From ae013976b24ce95140d3a9b129f15d4714532e28 Mon Sep 17 00:00:00 2001
From: Muxi Yan <mxyan@google.com>
Date: Tue, 7 Aug 2018 09:34:51 -0700
Subject: [PATCH] Surface error_string to ObjC users

---
 src/objective-c/GRPCClient/private/GRPCWrappedCall.m |  8 ++++++--
 src/objective-c/GRPCClient/private/NSError+GRPC.h    |  4 +++-
 src/objective-c/GRPCClient/private/NSError+GRPC.m    | 10 ++++++++--
 3 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/src/objective-c/GRPCClient/private/GRPCWrappedCall.m b/src/objective-c/GRPCClient/private/GRPCWrappedCall.m
index f28e494868e..7781d27ca4f 100644
--- a/src/objective-c/GRPCClient/private/GRPCWrappedCall.m
+++ b/src/objective-c/GRPCClient/private/GRPCWrappedCall.m
@@ -187,6 +187,7 @@
   grpc_slice _details;
   size_t _detailsCapacity;
   grpc_metadata_array _trailers;
+  const char *_errorString;
 }
 
 - (instancetype)init {
@@ -200,6 +201,7 @@
     _op.data.recv_status_on_client.status_details = &_details;
     grpc_metadata_array_init(&_trailers);
     _op.data.recv_status_on_client.trailing_metadata = &_trailers;
+    _op.data.recv_status_on_client.error_string = &_errorString;
     if (handler) {
       // Prevent reference cycle with _handler
       __weak typeof(self) weakSelf = self;
@@ -207,8 +209,9 @@
         __strong typeof(self) strongSelf = weakSelf;
         if (strongSelf) {
           char *details = grpc_slice_to_c_string(strongSelf->_details);
-          NSError *error =
-              [NSError grpc_errorFromStatusCode:strongSelf->_statusCode details:details];
+          NSError *error = [NSError grpc_errorFromStatusCode:strongSelf->_statusCode
+                                                     details:details
+                                                 errorString:strongSelf->_errorString];
           NSDictionary *trailers =
               [NSDictionary grpc_dictionaryFromMetadataArray:strongSelf->_trailers];
           handler(error, trailers);
@@ -223,6 +226,7 @@
 - (void)dealloc {
   grpc_metadata_array_destroy(&_trailers);
   grpc_slice_unref(_details);
+  gpr_free((void *)_errorString);
 }
 
 @end
diff --git a/src/objective-c/GRPCClient/private/NSError+GRPC.h b/src/objective-c/GRPCClient/private/NSError+GRPC.h
index e96b7297c28..a63e76ee4d0 100644
--- a/src/objective-c/GRPCClient/private/NSError+GRPC.h
+++ b/src/objective-c/GRPCClient/private/NSError+GRPC.h
@@ -24,5 +24,7 @@
  * Returns nil if the status code is OK. Otherwise, a NSError whose code is one of |GRPCErrorCode|
  * and whose domain is |kGRPCErrorDomain|.
  */
-+ (instancetype)grpc_errorFromStatusCode:(grpc_status_code)statusCode details:(char *)details;
++ (instancetype)grpc_errorFromStatusCode:(grpc_status_code)statusCode
+                                 details:(char *)details
+                             errorString:(const char *)errorString;
 @end
diff --git a/src/objective-c/GRPCClient/private/NSError+GRPC.m b/src/objective-c/GRPCClient/private/NSError+GRPC.m
index c2e65e4d8a2..199b2ebb6c3 100644
--- a/src/objective-c/GRPCClient/private/NSError+GRPC.m
+++ b/src/objective-c/GRPCClient/private/NSError+GRPC.m
@@ -23,13 +23,19 @@
 NSString *const kGRPCErrorDomain = @"io.grpc";
 
 @implementation NSError (GRPC)
-+ (instancetype)grpc_errorFromStatusCode:(grpc_status_code)statusCode details:(char *)details {
++ (instancetype)grpc_errorFromStatusCode:(grpc_status_code)statusCode
+                                 details:(char *)details
+                             errorString:(const char *)errorString {
   if (statusCode == GRPC_STATUS_OK) {
     return nil;
   }
   NSString *message = [NSString stringWithCString:details encoding:NSUTF8StringEncoding];
+  NSString *debugMessage = [NSString stringWithCString:errorString encoding:NSUTF8StringEncoding];
   return [NSError errorWithDomain:kGRPCErrorDomain
                              code:statusCode
-                         userInfo:@{NSLocalizedDescriptionKey : message}];
+                         userInfo:@{
+                           NSLocalizedDescriptionKey : message,
+                           NSDebugDescriptionErrorKey : debugMessage
+                         }];
 }
 @end