Checking if string path is valid [modified]

[Saksida Bojan]

I know, but the string path migt or might not exsist. I am already using this before atempting to create and delete folder

[realJSOP]

I don't understand. You mean the string itself might be empty/null? It really shouldn't matter. If you pass a null/empty string to the Exists method, it will return false (or throw an exception). Just write the appropriate code to handle either condition.

.45 ACP - because shooting twice is just silly
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"Why don't you tie a kerosene-soaked rag around your ankles so the ants won't climb up and eat your candy ass..." - Dale Earnhardt, 1997
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[Saksida Bojan]

John Simmons / outlaw programmer wrote:

I don't understand. You mean the string itself might be empty/null?

Might be. It could lead to an invalid folder like on Storage devices when removed. The folder itself doesn't have to exsist. Like temporary folder, where cache is placed. In other obvious errors, like invalid chars.

[AspDotNetDev]

Ah, so you just want to see if a hypothetical path (which may or may not already exist on the file system) is valid as far as the characters it uses and length and such? In that case, you have two options. Option 1 would be to use this code and catch exceptions for invalid characters and such (various types of exceptions will be thrown based on how the path is invalid):

// These will throw exceptions.
DirectoryInfo di = new DirectoryInfo("***");
FileInfo fi = new FileInfo("***");

The other option is to check this manually. Some things to consider when creating this code: Path.AltDirectorySeparatorChar Path.DirectorySeparatorChar Path.GetInvalidFileNameChars() Path.GetInvalidPathChars() Check if root drives exist (may not apply to network paths) Avoid known bad folder names (e.g., COM or something like that is invalid because it is reserved). Path.VolumeSeparatorChar Maximum path length (260 characters?) and max filename length. If the path does exist, then it must be valid (but determining if it is invalid will take more work).

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[Saksida Bojan]

Thank for your reply. It seems it is easiest to do is use Directory.CreateDirectory() and see if it can create. That Path class has some interesting methods.

[PIEBALDconsult]

I just use a FileInfo. Don't try to write your own.

[Lost User]

Saksida Bojan wrote:

Is there any better check to check if a path inside string is valid?

Building on the former posts, you'd like to check whether the parent-path is valid, and whether the name-part of the new folder is valid?

C:\Windows\MyBla:Folder

In order to verify whether "MyBla:Folder" is a valid name? You could check the parent-path as suggested, but there may be a *lot* more reasons why the creation of a folder might fail. Don't forget your try-except :)

I are Troll :suss:

[Saksida Bojan]

Nope. FileInfo is not what I wanted. I asked about Directory not file. I used like This: (From Memory) String path = "c:\TempCacheFolder";

Directory.CreateDirectory(path);
Directory.RemoveDirectory(path);

I needed to know if imputed string is valid before creating. I am currently designing Cache Engine for my custom control. The property CacheFilePath has get and set property. When someone programaticly enter an invalid area where it can't be written, without actually creating it before it is needed. And there is error within my approach. If I create directory with a path that have more subfolder that doesn't exsist: Example: Faze1. Test Create a folder. C:\MyApp\UnkownFolder\Unkownfolder2\TempImageCache. Faze2. Remove Folder. (Will remove only TempImageCache) I wan't to avoid this needless step. I only wan't to validate, that the unknown directory can be created without actually creating before needing. I am sorry if I was too cryptic about my previous posts

[Saksida Bojan]

I used like This: (From Memory) String path = "c:\TempCacheFolder";

Directory.CreateDirectory(path);
Directory.RemoveDirectory(path);

I needed to know if imputed string is valid before creating. I am currently designing Cache Engine for my custom control. The property CacheFilePath has get and set property. When someone programaticly enter an invalid area where it can't be written, without actually creating it before it is needed. And there is error within my approach. If I create directory with a path that have more subfolder that doesn't exsist: Example: Faze1. Test Create a folder. C:\MyApp\UnkownFolder\Unkownfolder2\TempImageCache. Faze2. Remove Folder. (Will remove only TempImageCache) I wan't to avoid this needless step. I only wan't to validate, that the unknown directory can be created without actually creating before needing. I am sorry if I was too cryptic about my previous posts

Eddy Vluggen wrote:

In order to verify whether "MyBla:Folder" is a valid name?

More like if it can create without creating new folder. I am designing custom control (Currently Cache Engine) I intend to handle it without trusting user input. And return errors that the user (developer) can easily repair problem

[realJSOP]

I suggest that you write a console app and play around with it. You seem to be aware of everything that coudl be wrong with a path name, so see what the DirectoryExists() method does with the various invalid possibilities. You could have figured all that out on your own by now... Be a programmer, fer christ's sake.

.45 ACP - because shooting twice is just silly
-----
"Why don't you tie a kerosene-soaked rag around your ankles so the ants won't climb up and eat your candy ass..." - Dale Earnhardt, 1997
-----
"The staggering layers of obscenity in your statement make it a work of art on so many levels." - J. Jystad, 2001

[Saksida Bojan]

Thanks for the info. It seems i would need to create my own parser. Thanks for everyone for their commets.

[Luc Pattyn]

In order to determine validity of a path, you should not modify the file system, hence CreateDirectory and RemoveDirectory are not acceptable. Calling them may cause a lot of unwanted side effects, e.g. when a FileSystemWatcher has been installed. What you can do is: 1. use Path.GetFullPath() 2. use new DirectoryInfo() each of those will throw an appropriate exception when the path isn't valid. And of course you could parse the path yourself (not recommended). :)

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[RichardM1]

I have to agree with the other posters, creating and deleting the dir is at best inelegant. You may have a valid path, with write permission, but not create permission. Worst case, I would check it for null, then get info on it from Directory. If this fails, get rid of everything from the last '/' back, inclusive, and try again. If that fails you know the proposed directory/file does not exist and that the directory holding also does not exist. If it succeeds, you would have needed to get file info to determine if you have write or create permissions to the paths given. We had a sergeant, in officer basic course, when (not if)one of us LTs came with an f'd up way to do something, he'd say: "it's a technique"

Opacity, the new Transparency.

[Giorgi Dalakishvili]

You can do it with NDepend.Helpers.FileDirectoryPath[^] library

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[Saksida Bojan]

tham. Didn't know DirecotryInfo had such flexebility. thanks. The code so far:

  public static bool IsValidPath(String path)
    {
        DirectoryInfo di;

        // Atempt to put String path into DirectoryInfo
        try
        {
            di = new DirectoryInfo(path);
        }
        catch (NotSupportedException) { return false; }

        // It must be logical drive. (HDD, SSD or USB Mass Storage)
        bool foundLogicalDrive = false;
        foreach (String str in Directory.GetLogicalDrives())
        {
            if (path.Substring(0, 3).ToUpper() == str)
                foundLogicalDrive = true;
        }
        
        if (!foundLogicalDrive)
            return false;

        return IsValidPathParser(di);
       
    }

    private static bool IsValidPathParser(DirectoryInfo di)
    {
        if (di.Exists)
        {
            // ACL checks here
            return true;
        }
        else
        {
            if (di.Name.ToUpper() != di.Root.Name.ToUpper())
                return IsValidPathParser(di.Parent);
            else
                return false;
        }
    }

The last part i wan't to check if users have permision to create and write in that folder. So far i haven't found anything usefull. Still googleing about DirectorySecurty.

[PIEBALDconsult]

Saksida Bojan wrote:

if imputed string is valid before creating

That's a waste of time -- things can change between the test and the creation. When it comes time to create, just try to create and report any errors.