Is there an API or straight forward way to simulate any data as a windows explorer drive/file-hierarchy? I don't want to create actual files I want to have a view on my data as though it were.
E.g. if my real data was in a database but I want it to look like a drive/folder/files?
You can create shell namespace extension or a virtual file system.
Shell namespace extension has many shortcomings but if you need files to be only exposed and copied, it can work.
Virtual file system or disk can be created only with help of third-party solutions such as our Callback File System or CallbackDisk. This approach fully emulates the local disk and the filesystem up to possibility to manipulate individual sectors (but this depends on the way used, i.e. whether you emulate the disk or the filesystem).
Related
I have two questions, both are them may be related so I am asking at once.
Linux has /proc directory which is runtime data structure and gives information about running process. Does windows have any such directory where I can get runtime info about process, like its layout and open handles. Please do no suggest tools like Process Explorer, its good but they are not part of core windows os.
Secondly, it is said for Windows that not everything is file, like socket is not a file. Does it mean that it is not a sort of file you can see in your hard disk but a runtime it creates file and in proc like data structure it has some entry.
Thanks.
While Windows has the ability to create virtual files (device drivers use this), there are no such files for process information.
Information about processes is available either through the process functions, the undocumented functions used by Process Explorer, or not at all.
Not every file is stored on some disk.
Virtual files are essentially just some value in memory, or some callback function that generates the file contents dynamically when you're trying to read it.
I have a big collection of folders for projects I'm working on. I've been trying to find a better way to sort them all for a long time and I want to write an app that creates groups based on whatever criteria I say, such as "folders from 2011" or "folders containing a x type of file" etc.
This is fairly straightforward, and wouldn't present much of a problem to code using its own UI in winForms or WPF or something. But I think it would be far better if I could make these folders appear to be part of the filesystem, so other apps (like existing file explorers) can see them.
Is this possible? Would it cause problems I haven't considered? How do I go about doing it if it is possible?
One way I thought of doing it would be to have the app monitor the filesystem and create folder shortcuts every time there's a change, but I'm curious about whether its possible to actually present a fake filesystem to explorer through a 'gateway' folder
EDIT: Ok it's obviously possible since http://www.virtualfolder.net/ can do it, and now that I think of it so can TrueCrypt, although it would be nice if it didn't have to appear as a separate drive. So the question becomes, how do I implement it?
You can create a Shell Namespace Extension that gathers the file information you want and displays it within Windows Explorer any way you wish. You can choose where your extension is located, whether as its own top-level node, a child of another system virtual folder/extension, or as a child of a file system folder.
Writing a SNE is not trivial, but it is a lot easier then writing a lower-level file system driver, and it does not require special driver-oriented compilers. Any compiler that supports developing COM objects will work.
This is accomplished using filesystem drivers or filesystem filter drivers. First let you create a virtual filesystem and mount it to a drive letter and also to a folder on NTFS drive (folder must exist but its contents are "replaced" with a virtual filesystem directory tree). Filesystem filter drivers let you introduce virtual files and folders in existing folders without replacing them.
VirtualFolder uses filesystem driver as it creates a drive letter.
Both types of drivers are written in C and work in kernel-mode. Writing them requires deep knowledge of Windows internals and experience with driver development (since filesystem drivers are one of the most complicated driver types).
We offer several products related to virtual storage. One of them, Callback File System, is a filesystem driver. It calls your user-mode code to perform actual filesystem functions. Another product, CallbackFilter, is an FS filter driver (and it also calls your user-mode code). However, current version of CallbackFilter doesn't let you introduce virtual files and folders (this would be implemented in the next release).
There's also Pismo File Mount product available, they use filter driver techniques. You can check with them if what you need can be accomplished.
From what I gather you are looking for a way to present the results of predefined file queries to appear as though they are located at a specific location in the file system. If that is correct you may want to look into Hard Links and Junctions. There are limits on what you can do with these file system services. However it is really straight forward to implement.
Using the raw Windows programming API from C/C++ and a file handle or a path to a file, folder, link, etc; how can I programmatically decide whether the file (etc) supports ADS (Alternate Data Streams)?
I assume one thing I have to know is whether the file is on an NTFS partition, but then again for all I know it might be possible to mount some kind of Mac or *nix filesystems which support data forks or alternate data streams of some kind, and all such cases might be covered by a single API call or data structure.
Secondly I'm not sure whether every kind of object that can exist on an NTFS partition can have ADSs - such as folders, symlinks, hardlinks, anything else?
What API etc can handle all cases to tell me whether a given file etc has the ability to have ADSs?
(For this question I'm not looking for whether files have ADSs, just whether its possible for files to have them. It could include a file I've just created for instance.)
ADS is a feature of NTFS. You can use GetVolumeInformation() to detect if a given path is on an NTFS file system, and even if that volume supports ADS at all. AFAIK, only a real file can have an ADS attached to it. You can use GetFileAttributes() to detect if a path is a file, directory, symbolic link, etc.
Like any other file, Directories can also host other ADS! Any file object on NTFS can store more than one DATA Stream. The 'visible' one is named, any additional data stream is 'invisible' as far as Explorer is concerned. Actually, at the prompt now one can display ADS using the /R switch when invoking dir.
I have an application that in a certain moment has to create a temporary file and then delete it. So I'm thinking about whether it is possible to create a temporary file into memory instead of directly into disk. Then I would like to read it from memory to perform some actions and finally after doing some stuff, delete if from memory. If it is possible, how to do this in .NET Framework and C#. Also, Can performance be affected by using directly memory and not disk?
I would like to use memory directly instead of disk because I am afraid of some kind of windows permissions that does not allow to write file to some places of disk... so another doubt is: if using disk instead of memory is there a safe place to write temporary files and avoid writting permissions conflicts for windows XP,Vista,7,8? I mean, a place where is always safe to write temporary files and then delete it. Maybe, in user\Local Settings\Temp folder? is it the best place? I would like to know a safe place to save temporary files and then delete them that is working for windows versions: XP, Vista, 7, and 8.
Thanks.
You can use the MemoryStream for writing to memory instead of disk. Preformance can possibly be better using a memorystream because disks are often slower to write to. As always: profile before optimizing.
For information about the temporary folder see this thread: How to get temporary folder for current user
You should be able to write your own class inherited from Stream class, override its methods (read/write etc), and inside them maintain your own stringbuilder or whatever suits you. Everything will be inside the memory and of course it'll be really fast.
I think XP had "Documents and Settings", vista/7 has Users folder which has its very own place for each user to write temp files at, you should not have a problem writing there. What you are thinking is correct imo.
I want to put some sort of "hook" into windows (only has to work on Windows Server 2008 R2 and above) which when I ask for a file on disk and it's not there it then requests it from a web server and caches it locally.
The files are immutable and have unique file names.
The application which is trying to open these files is written in C and just opens a file using the operating system in the normal way. Say it calls OpenFile asking for c:\scripts\1234.12.script, and that is there then it will just open it normally. If then it asks for c:\scripts\1234.13.script and it isn't then my hook in the operating system will then go and ask my web service for the file, download it and then return that file as it it were there all the time.
I'd prefer to write this as a usermode process (I've never written a windows driver), it should only fire when files are not found in a specific folder, and I'd prefer if possible to write it in a managed language (C# would be perfect). The files are small (< 50kB) and the web service is fast and the internet connection blinding so I'm not expecting it to take more than a second to download the file.
My question is - where do I start looking for information about this kind of thing? And if anyone has done anything similar - do you know what options I have (eg can it be done in C#?)?
You would need to create a kernel-mode filesystem filter driver which would intercept requests for opening such files and would "fake" those files. I should say that this is a very complicated task even for driver development. Our CallbackFilter product would be able to solve your problem however mechanism for "faking" files is not yet ready (we plan this feature for CallbackFilter 3). Until then I don't know any user-mode solutions (frankly speaking, no kernel-mode solutions as well) that would solve your problem.
If you can change the folder the application is accessing, then you can create a virtual file system and map it to the drive letter or a folder on NTFS drive. From the virtual file system you can direct most requests to/from real disk and if the file doesn't exist, you can download the file and cache it. Our other product, Callback File System, lets you do what I described in user-mode. If you have a one-time task you need to accomplish, and don't have a budget for it, please contact us anyway and maybe we can find some solution. There also exists an open-source solution with similar (but not so comprehensive) functionality named Dokan, yet I will refrain from commenting on its quality.
You can also try Dokan , it open source and you can check its discussion group for question and guides.