How to set clear attribute "X" on files with in C#?

Question

I have a hidden file on my USB removable storage (FAT file system).

I'm using Windows 7. If I go to Properties window of this file and then to the Details tab, I will see that the attributes of the file are HX. When I run cmd and use attrib, I was told that file has attribute H. Nothing about X. I've tried help attrib, but still nothing about attribute X.

I know that:

• H = Hidden
• S = System
• A = Archival
• R = Readonly

However, I have no idea what X stands for. I've also found what the N and E attributes are for.

Wikipedia has no mention of what the X attribute is.

Google found two topics mentioning attribute X:

• undeletable file in delphi
• file attribute of x.
• "better attrib"

None of these helped.

I'd like to be able to read/write this flag in C#, but so far I read the documentation for the FileAttributes enumeration and experimented with setting some of listed attributes (using File.GetAttributes & File.SetAttributes methods) on the file.

None of these experiments resulted in attribute X showing up in Properties -> Details. So, I have no idea how to approach it, especially since I still don't know what attribute X means.

So, what is attribute X and how can one set/clear it on the selected file in C#?

Answer 1

Unfortunately, the Windows API will prevent you from setting/unsetting FILE_ATTRIBUTE_DEVICE because it isn't meant to be set on files. If you really need the ability to do that you'll have to access the disk directly. I don't really recommend trying to do that in C#.

The quickest possible implementation would probably be to forget about doing it in Windows, download the source for mtools and make a couple of edits to the mattrib source in order to get it working.

eg add to msdos.h:

#define ATTR_DEVICE 0x40
#define IS_DEVICE(entry) (HAS_BIT((entry),ATTR_DEVICE))

Then add the code to mattr.c so you can set the attribute and verify the change:

static int view_attrib(direntry_t *entry, MainParam_t *mp)
{
    ...
    /* Add this if block */
    if(IS_DEVICE(entry))
        putchar('X');
    ...
}


static int concise_view_attrib(direntry_t *entry, MainParam_t *mp)
{
    ...
    /* Add the following if block */
    if(IS_DEVICE(entry))
        putchar('X');
    ...
}

static int letterToCode(int letter)
{
    switch (toupper(letter)) {
        ...
        /* Add the following case */
    case 'X':
        return ATTR_DEVICE;
        ...
    }
}

Then you would just have to setup your drive on mtools and call your newly created mattrib -x command on the file you wish to change.

Answer 2

File Attribute X correspondes to System.IO.FileAttributes.Device which has an integer value of 64 (0x40) using .NET you cannot directly set this value. The problem is that when you call File.SetAttributes(path, fileAttributes) it calls an internal dll import function in Mscorlib.dll, namely the static method Microsoft.Win32.Win32Native.SetFileAttributes, this is a direct dll import of kernel32.dll and is defined as:

// Microsoft.Win32.Win32Native
[DllImport("kernel32.dll", BestFitMapping = false, CharSet = CharSet.Auto, SetLastError = true)]
internal static extern bool SetFileAttributes(string name, int attr);

So put simply, even using kernel32.dll you cannot set this value. See: SetFileAttributes, and System.IO.FileAttributes.

But, you can write code that will effectively do the same as setting or removing this attribute.

Your best and likely only (reasonable) answer would be to keep a template file with the X permission, when you need to set a file to have X you rename the existing file, copy the template X file and then write the other attributes.

For removing the X permission you should read the file and write to a new file and then copy there permissions using a simple call to File.SetAttributes(path, File.GetAttributes(oldPath)); (which won't set the X permission.

This approach is pretty straight forward and would be entirely possible in native .NET (and wouldn't actually look too nasty either, compared to hacking around at the disk level or invoking cgywin - if that would even work).

Answer 3

Maybe I'm wrong but... I think that X attribute means that the file has extended attributes. Unfortunately, extended attributes can't be modified using C#.

Answer 4

I cannot reproduce your issue but as workaround to remove that attribute I think you can try with robocopy:

robocopy xattributefile copyoffile /copy:DT

/copy:DT: Specifies the file properties to be copied.

This should not copy attribute but i don't know if it works with X attribute)

Answer 5

The X is most likely the execute permissions. icalcs mentions it and you can possibly use this command from C# to set a file attribute, although I am not sure if it will work against a FAT filesystem or not.