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I am playing with the CFFI tutorial on Windows 10 and have installed the libcurl-devel package using msys2. I found a file libcurl.dll.a in the directory c:\msys2\usr\lib\ and added this directory to *foreign-library-directories* using:

(pushnew #P"c:/msys64/usr/lib/" *foreign-library-directories*
         :test #'equal)

But if I try (use-foreign-library libcurl) I get the following error:

Unable to load foreign library (LIBCURL).
  Error opening shared object "libcurl.dll"

What am I missing? I tried to point to libcurl.dll.a directly but the error stays the same:

(define-foreign-library libcurl
      (:darwin (:or "libcurl.3.dylib" "libcurl.dylib"))
      (:unix (:or "libcurl.so.3" "libcurl.so"))
      (t "libcurl.dll.a"))

Here is the complete code as given in the tutorial:

(asdf:load-system :cffi)

 ;;; Nothing special about the "CFFI-USER" package.  We're just
 ;;; using it as a substitute for your own CL package.
(defpackage :cffi-user
  (:use :common-lisp :cffi))

(in-package :cffi-user)

(pushnew #P"c:/msys64/usr/lib/" *foreign-library-directories*
         :test #'equal)

(define-foreign-library libcurl
  (:darwin (:or "libcurl.3.dylib" "libcurl.dylib"))
  (:unix (:or "libcurl.so.3" "libcurl.so"))
  (t (:default "libcurl")))

(use-foreign-library libcurl)

EDIT

I am using SBCL 1.4.16 from the portacle package.

EDIT 2

Just for the sake of completeness. If I change define-foreign-library to

(define-foreign-library libcurl
  (:darwin (:or "libcurl.3.dylib" "libcurl.dylib"))
  (:unix (:or "libcurl.so.3" "libcurl.so"))
  (t "libcurl.dll.a"))

the errors changes:

Unable to load foreign library (LIBCURL).
  Error opening shared object "c:\\msys64\\usr\\lib\\libcurl.dll.a":
 %1 ist keine zulässige Win32-Anwendung.

As far as I understand at least the file is found but seems not to be in the right format. I didn't find any further information about the difference between dynamic (.dll) and static (.dll.a) files with respect to cffi and don't have the resources at the moment to further investigate this.

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1 回答 1

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而不是使用use-foreign-library，尝试加载load-foreign-library。它是较低级别的代码，但它允许您尝试文件和路径。

还可以使用 cygcheck 找出libcurl.dll依赖项。然后确保您已安装组件，并且它们位于PATH.

最后，检查 libcurl.dll 在 MSYS2 中的位置。在我的系统上/c/msys64/mingw64/bin/libcurl-4.dll

于 2019-06-18T16:04:11.753 回答