gnu: qemu: Add wrapper for Samba.

* gnu/packages/virtualization.scm (qemu)[arguments]: Change #:configure-flags to
a list, add --smbd flag. Add 'create-samba-wrapper phase.

gnu/packages/virtualization.scm

@@ -96,7 +96,10 @@
      '(;; Running tests in parallel can occasionally lead to failures, like:
        ;; boot_sector_test: assertion failed (signature == SIGNATURE): (0x00000000 == 0x0000dead)
        #:parallel-tests? #f
-       #:configure-flags '("--enable-usb-redir" "--enable-opengl")
+       #:configure-flags (list "--enable-usb-redir" "--enable-opengl"
+                               (string-append "--smbd="
+                                              (assoc-ref %outputs "out")
+                                              "/libexec/samba-wrapper"))
        #:phases
        (modify-phases %standard-phases
          (replace 'configure
@@ -135,6 +138,20 @@
                                       (install-file info infodir))
                                     (find-files "." "\\.info"))
                           #t))))))
+         ;; Create a wrapper for Samba. This allows QEMU to use Samba without
+         ;; pulling it in as an input. Note that you need to explicitly install
+         ;; Samba in your Guix profile for Samba support.
+         (add-after 'install-info 'create-samba-wrapper
+           (lambda* (#:key inputs outputs #:allow-other-keys)
+             (let* ((out    (assoc-ref %outputs "out"))
+                    (libexec (string-append out "/libexec")))
+               (call-with-output-file "samba-wrapper"
+                 (lambda (port)
+                   (format port "#!/bin/sh
+exec smbd $@")))
+               (chmod "samba-wrapper" #o755)
+               (install-file "samba-wrapper" libexec))
+             #t))
          (add-before 'check 'make-gtester-verbose
            (lambda _
              ;; Make GTester verbose to facilitate investigation upon failure.