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AutoIt3 - read shared memory data example


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After coming across this post on the AutoIt forums while researching how to access shared memory of processes in AutoIt, I decided to have a go at translating the Delphi example code.

Below is a function w/ a working example showing how to access the AIDA64 shared memory.

First enable shared memory here: Preferences > Hardware Monitoring > External Applications > Enable Shared Memory

The length of the data depends on the number of active sensors and their content. As AIDA64 does not provide a buffer size value, we use _WinAPI_GetSystemInfo() <WinAPISys.au3> to get dwPageSize ($aArray[1]). This value is then used as an address offset, and we continue reading chunks of data until we encounter a 0x00 NUL character.

Based on the Delphi example found in the AIDA64 documentation: https://www.aida64.co.uk/user-manual/external-applications

Feedback appreciated, especially as all this shared memory stuff is not my ordinary cup of... cake. And regarding this whole ordeal of reading data without knowing the exact length; I'm suspecting my solution to read chunks of data like done below is not by the book, and I'm concerned what might happen if the final chunk is exactly 4096 bytes in length. Will there still be a NUL terminator there? Hmm.


#include <WinAPIFiles.au3>
#include <WinAPISys.au3>

; #INDEX# ===========================================================================================================================
; Title .........: AIDA64 Shared Memory access for AutoIt3
; Author(s) .....: demux4555
; Reference .....: https://www.aida64.co.uk/user-manual/external-applications
; ===================================================================================================================================

Global $vSharedmem_data                                                             ; The variable used to store the data we read from the shared memory
Global $return = ExtApp_SharedMem_ReadBuffer_v2($vSharedmem_data)                   ; Now, let's see what happens when we run the function...
If @error Then _Echo("! ExtApp_SharedMem_ReadBuffer_v2(): @errror = " & @error)

If IsBinary($vSharedmem_data) Then                                                  ; Convert type Binary to actual human readable text. We also remove the excess of trailing 0x00 characters.
    $vSharedmem_data = StringStripWS(BinaryToString($vSharedmem_data), $STR_STRIPLEADING+$STR_STRIPTRAILING)

_Echo("> return   = " & $return)                                                    ; The return value. Will be True if everything went ok.
_Echo("> length   = " & StringLen($vSharedmem_data))                                ; The number of characters read from shared memory.
_Echo("> data     = " & $vSharedmem_data)                                           ; The actual data.
_Echo("> data(40) = " & "..." & StringRight($vSharedmem_data, 40))                  ; shows the 40 right-most characters, and _should_ show the very end of the data at this point.


; #FUNCTION# ====================================================================================================================
; Name ..........: ExtApp_SharedMem_ReadBuffer_v2
; Description ...: AIDA64 Shared Memory Example for AutoIt3
; Syntax ........: ExtApp_SharedMem_ReadBuffer_v2(Byref $_dOutput[, $_sSharedmemName = "AIDA64_SensorValues"])
; Parameters ....: $_dOutput            - [in/out] Variable to store the read data.
;                  $_sSharedmemName     - [optional] Name of the AIDA64 shared memory. Default is "AIDA64_SensorValues".
; Return values .: Success: True. $_dOutput will be type Binary, containing a string of the XML values of the active sensors.
;                  Failure: False.
; Author ........: demux4555
; Reference .....: https://www.aida64.co.uk/user-manual/external-applications
; ===============================================================================================================================
Func ExtApp_SharedMem_ReadBuffer_v2(ByRef $_dOutput, $_sSharedmemName = "AIDA64_SensorValues")
    Local $_bReturn     = False
    Local $_aGSI        = _WinAPI_GetSystemInfo()                                   ; Retrieves information about the current system...                                                                     Ref: https://docs.microsoft.com/en-us/windows/win32/api/sysinfoapi/nf-sysinfoapi-getsysteminfo
    Local $_iPageSize   = $_aGSI[1]                                                 ; ... the page size and the granularity of page protection and commitment. Usually it is 4096, but we read it anyway.   Ref: https://docs.microsoft.com/en-us/windows/win32/api/sysinfoapi/ns-sysinfoapi-system_info

    Local $_hMapping    = _WinAPI_OpenFileMapping($_sSharedmemName, $FILE_MAP_READ) ; Opens a named file mapping object.                                                                                    Ref: https://docs.microsoft.com/en-us/windows/win32/api/memoryapi/nf-memoryapi-openfilemappingw
    If Not IsPtr($_hMapping) Then Return SetError(-2, 0, $_bReturn)

    Local $_pMappedData = _WinAPI_MapViewOfFile($_hMapping, 0, 0, $FILE_MAP_READ)   ; Pointer to the start address. Maps a view of a file mapping into the address space of a calling process.              Ref: https://docs.microsoft.com/en-us/windows/win32/api/memoryapi/nf-memoryapi-mapviewoffile
    If @error Or Not IsPtr($_pMappedData) Then Return SetError(-2, 0, $_bReturn)

    ; Now we loop until we reach the end of the data.
    Local $_tData, $_dBuffer
    While 1
        $_tData     = DllStructCreate("BYTE[" & $_iPageSize & "]", $_pMappedData)   ; Note: we use type BYTE[] (AutoIt type Binary) instead of CHAR[] (AutoIt type String). This allows us to look for value 0x00 (NUL termination of the data).
        If @error Then ExitLoop

        $_dBuffer   = DllStructGetData($_tData, 1)                                  ; The returned value is type Binary.
        If @error Or ($_dBuffer==0) Or (BinaryLen($_dBuffer)=0) Then ExitLoop       ; Pretty sure $_dBuffer==0 can not happen, so just in case.

        $_dOutput   = Binary($_dOutput & $_dBuffer)                                 ; Add the read data to the end of the output variable.
        If StringRight($_dBuffer, 2)=="00" Then ExitLoop                            ; Look for NUL termination of the string data.
        $_pMappedData += $_iPageSize                                                ; We change the address by using the page granularity value (i.e. 4096) as the offset.

    ; Quick cleanup
    $_bReturn       = _WinAPI_UnmapViewOfFile($_pMappedData)=1                      ; Unmaps a mapped view of a file from the calling process's address space.                                              Ref: https://docs.microsoft.com/en-us/windows/win32/api/memoryapi/nf-memoryapi-unmapviewoffile

    Return $_bReturn


Func _Echo($_data = "")
    ConsoleWrite($_data & @CRLF)


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