gnu: Add unicorn.

* gnu/packages/emulators.scm (unicorn): New variable.

gnu/packages/emulators.scm

@@ -44,7 +44,9 @@
   #:use-module (gnu packages boost)
   #:use-module (gnu packages backup)
   #:use-module (gnu packages cdrom)
+  #:use-module (gnu packages check)
   #:use-module (gnu packages compression)
+  #:use-module (gnu packages cross-base)
   #:use-module (gnu packages curl)
   #:use-module (gnu packages elf)
   #:use-module (gnu packages fonts)
@@ -88,7 +90,8 @@
   #:use-module (gnu packages web)
   #:use-module (guix build-system cmake)
   #:use-module (guix build-system glib-or-gtk)
-  #:use-module (guix build-system gnu))
+  #:use-module (guix build-system gnu)
+  #:use-module (guix build-system python))
 
 (define-public desmume
   (package
@@ -1663,3 +1666,115 @@ from various forks of Gens, and improved platform portability.")
      "bsnes is a Super Nintendo / Super Famicom emulator that focuses on
 performance, features, and ease of use.")
     (license license:gpl3)))
+
+;; python-pwntools requires a -rc release of unicorn
+(define-public unicorn
+  (let ((unless-x86
+          (lambda (code)
+            (if (member (%current-system) '("x86_64-linux" "i686-linux"))
+              '()
+              code))))
+    (package
+      (name "unicorn")
+      (version "1.0.2-rc4")
+      ;; NOTE: unicorn ships a bundled QEMU, but with a lot of custom modifications.
+      (source
+       (origin
+         (method git-fetch)
+         (uri (git-reference
+               (url "https://github.com/unicorn-engine/unicorn")
+               (commit version)))
+         (file-name (git-file-name name version))
+         (sha256
+          (base32
+           "17nyccgk7hpc4hab24yn57f1xnmr7kq4px98zbp2bkwcrxny8gwy"))))
+      (outputs '("out" "python"))
+      ;; The main library is not written in Python, but the build process has
+      ;; little in common with any defined build system, so we might as well
+      ;; build on top of python-build-system and make use of all
+      ;; the Python-specific phases that can be reused.
+      (build-system python-build-system)
+      (arguments
+       `(#:modules ((srfi srfi-26)
+                    (guix build python-build-system)
+                    (guix build utils))
+         #:phases
+         (modify-phases %standard-phases
+           (add-after 'unpack 'install-bindings-to-python-output
+             (lambda* (#:key outputs #:allow-other-keys)
+               ;; python-build-system will build the bindings and install them to
+               ;; the "out" output, so change the build-internal names of the
+               ;; outputs.
+               ;;
+               ;; TODO: remove this once #40469 lands, through the core-updates
+               ;; holding zone, on master.
+               (set-car! (assoc "out" outputs) "lib")
+               (set-car! (assoc "python" outputs) "out")
+               #t))
+           (add-before 'build 'build-library
+             (lambda* (#:key inputs #:allow-other-keys)
+               (invoke "make"
+                       "-j" (number->string (parallel-job-count))
+                       "UNICORN_STATIC=no"
+                       "CC=gcc")))
+           (add-after 'build-library 'install-library
+             (lambda* (#:key outputs #:allow-other-keys)
+               (invoke "make" "install"
+                       "UNICORN_STATIC=no"
+                       (string-append
+                        "PREFIX="
+                        (assoc-ref outputs "lib")))))
+           (add-before 'build 'prepare-bindings
+             (lambda* (#:key outputs #:allow-other-keys)
+               (chdir "bindings/python")
+               ;; Set this environment variable so that the Python bindings
+               ;; don't build their own copy of the shared object, but use
+               ;; a dummy value such that the bindings test suite uses the
+               ;; same mechanism for loading the library as any other user.
+               (setenv "LIBUNICORN_PATH" "1")
+               (substitute* "unicorn/unicorn.py"
+                 (("_path_list = \\[.*")
+                  (string-append
+                   "_path_list = [\""
+                   (assoc-ref outputs "lib")
+                   ;; eat the rest of the list
+                   "/lib\"] + 0*[")))
+               #t))
+           (add-before 'check 'check-library
+             (lambda* (#:key outputs #:allow-other-keys)
+               (for-each
+                 (lambda (suite)
+                   (with-directory-excursion
+                     (string-append "../../tests/" suite)
+                     (invoke "make" "test" "CC=gcc"
+                             ,@(unless-x86
+                                '("AS=i686-unknown-linux-gnu-as"
+                                  "OBJCOPY=i686-unknown-linux-gnu-objcopy")))))
+                 '("unit" "regress"))
+               #t))
+           (add-after 'install 'install-samples
+             (lambda* (#:key outputs #:allow-other-keys)
+               (let* ((python-samples (find-files "." "sample_.*"))
+                      (c-samples (find-files "../../samples" ".*\\.c"))
+                      (python-docdir
+                        (string-append (assoc-ref outputs "out")
+                                       "/share/doc/unicorn/samples"))
+                      (c-docdir
+                        (string-append (assoc-ref outputs "lib")
+                                       "/share/doc/unicorn/samples")))
+                 (for-each (cut install-file <> c-docdir) c-samples)
+                 (for-each (cut install-file <> python-docdir) python-samples)
+                 #t))))))
+      (native-inputs
+       ;; NOTE: cross-binutils needs to be wrapped with unless-x86, as otherwise
+       ;; the linker provided by the package will be used, circumventing the ld-wrapper.
+       `(,@(unless-x86
+            `(("assembler-for-tests" ,(cross-binutils "i686-unknown-linux-gnu"))))
+         ("cmocka" ,cmocka)
+         ("hexdump-for-tests" ,util-linux)))
+      (home-page "http://www.unicorn-engine.org")
+      (synopsis "Unicorn CPU emulator framework")
+      (description
+       "Unicorn is a lightweight, multi-platform, multi-architecture CPU emulator
+framework based on QEMU.")
+      (license license:gpl2+))))