[Lazarus] "Running" a library

Sven Barth pascaldragon at googlemail.com
Sat Sep 15 11:16:25 CEST 2012

On 15.09.2012 07:10, Rolf Grunsky wrote:
> On 12-09-14 10:39 AM, leledumbo wrote:
>> Currently, if we have a library project, there's no way to test it
>> without
>> creating 2nd project which is an application. Should Lazarus implement
>> something like V$ does? i.e. when "Run" is executed on a library project,
>> the IDE then ask for an executable to run (the executable uses the
>> library,
>> so it will step into the library eventually). I have no idea whether gdb
>> supports something like this or not.
> It's been a very long time since I looked at this, and this is specific
> to Windows. An exe and dll have the same basic structure, the difference
> is that an exe can not export entry points and part of the startup will
> initialize the stack and data segments. On the other hand, any procedure
> called in a dll will assume that the stack pointer and segment registers
> have been already set up. Also, I believe that there is only a single
> entry point in an exe. Windows does provide a method to run a dll as a
> program but I would assume that you have to pass the procedure in the
> dll that you want to run. As I said this is from vague memory so the
> details are fuzzy. At a minimum, to run a procedure in the dll you will
> need some code to set up stack and data segments.

Note: You can export symbols from a program (this even works with FPC), 
but you should only do a LoadLibrary for that application from a library 
that is loaded by that application to avoid that the entry point is 
called ;) The only program that I'm aware of that utilizes this is the 
kernel itself: ntoskrnl.exe is linked to by device drivers.


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