Oddity Copying Global Memory

[Steve Thresher]

Can anybody tell me why copying an unlocked block of global memory using memcpy() would cause the call stack to change. The code looked like this: UINT size=GlobalSize(hGlobal); LPBYTE pBuffer=new BYTE[size]; // Buffer allocation is successful memcpy(pBuffer,hGlobal,size); // <-- Call stack changes in memcpy() I realised the problem was caused by not using GlobalLock() to get the actual address of the memory to copy but I have no idea why using the hGlobal handle as the source address would cause the call stack to change! Systems AXIS Ltd - Software for Business ...

[Mukkie]

Hello! GlobalAlloc() returns a "handle to the newly allocated memory object", and this does not mean pointer to allocated memory. So I suspect, that this handle is a pointer to structure, in which one of the field is pointer to memory (only suspission). But: it did not overwrite my stack: HANDLE hGlobal = GlobalAlloc( GMEM_ZEROINIT, 2048); UINT size=GlobalSize(hGlobal); LPBYTE pBuffer=new BYTE[size]; // Buffer allocation is successful memcpy(pBuffer,hGlobal,size); // <-- Call stack changes in memcpy() If you want to use memory pointer, take a look at the flag GMEM_FIXED in GlobalAlloc() :)