i can have up to 54 differint scripts/macro's.
I want to know what i have to put after the last 'then' so my pc goes to sleep.
thx ahead
edit 1:
got this:
if gkey == 1 and mkey == 3 then
if event == "G_PRESSED" then
execute("rundll32.exe powrprof.dll,SetSuspendState 0,1,0");
end
end
error is: [string "LuaVM"]:40: attempt to call global 'execute'(a nil value)
and with os.execute i get this error:
[string "LuaVM"]:40: attempt to index global 'os'(a nil value)
final answer: not possible with gseries keyboard. use a shortcut
Given the reference to G-keys and the G_PRESSED in your code snippet, I am assuming you have one of the Logitech G-Series keyboards. These keyboards can be programmed so that certain keys run Lua scripts using a custom Lua 5.1 interpreter. The documentation is included with Logitech's Gaming Software program.
According to the documentation, only some of the standard library functions are supported: the string, math and table are available. However, the io, os and debug libraries are not available.
So I doubt you'll be able to make your PC go to sleep.
EDIT in response to OP edit: the Lua library you have access to has the os library removed, so you're probably not going to be able to make your computer sleep directly.
There might be an indirect way to do this by writing something that listens for debugging messages, which you can generate with OutputDebugMessage. There's a Team Speak plugin that does this. But it's probably beyond your programming ability right now and far beyond the scope of a Stackoverflow post to explain.
You can use os.execute to run an executable from Lua.
If you google "Windows sleep command line" you'll get another Stackoverflow post which shows two ways of doing it. One requires that you turn hibernation off, the other requires that you download an additional utility (PsShutdown).
Assuming you've downloaded PsShutdown and put it somewhere in your PATH, then you can use the following to sleep the computer:
os.execute('psshutdown -d -t 0')
I use VLC media player 1.1.9 on Ubuntu 11.04. I'm trying to experiment with lua extensions for VLC; so I've added the file test.lua in ~/.local/share/vlc/lua/extensions/, which has only these two lines:
fps="25.000"
frame_duration=1/tonumber(fps)
When I run vlc with verbose output for debugging, I get (edited to split on multiple lines:):
$ vlc --verbose 2
...
[0xa213874] lua generic warning: Error loading script
~/.local/share/vlc/lua/extensions/test.lua:
.../.local/share/vlc/lua/extensions/test.lua:2:
attempt to call global 'tonumber' (a nil value)
...
Now, as far as I know, tonumber as function is part of Lua5.1 proper (Lua 5.1 Reference Manual: tonumber) - and on my system:
$ locate --regex 'lua.*so.*' | head -4
/usr/lib/libipelua.so.7.0.10
/usr/lib/liblua5.1.so
/usr/lib/liblua5.1.so.0
/usr/lib/liblua5.1.so.0.0.0
... apparently I do have Lua 5.1 installed.
So, why do I get an error on using tonumber here - and how can I use this (and other) standard functions in a VLC lua extension properly?
Documentation is sparse for VLC Lua extensions to say the least but I did find an example in the github vlc repository here: https://github.com/videolan/vlc/blob/master/share/lua/extensions/VLSub.lua
Judging from that example it appears you need to supply some basic event functions for your addon for VLC to call into when certain events happen. Some of the obvious callback handlers I've noticed:
descriptor, this should return a table that contains fields describing your addon.
activate, this seems to get called when you activate it from view menubar.
deactivate, called when you deactivate the addon from view menubar.
plus a couple of other functions like close and input_change which you can guess what they're for.
From my brief testing done on VLC 2.0.8 under Win7 it appears VLC loads the lua extension using an empty sandbox environment. This is likely the reason you're getting nil for tonumber and I'm betting none of the other standard lua functions are accessible either when you try to perform computation at this global scope.
However, if I move that code into one of the event handling functions then all those standard functions are accessible again. For example:
function descriptor()
return
{
title = "Test Ext";
version = "0.1";
author = "";
shortdesc = "Testing Lua Extension";
capabilities = {};
description = "VLC Hello Test Addon";
}
end
function activate()
print "test activating"
local fps = tonumber "25.000"
local frame_duration = 1 / fps
print(frame_duration)
return true
end
-- ...
That prints out what you would expect in the console debug log. Now the documentation (what little there is) doesn't mention any of this but what's probably happening here is VLC is injecting the standard lua functions and vlc api table into the sandboxed environment when any of these event handlers get called. But during the extension loading phase, it is done in an empty sandbox environment which explains why all those lua function calls end up being nil when you try to use it at the outter most scope.
I recommend cloning the VLC source tree from github and then performing a grep on the C source that's embedding lua to see what VLC is really doing behind the scenes. Most of the relevant code will likely be here: https://github.com/videolan/vlc/tree/master/modules/lua
Probably some extension script installed in your system overwrites the function and the Lua interpreter instance is shared between all extension scripts, so you end up not being able to call the function if that script is called before yours.
As a quick workaround, Lua being dynamically typed, you can still do things like:
1 / "25.000"
and the string will be coerced to a number.
Alternatively, you can define a tonumber equivalent like:
string_to_num = function(s) return s + 0 end
This again relies on dynamic typing.
I'm trying to script a lua file to check if a certain file is open. Then I want it to close that file if it is open. I know how to check if the file exist but I need to know how to check if the file is open, meaning the file is running.
Lua, like C, C++, and pretty much every other language, can only close files that it opens itself. You cannot close files open by other people (not with standard Lua calls); this would be incredibly rude.
So you can't test to see if a file is opened by someone else. Nor can you close their file. There may be system API calls you could make to do this, but you would have to give Lua scripts access to those APIs yourself. Lua's standard libraries can't do this.
Sounds like you want to check which if any programs have a given file open.
first thing that comes to mind is parsing the output of lsof on linux.
fd = io.popen("lsof path/to/my/file")
fileopened = (#fd:read("a*") > 0)
Kind of a hacky way to do it, but it works:
processname = "process_name_here.exe"
filedata = io.popen("tasklist /NH /FO CSV /FI \"IMAGENAME eq "..processname.."\"")
output = filedata:read()
filedata:close()
if output ~= "INFO: No tasks are running which match the specified criteria." then
-- Program is running. Close the program
os.execute("taskkill -im "..processname)
else
-- Program is not running
end
Just make sure to replace "process_name_here.exe" with the process name that shows up in task manager
Alternatively you can just use this to close it without checking if it was actually running:
os.execute("taskkill -im process_name_here.exe")