[Lldb-commits] [lldb] [lldb-dap] Refactoring IOStream into Transport handler. (PR #130026)

[Jonas Devlieghere via lldb-commits]

================
@@ -0,0 +1,146 @@
+//===-- Transport.cpp -----------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "Transport.h"
+#include "Protocol.h"
+#include "c++/v1/__system_error/error_code.h"
+#include "lldb/Utility/IOObject.h"
+#include "lldb/Utility/Status.h"
+#include "lldb/lldb-forward.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/Support/Error.h"
+#include "llvm/Support/raw_ostream.h"
+#include <string>
+#include <system_error>
+#include <utility>
+
+using namespace llvm;
+using namespace lldb;
+using namespace lldb_private;
+using namespace lldb_dap;
+using namespace lldb_dap::protocol;
+
+static Expected<std::string> ReadFull(IOObjectSP &descriptor, size_t length) {
+  if (!descriptor || !descriptor->IsValid())
+    return createStringError("transport input is closed");
+
+  std::string data;
+  data.resize(length);
+
+  auto status = descriptor->Read(data.data(), length);
+  if (status.Fail())
+    return status.takeError();
+
+  // If we got back zero then we have reached EOF.
+  if (length == 0)
+    return createStringError(Transport::kEOF, "end-of-file");
+
+  return data.substr(0, length);
+}
+
+static Expected<std::string> ReadUntil(IOObjectSP &descriptor,
+                                       StringRef delimiter) {
+  std::string buffer;
+  buffer.reserve(delimiter.size() + 1);
+  while (!llvm::StringRef(buffer).ends_with(delimiter)) {
+    auto next = ReadFull(descriptor, 1);
+    if (auto Err = next.takeError())
+      return std::move(Err);
+    buffer += *next;
+  }
+  return buffer.substr(0, buffer.size() - delimiter.size());
+}
+
+static Error ReadExpected(IOObjectSP &descriptor, StringRef want) {
+  auto got = ReadFull(descriptor, want.size());
+  if (auto Err = got.takeError())
+    return Err;
+  if (*got != want) {
+    return createStringError("want %s, got %s", want.str().c_str(),
+                             got->c_str());
+  }
+  return Error::success();
+}
+
+namespace lldb_dap {
+
+const std::error_code Transport::kEOF =
+    std::error_code(0x1001, std::generic_category());
+
+Transport::Transport(StringRef client_name, IOObjectSP input, IOObjectSP output)
+    : m_client_name(client_name), m_input(std::move(input)),
+      m_output(std::move(output)) {}
+
+Expected<protocol::Message> Transport::Read(std::ofstream *log) {
+  // If we don't find the expected header we have reached EOF.
+  if (auto Err = ReadExpected(m_input, "Content-Length: "))
+    return std::move(Err);
+
+  auto rawLength = ReadUntil(m_input, "\r\n\r\n");
+  if (auto Err = rawLength.takeError())
+    return std::move(Err);
+
+  size_t length;
+  if (!to_integer(*rawLength, length))
+    return createStringError("invalid content length %s", rawLength->c_str());
+
+  auto rawJSON = ReadFull(m_input, length);
+  if (auto Err = rawJSON.takeError())
+    return std::move(Err);
+  if (rawJSON->length() != length)
+    return createStringError(
+        "malformed request, expected %ld bytes, got %ld bytes", length,
----------------
JDevlieghere wrote:

We have a few places in lldb which concatenate errors with `:` so I'm trying to be more consistent in using coons to separate error messages. You used a colon on line 120 so let's do the same here. 

```suggestion
        "malformed request: expected %ld bytes and got %ld bytes", length,
```

https://github.com/llvm/llvm-project/pull/130026