1 files changed, 163 insertions, 0 deletions
diff --git a/init/modalias_handler.cpp b/init/modalias_handler.cpp
new file mode 100644
index 000000000..1734a7e0f
--- /dev/null
+++ b/init/modalias_handler.cpp
@@ -0,0 +1,163 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "modalias_handler.h"
+
+#include <fnmatch.h>
+#include <sys/syscall.h>
+
+#include <algorithm>
+#include <functional>
+#include <string>
+#include <vector>
+
+#include <android-base/chrono_utils.h>
+#include <android-base/logging.h>
+#include <android-base/unique_fd.h>
+
+#include "parser.h"
+
+namespace android {
+namespace init {
+
+Result<Success> ModaliasHandler::ParseDepCallback(std::vector<std::string>&& args) {
+    std::vector<std::string> deps;
+
+    // Set first item as our modules path
+    std::string::size_type pos = args[0].find(':');
+    if (pos != std::string::npos) {
+        deps.emplace_back(args[0].substr(0, pos));
+    } else {
+        return Error() << "dependency lines must start with name followed by ':'";
+    }
+
+    // Remaining items are dependencies of our module
+    for (auto arg = args.begin() + 1; arg != args.end(); ++arg) {
+        deps.push_back(*arg);
+    }
+
+    // Key is striped module name to match names in alias file
+    std::size_t start = args[0].find_last_of("/");
+    std::size_t end = args[0].find(".ko:");
+    if ((end - start) <= 1) return Error() << "malformed dependency line";
+    auto mod_name = args[0].substr(start + 1, (end - start) - 1);
+    // module names can have '-', but their file names will have '_'
+    std::replace(mod_name.begin(), mod_name.end(), '-', '_');
+    this->module_deps_[mod_name] = deps;
+
+    return Success();
+}
+
+Result<Success> ModaliasHandler::ParseAliasCallback(std::vector<std::string>&& args) {
+    auto it = args.begin();
+    const std::string& type = *it++;
+
+    if (type != "alias") {
+        return Error() << "we only handle alias lines, got: " << type;
+    }
+
+    if (args.size() != 3) {
+        return Error() << "alias lines must have 3 entries";
+    }
+
+    std::string& alias = *it++;
+    std::string& module_name = *it++;
+    this->module_aliases_.emplace_back(alias, module_name);
+
+    return Success();
+}
+
+ModaliasHandler::ModaliasHandler() {
+    using namespace std::placeholders;
+
+    static const std::string base_paths[] = {
+            "/vendor/lib/modules/",
+            "/lib/modules/",
+            "/odm/lib/modules/",
+    };
+
+    Parser alias_parser;
+    auto alias_callback = std::bind(&ModaliasHandler::ParseAliasCallback, this, _1);
+    alias_parser.AddSingleLineParser("alias", alias_callback);
+    for (const auto& base_path : base_paths) alias_parser.ParseConfig(base_path + "modules.alias");
+
+    Parser dep_parser;
+    auto dep_callback = std::bind(&ModaliasHandler::ParseDepCallback, this, _1);
+    dep_parser.AddSingleLineParser("", dep_callback);
+    for (const auto& base_path : base_paths) dep_parser.ParseConfig(base_path + "modules.dep");
+}
+
+Result<Success> ModaliasHandler::Insmod(const std::string& path_name, const std::string& args) {
+    base::unique_fd fd(
+            TEMP_FAILURE_RETRY(open(path_name.c_str(), O_RDONLY | O_NOFOLLOW | O_CLOEXEC)));
+    if (fd == -1) return ErrnoError() << "Could not open module '" << path_name << "'";
+
+    int ret = syscall(__NR_finit_module, fd.get(), args.c_str(), 0);
+    if (ret != 0) {
+        if (errno == EEXIST) {
+            // Module already loaded
+            return Success();
+        }
+        return ErrnoError() << "Failed to insmod '" << path_name << "' with args '" << args << "'";
+    }
+
+    LOG(INFO) << "Loaded kernel module " << path_name;
+    return Success();
+}
+
+Result<Success> ModaliasHandler::InsmodWithDeps(const std::string& module_name,
+                                                const std::string& args) {
+    if (module_name.empty()) {
+        return Error() << "Need valid module name";
+    }
+
+    auto it = module_deps_.find(module_name);
+    if (it == module_deps_.end()) {
+        return Error() << "Module '" << module_name << "' not in dependency file";
+    }
+    auto& dependencies = it->second;
+
+    // load module dependencies in reverse order
+    for (auto dep = dependencies.rbegin(); dep != dependencies.rend() - 1; ++dep) {
+        if (auto result = Insmod(*dep, ""); !result) return result;
+    }
+
+    // load target module itself with args
+    return Insmod(dependencies[0], args);
+}
+
+void ModaliasHandler::HandleModaliasEvent(const Uevent& uevent) {
+    if (uevent.modalias.empty()) return;
+
+    for (const auto& [alias, module] : module_aliases_) {
+        if (fnmatch(alias.c_str(), uevent.modalias.c_str(), 0) != 0) continue;  // Keep looking
+
+        LOG(DEBUG) << "Loading kernel module '" << module << "' for alias '" << uevent.modalias
+                   << "'";
+
+        if (auto result = InsmodWithDeps(module, ""); !result) {
+            LOG(ERROR) << "Cannot load module: " << result.error();
+            // try another one since there may be another match
+            continue;
+        }
+
+        // loading was successful
+        return;
+    }
+}
+
+}  // namespace init
+}  // namespace android