From b690bd011fac0d3a7a6fc57a34b2e449cb24c759 Mon Sep 17 00:00:00 2001
From: Craig Tiller <ctiller@google.com>
Date: Thu, 11 Nov 2021 14:33:17 -0800
Subject: [PATCH] Allow API fuzzer to send multiple slices (#27993)

* Allow API fuzzer to send multiple slices

* fixes
---
 src/core/lib/transport/byte_stream.cc      | 4 ++++
 test/core/end2end/fuzzers/api_fuzzer.cc    | 7 +++++--
 test/core/end2end/fuzzers/api_fuzzer.proto | 2 +-
 3 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/core/lib/transport/byte_stream.cc b/src/core/lib/transport/byte_stream.cc
index 3cc5275e51d..8d3b22bd26e 100644
--- a/src/core/lib/transport/byte_stream.cc
+++ b/src/core/lib/transport/byte_stream.cc
@@ -40,6 +40,10 @@ SliceBufferByteStream::SliceBufferByteStream(grpc_slice_buffer* slice_buffer,
   GPR_ASSERT(slice_buffer->length <= UINT32_MAX);
   grpc_slice_buffer_init(&backing_buffer_);
   grpc_slice_buffer_swap(slice_buffer, &backing_buffer_);
+  if (backing_buffer_.count == 0) {
+    grpc_slice_buffer_add_indexed(&backing_buffer_, grpc_empty_slice());
+    GPR_ASSERT(backing_buffer_.count > 0);
+  }
 }
 
 SliceBufferByteStream::~SliceBufferByteStream() {}
diff --git a/test/core/end2end/fuzzers/api_fuzzer.cc b/test/core/end2end/fuzzers/api_fuzzer.cc
index e231c01a505..c8cb41fb6c8 100644
--- a/test/core/end2end/fuzzers/api_fuzzer.cc
+++ b/test/core/end2end/fuzzers/api_fuzzer.cc
@@ -379,9 +379,12 @@ class Call : public std::enable_shared_from_this<Call> {
           *batch_is_ok = false;
         } else {
           *batch_ops |= 1 << GRPC_OP_SEND_MESSAGE;
-          auto send = ReadSlice(batch_op.send_message().message());
+          std::vector<grpc_slice> slices;
+          for (const auto& m : batch_op.send_message().message()) {
+            slices.push_back(ReadSlice(m));
+          }
           send_message_ = op.data.send_message.send_message =
-              grpc_raw_byte_buffer_create(&send, 1);
+              grpc_raw_byte_buffer_create(slices.data(), slices.size());
           unwinders->push_back([this]() {
             grpc_byte_buffer_destroy(send_message_);
             send_message_ = nullptr;
diff --git a/test/core/end2end/fuzzers/api_fuzzer.proto b/test/core/end2end/fuzzers/api_fuzzer.proto
index 84968b90ed3..b546d93f96d 100644
--- a/test/core/end2end/fuzzers/api_fuzzer.proto
+++ b/test/core/end2end/fuzzers/api_fuzzer.proto
@@ -110,7 +110,7 @@ message SendInitialMetadata {
 }
 
 message SendMessage {
-    ByteSlice message = 1;
+    repeated ByteSlice message = 1;
 }
 
 message SendCloseFromClient {