Allow parameters in store URIs

This is to allow store-specific configuration,
e.g. s3://my-cache?compression=bzip2&secret-key=/path/to/key.

src/libstore/http-binary-cache-store.cc

@@ -85,7 +85,10 @@ protected:
 
 };
 
-static RegisterStoreImplementation regStore([](const std::string & uri) -> std::shared_ptr<Store> {
+static RegisterStoreImplementation regStore([](
+    const std::string & uri, const StoreParams & params)
+    -> std::shared_ptr<Store>
+{
     if (std::string(uri, 0, 7) != "http://" &&
         std::string(uri, 0, 8) != "https://") return 0;
     auto store = std::make_shared<HttpBinaryCacheStore>(std::shared_ptr<Store>(0),

src/libstore/local-binary-cache-store.cc

@@ -16,6 +16,11 @@ public:
 
     void init() override;
 
+    std::string getUri() override
+    {
+        return "file://" + binaryCacheDir;
+    }
+
 protected:
 
     bool fileExists(const std::string & path) override;
@@ -78,7 +83,10 @@ ref<Store> openLocalBinaryCacheStore(std::shared_ptr<Store> localStore,
     return store;
 }
 
-static RegisterStoreImplementation regStore([](const std::string & uri) -> std::shared_ptr<Store> {
+static RegisterStoreImplementation regStore([](
+    const std::string & uri, const StoreParams & params)
+    -> std::shared_ptr<Store>
+{
     if (std::string(uri, 0, 7) != "file://") return 0;
     return openLocalBinaryCacheStore(std::shared_ptr<Store>(0),
         settings.get("binary-cache-secret-key-file", string("")),

src/libstore/local-store.cc

@@ -229,6 +229,12 @@ LocalStore::~LocalStore()
 }
 
 
+std::string LocalStore::getUri()
+{
+    return "local";
+}
+
+
 int LocalStore::getSchema()
 {
     int curSchema = 0;

src/libstore/local-store.hh

@@ -87,6 +87,8 @@ public:
 
     /* Implementations of abstract store API methods. */
 
+    std::string getUri() override;
+
     bool isValidPathUncached(const Path & path) override;
 
     PathSet queryValidPaths(const PathSet & paths) override;

src/libstore/remote-store.cc

@@ -49,6 +49,12 @@ RemoteStore::RemoteStore(size_t maxConnections)
 }
 
 
+std::string RemoteStore::getUri()
+{
+    return "daemon";
+}
+
+
 ref<RemoteStore::Connection> RemoteStore::openConnection()
 {
     auto conn = make_ref<Connection>();

src/libstore/remote-store.hh

@@ -26,6 +26,8 @@ public:
 
     /* Implementations of abstract store API methods. */
 
+    std::string getUri() override;
+
     bool isValidPathUncached(const Path & path) override;
 
     PathSet queryValidPaths(const PathSet & paths) override;

src/libstore/s3-binary-cache-store.cc

@@ -239,7 +239,10 @@ struct S3BinaryCacheStoreImpl : public S3BinaryCacheStore
 
 };
 
-static RegisterStoreImplementation regStore([](const std::string & uri) -> std::shared_ptr<Store> {
+static RegisterStoreImplementation regStore([](
+    const std::string & uri, const StoreParams & params)
+    -> std::shared_ptr<Store>
+{
     if (std::string(uri, 0, 5) != "s3://") return 0;
     auto store = std::make_shared<S3BinaryCacheStoreImpl>(std::shared_ptr<Store>(0),
         settings.get("binary-cache-secret-key-file", string("")),

src/libstore/store-api.cc

@@ -461,10 +461,22 @@ namespace nix {
 RegisterStoreImplementation::Implementations * RegisterStoreImplementation::implementations = 0;
 
 
-ref<Store> openStoreAt(const std::string & uri)
+ref<Store> openStoreAt(const std::string & uri_)
 {
+    auto uri(uri_);
+    StoreParams params;
+    auto q = uri.find('?');
+    if (q != std::string::npos) {
+        for (auto s : tokenizeString<Strings>(uri.substr(q + 1), "&")) {
+            auto e = s.find('=');
+            if (e != std::string::npos)
+                params[s.substr(0, e)] = s.substr(e + 1);
+        }
+        uri = uri_.substr(0, q);
+    }
+
     for (auto fun : *RegisterStoreImplementation::implementations) {
-        auto store = fun(uri);
+        auto store = fun(uri, params);
         if (store) return ref<Store>(store);
     }
 
@@ -478,7 +490,10 @@ ref<Store> openStore()
 }
 
 
-static RegisterStoreImplementation regStore([](const std::string & uri) -> std::shared_ptr<Store> {
+static RegisterStoreImplementation regStore([](
+    const std::string & uri, const StoreParams & params)
+    -> std::shared_ptr<Store>
+{
     enum { mDaemon, mLocal, mAuto } mode;
 
     if (uri == "daemon") mode = mDaemon;

src/libstore/store-api.hh

@@ -192,7 +192,7 @@ public:
 
     virtual ~Store() { }
 
-    virtual std::string getUri();
+    virtual std::string getUri() = 0;
 
     /* Check whether a path is valid. */
     bool isValidPath(const Path & path);
@@ -540,7 +540,10 @@ std::list<ref<Store>> getDefaultSubstituters();
 
 
 /* Store implementation registration. */
-typedef std::function<std::shared_ptr<Store>(const std::string & uri)> OpenStore;
+typedef std::map<std::string, std::string> StoreParams;
+
+typedef std::function<std::shared_ptr<Store>(
+    const std::string & uri, const StoreParams & params)> OpenStore;
 
 struct RegisterStoreImplementation
 {