using wkhtmltopdf with D

[Mike Parker]

On Monday, 28 May 2018 at 21:05:00 UTC, Dr.No wrote:
> On Monday, 28 May 2018 at 02:10:48 UTC, sarn wrote:
>> On Monday, 28 May 2018 at 01:28:10 UTC, Dr.No wrote:
>>> What's likely the reason of the crash? mismatch between D and 
>>> C memory alignment?
>>
>> From an ABI point of view, the raw pointers won't care about 
>> the memory structure they point to.  The function call is the 
>> only thing that depends on the binary interface.
>>
>> If you translate the code into C, does it work?
>
> Yep, the C version work just fine.

This sort of issue is most often caused by a mistake in the 
bindings: incorrect calling convention, wrong parameter/return 
types, incorrect number of parameters, etc. In this case, if we 
look in pdf.h we can see it includes "dllbegin.inc'. There, 
you'll find the following:

#if defined _WIN32
#define CALLTYPE __stdcall
#else
#define CALLTYPE
#endif

#ifdef __cplusplus
   #define CAPI(type) extern "C" DLL_PUBLIC type CALLTYPE
#else
   #define CAPI(type) DLL_PUBLIC type CALLTYPE
#endif

https://github.com/clowder/wkhtmltopdf/blob/master/src/lib/dllbegin.inc#L43

In pdf.h, that CAPI macro is used in every function declaration. 
That means that on Windows, all of the functions have the 
__stdcall calling convention (which, in D, would be 
extern(Windows)) and the standard cdecl calling convetion on 
other platforms (extern(C) in D).

In the D binding, we see that all of the functions are declared 
as extern(C) (line 4 of pdf.d). That means on Windows, the 
calling convention on the D side is incorrect.

What you need to do is to change that extern(C) delcaration in 
pdf.d to extern(System). This will translate to extern(Windows) 
on Windows and extern(C) elsewhere to match the C headers.