I'd like to get notified when a specific file get accessed (AFAIK, most generally for a Userland code - by CreateFile() / NtCreateFile())
I already know about FileSystemWatcher which should do the same within the .NET environment, But I'm working in plain C + WinAPI.
As for the type of notification , raising a specified Event would be perfect, but sending a callback to be called , will also work.
See FindFirstChangeNotification function in WinAPI and related links.
Alternatively, when functionality of that function is not enough, you can use a filesystem filter driver (write yours or use our CallbackFilter product).
Related
I'm in the process of writing an app to interface with a service running on another machine. When I ask this service for some information, this service adds the requested information to a separate queue, and sends a windows message to the calling application (my application) indicating there is a message waiting in this separate queue which needs to be decoded.
The windows message this service sends is a custom message, defined in the service code as having some constant int value. I've found examples of creating custom events in wxpython, and using TryBefore() and TryAfter() to react to these events in specific ways, but I haven't found any way to associate this NewEvent() with an int value so I can identify it when it comes in, much less any way to determine what an int value of an incoming event is.
Has anyone done this before or know of any functions I'm not aware of? I'm using python 3.6 and wxpython 4.0.
Thanks for your help, everyone.
I think this is what you are looking for: https://wiki.wxpython.org/HookingTheWndProc
When you get the custom message from the hooked WndProc you can either react to it there, or you can turn it into a wx event and send it so it can be caught by binding an event handler like normal. The wx.lib.newevent module has some helpers for creating a custom event class and an event binder. Its use is demonstrated in some of the demo samples and library modules.
I have a Finder Sync Extension that will display a badge on a file based on the state of a local database. It's straightforward enough to query this database in the requestBadgeIdentifierForURL function, but what if I want the badge to change for a Finder item that's already visible if the state of that database has changed (which can be via a notification through any variety of mechanisms). The documentation (https://developer.apple.com/library/content/documentation/General/Conceptual/ExtensibilityPG/Finder.html) would seem to imply this is possible with this statement:
You might also want to track these URLs, in order to update their
badges whenever their state changes.
The only ways I can imagine this would be possible (and most seem wrong) would be:
call setBadgeIdentifier:forURL from another application that is aware of the change
Launch a thread in the init function of my extension which listens for notifications and calls setBadgeIdentifier:forURL when it receives them
Call some OS API that prompts Finder that the extension should be triggered via requestBadgeIdentifierForURL.
Only the last one seems feasible, and could be managed via the extension informing the outside resource what needs refreshing via the beginObservingDirectoryAtURL/endObservingDirectoryAtURL callbacks, but i don't know what mechanism could do this.
I am unable to read clipboard data in Microsoft Edge browser. i am using the below javascript.
if (window.clipboardData && window.clipboardData.getData) { // IE
pastedText = window.clipboardData.getData('Text');
} else if (e.clipboardData && e.clipboardData.getData) { //non-IE
pastedText = e.clipboardData.getData('text/plain');
}
Non of the if/elseif block is executed in Edge. I tried using
e.originalEvent.clipboardData.getData('text/plain');
But I am getting 'Access is denied.' error.
Let me know, if anybody know how to fix this issue.
Edge does not currently support the clipboard api, but it is under consideration and likely to be added in near future.
I do not have edge, but it seems that you are not authorized to access the clipboard data. Is this on a website or are you calling this from within a JavaScript script executed locally?
Make sure the website is in the trusted sites.
See https://w3c.github.io/clipboard-apis/#clipboard-event-interfaces, or more precisely:
12.1 Privacy concerns
Untrusted scripts should not get uncontrolled access to a user's clipboard data. This specification assumes that granting access to the current clipboard data when a user explicitly initiates a paste operation from the user agent's trusted chrome is acceptable. However, implementors must proceed carefully, and as a minimum implement the precautions below:
Objects implementing the DataTransfer interface to return clipboard data must not be available outside the ClipboardEvent event handler.
If a script stores a reference to an object implementing the DataTransfer interface to use from outside the ClipboardEvent event handler, all methods must be no-ops when called outside the expected context.
Implementations must not let scripts create synthetic clipboard events to get access to real clipboard data except if configured to do so.
Implementations should not let scripts call document.execCommand('paste') unless the user has explicitly allowed it.
Implementations may choose to further limit the functionality provided by the DataTransfer interface. For example, an implementation may allow the user to disable this API, or configure which web sites should be granted access to it.
I am trying to hook an API (say, MessageBox()) in other processes (I may not know the process ID) on Windows, I know that I have to use the SetWindowsHookEx() function. But still, I have three questions:
1) Can SetWindowsHookEx() function makes the hook global, i.e., not limited to current process? (When ther applications call this API, it is hooked?)
2) If I want to replace the to-be-hooked API with my own function, how should I do?
3) I read many materials, and I found the term "hook procedure" or "hook function". How should I comprehend this? Currently, I take it as the function that I will use to replace the API (say again, MessageBox).
This is not what SetWindowsHookEx is for. SetWindowsHookEx is for hooking into windows messages, not APIs (for example if you want to know when a window changes size or gets created).
Hooking API calls is more complicated, more messy. There is no built-in way to do it; you usually want to find a library to help you such as Detours.
You can use Deviare API Hook for this. With this library you can hook any API in 10 lines of code even with .NET
The difference with Detours is that you don't have to write the code that is inserted in each process. You can hook all the processes you want just attaching them. Then, you receive the calls in your own process.
I was wondering if there's some sort of system event that gets fired every time a user changes the time in Windows. I know there's a way to enable this in Windows' EventLog, but I was looking for a way to respond to this event programatically (like using the Windows API).
A WM_TIMECHANGE message is sent whenever there is a change in the system time
I'm not sure from your question if you're working in managed or native code. But if you're working in managed code you can use the TimeChanged event on the SystemEvents class.
Microsoft.Win32.SystemEvents.TimeChanged