pkgs: Add a small utility to dump joystick GUIDs

SDL 2 has an environment variable called SDL_GAMECONTROLLERCONFIG, which
lists button/axis mappings of various game controllers attached to the
system.

The game controllers are themselves identified using a GUID which is SDL
2 specific and this tool is there to just dump the name of a particular
game controller along with the GUID so it's easier to get the GUID.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>

3 files changed, 42 insertions, 0 deletions

diff --git a/pkgs/default.nix b/pkgs/default.nix
index d7057820..6eec67a4 100644
--- a/pkgs/default.nix
+++ b/pkgs/default.nix
@@ -15,6 +15,7 @@ let
     nixops = callPackage ./nixops { };
     libCMT = callPackage ./libcmt { };
     librxtx_java = callPackage ./librxtx-java { };
+    list-gamecontrollers = callPackage ./list-gamecontrollers { };
     lockdev = callPackage ./lockdev { };
     pvolctrl = callPackage ./pvolctrl { };
     show-qr-code = callPackage ./show-qr-code { };
diff --git a/pkgs/list-gamecontrollers/default.nix b/pkgs/list-gamecontrollers/default.nix
new file mode 100644
index 00000000..c207d2eb
--- /dev/null
+++ b/pkgs/list-gamecontrollers/default.nix
@@ -0,0 +1,10 @@
+{ runCommand, pkgconfig, SDL2 }:
+
+runCommand "list-gamecontrollers" {
+  buildInputs = [ pkgconfig SDL2 ];
+} ''
+  mkdir -p "$out/bin"
+  gcc -Werror "${./list-gc.c}" \
+    $(pkg-config --libs --cflags sdl2) \
+    -o "$out/bin/list-gamecontrollers"
+''
diff --git a/pkgs/list-gamecontrollers/list-gc.c b/pkgs/list-gamecontrollers/list-gc.c
new file mode 100644
index 00000000..f40b7da6
--- /dev/null
+++ b/pkgs/list-gamecontrollers/list-gc.c
@@ -0,0 +1,31 @@
+#include <SDL.h>
+
+void dump_guid(SDL_Joystick *js) {
+    SDL_JoystickGUID guid;
+    const char *name;
+    char guidstr[33];
+
+    guid = SDL_JoystickGetGUID(js);
+    name = SDL_JoystickName(js);
+    SDL_JoystickGetGUIDString(guid, guidstr, sizeof(guidstr));
+
+    printf("%s: %s\n", name, guidstr);
+}
+
+int main()
+{
+    int i;
+    SDL_Joystick *js;
+
+    SDL_Init(SDL_INIT_JOYSTICK);
+    atexit(SDL_Quit);
+
+    for (i = 0; i < SDL_NumJoysticks(); ++i) {
+        if ((js = SDL_JoystickOpen(i)) != NULL) {
+            dump_guid(js);
+            SDL_JoystickClose(js);
+        }
+    }
+
+    return EXIT_SUCCESS;
+}