gnu: obs: Use an environment variable for plugins location.

* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/video.scm (obs): Use it.
* gnu/packages/patches/obs-modules-location.patch: Patch it.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

gnu/local.mk

@@ -1411,6 +1411,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/nvi-dbpagesize-binpower.patch		\
   %D%/packages/patches/nvi-db4.patch				\
   %D%/packages/patches/nyacc-binary-literals.patch		\
+  %D%/packages/patches/obs-modules-location.patch		\
   %D%/packages/patches/ocaml-bitstring-fix-configure.patch \
   %D%/packages/patches/ocaml-cairo2-caml_ba_array-fix.patch     \
   %D%/packages/patches/ocaml-CVE-2015-8869.patch		\

gnu/packages/patches/obs-modules-location.patch

@@ -0,0 +1,33 @@
+From d250434e6c8eb4f8c8cb47ef3cc6e6de8fa8f828 Mon Sep 17 00:00:00 2001
+From: Alexey Abramov <levenson@mmer.org>
+Date: Fri, 15 Jan 2021 17:07:17 +0100
+Subject: [PATCH] Use environment variable for a default module location
+
+diff --git a/libobs/obs-nix.c b/libobs/obs-nix.c
+index 382fa0546..481ea0f14 100644
+*** a/libobs/obs-nix.c
+--- b/libobs/obs-nix.c
+@@ -66,8 +66,19 @@
+ 
+ void add_default_module_paths(void)
+ {
+-	for (int i = 0; i < module_patterns_size; i++)
+-		obs_add_module_path(module_bin[i], module_data[i]);
++	char *bin_directory = getenv("OBS_PLUGINS_DIRECTORY");
++	char *data_directory = getenv("OBS_PLUGINS_DATA_DIRECTORY");
++	if (bin_directory && data_directory) {
++		struct dstr dstr_data_directory;
++		dstr_init_copy(&dstr_data_directory, data_directory);
++		dstr_cat(&dstr_data_directory, "/%module%");
++		obs_add_module_path(bin_directory, dstr_data_directory.array);
++		dstr_free(&dstr_data_directory);
++
++	} else {
++		for (int i = 0; i < module_patterns_size; i++)
++			obs_add_module_path(module_bin[i], module_data[i]);
++	}
+ }
+ 
+ /*
+-- 
+2.29.2

gnu/packages/video.scm

@@ -47,6 +47,7 @@
 ;;; Copyright © 2020 Alexandru-Sergiu Marton <brown121407@posteo.ro>
 ;;; Copyright © 2020 Ivan Kozlov <kanichos@yandex.ru>
 ;;; Copyright © 2020 Antoine Côté <antoine.cote@posteo.net>
+;;; Copyright © 2021 Alexey Abramov <levenson@mmer.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -3083,7 +3084,9 @@ be used for realtime video capture via Linux-specific APIs.")
               (file-name (git-file-name name version))
               (sha256
                (base32
-                "1k1asqiqw757v59ayx0w029ril947hs0lcp8n91knzjl891fr4nc"))))
+                "1k1asqiqw757v59ayx0w029ril947hs0lcp8n91knzjl891fr4nc"))
+              (patches
+               (search-patches "obs-modules-location.patch"))))
     (build-system cmake-build-system)
     (arguments
      `(#:configure-flags
@@ -3098,6 +3101,15 @@ be used for realtime video capture via Linux-specific APIs.")
                (wrap-program (string-append out "/bin/obs")
                  `("QT_PLUGIN_PATH" ":" prefix (,plugin-path))))
              #t)))))
+    (native-search-paths
+     (list (search-path-specification
+            (variable "OBS_PLUGINS_DIRECTORY")
+            (separator #f)                         ;single entry
+            (files '("lib/obs-plugins")))
+           (search-path-specification
+            (variable "OBS_PLUGINS_DATA_DIRECTORY")
+            (separator #f)                         ;single entry
+            (files '("share/obs/obs-plugins")))))
     (native-inputs
      `(("cmocka" ,cmocka)
        ("pkg-config" ,pkg-config)))