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antik-devel@common-lisp.net

February 2012

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2 discussions

[Antik-devel] Reader macro for sharp-m returns literal foreign-array (patch included)
by James Wright 06 Mar '12

06 Mar '12

Hi, I have encountered the following problem a couple of times before, although not as reproducibly as the memory corruption issue from my previous message: If I use the #m reader macro in a function somewhere, dump an SBCL core image, load the image, and call the function, I get memory corruption. I have mostly dealt with it up until now by not using the #m() notation in anything that I plan to dump to a binary. I believe that the cause is that the #m macro returns a foreign-array object directly (when foreign-array is the default grid type). If it returned a `make-grid' form instead, it would operate identically on e.g. the REPL. It would have the advantage, however, of being usable in a dumped image, since the array would be created at run-time instead of at read-time, and hence no foreign-pointers would be saved into the image. I've attached a patch that changes the #m reader macro to return a creation form instead of a literal. I hope you'll consider adding it. I've pasted a repl session below that demonstrates the difference. Thanks, James ;;; Before the patch GRID> (read-from-string "#m(1d0 2d0)") #m(1.000000000000000d0 2.000000000000000d0) 11 GRID> #m(1d0 2d0) #m(1.000000000000000d0 2.000000000000000d0) ;;; After the patch GRID> (read-from-string "#m(1d0 2d0)") (MAKE-GRID '((FOREIGN-ARRAY) DOUBLE-FLOAT) :INITIAL-CONTENTS '(1.0 2.0)) 11 GRID> #m(1d0 2d0) #m(1.000000000000000d0 2.000000000000000d0)

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[Antik-devel] Memory corruption when loading an SBCL core containing antik (patch included)
by James Wright 06 Mar '12

06 Mar '12

Hi, When I dump an SBCL core from an image that has antik loaded, I get a memory corruption error when loading the core: *** glibc detected *** sbcl: free(): invalid pointer: 0x0808d588 *** This happens even with a minimal project that does nothing but load antik; I've attached a script to reproduce the problem. I did some investigation, and it looks like the problem is the `*formatting-test-grid*' variable in `format-grid.lisp'. It contains a list of grids, including some foreign arrays. Presumably the foreign pointers in these arrays will be pointing to random/unowned memory when the core is loaded. I've run into similar problems before in my own code (attempting to dump a global `*rng*' variable that contained a GSLL random number generator). I've attached a patch that replaces the problem `defparameter' form with a function instead. I can't find any references to this variable in the source tree, so I assume it's just there for manual testing. Thanks, James

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