Read/WriteProcessMemory examples, GetLastError()

[krll-kov]

👋 Does someone have any example of proper usage of ReadProcessMemory and WriteProcessMemory? Because for me function always returns 0 (what means that it did not succeed) and i have no idea what is wrong because GetLastError() does not work either and i can not check msdn error codes to find out the problem.

static int readProcessMemory(int lpBaseAddress, int nSize) {

    Pointer<Uint32> _lpBaseAddress = calloc<Uint32>();
    _lpBaseAddress.value = lpBaseAddress;
    Pointer<Uint32> lpBuffer = calloc<Uint32>();

    int result = ReadProcessMemory(activeHandle, _lpBaseAddress, lpBuffer, nSize, nullptr);
    print(result);

    return lpBuffer.value;
  }

Handle to the process is opened with full access flag and application is launched with admin privileges.

[dcharkes]

GetLastError does not work at this point dart-lang/sdk#38832.

[dcharkes]

As a workaround you could write some C code that wraps your call and GetLastError and then call this helper function from Dart.

[krll-kov]

How to do it?. I saw that android and ios flutter has a platform.invokeMethod functionality, but i did not see any examples or usage for desktop Windows

[mraleph]

First of all, you have a number of bugs in your code. You are passing a pointer to a pointer into the function (you even truncate it for some reason by doing int64 to int32 conversion), but you should just pass a pointer, e.g.

ReadProcessMemory(activeHandle, Pointer<int>.fromAddress(lpBaseAddress), lpBuffer, nSize, nullptr)

Then you should make sure that lpBuffer has enough space to store the data you are reading (it should have nSize bytes capacity).

Finally, make sure that process handle has READ access right associated with it.

[krll-kov]

static int readProcessMemory(int lpBaseAddress, int nSize) {
    Pointer<Int64> lpBuffer = calloc<Int64>();

    int result = ReadProcessMemory(activeHandle, Pointer<Int64>.fromAddress(lpBaseAddress), lpBuffer, nSize, nullptr);
    print(result);

    return lpBuffer.value;
  }

activeHandle has full access rights, application is launched with admin rights. lpBuffer has enough size, but the function still returns 0

[krll-kov]

If anyone is looking for the answer:

static int readProcessMemory(int lpBaseAddress, num nSize) {
    Pointer<Int32> lpBuffer = calloc<Int32>();

    ReadProcessMemory(activeHandle,
        Pointer<Int32>.fromAddress(lpBaseAddress), lpBuffer, nSize.toInt(), nullptr);

    return lpBuffer.value;
  }

nSize should be the same size as lpBuffer, not more, not less. (after working with java jni i thought that it's okay to make nSize even more than buffer itselft)

However, writeProcessMemory still fails and i have no idea how to use it properly