I am new to coding and trying to understand something. I have read that a .EXE can not change itself or change embedded files inside itself. So lets say you make a game and that game has setting that the user can adjust like difficulty or level or whatever. Maybe it is an RPG game and they need to save progress. Where does that information get saved? If you save it to a text file then the user could go into the text file and adjust their level and cheat. Also you would not save a password to a text file because then anyone could open the text file and see the password.
Another problem would be that, if they moved the game to a different computer and did not also move the save file they would not have access to their saved information.
For C# applications, there are several ways to save application data; various practices are dicsussed in this question; the most usual ways are custom data files (Xml, Json, binary formats), the Windows registry, or the cofiguration settings file of the application. The problem that a user could manually edit the saved data is always present and somewhat unrelated; this is a drawback of either possibility. One solution would be to encrypt the saved data or use checksums to detect manipulation.
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I need to be able to uniquely identify a file.
The file would be uploaded to a web application and could be uploaded from anywhere. The file could be mailed to someone, renamed, edited and then uploaded from a different machine altogether and need a way of identifying that this was the original file that was originally uploaded. I need a reliable way of identifying a file across different file systems.
I cannot use the filename as the identifier as the file could be renamed. I still need to be able to uniquely identify the file even though it was renamed.
I cannot use the the Hash on the file as the Hash would change if the file was edited.
I understand Linux has inode number property and windows has the IndexNumber. I can use the NtQueryInformationFile and get the indexNumber. The indexNumber was same when the file was edited and when the file was renamed. But then IndexNumber was different when the file was moved from one folder to another.
From all the reading I have done, it seems like the 'indexNumber' is not reliable for all documents. I almost have a feeling that there is no unique identifier for a file that would be constant across different folders, machines and that would remain unchanged when edited, renamed etc. But here I am StackOverflow. Any help is appreciated.
Edit: Here is the business problem I am trying to solve. A user uploads a file to our web application. Then inputs a bunch of metadata for the file. Similar to adding tags on the file. We keep the file in blob storage but the user still has his local copy that he mails to another user. He maybe edits and renames the file before mailing. When the other user uploads the file to our web application, is there any way we can identify that this was the original file so as to pre-populate the metadata that the original user had entered.
The simple answer to your question is that it can't be done.
Let me summarize what you're trying to accomplish.
If I have a file on my office computer, and upload that to your web application, you want to store that into your system as a new file. Then, if I copy the file from my office computer to my home computer, edit the file contents, rename the file, and then upload it into your web application, you want to identify that this is the same file as the one I previously uploaded.
It can't be done.
Not with a 100% guarantee that you can identify this.
When you are uploading files to a web application, what is sent is this:
The name of the file
The length of the file
The contents of the file
Things such as alternate data streams (NTFS), from the other answer here, or inode or similar identifiers, from the comments, are not sent. Your web application will not see them. Nor would these things be "across multiple computers".
So bottom line, this is impossible.
Your options are:
Let the user uniquely pick the file they want to overwrite, meaning that the user could pick unrelated files and thus be "wrong"
Work out a reasonable chance that you identified the right file, accepting the chance that you identified incorrectly
Embed a unique id into the file itself, however since the file contents can be edited (and the id can be changed) this is not guaranteed
... other options that doesn't have a 100% guarantee of being right
The first option is of course the easiest.
The second option could use systems such as what git is doing when it tracks renames, but even this will fail depending on how much the file was edited between the uploads. Git fail in this respect too, except that "failure" here simply means it doesn't show you the full history of a file, it doesn't break down and become unusable.
The third option might work if the file should be edited by a program similar to Word or Excel or Photoshop, etc. You could embed the ID and just make sure that program doesn't change it. It would probably have a higher and acceptable chance of being right, but it might still be possible to edit.
So you will have to decide what would be acceptable to you, but you cannot create a system in which you are guaranteed to identify the file, even if it was renamed and the contents changed. Because at that point you have no guarantee that the user is simply trying to upload a different file altogether.
On windows with the NTFS file system you could use alternate data streams or NTFS streams;
http://ntfs.com/ntfs-multiple.htm
stream: A sequence of bytes written to a file on the target file system. Every file stored on a volume that uses the file system contains at least one stream, which is normally used to store the primary contents of the file. Additional streams within the file can be used to store file attributes, application parameters, or other information specific to that file. Every file has a default data stream, which is unnamed by default. That data stream, and any other data stream associated with a file, can optionally be named.
https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-fscc/8ac44452-328c-4d7b-a784-d72afd19bd9f
There is not a lot of official documentation however. But you can inject a GUID there to be able to track the file.
On limitation about this solution is that this only works for the NTFS filesystem, when the file is copied to e.g. a FAT file system, the information is lost.
You need to access native win32 api's however. Check for example this SO:
https://stackoverflow.com/a/605167/4122889
Or this random blog:
https://blogs.msmvps.com/bsonnino/2016/11/24/alternate-data-streams-in-c/
I would like to identify users in my Universal App each time they run it.
So I am thinking I want to have Johnny open a separate app which will save an array of his DetectedFace(s). Then I have Sally use the separate app and save an array of her DetectedFace(s).
How do I transfer these arrays to my actual program so it can differentiate between Johnny and Sally?
For text it is easy to save to a text file and then pull from that text file, but I don't think I can save a DetectedFace to a Text File?
Is this something a Database could store?
I think I will just save images with Johnny's face and then generate the DetectedFace(s) from these saved images in the actual program. Then get the DetectedFace(s) from the person in the current video stream. Then compare the two. Doesn't seem very efficient if I had 1000 users though.
I'm trying to create a card game in C# and for this I have alot of images that I need to load. They're all jpg images and there are about 7000 of them.
I would like to make sure that if you download the game, the images will not be easily accessible, meaning that they should not just be JPG images in a sub folder of the application. So I thought about imbedding them in a DLL file.
But how do I do this? And how do I handle this efficiently? Is there a tecnique to this sort of thing, or is another method preferable?
I would like to make sure that [...] the images will not be easily accessible
First, you should ask yourself why you want to forbid this. If you just want to avoid that someone else manipulates the pictures, you can leave them in a bunch of subfolders as JPGs, just generate checksums for each file and check them at the time the program loads the pictures.
If you want to avoid reuse of the pictures, you can leave them in a bunch of subfolders, but not as JPGs. Encode them with for example with the standard AES algorithm. But beware, that won't prevent anyone else of making screenshots while you application is running, so you should consider if that's really worth the effort.
EDIT: if you want to embed the images because installation gets easier when you have just one big file to deploy instead of 7000 single files, then you may write a helper program for creating resource files programmatically. See this page from Microsoft, especially the part about .resource files, to learn how to utilize the ResourceWriter class for that purpose.
If you have 7000 image, you need a database. Microsoft SQL Server Compact 4.0 is an option. It's small and easy to use.
I'm assuming that this is a windows application
In order to Embed a Image to the assembly
1. Right click the Image file and Select properties
2. In the Properties Pane Set the BuildAction as Embeded resource
So this Image becomes a embeded resource when the application is compiled
Then you can access the Image from the assembly like:
global::[[MyNameSpace]].Properties.Resources.[[ImageName]]
for eg:this.pictureBox1.Image = global::[[MyNameSpace]].Properties.Resources.[[ImageName]]
I am building an interface whose primary function would be to act as a file renaming tool (the underlying task here is to manually classify each file within a folder according to rules that describe their content). So far, I have implemented a customized file explorer and a preview window for the files.
I now have to find a way to inform a user if a file has already been renamed (this will show up in the file explorer's listView). The program should be able to read as well as modify that state as the files are renamed. I simply do not know what method is optimal to save this kind of information, as I am not fully used to C#'s potential yet. My initial solution involved text files, but again, I do not know if there should be only one text file for all files and folders or simply a text file per folder indicating the state of its contained items.
A colleague suggested that I use an Excel spreadsheet and then simply import the row or columns corresponding to my query. I tried to find more direct data structures, but again I would feel a lot more comfortable with some outside opinion.
So, what do you think would be the best way to store this kind of data?
PS: There are many thousands of files, all of them TIFF images, located on a remote server to which I have complete access.
I'm not sure what you're asking for, but if you simply want to keep some file's information such as name, date, size etc. you could use the FileInfo class. It is marked as serializable, so that you could easily write an array of them in an xml file by invoking the serialize method of an XmlSerializer.
I am not sure I understand you question. But what I gather you want to basically store the meta-data regarding each file. If this is the case I could make two suggestions.
Store the meta-data in a simple XML file. One XML file per folder if you have multiple folders, the XML file could be a hidden file. Then your custom application can load the file if it exists when you navigate to the folder and present the data to the user.
If you are using NTFS and you know this will always be the case, you can store the meta-data for the file in a file stream. This is not a .NET stream, but a extra stream of data that can be store and moved around with each file without impacting the actual files content. The nice thin about this is that no matter where you move the file, the meta-data will move with the file, as long as it is still on NTFS
Here is more info on the file streams
http://msdn.microsoft.com/en-us/library/aa364404(VS.85).aspx
You could create an object oriented structure and then serialize the root object to a binary file or to an XML file. You could represent just about any structure this way, so you wouldn't have to struggle with the
I do not know if there should be only one text file for all files and folders or simply a text file per folder indicating the state of its contained items.
design issues. You would just have one file containing all of the metadata that you need to store. If you want speedier opening/saving and smaller size, go with binary, and if you want something that other people could open and view and potentially write their own software against, you can use XML.
There's lots of variations on how to do this, but to get you started here is one article from a quick Google:
http://www.codeproject.com/KB/cs/objserial.aspx
I'm trying to do the following(in this order):
Create a Rich Text Format file
Add company image to the top of page and write the data to the RTF
Print the RTF file as PDF through CutePDF or other printer that are
able to convert my RTF to a PDF and thereby save locally on the users PC - The pdf should be saved at a location without prompting the user
After this is done, the RTF file should be deleted and return a message, that confirms the action is successfully done.
Other stuff:
The website where these actions take place, are not meant to host the outcome(the PDFs) but these are supposed to be saved on the users PC. (is this possible without prompting the user to save it? i imagine the website would write directly to the users PC instead of doing the work on the website and save it and then transfer the file to the PC)
OBS: i do not wish to use any 3th party program/DLL other then the converter like cutePDF :)
My question is quite simple i hope :)
Will this work?
No. You can send the PDF back to the user but the user will either be prompted to download the file or it will open automatically (depending on the user's configuration and the response headers you're sending). Without using some sort of plugin you can't save any files directly to the user's computer.
If it was possible to write a file directly to the user's the world as we know it would have ceased to exist. Cities would lie in ruin as idle youtube commentators roamed the streets in violent gangs yelling "FIRST" and engaging in brutal and pointless gang wars. A generation of youth superbly trained by video games would manage to destroy civilization in a matter of days. Fortunately civilization would eventually be rebuilt by Minecraft players but it would take time.
If that functionality is really vital I would suggest looking at a plugin.