Wallpaper (Haiku): Add support

CMakeLists.txt

@@ -1240,7 +1240,7 @@ elseif(Haiku)
         src/detection/tpm/tpm_nosupport.c
         src/detection/uptime/uptime_haiku.c
         src/detection/users/users_linux.c
-        src/detection/wallpaper/wallpaper_nosupport.c
+        src/detection/wallpaper/wallpaper_haiku.cpp
         src/detection/wifi/wifi_nosupport.c
         src/detection/wm/wm_nosupport.c
         src/detection/de/de_nosupport.c

src/detection/wallpaper/wallpaper_haiku.cpp

@@ -0,0 +1,54 @@
+extern "C" {
+#include "wallpaper.h"
+#include "common/mallocHelper.h"
+}
+
+#include <Application.h>
+#include <FindDirectory.h>
+#include <InterfaceDefs.h>
+#include <Node.h>
+#include <Path.h>
+#include <Screen.h>
+#include <fs_attr.h>
+#include <be_apps/Tracker/Background.h>
+
+const char* ffDetectWallpaper(FFstrbuf* result) {
+    BMessage backgrounds;
+    BPath pDesktop;
+    BString path;
+
+    if (find_directory(B_DESKTOP_DIRECTORY, &pDesktop) < B_OK) {
+        return "find_directory(B_DESKTOP_DIRECTORY) failed";
+    }
+
+    // We need a valid be_app to query the app_server here.
+    BApplication app("application/x-vnd.fastfetch-cli-fastfetch");
+
+    BNode nDesktop(pDesktop.Path());
+    if (nDesktop.InitCheck() == B_OK) {
+        struct attr_info ai;
+        if (nDesktop.GetAttrInfo(B_BACKGROUND_INFO, &ai) == B_OK && ai.size > 0) {
+            FF_AUTO_FREE char* pAttr = (char*) malloc(ai.size);
+            if (nDesktop.ReadAttr(B_BACKGROUND_INFO, ai.type, 0LL, pAttr, (size_t) ai.size) >= B_OK) {
+                if (backgrounds.Unflatten(pAttr) == B_OK) {
+                    for (int i = 0; backgrounds.FindString(B_BACKGROUND_IMAGE, i, &path) == B_OK; i++) {
+                        int32 ws;
+                        if (backgrounds.FindInt32(B_BACKGROUND_WORKSPACES, i, &ws) == B_OK) {
+                            if (ws & (1 << current_workspace())) {
+                                // We try to match the one for the current workspace
+                                break;
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    if (path.Length() < 1) {
+        return "Failed to detect the current wallpaper path";
+    }
+
+    ffStrbufAppendS(result, path.String());
+    return NULL;
+}