What inspired you to the particular design of string_to_SCMOBJ (things like ___CTOS_HEAP_OVERFLOW_ERR+arg_num;)?

2012/9/28 Mikael <mikael.rcv@gmail.com>
Just to start, are you sure that when you return that string, that it remains on the C heap somewhere all until your string_to_SCMOBJ procedure digests it?

I mean, if it's on the stack, then probably it's overwritten by the subsequent C procedure call to string_to_SCMOBJ, which consumes stack space (the unsigned int and ___SCMOBJ in string_to_SCMOBJ should take the first positions of stack space that f1b_hello previously occupied, and thus destroy the structure?).

If it had been a char* constant you had returned instead, I suppose the C compiler would have put it in some separate, reserved area.

Well just a wild guess.


What about adding Lots of debug printf:s in string_to_SCMOBJ as to check that it produces the right thing.


Last, in your type definition (c-define-type string "string" "string_to_SCMOBJ" "SCMOBJ_to_string" #f) you use #f for release function i.e. afaik free()?

That's not the right thing right, you'd want C++' delete or sth..?

Also why is not the string type you use pointered? Please correct me on this one.

Brgds

2012/9/28 REPLeffect <repleffect@gmail.com>
I came across a strange behavior with Gambit Scheme on Windows (XP, in
this case).  I wrote a module to convert C++ std::string types to
Gambit char-strings.  I wanted to use that in a loadable module.  This
all works fine on Linux, but I also need to use it on Windows.  I'm
using MinGW's C++ compiler (g++ version 4.6.2 -- which I also used to
compile Gambit).  And I'm still on version 4.6.5 of Gambit Scheme.

I've attached a zipped tar file with an example (6 files, including a
build.windows script and a build.linux script).

When I load the shared module in gsi on Windows XP, it segfaults in
___garbage_collect(long) -- I believe it was in the call to
___alloc_scmobj.  When I load it on Linux it works just fine.  The
executable built by the scripts on both platforms works just fine.

I would love to know what is causing this.  I've spent many hours
trying to find the source of the problem, and finally narrowed it down
to this.

Any help/explanations/suggestions would be much appreciated.

repleffect

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