Correct way to check if some path refers to something inside specified folder

Question

For example, I want to find out if specified directory path refers to Windows folder or anything inside it:

private static bool IsInsideWidowsFolder(string path)
{
    // windowsFolder = "C:\Windows"
    string windowsFolder = Environment.GetFolderPath(Environment.SpecialFolder.Windows);

    if (path.Contains(windowsFolder)) returen true
    return false;
}

But this will also consider true other strings like:

C:\WindowsApp

Which class is able to consider that string invalid while considering following as true?

C:\Windows\system32

https://stackoverflow.com/a/5617346/440030 – Reza ArabQaeni Jan 29 '18 at 07:51 — Reza ArabQaeni, Jan 29 '18 at 07:51

Mong Zhu · Accepted Answer · 2018-01-29T08:04:29.777

you could just add a \ at the end of your windowsFolder path. This will mark the end of the word and allow you to match only the correct pattern: C:\Windows\

Looking closer at the problem actually the call :

string windowsFolder = Environment.GetFolderPath(Environment.SpecialFolder.Windows);

returns C:\WINDOWS . But the Contains method is case sensitive. This would lead to a false match even with this path: C:\Windows\system32. You can use ToLower to make it case insensitive

if (path.ToLower().Contains(windowsFolder.ToLower() + "\\"))

another approach would be to parse the path up the parent hierarchy using Directory.GetParent and check each parent using the Equals method. It will allow you for a case insensitive comparison if you use the StringComparison.OrdinalIgnoreCase option

private static bool IsInsideWidowsFolder(string path)
{
    // windowsFolder = "C:\WINDOWS"
    string windowsFolder = Environment.GetFolderPath(Environment.SpecialFolder.Windows);

    string parent = "";
    while ((parent = Directory.GetParent(path)?.FullName) != null)
    {
        if (windowsFolder.Equals(parent, StringComparison.OrdinalIgnoreCase))
        {
            return true;
        }
        path = parent;
    }

    return false;
}

This answer shows pretty much the same: stackoverflow.com/a/5617346/440030 . But your seems better. — InfernumDeus, Jan 29 '18 at 09:15
@InfernumDeus ah seems legit. shall we mark it as duplicate ?=! — Mong Zhu, Jan 29 '18 at 09:18
@InfernumDeus but actually your question has the case sensitivity part, which lacks in the other question and some of the answers, so I would not vote for a dauplicate — Mong Zhu, Jan 29 '18 at 09:20
I consider it connected but not the same. People may search for something like that. — InfernumDeus, Jan 29 '18 at 09:53

score 0 · Answer 2 · answered Jan 29 '18 at 08:00

You can ensure both paths have backslashes

public static string EnsureBackSlash(this string input)
{
    return Path.GetFullPath(input)
        .TrimEnd(Path.DirectorySeparatorChar, Path.AltDirectorySeparatorChar)
        + Path.DirectorySeparatorChar;
}

score 0 · Answer 3 · answered Jan 29 '18 at 08:04

0

Append a backslash on windowsFolder

string windowsFolder = Environment.GetFolderPath(Environment.SpecialFolder.Windows) + "\\";

You may also want to use a case insensitive method for checking such as:

return path.IndexOf(windowsFolder, StringComparison.OrdinalIgnoreCase)==0;

answered Jan 29 '18 at 08:04

Jim Berg

609
4
7

Mong Zhu's answer is more complete, but instead of using Directory.GetParent you should use Path.GetDirectoryName. Directory will actually use the file system to figure out the parent directory (disk reads involved) while Path will just parse the path string which will be more efficient. – Jim Berg Jan 29 '18 at 08:18

Correct way to check if some path refers to something inside specified folder

3 Answers3