cffi-devel April 2015

cffi-devel@common-lisp.net

4 participants
4 discussions

Unable to load cffi-libffi in Debian jessie
by Marshall Mason 02 May '15

02 May '15

Hello, I'm new to cffi and Lisp in general. I've been having a lot of trouble getting cffi to work with passing structs using libffi. I fussed with it for weeks and decided to wait until I upgraded Debian to jessie to see if that helped. Now I can't even load cffi-libffi. :( Failed to find the TRUENAME of /usr/share/common-lisp/source/cl-cffi/libffi/init.lisp: No such file or directory Before that there are a bunch of warnings like this: compiling #<STATIC-FILE "alexandria" "LICENCE"> completed without its input file #P"/usr/share/common-lisp/source/alexandria/LICENCE" The code: #!/usr/bin/sbcl --script (require "asdf") (asdf:load-system :cffi) (asdf:load-system :cffi-libffi) This could just be a missing package, but I have everything I can think of. I searched the Debian respository for /usr/share/common-lisp/source/cl-cffi/libffi/init.lisp and none of them provide it. Here are my package versions: sbcl 2:1.2.4-2 cl-cffi 1:0.14.0-1 cl-asdf 2:3.1.4-1 libffi6 3.1-2+b2 libffi-dev 3.1-2+b2 Can anyone help me solve this? Marshall

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Error when passing struct by value
by Marshall Mason 01 May '15

01 May '15

Hello, I'm using SBCL version 1.2.4, CFFI version 0.14.0, and libffi version 3.1. I've been trying to pass a struct by value using CFFI and libffi. I'm a newbie to both CFFI and Lisp so I had to piece this together from the manual as well as some of the unit tests that come with CFFI. I'm getting an error that I just can't get past: The value READ-FUNC is not of type SB-SYS:SYSTEM-AREA-POINTER The library I'm trying to wrap is libvorbisfile, which decodes Ogg Vorbis files. It has an init function called ov_open_callbacks: int ov_open_callbacks(void *datasource, OggVorbis_File *vf, const char *initial, long ibytes, ov_callbacks callbacks); The part it's choking on is the last argument, a struct, passed by value, of callback functions: typedef struct { size_t (*read_func) (void *ptr, size_t size, size_t nmemb, void *datasource); int (*seek_func) (void *datasource, ogg_int64_t offset, int whence); int (*close_func) (void *datasource); long (*tell_func) (void *datasource); } ov_callbacks; The library is designed to use one of a few static structs defined in a header file. Since it's defined in the header file and not in libvorbisfile.so, I must create CFFI translation code. There were a lot of other structs I had to wrap with CFFI as well. Here is my code: http://pastie.org/10122885 Does anyone have any clues about what I'm doing wrong here? (Regarding my previous email about getting CFFI working on Debian jessie, it turns out the Debian version of cl-alexandria is missing a file and cl-cffi is buggy, so I just added the missing file and installed the CFFI source by hand. Thanks for the response, Fau.) Marshall

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[Resend] How to free the array element
by Huang, Ying 14 Apr '15

14 Apr '15

Hi, All, I found the format of my original email is not correct (sent with web mail), and I got no response for some while, so I resend it in Emacs, hopes it works better this time. I am working on cl-gobject-introspection (https://github.com/andy128k/cl-gobject-introspection), a common lisp gobject introspection binding. I was trying to use extended foreign type system of CFFI to implement some foreign memory operations. I have some questions about that. I need to manipulate foreign array. I tried to define an extended foreign array type because there are some features that are lacking in foreign-array-type of cffi. I can access/assign element of foreign array with cffi:mem-ref and (setf cffi:mem-ref). But I don't know how to free element of foreign array (the element type can be aggregated). Then I checked foreign-array-type implementation of CFFI, and found there appears no way to free translated element of array with that type too. For example: (defvar *string-array* (cffi:convert-to-foreign #("a" "b" "c") '(:array :string 3))) (cffi:free-foreign-object *string-array* '(:array :string 3) t) The translated foreign objects corresponding to string "a", "b" and "c" are not freed if my understanding were correct. I think if there is a cffi:mem-free (I know, the name is bad) like cffi:mem-ref, may be this can be resolved. (defun mem-free (ptr type param &optional (offset 0)) (let* ((parsed-type (parse-type type)) (ctype (canonicalize parsed-type))) (if (aggregatep parsed-type) (free-translated-object (inc-pointer ptr offset) parsed-type param) (free-translated-object (%mem-ref ptr ctype offset) parsed-type param)))) I think you guys may have better idea about how to resolve the question. Best Regards, Huang, Ying

2 2

How to free the array element
by Huang, Ying 01 Apr '15

01 Apr '15

I am working on cl-gobject-introspection (https://github.com/andy128k/cl-gobject-introspection), a common lisp gobject introspection binding. I am trying to use extended foreign type system of CFFI to implement foreign memory operations. I have some questions about that. I need to manipulate foreign array. I tried to define an extended foreign array type because there is some features that is lacking in foreign-array-type. I can access/assign element of foreign array with cffi:mem-ref and setf. But I don't know how to free element of foreign array (the element type can be aggregated). Then I checked foreign-array-type implementation of CFFI, and found there appears no way to free translated element of array too. For example: (defvar *string-array* (cffi:convert-to-foreign #("a" "b" "c") '(:array :string 3))) (cffi:free-foreign-object *string-array* '(:array :string 3) t) The foreign memory corresponding to string "a", "b" and "c" is not freed if my understanding were correct. I think if there is something like cffi:mem-free like cffi:mem-ref, may be this can be resolved. It can be something like. (defun mem-free (ptr type param &optional (offset 0)) (let* ((parsed-type (parse-type type)) (ctype (canonicalize parsed-type))) (if (aggregatep parsed-type) (free-translated-object (inc-pointer ptr offset) parsed-type param) (free-translated-object (%mem-ref ptr ctype offset) parsed-type param)))) I think you guys may have better idea about how to resolve the question. Best Regards, Huang, Ying

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cffi-devel April 2015