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Call HtmlHelp API from C++ compiled with SCC

 
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Ryan



Joined: 25 Feb 2016
Posts: 15

PostPosted: Thu Feb 25, 2016 9:32 pm    Post subject: Call HtmlHelp API from C++ compiled with SCC Reply with quote

I have an existing hybrid Fortran / C++ app that calls WinHelp.

I have rewritten the API call from WinHelp to HtmlHelp as we are now using the newer help format.

Unfortunately I cannot get the SCC / SLINK combination to bring in the HtmlHelp library.

In the C++ code I have 'Include "HtmlHelp.h"' at the top and reworked the API call, this passes through the compiler OK.

The problem comes when I link using SLINK, it is finding and using the htmlhelp.lib file fine, but this has a further dependency on some other API calls with odd prefixes. I've included the command 'lo htmlhelp.lib' to reference the file.

The errors generated are;

Code:
WARNING the following symbols are missing:
_imp__GetProcAddress                     H:\MyApp\htmlhelp.lib (/0             )
                                              (release/init.obj)
_imp__LoadLibraryA                       H:\MyApp\htmlhelp.lib (/0             )
                                              (release/init.obj)
_imp__RegCloseKey                        H:\MyApp\htmlhelp.lib (/0             )
                                              (release/init.obj)
_imp__RegQueryValueExA                   H:\MyApp\htmlhelp.lib (/0             )
                                              (release/init.obj)
_imp__RegOpenKeyExA                      H:\MyApp\htmlhelp.lib (/0             )
                                              (release/init.obj)


I understand why it needs GetProcAddress etc, I can't figure out why the lib has references to _imp__ versions which won't resolve. Using a hex editor I can see the htmlhelp.lib file has '!<arch>' as a header which I thought was a COFF archive, supposedly linkable.

I'm OK with C++ inside Visual Studio but I can't figure out how to get the Salford compiler (SCC) to compile and link this particular library.

What obvious thing am I missing?

Thanks in advance,

Ryan
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PaulLaidler
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Joined: 21 Feb 2005
Posts: 4624
Location: Salford, UK

PostPosted: Thu Feb 25, 2016 9:42 pm    Post subject: Reply with quote

I am guessing that the problem is that the library resides in an ocx (ActiveX) file rather than a DLL.

Which HTML functions are you accessing?
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Ryan



Joined: 25 Feb 2016
Posts: 15

PostPosted: Thu Feb 25, 2016 9:48 pm    Post subject: Reply with quote

Hi Paul,

Yes, the lib does something with HHCTRL.OCX. I was hoping that the lib would be statically linked in and handle all of the OCX loading at runtime, but I'm not sure what I am doing.

The API call I am trying to execute is HtmlHelp as defined at https://msdn.microsoft.com/en-us/library/windows/desktop/ms670172(v=vs.85).aspx

My test code is;

Code:
  HWND return_code = HtmlHelp(GetDesktopWindow(), "hlp.chm\::/copyright.htm", HH_DISPLAY_TOPIC, NULL);


I have been able to compile and run a console app launching help in Visual C using this code. So I'm a little lost.
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PaulLaidler
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Joined: 21 Feb 2005
Posts: 4624
Location: Salford, UK

PostPosted: Fri Feb 26, 2016 8:39 am    Post subject: Reply with quote

Here is my test program...

Code:
#include <windows.h>
#define HH_DISPLAY_TOPIC 0x0000
HWND WINAPI HtmlHelpA(HWND hwndCaller,LPCSTR pszFile,UINT uCommand,DWORD dwData);
 
int main()
{
   HWND return_code = HtmlHelpA(GetDesktopWindow(), "hlp.chm\::/copyright.htm", HH_DISPLAY_TOPIC, NULL);
   return 0;
}


For SLINK you can load hhctrl.ocx but you will need to put hhctrl.ocx somewhere where SLINK can see it.
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Ryan



Joined: 25 Feb 2016
Posts: 15

PostPosted: Fri Feb 26, 2016 10:23 pm    Post subject: Reply with quote

Thanks Paul,

That's moved me along somewhat. I can understand what's going on there.

I'm now getting a hang when calling the API but that's something I think I can troubleshoot. Probably down to bad parameters.

Regards

Ryan
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PaulLaidler
Site Admin


Joined: 21 Feb 2005
Posts: 4624
Location: Salford, UK

PostPosted: Sat Feb 27, 2016 8:47 am    Post subject: Reply with quote

You might need
Code:
extern "C" HWND WINAPI HtmlHelpA....
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Ryan



Joined: 25 Feb 2016
Posts: 15

PostPosted: Wed Mar 02, 2016 4:02 pm    Post subject: Reply with quote

Hi Paul,

I'm still stuck, I have attempted to use just your sample and replaced the .chm file too in case that is causing it.

I have also linked to both WOW64 and System32 versions of hhctrl.ocx but the app still hangs and never returns from the API call.

Do you have any more ideas? I have noticed that memory usage climbs dramatically for the process once in while so I have a leak or a bad calling convention.

Here is what I have;

helphang.cpp;
Code:
#include <windows.h>
#define HH_DISPLAY_TOPIC 0x0000

extern HWND WINAPI HtmlHelpA(HWND hwndCaller, LPCSTR pszFile, UINT uCommand, DWORD dwData);

int main()
{
   HWND return_code = HtmlHelpA(GetDesktopWindow(), "hlp.chm\\::/copyright.htm", HH_DISPLAY_TOPIC, NULL);
   return 0;
}


I then compile and link it with;
Code:
scc helphang.cpp
slink helphang.dat


The linker command file is;
Code:
lo helphang
lo C:\Windows\System32\hhctrl.ocx
; lo C:\Windows\SysWOW64\hhctrl.ocx

file helphang
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Ryan



Joined: 25 Feb 2016
Posts: 15

PostPosted: Wed Mar 02, 2016 4:17 pm    Post subject: Reply with quote

I've narrowed it down.

Part of the problem I was experiencing was that the first of my many test API calls failed and ran up a huge memory bill. During that time, it locked the CHM file.

So when I quit and retried another API approach, I just got a plain hang as the file was locked.

They both looked the same though.

I'll keep going and will post the answer, I suspect it is due to stack space as there is a note in the HTML API about that and a specific stack size is set in my original code.
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PaulLaidler
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Joined: 21 Feb 2005
Posts: 4624
Location: Salford, UK

PostPosted: Wed Mar 02, 2016 5:08 pm    Post subject: Reply with quote

I think that, on a 64 bit system, the ocx in System32 will be the 64 bit version.
Not the one that you want.
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Ryan



Joined: 25 Feb 2016
Posts: 15

PostPosted: Wed Mar 02, 2016 5:37 pm    Post subject: Reply with quote

It seems to be the location of the stack that is causing it, which is a worry as I don't really understand why the stack was set so high.

It works if I relocate (or shrink?) the stack, I'm not sure what the parameters do.

The slink command file and adjustments;

Code:

lo helphang
lo C:\Windows\System32\hhctrl.ocx
; lo C:\Windows\SysWOW64\hhctrl.ocx

; Takes about 40 seconds delay before launching and help app is corrupt.
; stack 0x21000000

; Does not come back.
; stack 0x40000000

; Launches immediately.
stack 0x01000000

file helphang


Obviously the stack was set that way for a reason so if I change it I may cause issues.
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