Check write permission

[Terenz]

How can i know if i can write a file in a folder without really write a file and check for errors?

[youtuber]

Is there a code snippet? sample code

[Terenz]

Snippet of what? I have ask a question and i expect an answer like "use this API-function" because i don't have found nothing except check error code if the function fail example FileOpen/IniWrite and so on.

[Danyfirex]

You can do this.

 

I don't have time to traslate it to AutoIt . but it's easy.

 

Regards

[water]

Maybe this UDF helps

 

[orbs]

following this:

this is a rephrasing of mine. it works with files as well as folders, local and network - and even knows when elevation is required. try this - uncomment the first line:

; #RequireAdmin
MsgBox(0, '', _PathIsWritable(@SystemDir) & @CRLF) ; without @RequireAdmin this should return False, with @RequireAdmin this should return True.

Func _PathIsWritable($sFile)
    Local $aRet = DllCall('kernel32.dll', 'handle', 'CreateFileW', _
            'wstr', $sFile, _
            'dword', 2, _
            'dword', 7, _
            'struct*', 0, _
            'dword', 3, _
            'dword', 0x02000000, _
            'handle', 0)
    If @error Or $aRet[0] = Ptr(-1) Or $aRet[0] = 0 Then Return False
    DllCall('kernel32.dll', 'bool', 'CloseHandle', 'handle', $aRet[0])
    Return True
EndFunc   ;==>_PathIsWritable

z

[guinness]

@orbs I would prefer you use the _WinAPI_* associated calls than DllCall, as not everyone is familiar with these.

[Terenz]

Danyfirex,

I'm not able to convert that. When you have time, for future reference...

Orbs,

Really a fast and easy solution using _WinAPI_CreateFileEx() thanks to all

Edited June 5, 2016 by Terenz

[Danyfirex]

Hello. Here you have.

 

expandcollapse popup

#include <WinAPIProc.au3>
#include <WinAPI.au3>
Opt("MustDeclareVars", 1)
#RequireAdmin
Global Const $OWNER_SECURITY_INFORMATION = 0x1
Global Const $GROUP_SECURITY_INFORMATION = 0x2
Global Const $DACL_SECURITY_INFORMATION = 0x4
Global Const $FILE_GENERIC_READ = 0x120089 ;STANDARD_RIGHTS_READ Or FILE_READ_DATA Or FILE_READ_ATTRIBUTES Or _FILE_READ_EA Or SYNCHRONIZE
Global Const $FILE_GENERIC_WRITE = 0x120116 ;STANDARD_RIGHTS_WRITE Or FILE_WRITE_DATA Or FILE_WRITE_ATTRIBUTES Or _FILE_WRITE_EA Or FILE_APPEND_DATA Or SYNCHRONIZE
Global Const $FILE_GENERIC_EXECUTE = 0x1200A0 ;STANDARD_RIGHTS_EXECUTE Or FILE_READ_ATTRIBUTES Or FILE_EXECUTE Or SYNCHRONIZE
Global Const $FILE_ALL_ACCESS = 0x1F01FF ;STANDARD_RIGHTS_REQUIRED Or SYNCHRONIZE Or &H1FF
Global Const $sTag_GENERIC_MAPPING = "dword GenericRead;dword GenericWrite;dword GenericExecute;dword GenericAll;"





If _CanAccessFolder("C:\System Volume Information", $GENERIC_WRITE) Then
    MsgBox(0, ":)", "I can Write...")
Else
    MsgBox(0, ":(", "I can't Write...")
EndIf


If _CanAccessFolder("C:\", $GENERIC_WRITE) Then
    MsgBox(0, ":)", "I can Write...")
Else
    MsgBox(0, ":(", "I can't Write...")
EndIf


Func _CanAccessFolder($sDir, $genericAccessRights)
    Local $bRet = False


    Local $tSecurityDescriptor = _GetSecurityDescriptor($sDir)
    ConsoleWrite("$tSecurityDescriptor: " & DllStructGetData($tSecurityDescriptor, 1) & @CRLF)

    Local $hToken = _WinAPI_OpenProcessToken(BitOR($TOKEN_IMPERSONATE, $TOKEN_QUERY, $TOKEN_DUPLICATE, $STANDARD_RIGHTS_READ))

    ConsoleWrite("$hToken: " & $hToken & @CRLF)

    Local $hImpersonatedToken = _WinAPI_DuplicateTokenEx($hToken, 0, $SECURITYIMPERSONATION, $TOKENIMPERSONATION)
    ConsoleWrite("$hImpersonatedToken: " & $hImpersonatedToken & @CRLF)

    Local $tmapping = DllStructCreate($sTag_GENERIC_MAPPING)

    $tmapping.GenericRead = $FILE_GENERIC_READ
    $tmapping.GenericWrite = $FILE_GENERIC_WRITE
    $tmapping.GenericExecute = $FILE_GENERIC_EXECUTE
    $tmapping.GenericAll = $FILE_ALL_ACCESS

    _MapGenericMask($tmapping, $genericAccessRights)
    ConsoleWrite("$genericAccessRights: " & $genericAccessRights & @CRLF)

    Local $tprivilege_set = DllStructCreate("dword;dword;dword;dword;dword")

    Local $aRet = DllCall("Advapi32.dll", "bool", "AccessCheck", "ptr", DllStructGetPtr($tSecurityDescriptor), "handle", $hImpersonatedToken, "dword", $genericAccessRights, _
            "ptr", DllStructGetPtr($tmapping), "ptr", DllStructGetPtr($tprivilege_set), "dword*", DllStructGetSize($tprivilege_set), "dword*", 0, "bool*", 0)

    $bRet = $aRet[8]

    If $hImpersonatedToken Then _WinAPI_CloseHandle($hImpersonatedToken)
    If $hToken Then _WinAPI_CloseHandle($hToken)


    Return $bRet

EndFunc   ;==>_CanAccessFolder












Func _GetSecurityDescriptor($sDir)
    Local $aRet = DllCall("Advapi32.dll", "bool", "GetFileSecurityW", _
            "wstr", $sDir, _
            "dword", BitOR($OWNER_SECURITY_INFORMATION, $GROUP_SECURITY_INFORMATION, $DACL_SECURITY_INFORMATION), _
            "ptr", Null, _
            "dword", Null, _
            "dword*", 0)

    Local $iBufferSize = $aRet[5]

    ConsoleWrite("$iNeededSize: " & $iBufferSize & @CRLF)

    Local $tSecurityDescriptor = DllStructCreate("byte[" & $iBufferSize & "]")

    $aRet = DllCall("Advapi32.dll", "bool", "GetFileSecurityW", _
            "wstr", $sDir, _
            "dword", BitOR($OWNER_SECURITY_INFORMATION, $GROUP_SECURITY_INFORMATION, $DACL_SECURITY_INFORMATION), _
            "ptr", DllStructGetPtr($tSecurityDescriptor), _
            "dword", $iBufferSize, _
            "dword*", 0)
    Return $tSecurityDescriptor
EndFunc   ;==>_GetSecurityDescriptor


Func _MapGenericMask(ByRef $GenericMapping, ByRef $genericAccessRights)
    Local $aRet = DllCall("Advapi32.dll", "none", "MapGenericMask", "dword*", $genericAccessRights, "ptr", DllStructGetPtr($GenericMapping))
    $genericAccessRights = $aRet[1]
EndFunc   ;==>_MapGenericMask

Saludos

[Trong]

I think to check write permissions on the current permissions,  simply is write test files!

Edited June 5, 2016 by Trong
grammar

[water]

But that's exactly what the OP tries to avoid!

Quote

without really write a file and check for errors?

 

[Trong]

Yes!

I tested the code of @Danyfirex, it working faster test file writes. 

[Terenz]

Thanks Danyfirex, i'll study it and i'm sure in future will be useful also to others. It require admin because the folder you have choice or in any case?

Trong i need to check many directory...write file-delete file, write file-delete file and so on isn't be best choice for me or i'll be using simply FileOpen and check the return.

Edited June 6, 2016 by Terenz

[orbs]

@Terenz,

30 minutes ago, Terenz said:

... i need to check many directory ...

the solutions you are offered here are more suitable for a script running at user level to check that it is allowed to write to a specific folder or file before actually doing so, to avoid errors. if you need a mass checkup operation, then perhaps a dedicated utility is due here? look at Sysinternals security utilities here, and more specifically at AccessEnum on that page - this utility traverses the directory tree and displays users permissions in a very convenient manner.

 

[Danyfirex]

5 hours ago, Terenz said:

Thanks Danyfirex, i'll study it and i'm sure in future will be useful also to others. It require admin because the folder you have choice or in any case?

Trong i need to check many directory...write file-delete file, write file-delete file and so on isn't be best choice for me or i'll be using simply FileOpen and check the return.

Hello. #RequiereAdmin Is just for test that even if you run with admin you can't write in "C:\System Volume Information" But can in "C:\".  (All this if UAC is enable)

You can check removing #RequiereAdmin and will notice that you can't write in "C:\" (If UAC is enable).

 

Saludos

 

[DannyJ]

il

[Somerset]

Don't bump threads.

That is what i am assuming, you are doing.