lldb/tools/lldb-vscode/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
  11 #if !defined(_WIN32)
  12 #include <sys/stat.h>
  13 #include <sys/types.h>
  14 #include <unistd.h>
  15 #endif
  16
  17 #include <chrono>
  18 #include <fstream>
  19 #include <future>
  20 #include <optional>
  21 #include <thread>
  22
  23 #include "llvm/Support/FileSystem.h"
  24
  25 #include "lldb/lldb-defines.h"
  26
  27 using namespace llvm;
  28
  29 namespace lldb_vscode {
  30
  31 FifoFile::FifoFile(StringRef path) : m_path(path) {}
  32
  33 FifoFile::~FifoFile() {
  34 #if !defined(_WIN32)
  35   unlink(m_path.c_str());
  36 #endif
  37 }
  38
  39 Expected<std::shared_ptr<FifoFile>> CreateFifoFile(StringRef path) {
  40 #if defined(_WIN32)
  41   return createStringError(inconvertibleErrorCode(), "Unimplemented");
  42 #else
  43   if (int err = mkfifo(path.data(), 0600))
  44     return createStringError(std::error_code(err, std::generic_category()),
  45                              "Couldn't create fifo file: %s", path.data());
  46   return std::make_shared<FifoFile>(path);
  47 #endif
  48 }
  49
  50 FifoFileIO::FifoFileIO(StringRef fifo_file, StringRef other_endpoint_name)
  51     : m_fifo_file(fifo_file), m_other_endpoint_name(other_endpoint_name) {}
  52
  53 Expected<json::Value> FifoFileIO::ReadJSON(std::chrono::milliseconds timeout) {
  54   // We use a pointer for this future, because otherwise its normal destructor
  55   // would wait for the getline to end, rendering the timeout useless.
  56   std::optional<std::string> line;
  57   std::future<void> *future =
  58       new std::future<void>(std::async(std::launch::async, [&]() {
  59         std::ifstream reader(m_fifo_file, std::ifstream::in);
  60         std::string buffer;
  61         std::getline(reader, buffer);
  62         if (!buffer.empty())
  63           line = buffer;
  64       }));
  65   if (future->wait_for(timeout) == std::future_status::timeout || !line)
  66     // Indeed this is a leak, but it's intentional. "future" obj destructor
  67     //  will block on waiting for the worker thread to join. And the worker
  68     //  thread might be stuck in blocking I/O. Intentionally leaking the  obj
  69     //  as a hack to avoid blocking main thread, and adding annotation to
  70     //  supress static code inspection warnings
  71
  72     // coverity[leaked_storage]
  73     return createStringError(inconvertibleErrorCode(),
  74                              "Timed out trying to get messages from the " +
  75                                  m_other_endpoint_name);
  76   delete future;
  77   return json::parse(*line);
  78 }
  79
  80 Error FifoFileIO::SendJSON(const json::Value &json,
  81                            std::chrono::milliseconds timeout) {
  82   bool done = false;
  83   std::future<void> *future =
  84       new std::future<void>(std::async(std::launch::async, [&]() {
  85         std::ofstream writer(m_fifo_file, std::ofstream::out);
  86         writer << JSONToString(json) << std::endl;
  87         done = true;
  88       }));
  89   if (future->wait_for(timeout) == std::future_status::timeout || !done) {
  90     // Indeed this is a leak, but it's intentional. "future" obj destructor will
  91     // block on waiting for the worker thread to join. And the worker thread
  92     // might be stuck in blocking I/O. Intentionally leaking the  obj as a hack
  93     // to avoid blocking main thread, and adding annotation to supress static
  94     // code inspection warnings"
  95
  96     // coverity[leaked_storage]
  97     return createStringError(inconvertibleErrorCode(),
  98                              "Timed out trying to send messages to the " +
  99                                  m_other_endpoint_name);
 100   }
 101   delete future;
 102   return Error::success();
 103 }
 104
 105 } // namespace lldb_vscode