Thanks for the report and patch! I've adjusted the implementation to replace `int' with `intptr_t' and add checks for arithmetic overflow. I didn't switch to `uintptr_t', though, because I doubt that the extra bit is useful enough to be worth reasoning about signed and unsigned conversions.
At Thu, 31 May 2012 16:39:36 +0200, Tobias Hammer wrote: > Hi, > > i stumbled over strange error messages and some unexpected behavior > in the ffi implementation. > > The following code raises a very misleading error message: > (define _tm (_array _byte 1024 1024 1200 2)) > (malloc _tm) > > -> malloc: expects argument of type <non-void-C-type>; given #<ctype> > > One dimensional arrays fail eariler and with a slightly better error: > (_array _byte 2147483649) > > -> make-array-type: expects type <pointer-sized nonnegative exact integer> > as 2nd argument, given: 2147483649; other arguments were: #<ctype:uint8> > > Searching in foreign.c for the cause i found out, that the current > implementation > fails badly with types > 2GB size (not only arrays) because it uses int as > result for ctype_sizeof. > As a consequence it should even fail at the 2GB mark on 64bit > (gcc-)systems where > int is usually fixed to 32bit for compatibility reasons. > > The problem seems to be limited to the foreign.c as libc, libffi and > rackets gc2 functions > use size_t for all size arguments. I tried to fix it and attached a patch > vs git > head. But it may be that the use of size_t leads to strange overflow > behavior whenever > size is multiplied by a potentially negative value to get an offset that > is stored in > a intptr_t. As far as i can see these overflow cases are not handled in > the current > implementation so it may be ok to continue to ignore them. > > As a side question: What is the sense of foreign.rktc if it is never used > to generate > the c file from it? > > Tobias > > > > -- > --------------------------------------------------------- > Tobias Hammer > DLR / Institute of Robotics and Mechatronics > Tel.: 08153/28-1487 > Mail: [email protected] > ------------------------------------------------------------------------------ > [application/octet-stream "ffi-2gb.patch"] [~/Desktop & open] [~/Temp & open] > > ------------------------------------------------------------------------------ > [application/octet-stream "ffi-2gb-limit-demo.rkt"] [~/Desktop & open] > [~/Temp & > open] > _________________________ > Racket Developers list: > http://lists.racket-lang.org/dev _________________________ Racket Developers list: http://lists.racket-lang.org/dev
