lldb/tools/lldb-dap/FifoFiles.cpp

   1 //===-- FifoFiles.cpp -------------------------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "FifoFiles.h"
  10 #include "JSONUtils.h"
  11
  12 #if !defined(_WIN32)
  13 #include <sys/stat.h>
  14 #include <sys/types.h>
  15 #include <unistd.h>
  16 #endif
  17
  18 #include <chrono>
  19 #include <fstream>
  20 #include <future>
  21 #include <optional>
  22
  23 using namespace llvm;
  24
  25 namespace lldb_dap {
  26
  27 FifoFile::FifoFile(StringRef path) : m_path(path) {}
  28
  29 FifoFile::~FifoFile() {
  30 #if !defined(_WIN32)
  31   unlink(m_path.c_str());
  32 #endif
  33 }
  34
  35 Expected<std::shared_ptr<FifoFile>> CreateFifoFile(StringRef path) {
  36 #if defined(_WIN32)
  37   return createStringError(inconvertibleErrorCode(), "Unimplemented");
  38 #else
  39   if (int err = mkfifo(path.data(), 0600))
  40     return createStringError(std::error_code(err, std::generic_category()),
  41                              "Couldn't create fifo file: %s", path.data());
  42   return std::make_shared<FifoFile>(path);
  43 #endif
  44 }
  45
  46 FifoFileIO::FifoFileIO(StringRef fifo_file, StringRef other_endpoint_name)
  47     : m_fifo_file(fifo_file), m_other_endpoint_name(other_endpoint_name) {}
  48
  49 Expected<json::Value> FifoFileIO::ReadJSON(std::chrono::milliseconds timeout) {
  50   // We use a pointer for this future, because otherwise its normal destructor
  51   // would wait for the getline to end, rendering the timeout useless.
  52   std::optional<std::string> line;
  53   std::future<void> *future =
  54       new std::future<void>(std::async(std::launch::async, [&]() {
  55         std::ifstream reader(m_fifo_file, std::ifstream::in);
  56         std::string buffer;
  57         std::getline(reader, buffer);
  58         if (!buffer.empty())
  59           line = buffer;
  60       }));
  61   if (future->wait_for(timeout) == std::future_status::timeout || !line)
  62     // Indeed this is a leak, but it's intentional. "future" obj destructor
  63     //  will block on waiting for the worker thread to join. And the worker
  64     //  thread might be stuck in blocking I/O. Intentionally leaking the  obj
  65     //  as a hack to avoid blocking main thread, and adding annotation to
  66     //  supress static code inspection warnings
  67
  68     // coverity[leaked_storage]
  69     return createStringError(inconvertibleErrorCode(),
  70                              "Timed out trying to get messages from the " +
  71                                  m_other_endpoint_name);
  72   delete future;
  73   return json::parse(*line);
  74 }
  75
  76 Error FifoFileIO::SendJSON(const json::Value &json,
  77                            std::chrono::milliseconds timeout) {
  78   bool done = false;
  79   std::future<void> *future =
  80       new std::future<void>(std::async(std::launch::async, [&]() {
  81         std::ofstream writer(m_fifo_file, std::ofstream::out);
  82         writer << JSONToString(json) << std::endl;
  83         done = true;
  84       }));
  85   if (future->wait_for(timeout) == std::future_status::timeout || !done) {
  86     // Indeed this is a leak, but it's intentional. "future" obj destructor will
  87     // block on waiting for the worker thread to join. And the worker thread
  88     // might be stuck in blocking I/O. Intentionally leaking the  obj as a hack
  89     // to avoid blocking main thread, and adding annotation to supress static
  90     // code inspection warnings"
  91
  92     // coverity[leaked_storage]
  93     return createStringError(inconvertibleErrorCode(),
  94                              "Timed out trying to send messages to the " +
  95                                  m_other_endpoint_name);
  96   }
  97   delete future;
  98   return Error::success();
  99 }
 100
 101 } // namespace lldb_dap