cffi cannot open GNU ld scripts.

[Pascal J. Bourguignon]

On Gentoo 64-bit, a lot of /usr/lib/lib*.so are actually GNU ld scripts, redirecting to the actual ELF libraries in /lib64.

Here is a proposed function to read them when the library cannot be opened, and redirect to the true library:

(defun load-foreign-library-if-gnu-ld-script (libname libpath error)
  (let ((newpath
         (with-open-file (stream libpath
                                 :direction :input
                                 :element-type 'character
                                 :external-format :default
                                 :if-does-not-exist nil)
           (when stream
             (let ((buffer (make-array 80
                                       :element-type 'character
                                       :fill-pointer 80)))
               (setf (fill-pointer buffer) (read-sequence buffer stream))
               (when (search "GNU ld script" buffer)
                 (file-position stream 0)
                 (loop
                   (let ((line (read-line stream nil nil)))
                     (cond
                       ((null line) (return nil))
                       ((and (< 5 (length line))
                             (string= "GROUP" (subseq line 0 5)))
                        (let* ((left (position #\( line))
                               (ppos (and left (position #\space line
                                                          :start (1+ left)
                                                          :test (function char/=))))
                               (right (and ppos (position #\space line :start ppos))))
                          (return
                            (and right (subseq line ppos right))))))))))))))
    (if newpath
        (cffi::%load-foreign-library libname newpath)
        (error error))))

In load-foreign-library-path, the two calls to %load-foreigh-library could be replaced by:

  (handler-case (cffi::%load-foreign-library name path)
    (error (err)
      (LOAD-FOREIGN-LIBRARY-IF-GNU-LD-SCRIPT name path err)))

[Luís Oliveira (luismbo)]

Thanks for your bug report. Do you have any information on how to create these scripts so I can test your function locally and perhaps add a new test to the suite? A quick search for "ld scripts" didn't find much.

[Pascal J. Bourguignon (pjb-informatimago)]

On 2012/03/04, at 19:26 , Luís Oliveira wrote:

> Thanks for your bug report. Do you have any information on how to create
> these scripts so I can test your function locally and perhaps add a new
> test to the suite? A quick search for "ld scripts" didn't find much.

Here is /usr/lib/libncurses.so on my gentoo system:

>

The documentation of GNU ld can be found there:

http://sourceware.org/binutils/docs/ld/index.html

And specifically the GROUP command:

http://sourceware.org/binutils/docs/ld/File-Commands.html#index-GROUP_0028_0040var_007bfiles_007d_0029-357

--
__Pascal Bourguignon__
http://www.informatimago.com