From 97f17e93f1dd5fedcf290effb7d37bccfa9c087f Mon Sep 17 00:00:00 2001
From: deadprogram <ron@hybridgroup.com>
Date: Sat, 3 Oct 2020 23:24:38 +0200
Subject: [PATCH] gatt/darwin: macOS implementation and ensure pointer usage

Signed-off-by: deadprogram <ron@hybridgroup.com>
---
 gap_darwin.go   |  4 ++++
 gattc_darwin.go | 17 +++++++++++++++--
 gattc_linux.go  |  2 +-
 gattc_sd.go     |  2 +-
 4 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/gap_darwin.go b/gap_darwin.go
index ae6c8fb..4c52deb 100644
--- a/gap_darwin.go
+++ b/gap_darwin.go
@@ -162,5 +162,9 @@ func (pd *peripheralDelegate) DidUpdateValueForCharacteristic(prph cbgo.Peripher
 		if char != nil && char.callback != nil {
 			go char.callback(chr.Value())
 		}
+
+		if char.readChan != nil {
+			char.readChan <- nil
+		}
 	}
 }
diff --git a/gattc_darwin.go b/gattc_darwin.go
index e1e224d..d661147 100644
--- a/gattc_darwin.go
+++ b/gattc_darwin.go
@@ -114,6 +114,7 @@ type DeviceCharacteristic struct {
 
 	characteristic cbgo.Characteristic
 	callback       func(buf []byte)
+	readChan       chan error
 }
 
 // UUID returns the UUID for this DeviceCharacteristic.
@@ -147,6 +148,18 @@ func (c *DeviceCharacteristic) EnableNotifications(callback func(buf []byte)) er
 }
 
 // Read reads the current characteristic value.
-func (c DeviceCharacteristic) Read() (data []byte, err error) {
-	return nil, nil
+func (c *DeviceCharacteristic) Read() (data []byte, err error) {
+	c.readChan = make(chan error)
+	c.service.device.prph.ReadCharacteristic(c.characteristic)
+
+	// wait for result
+	select {
+	case <-c.readChan:
+		c.readChan = nil
+	case <-time.NewTimer(10 * time.Second).C:
+		c.readChan = nil
+		return nil, errors.New("timeout on Read()")
+	}
+
+	return c.characteristic.Value(), nil
 }
diff --git a/gattc_linux.go b/gattc_linux.go
index c353ebf..65f5994 100644
--- a/gattc_linux.go
+++ b/gattc_linux.go
@@ -234,7 +234,7 @@ func (c *DeviceCharacteristic) EnableNotifications(callback func(buf []byte)) er
 }
 
 // Read reads the current characteristic value.
-func (c DeviceCharacteristic) Read() ([]byte, error) {
+func (c *DeviceCharacteristic) Read() ([]byte, error) {
 	options := make(map[string]interface{})
 	return c.characteristic.ReadValue(options)
 }
diff --git a/gattc_sd.go b/gattc_sd.go
index 43ce47a..078edee 100644
--- a/gattc_sd.go
+++ b/gattc_sd.go
@@ -348,7 +348,7 @@ var readingCharacteristic struct {
 // Read reads the current characteristic value up to MTU length.
 // A future enhancement would be to be able to retrieve a longer
 // value by making multiple calls.
-func (c DeviceCharacteristic) Read() ([]byte, error) {
+func (c *DeviceCharacteristic) Read() ([]byte, error) {
 	errCode := C.sd_ble_gattc_read(c.connectionHandle, c.valueHandle, 0)
 	if errCode != 0 {
 		return nil, Error(errCode)