Merge "Revert "Revert "Flag(env) guarding clear endpoint (device) feature for OSX usb start.""" am: 2ae387b3c0

Original change: https://android-review.googlesource.com/c/platform/packages/modules/adb/+/2504219

Change-Id: Ib20f2253985d5fb6f8a2740c44b779b8aa97d001
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

1 files changed, 28 insertions, 2 deletions

diff --git a/client/usb_osx.cpp b/client/usb_osx.cpp
index e1541ec1..99857e26 100644
--- a/client/usb_osx.cpp
+++ b/client/usb_osx.cpp
@@ -110,6 +110,16 @@ static void AndroidInterfaceAdded(io_iterator_t iterator);
 static std::unique_ptr<usb_handle> CheckInterface(IOUSBInterfaceInterface550** iface, UInt16 vendor,
                                                   UInt16 product);
 
+// Flag-guarded (using host env variable) feature that turns on
+// the ability to clear the device-side endpoint also before
+// starting. See public bug https://issuetracker.google.com/issues/37055927
+// for historical context.
+static bool clear_endpoints() {
+    static const char* env(getenv("ADB_OSX_USB_CLEAR_ENDPOINTS"));
+    static bool result = env && strcmp("1", env) == 0;
+    return result;
+}
+
 static bool FindUSBDevices() {
     // Create the matching dictionary to find the Android device's adb interface.
     CFMutableDictionaryRef matchingDict = IOServiceMatching(kIOUSBInterfaceClassName);
@@ -322,7 +332,17 @@ AndroidInterfaceAdded(io_iterator_t iterator)
 // Used to clear both the endpoints before starting.
 // When adb quits, we might clear the host endpoint but not the device.
 // So we make sure both sides are clear before starting up.
+// Returns true if:
+//      - the feature is disabled (OSX/host only)
+//      - the feature is enabled and successfully clears both endpoints
+// Returns false otherwise (if an error is encountered)
 static bool ClearPipeStallBothEnds(IOUSBInterfaceInterface550** interface, UInt8 bulkEp) {
+    // If feature-disabled, (silently) bypass clearing both
+    // endpoints (including device-side).
+    if (!clear_endpoints()) {
+        return true;
+    }
+
     IOReturn rc = (*interface)->ClearPipeStallBothEnds(interface, bulkEp);
     if (rc != kIOReturnSuccess) {
         LOG(ERROR) << "Could not clear pipe stall both ends: " << std::hex << rc;
@@ -415,12 +435,18 @@ static std::unique_ptr<usb_handle> CheckInterface(IOUSBInterfaceInterface550** i
 
         if (kUSBIn == direction) {
             handle->bulkIn = endpoint;
-            if (!ClearPipeStallBothEnds(interface, handle->bulkIn)) goto err_get_pipe_props;
+
+            if (!ClearPipeStallBothEnds(interface, handle->bulkIn)) {
+                goto err_get_pipe_props;
+            }
         }
 
         if (kUSBOut == direction) {
             handle->bulkOut = endpoint;
-            if (!ClearPipeStallBothEnds(interface, handle->bulkOut)) goto err_get_pipe_props;
+
+            if (!ClearPipeStallBothEnds(interface, handle->bulkOut)) {
+                goto err_get_pipe_props;
+            }
         }
 
         // Compute the packet-size, in case the system did not return the correct value.