Delphi 中的 COM 方法偏移量 [英] COM method offsets in Delphi

问题描述

在Delphi 中，如何找出COM 方法的地址?我可以硬编码偏移量

In Delp how do I find out the the address of a COM method? I can hardcode the offsets

//0 is the offset of the QueryInterface method
p := TPonterArray(pointer(SomeInterface)^)[0];

但我更喜欢使用符号名称.以下显然不起作用:

but I would prefer to use symbolic names. The folllowing obviously does not work:

var M : TMethod;
...
M := TMethod(SomeInterface.QueryInterface);

谢谢！

推荐答案

您可以使用 vmtoffset 汇编指令来获取接口方法相对于接口方法表开头的字节偏移量.看看System.pas中_IntfCast的实现，例如:

You can use the vmtoffset assembler directive to get the byte offset of an interface method relative to the start of the interface's method table. Take a look at the implementation of _IntfCast in System.pas, for example:

call dword ptr [eax] + vmtoffset IInterface.QueryInterface
...
call dword ptr [eax] + vmtoffset IInterface._Release

第一个表达式加0；第二个，8.

The first expression adds 0; the second, 8.

但是，您不能参数化这些表达式.它们是编译时常量，因此您无法在运行时选择所需的方法.您需要提前表示所有可能的方法名称.

You cannot parameterize those expressions, though. They're compile-time constants, so you cannot choose which method you want at run time. You need to have all possible method names represented in advance.

您真正需要挂钩的只是QueryInterface.一旦你有了它，你就可以返回任何你想要的代理对象，它可以拦截对所有其他方法的调用.

All you really need to hook is QueryInterface. Once you have that, you can return whatever proxy object you want that can intercept calls to all the other methods.

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