Add statusToString function.

For libbinder, not having these statuses printed out causes never ending
problems for developers.

Bug: 144534032
Test: libhidl_test tests this, which is on TH here
Change-Id: I02f37fb1e5b743131598ddc95ef89ebdfbdff615

libutils/Android.bp

@@ -125,6 +125,7 @@ cc_library {
     native_bridge_supported: true,
 
     srcs: [
+        "Errors.cpp",
         "FileMap.cpp",
         "JenkinsHash.cpp",
         "NativeHandle.cpp",

libutils/Errors.cpp

@@ -0,0 +1,51 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include <utils/Errors.h>
+
+namespace android {
+
+std::string statusToString(status_t s) {
+#define STATUS_CASE(STATUS) \
+    case STATUS:            \
+        return #STATUS
+
+    switch (s) {
+        STATUS_CASE(OK);
+        STATUS_CASE(UNKNOWN_ERROR);
+        STATUS_CASE(NO_MEMORY);
+        STATUS_CASE(INVALID_OPERATION);
+        STATUS_CASE(BAD_VALUE);
+        STATUS_CASE(BAD_TYPE);
+        STATUS_CASE(NAME_NOT_FOUND);
+        STATUS_CASE(PERMISSION_DENIED);
+        STATUS_CASE(NO_INIT);
+        STATUS_CASE(ALREADY_EXISTS);
+        STATUS_CASE(DEAD_OBJECT);
+        STATUS_CASE(FAILED_TRANSACTION);
+        STATUS_CASE(BAD_INDEX);
+        STATUS_CASE(NOT_ENOUGH_DATA);
+        STATUS_CASE(WOULD_BLOCK);
+        STATUS_CASE(TIMED_OUT);
+        STATUS_CASE(UNKNOWN_TRANSACTION);
+        STATUS_CASE(FDS_NOT_ALLOWED);
+        STATUS_CASE(UNEXPECTED_NULL);
+#undef STATUS_CASE
+    }
+
+    return std::to_string(s) + ' ' + strerror(-s);
+}
+
+}  // namespace android

libutils/include/utils/Errors.h

@@ -19,6 +19,7 @@
 #include <errno.h>
 #include <stdint.h>
 #include <sys/types.h>
+#include <string>
 
 namespace android {
 
@@ -72,6 +73,9 @@ enum {
     UNEXPECTED_NULL     = (UNKNOWN_ERROR + 8),
 };
 
+// Human readable name of error
+std::string statusToString(status_t status);
+
 // Restore define; enumeration is in "android" namespace, so the value defined
 // there won't work for Win32 code in a different namespace.
 #ifdef _WIN32