Find the correct library file from the chainloader

Instead of using this hardcdoed path.

src/chainloader/utils.cpp

@@ -0,0 +1,81 @@
+// yabridge: a Wine plugin bridge
+// Copyright (C) 2020-2022 Robbert van der Helm
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+#include "utils.h"
+
+#include <dlfcn.h>
+
+// Generated inside of the build directory
+#include <config.h>
+
+#include "../common/linking.h"
+#include "../common/logging/common.h"
+#include "../common/notifications.h"
+#include "../common/process.h"
+
+namespace fs = ghc::filesystem;
+
+void* find_plugin_library(const std::string& name) {
+    // Just using a goto for this would probably be cleaner, but yeah...
+    const auto impl = [&name]() -> void* {
+        // If `name` exists right next to the Wine plugin host binary, then
+        // we'll try loading that. Otherwise we'll fall back to regular
+        // `dlopen()` for distro packaged versions of yabridge
+        const std::vector<fs::path> search_path = get_augmented_search_path();
+        if (const auto& yabridge_host_path =
+                search_in_path(search_path, yabridge_individual_host_name)) {
+            const fs::path candidate = yabridge_host_path->parent_path() / name;
+            if (fs::exists(candidate)) {
+                return dlopen(candidate.c_str(), RTLD_LAZY | RTLD_LOCAL);
+            }
+        }
+
+        if (const auto& yabridge_host_32_path = search_in_path(
+                search_path, yabridge_individual_host_name_32bit)) {
+            const fs::path candidate =
+                yabridge_host_32_path->parent_path() / name;
+            if (fs::exists(candidate)) {
+                return dlopen(candidate.c_str(), RTLD_LAZY | RTLD_LOCAL);
+            }
+        }
+
+        return dlopen(name.c_str(), RTLD_LAZY | RTLD_LOCAL);
+    };
+
+    void* handle = impl();
+    if (!handle) {
+        const fs::path this_plugin_path = get_this_file_location();
+
+        Logger logger = Logger::create_exception_logger();
+
+        logger.log("");
+        logger.log("Could not find '" + name + "'.");
+        logger.log("Make sure you followed the installation instructions from");
+        logger.log("yabridge's readme");
+        logger.log("");
+        logger.log("Source: '" + this_plugin_path.string() + "'");
+        logger.log("");
+
+        // Also show a desktop notification since most people likely won't see
+        // the above message
+        send_notification("Could not find '" + name + "'",
+                          "Make sure you followed the installation "
+                          "instructions from yabridge's readme",
+                          this_plugin_path);
+    }
+
+    return handle;
+}