libbinder: add BINDER_GET_EXTENDED_ERROR support

This adds basic support to pull extended error information provided by
the driver via BINDER_GET_EXTENDED_ERROR ioctl. For now, we'll only log
the information upon a failed transaction. However, this data can later
be used to handle error scenarios such as retry strategies.

Bug: 28321379
Test: atest binderLibTest
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Change-Id: I8aed63cb0d1aa15aa96db4ab8999e300fef1f505

1 files changed, 18 insertions, 0 deletions

diff --git a/libs/binder/IPCThreadState.cpp b/libs/binder/IPCThreadState.cpp
index 3c97dcab93..d453ac7532 100644
--- a/libs/binder/IPCThreadState.cpp
+++ b/libs/binder/IPCThreadState.cpp
@@ -989,6 +989,7 @@ finish:
         if (acquireResult) *acquireResult = err;
         if (reply) reply->setError(err);
         mLastError = err;
+        logExtendedError();
     }
 
     return err;
@@ -1443,6 +1444,23 @@ status_t IPCThreadState::freeze(pid_t pid, bool enable, uint32_t timeout_ms) {
     return ret;
 }
 
+void IPCThreadState::logExtendedError() {
+    struct binder_extended_error ee = {.command = BR_OK};
+
+    if (!ProcessState::isDriverFeatureEnabled(ProcessState::DriverFeature::EXTENDED_ERROR))
+        return;
+
+#if defined(__ANDROID__)
+    if (ioctl(self()->mProcess->mDriverFD, BINDER_GET_EXTENDED_ERROR, &ee) < 0) {
+        ALOGE("Failed to get extended error: %s", strerror(errno));
+        return;
+    }
+#endif
+
+    ALOGE_IF(ee.command != BR_OK, "Binder transaction failure: %d/%d/%d",
+             ee.id, ee.command, ee.param);
+}
+
 void IPCThreadState::freeBuffer(Parcel* parcel, const uint8_t* data,
                                 size_t /*dataSize*/,
                                 const binder_size_t* /*objects*/,