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[lldb-dap] Partially reverting OutputRedirector changes. #125136

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Merged
merged 1 commit into from
Jan 31, 2025
Merged

[lldb-dap] Partially reverting OutputRedirector changes. #125136

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66 changes: 42 additions & 24 deletions lldb/tools/lldb-dap/OutputRedirector.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,9 @@
//
//===----------------------------------------------------------------------===/

#include "OutputRedirector.h"
#include "DAP.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/Error.h"
#include <system_error>
#if defined(_WIN32)
Expand All @@ -15,45 +18,59 @@
#include <unistd.h>
#endif

#include "DAP.h"
#include "OutputRedirector.h"
#include "llvm/ADT/StringRef.h"

using lldb_private::Pipe;
using lldb_private::Status;
using llvm::createStringError;
using llvm::Error;
using llvm::Expected;
using llvm::inconvertibleErrorCode;
using llvm::StringRef;

namespace lldb_dap {

int OutputRedirector::kInvalidDescriptor = -1;

OutputRedirector::OutputRedirector() : m_fd(kInvalidDescriptor) {}

Expected<int> OutputRedirector::GetWriteFileDescriptor() {
if (!m_pipe.CanWrite())
if (m_fd == kInvalidDescriptor)
return createStringError(std::errc::bad_file_descriptor,
"write handle is not open for writing");
return m_pipe.GetWriteFileDescriptor();
return m_fd;
}

Error OutputRedirector::RedirectTo(std::function<void(StringRef)> callback) {
Status status = m_pipe.CreateNew(/*child_process_inherit=*/false);
if (status.Fail())
return status.takeError();
assert(m_fd == kInvalidDescriptor && "Output readirector already started.");
int new_fd[2];

m_forwarder = std::thread([this, callback]() {
char buffer[OutputBufferSize];
while (m_pipe.CanRead() && !m_stopped) {
size_t bytes_read;
Status status = m_pipe.Read(&buffer, sizeof(buffer), bytes_read);
if (status.Fail())
continue;
#if defined(_WIN32)
if (::_pipe(new_fd, OutputBufferSize, O_TEXT) == -1) {
#else
if (::pipe(new_fd) == -1) {
#endif
int error = errno;
return createStringError(inconvertibleErrorCode(),
"Couldn't create new pipe %s", strerror(error));
}

// EOF detected
if (bytes_read == 0 || m_stopped)
int read_fd = new_fd[0];
m_fd = new_fd[1];
m_forwarder = std::thread([this, callback, read_fd]() {
char buffer[OutputBufferSize];
while (!m_stopped) {
ssize_t bytes_count = ::read(read_fd, &buffer, sizeof(buffer));
// EOF detected.
if (bytes_count == 0)
break;
if (bytes_count == -1) {
// Skip non-fatal errors.
if (errno == EAGAIN || errno == EINTR || errno == EWOULDBLOCK)
continue;
break;
}

callback(StringRef(buffer, bytes_read));
callback(StringRef(buffer, bytes_count));
}
::close(read_fd);
});

return Error::success();
Expand All @@ -62,14 +79,15 @@ Error OutputRedirector::RedirectTo(std::function<void(StringRef)> callback) {
void OutputRedirector::Stop() {
m_stopped = true;

if (m_pipe.CanWrite()) {
if (m_fd != kInvalidDescriptor) {
int fd = m_fd;
m_fd = kInvalidDescriptor;
// Closing the pipe may not be sufficient to wake up the thread in case the
// write descriptor is duplicated (to stdout/err or to another process).
// Write a null byte to ensure the read call returns.
char buf[] = "\0";
size_t bytes_written;
m_pipe.Write(buf, sizeof(buf), bytes_written);
m_pipe.CloseWriteFileDescriptor();
::write(fd, buf, sizeof(buf));
::close(fd);
m_forwarder.join();
}
}
Expand Down
6 changes: 4 additions & 2 deletions lldb/tools/lldb-dap/OutputRedirector.h
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,8 @@ namespace lldb_dap {

class OutputRedirector {
public:
static int kInvalidDescriptor;

/// Creates writable file descriptor that will invoke the given callback on
/// each write in a background thread.
///
Expand All @@ -33,13 +35,13 @@ class OutputRedirector {

~OutputRedirector() { Stop(); }

OutputRedirector() = default;
OutputRedirector();
OutputRedirector(const OutputRedirector &) = delete;
OutputRedirector &operator=(const OutputRedirector &) = delete;

private:
std::atomic<bool> m_stopped = false;
lldb_private::Pipe m_pipe;
int m_fd;
std::thread m_forwarder;
};

Expand Down