Add an adapter iterator class to bluez (#4838)

* Add an adapter iterator class to bluez

* code review updates

* Fix typo in method

* Fix compilation and off-by-one error

* Ensure we unref the adapter during listing

* Remove unused variable

* Fix typos in comments - I clobbered the fixes that Justin pushed

* Fix typos in comments - I clobbered the fixes that Justin pushed

src/lib/support/CHIPMemString.h

@@ -57,6 +57,15 @@ inline char * CopyString(char * dest, const char * source, size_t length)
     return dest;
 }
 
+/**
+ * Convenience method for CopyString to auto-detect destination size.
+ */
+template <size_t N>
+inline char * CopyString(char (&dest)[N], const char * source)
+{
+    return CopyString(dest, source, N);
+}
+
 /**
  * This function copies a C-style string to memory newly allocated by Platform::MemoryAlloc().
  *

src/platform/Linux/CHIPBluezHelper.cpp

@@ -53,6 +53,7 @@
 #include <ble/CHIPBleServiceData.h>
 #include <platform/CHIPDeviceLayer.h>
 #include <protocols/Protocols.h>
+#include <support/CHIPMemString.h>
 
 #if CHIP_DEVICE_CONFIG_ENABLE_CHIPOBLE
 #include <errno.h>
@@ -72,6 +73,7 @@
 using namespace ::nl;
 using namespace chip::SetupPayloadData;
 using namespace chip::Protocols;
+using chip::Platform::CopyString;
 
 namespace chip {
 namespace DeviceLayer {
@@ -2008,6 +2010,95 @@ CHIP_ERROR ConnectDevice(BluezDevice1 * apDevice)
     return error;
 }
 
+AdapterIterator::~AdapterIterator()
+{
+    if (mManager != nullptr)
+    {
+        g_object_unref(mManager);
+    }
+
+    if (mObjectList != nullptr)
+    {
+        g_list_free_full(mObjectList, g_object_unref);
+    }
+}
+
+void AdapterIterator::Initialize()
+{
+    GError * error = nullptr;
+
+    mManager = g_dbus_object_manager_client_new_for_bus_sync(G_BUS_TYPE_SYSTEM, G_DBUS_OBJECT_MANAGER_CLIENT_FLAGS_NONE,
+                                                             BLUEZ_INTERFACE, "/", bluez_object_manager_client_get_proxy_type,
+                                                             nullptr /* unused user data in the Proxy Type Func */,
+                                                             nullptr /*destroy notify */, nullptr /* cancellable */, &error);
+
+    VerifyOrExit(mManager != nullptr, ChipLogError(DeviceLayer, "Failed to get DBUS object manager for listing adapters."));
+
+    mObjectList      = g_dbus_object_manager_get_objects(mManager);
+    mCurrentListItem = mObjectList;
+
+exit:
+    if (error != nullptr)
+    {
+        ChipLogError(DeviceLayer, "DBus error: %s", error->message);
+        g_error_free(error);
+    }
+}
+
+bool AdapterIterator::Advance()
+{
+    if (mCurrentListItem == nullptr)
+    {
+        return false;
+    }
+
+    while (mCurrentListItem != nullptr)
+    {
+        BluezAdapter1 * adapter = bluez_object_get_adapter1(BLUEZ_OBJECT(mCurrentListItem->data));
+        if (adapter == nullptr)
+        {
+            mCurrentListItem = mCurrentListItem->next;
+            continue;
+        }
+
+        // PATH is of the for  BLUEZ_PATH / hci<nr>, i.e. like
+        // '/org/bluez/hci0'
+        // Index represents the number after hci
+        const char * path = g_dbus_proxy_get_object_path(G_DBUS_PROXY(adapter));
+        unsigned index    = 0;
+
+        if (sscanf(path, BLUEZ_PATH "/hci%u", &index) != 1)
+        {
+            ChipLogError(DeviceLayer, "Failed to extract HCI index from '%s'", path);
+            index = 0;
+        }
+
+        mCurrent.index = index;
+        CopyString(mCurrent.address, bluez_adapter1_get_address(adapter));
+        CopyString(mCurrent.alias, bluez_adapter1_get_alias(adapter));
+        CopyString(mCurrent.name, bluez_adapter1_get_name(adapter));
+        mCurrent.powered = bluez_adapter1_get_powered(adapter);
+
+        g_object_unref(adapter);
+
+        mCurrentListItem = mCurrentListItem->next;
+
+        return true;
+    }
+
+    return false;
+}
+
+bool AdapterIterator::Next()
+{
+    if (mManager == nullptr)
+    {
+        Initialize();
+    }
+
+    return Advance();
+}
+
 } // namespace Internal
 } // namespace DeviceLayer
 } // namespace chip

src/platform/Linux/CHIPBluezHelper.h

@@ -205,6 +205,61 @@ CHIP_ERROR StopDiscovery(BluezEndpoint * apEndpoint);
 
 CHIP_ERROR ConnectDevice(BluezDevice1 * apDevice);
 
+/// Iterates over available BlueZ adapters
+///
+/// Usage example:
+///
+///  AdapterIterator iterator;
+///  while (iterator.Next()) {
+///      std::cout << iterator.GetAddress() << std::endl;
+///  }
+class AdapterIterator
+{
+public:
+    ~AdapterIterator();
+
+    /// Moves to the next DBUS interface.
+    ///
+    /// MUST be called before any of the 'current value' methods are
+    /// used (iterator gets initialized on the first call of Next).
+    bool Next();
+
+    // Information about the current value. Safe to call only after
+    // "Next" has returned true.
+    uint32_t GetIndex() const { return mCurrent.index; }
+    const char * GetAddress() const { return mCurrent.address; }
+    const char * GetAlias() const { return mCurrent.alias; }
+    const char * GetName() const { return mCurrent.name; }
+    bool IsPowered() const { return mCurrent.powered; }
+
+private:
+    /// Sets up the DBUS manager and loads the list
+    void Initialize();
+
+    /// Loads the next value in the list.
+    ///
+    /// Returns true if a value could be loaded, false if no more items to
+    /// iterate through.
+    bool Advance();
+
+    static constexpr size_t kMaxAddressLength = 19; // xx:xx:xx:xx:xx:xx
+    static constexpr size_t kMaxNameLength    = 64;
+
+    GDBusObjectManager * mManager = nullptr; // DBus connection
+    GList * mObjectList           = nullptr; // listing of objects on the bus
+    GList * mCurrentListItem      = nullptr; // current item viewed in the list
+
+    // data valid only if Next() returns true
+    struct
+    {
+        uint32_t index;
+        char address[kMaxAddressLength];
+        char alias[kMaxNameLength];
+        char name[kMaxNameLength];
+        bool powered;
+    } mCurrent = { 0 };
+};
+
 } // namespace Internal
 } // namespace DeviceLayer
 } // namespace chip