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Deleting folders is a risky business

, 30 Jan 2012 CPOL
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Deleting folder programmatically is extremely dangerous. It can erase your system.
Deleting folder programmatically is extremely dangerous. It is enough for somebody else to change a configuration file or constant variable including the target folder's name to, say C:\, and that's it: the workstation is paralyzed!
 
Following suggested methods are to prevent such a situation. Their aim is to wrap the low level, possibly recursive file system operation with the necessary validation and clear facade - look twice, delete once.
 

Delete temporary directory created by current user (non recursive!)

 
    /// <summary>
    /// carefully remove directory and its files
    /// verify the directory is located under the %temp%
    /// and it is not e.g. C:\
    /// </summary>
    /// <param name="dir"></param>

    public static void DeleteTempDirShallow(string dir)
    {
        // check if it is an invalid directory path,
        // e.g. a disk drive or just a bad string

        if (! Directory.Exists(dir)) return;
 
        DirectoryInfo userTempDirInfo = new DirectoryInfo(Path.GetTempPath());
        DirectoryInfo dirInfo = new DirectoryInfo(dir);
 
        if (dirInfo.FullName.Contains(userTempDirInfo.FullName))
        {
            foreach (FileInfo file in dirInfo.GetFiles())
                file.Delete();
 
            dirInfo.Delete(); // just clean up the empty dir
        }
    }
 

Delete temporary directory created by current user (recursive!)

 
    public static void DeleteTempDirRecursive(string dir)
    {
        // check if it is an invalid directory path,
        // e.g. a disk drive or just a bad string
        if (! Directory.Exists(dir)) return;
 
        DirectoryInfo userTempDirInfo = new DirectoryInfo(Path.GetTempPath());
        DirectoryInfo dirInfo = new DirectoryInfo(dir);
 
        if (dirInfo.FullName.Contains(userTempDirInfo.FullName))
        {
            dirInfo.Delete(recursive: true);
        }
    }
 

Do I try to delete any root or system folder?

 
    static List<string> systemDirs = new List<string>
    {
        Environment.GetFolderPath(Environment.SpecialFolder.CommonProgramFiles),
        Environment.GetFolderPath(Environment.SpecialFolder.CommonProgramFilesX86),
        Environment.GetFolderPath(Environment.SpecialFolder.CommonPrograms),
        Environment.GetFolderPath(Environment.SpecialFolder.CommonStartMenu),
        Environment.GetFolderPath(Environment.SpecialFolder.CommonStartup),
        Environment.GetFolderPath(Environment.SpecialFolder.Fonts),
        Environment.GetFolderPath(Environment.SpecialFolder.NetworkShortcuts),
        Environment.GetFolderPath(Environment.SpecialFolder.PrinterShortcuts),
        Environment.GetFolderPath(Environment.SpecialFolder.ProgramFiles),
        Environment.GetFolderPath(Environment.SpecialFolder.ProgramFilesX86),
        Environment.GetFolderPath(Environment.SpecialFolder.Resources),
        Environment.GetFolderPath(Environment.SpecialFolder.StartMenu),
        Environment.GetFolderPath(Environment.SpecialFolder.Startup),
        Environment.GetFolderPath(Environment.SpecialFolder.System),
        Environment.GetFolderPath(Environment.SpecialFolder.SystemX86),
        Environment.GetFolderPath(Environment.SpecialFolder.Templates),
        Environment.GetFolderPath(Environment.SpecialFolder.UserProfile),
        Environment.GetFolderPath(Environment.SpecialFolder.Windows),
    };
 
    /// <summary>
    /// check if the argument dir is a disk drive,
    /// is a system (sub-)folder
    /// and should not be erased
    /// </summary>
    /// <param name="dir"></param>
    /// <returns></returns>
    public static bool IsSystemOrRootDir(string dir)
    {
        // check if it is an invalid directory path,
        // or just a bad string
        if (! Directory.Exists(dir)) return true;
 
        DirectoryInfo dirInfo = new DirectoryInfo(dir);
 
        // is it a root (disk drive)? 
        if (dirInfo.Parent == null) return true;
 
        bool result = false;
        systemDirs.ForEach(sysDir => { result = result ||
                                       dirInfo.FullName.Contains(sysDir); } );
        return result;
    }
 

References

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

Michael Gr

United States United States
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Comments and Discussions

 
GeneralMy vote of 5 Pinmemberhypermellow11-Feb-13 23:53 
GeneralMy vote of 4 Pinmemberjfriedman13-May-12 4:57 
GeneralRe: My vote of 4 PinmemberDelphiCoder31-Aug-14 13:36 
GeneralRe: Thank You! PinmemberMichael Gr30-Jan-12 3:10 
GeneralRe: OK , I updated my Vote, +5 PinmemberRajesh Anuhya30-Jan-12 2:55 
Generalnice !! PinmemberAbhishek Unnikrishnan12-Feb-12 6:45 
GeneralReason for my vote of 5 I wasn't aware of this in 24 years o... Pinmemberjavaevangelist7-Feb-12 9:18 
GeneralReason for my vote of 5 Very nice PinmemberTigerHajtos6-Feb-12 22:24 
GeneralReason for my vote of 5 I have to admit, I have never (thank... PinmemberMarek Roszak6-Feb-12 21:55 
GeneralNever thought about this.. Thankyou. Have 5 PinmemberPankaj Chamria30-Jan-12 3:55 
GeneralRe: Thanks Pankaj. PinmemberMichael Gr30-Jan-12 23:34 
GeneralCopied from Here:http://codereview.stackexchange.com/questio... PinmemberRajesh Anuhya30-Jan-12 2:18 
GeneralReason for my vote of 1 Copied from Here : http://codereview... PinmemberRajesh Anuhya30-Jan-12 2:18 
GeneralRe: Dear Rajesh. Actually I have published the article first at ... Pinmemberquiet.step30-Jan-12 2:38 
GeneralReason for my vote of 5 Very nice! PinmemberPablo Aliskevicius29-Jan-12 20:35 
GeneralRe: Thanks. PinmemberMichael Gr30-Jan-12 3:11 

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