InstallDllImportHook - Hook calls between modules
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<aHookInfo> := InstallDllImportHook( <cCallingModule>, <cCalledFunctionName>, <cCalledModule>, <nCallback> )
Name of module from which calls to <cCalledFunctionName> are to be hooked.
Name of function to which calls from <cCallingModule> are to be hooked.
Name of module to which calls are to be hooked.
When the operation succeeds an Array of two numeric elements (LONG values) is returned. The first element is the memory address of the original call address in the import table of <cCallingModule> that was modified. The constant to access it is DLLHOOKINFO_INDEX_HOOKADDRESS. The second element is the original call address found in the import table. The constant to access it is DLLHOOKINFO_INDEX_ORIGINALPROCADDRESS. These values can later be used to restore the original call with RemoveDllImportHook.
If the operation fails, NIL is returned.
InstallDllImportHook hooks calls between modules. When a module is loaded, its calls to functions in other modules must be "resolved". Normally the load address of a called module is not known at link time, hence the final addresses of called functions in it cannot be placed in the calling module at link time. This resolution takes place when a module is loaded. Every module comes with an import table containing references to all used functions in other modules. After loading a module (and the ones which it needs that have not been loaded before) the loader fixes its import table: All memory addresses of the used functions are written to its import table. This import table is changed by InstallDllImportHook.
The installed callback must receive the passed parameters and use the correct calling convention. If the call is not handled by the callback, it must pass on to the original function. This can be accomplished with CallAddress using the second element of <aHookInfo> as address to be called. Don't forget to pass on the received parameters in this case.
Library: cckptcor.lib /cckptcor.dll