[Lldb-commits] [lldb] [lldb-dap] Ensure the IO forwarding threads are managed by the DAP object lifecycle. (PR #120457)

[John Harrison via lldb-commits]

================
@@ -17,47 +19,59 @@
 #include "OutputRedirector.h"
 #include "llvm/ADT/StringRef.h"
 
-using namespace llvm;
+using lldb_private::Pipe;
+using lldb_private::Status;
+using llvm::createStringError;
+using llvm::Error;
+using llvm::Expected;
+using llvm::StringRef;
 
 namespace lldb_dap {
 
-Error RedirectFd(int fd, std::function<void(llvm::StringRef)> callback) {
-  int new_fd[2];
-#if defined(_WIN32)
-  if (_pipe(new_fd, 4096, O_TEXT) == -1) {
-#else
-  if (pipe(new_fd) == -1) {
-#endif
-    int error = errno;
-    return createStringError(inconvertibleErrorCode(),
-                             "Couldn't create new pipe for fd %d. %s", fd,
-                             strerror(error));
-  }
+Expected<int> OutputRedirector::GetWriteFileDescriptor() {
+  if (!m_pipe.CanWrite())
+    return createStringError(std::errc::bad_file_descriptor,
+                             "write handle is not open for writing");
+  return m_pipe.GetWriteFileDescriptor();
+}
 
-  if (dup2(new_fd[1], fd) == -1) {
-    int error = errno;
-    return createStringError(inconvertibleErrorCode(),
-                             "Couldn't override the fd %d. %s", fd,
-                             strerror(error));
-  }
+Error OutputRedirector::RedirectTo(std::function<void(StringRef)> callback) {
+  Status status = m_pipe.CreateNew(/*child_process_inherit=*/false);
+  if (status.Fail())
+    return status.takeError();
 
-  int read_fd = new_fd[0];
-  std::thread t([read_fd, callback]() {
+  m_forwarder = std::thread([this, callback]() {
     char buffer[OutputBufferSize];
-    while (true) {
-      ssize_t bytes_count = read(read_fd, &buffer, sizeof(buffer));
-      if (bytes_count == 0)
-        return;
-      if (bytes_count == -1) {
-        if (errno == EAGAIN || errno == EINTR)
-          continue;
+    while (m_pipe.CanRead() && !m_stopped) {
+      size_t bytes_read;
+      Status status = m_pipe.Read(&buffer, sizeof(buffer), bytes_read);
+      if (status.Fail())
+        continue;
+
+      // EOF detected
+      if (bytes_read == 0)
         break;
-      }
-      callback(StringRef(buffer, bytes_count));
+
+      callback(StringRef(buffer, bytes_read));
     }
   });
-  t.detach();
+
   return Error::success();
 }
 
+void OutputRedirector::Stop() {
+  m_stopped = true;
+
+  if (m_pipe.CanWrite()) {
+    // If the fd is waiting for input and is closed it may not return from the
+    // current select/poll/kqueue/etc. asyncio wait operation. Write a null byte
+    // to ensure the read fd wakes to detect the closed FD.
----------------
ashgti wrote:

Done

https://github.com/llvm/llvm-project/pull/120457