Mail Archives: cygwin/2001/06/14/17:09:25
Slight goof on that post. The make file I posted didn't have everything set
(it was missing the -lole32 flag to the link). Here is the correct
makefile:
-----------------
makefile
-----------------
.PHONY: clean all
istreamtest.exe : istreamtest.obj
gcc -o istreamtest.exe -mwindows -mno-cygwin -lole32 istreamtest.obj
istreamtest.obj : IStreamTest.cpp
gcc -c -o istreamtest.obj -g -fvtable-thunks -e _mainCRTStartup
istreamtest.cpp
clean :
rm istreamtest.exe istreamtest.obj
all : istreamtest.exe
-----Original Message-----
From: Paul K Gleske [mailto:pkg AT gleske DOT org]
Sent: Thursday, June 14, 2001 4:40 PM
To: cygwin AT cygwin DOT com
Subject: RE: Issue calling Com function(s)
I've made a simple program that isolates the trouble I've been having
getting CreateStreamOnHGlobal to work. I've included the source file
(IStreamTest.cpp) and the makefile. As I don't know if this list allows
attachments the files are here in their entirety.
The problem I'm having now is a link issue. It keeps complaining that
CoInitialize and CreateStreamOnHGlobal are not found. I wanted to get a
very simple program working in VC and gcc and then I would tackle my big
program. But, the simple program won't even link now.
BTW, this program works correctly when compiled and linked as a VC++
project.
Thanks for the link to the description of -fvtable-thunk. However, I don't
think it helps me to understand how/when it should be used. There is the
comment that all libs must be re-compiled including libgcc.a. How do I do
that? Is it really necessary? How does this vtable-thunk help the call to
the IStream pointer?
tia,
-pkg
-----------------
IStreamTest.cpp
-----------------
// IStreamTest.cpp
//
#define WIN32_LEAN_AND_MEAN // Exclude rarely-used stuff from Windows
headers
#include <stdio.h>
#include <objbase.h>
#include <ole2.h>
int main(int argc, char* argv[])
{
printf("Hello World!\n");
// First init Com
HRESULT hr = CoInitialize(NULL);
char data[] = "This is the data for the IStream";
DWORD size = sizeof(data);
UINT flags = LMEM_MOVEABLE | LMEM_NODISCARD | LMEM_ZEROINIT;
HLOCAL block = ::LocalAlloc(flags, size);
if (block) {
// Load the allocated memory block with data.
memcpy(LocalLock(block), data, size);
LocalUnlock(block);
// Create the stream from the HGlobal
IStream *is;
if( hr=CreateStreamOnHGlobal(block, FALSE, &is) == S_OK ) {
// Now try to use the stream
STATSTG stats;
if (is->Stat(&stats, STATFLAG_NONAME) == S_OK ) {
printf("We were able to get the stats\n");
}
// All done, release the stream
is->Release();
}
}
// Free up the memory block
if (!block)
::LocalFree(block);
return 0;
}
/// End of IStreamTest.cpp
-----------------
makefile
-----------------
.PHONY: clean all
istreamtest.exe : istreamtest.obj
gcc -o istreamtest.exe -mwindows -mno-cygwin istreamtest.obj
istreamtest.obj : IStreamTest.cpp
gcc -c -o istreamtest.obj -g -fvtable-thunks -e _mainCRTStartup
istreamtest.cpp
clean :
rm istreamtest.exe istreamtest.obj
all : istreamtest.exe
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