https://github.com/labath updated
https://github.com/llvm/llvm-project/pull/145021
>From 4e29066da132ed85a4ee5e5754bb547305759afe Mon Sep 17 00:00:00 2001
From: Pavel Labath <pa...@labath.sk>
Date: Fri, 20 Jun 2025 11:20:10 +0200
Subject: [PATCH] [lldb] Clean up
GDBRemoteCommunication::StartDebugserverProcess
The function was extremely messy in that it, depending on the set of
arguments, it could either modify the Connection object in `this` or
not. It had a lot of arguments, with each call site passing a different
combination of null values. This PR:
- packs "url" and "comm_fd" arguments into a variant as they are
mutually exclusive
- removes the "null url *and* null comm_fd" which is not used as of #145017
- marks the function as `static` to make it clear it (now) does not
operate on the `this` object.
---
.../gdb-remote/GDBRemoteCommunication.cpp | 169 ++++++------------
.../gdb-remote/GDBRemoteCommunication.h | 10 +-
.../GDBRemoteCommunicationServerPlatform.cpp | 30 ++--
.../Process/gdb-remote/ProcessGDBRemote.cpp | 6 +-
4 files changed, 78 insertions(+), 137 deletions(-)
diff --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp
b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp
index 0d3ead840b080..bea2faff2330e 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp
@@ -31,6 +31,7 @@
#include <climits>
#include <cstring>
#include <sys/stat.h>
+#include <variant>
#if defined(__APPLE__)
#define DEBUGSERVER_BASENAME "debugserver"
@@ -894,11 +895,9 @@ FileSpec
GDBRemoteCommunication::GetDebugserverPath(Platform *platform) {
}
Status GDBRemoteCommunication::StartDebugserverProcess(
- const char *url, Platform *platform, ProcessLaunchInfo &launch_info,
- uint16_t *port, const Args *inferior_args, shared_fd_t pass_comm_fd) {
+ std::variant<llvm::StringRef, shared_fd_t> comm, Platform *platform,
+ ProcessLaunchInfo &launch_info, const Args *inferior_args) {
Log *log = GetLog(GDBRLog::Process);
- LLDB_LOG(log, "Starting debug server: url={0}, port={1}",
- url ? url : "<empty>", port ? *port : uint16_t(0));
FileSpec debugserver_file_spec = GetDebugserverPath(platform);
if (!debugserver_file_spec)
@@ -911,89 +910,58 @@ Status GDBRemoteCommunication::StartDebugserverProcess(
#if !defined(__APPLE__)
// First argument to lldb-server must be mode in which to run.
- debugserver_args.AppendArgument(llvm::StringRef("gdbserver"));
+ debugserver_args.AppendArgument("gdbserver");
#endif
- // If a url is supplied then use it
- if (url && url[0])
- debugserver_args.AppendArgument(llvm::StringRef(url));
-
- if (pass_comm_fd != SharedSocket::kInvalidFD) {
- StreamString fd_arg;
- fd_arg.Printf("--fd=%" PRIi64, (int64_t)pass_comm_fd);
- debugserver_args.AppendArgument(fd_arg.GetString());
- // Send "pass_comm_fd" down to the inferior so it can use it to
- // communicate back with this process. Ignored on Windows.
- launch_info.AppendDuplicateFileAction((int64_t)pass_comm_fd,
- (int64_t)pass_comm_fd);
- }
-
// use native registers, not the GDB registers
- debugserver_args.AppendArgument(llvm::StringRef("--native-regs"));
+ debugserver_args.AppendArgument("--native-regs");
if (launch_info.GetLaunchInSeparateProcessGroup())
- debugserver_args.AppendArgument(llvm::StringRef("--setsid"));
+ debugserver_args.AppendArgument("--setsid");
llvm::SmallString<128> named_pipe_path;
// socket_pipe is used by debug server to communicate back either
- // TCP port or domain socket name which it listens on.
- // The second purpose of the pipe to serve as a synchronization point -
+ // TCP port or domain socket name which it listens on. However, we're not
+ // interested in the actualy value here.
+ // The only reason for using the pipe is to serve as a synchronization point
-
// once data is written to the pipe, debug server is up and running.
Pipe socket_pipe;
- std::unique_ptr<TCPSocket> sock_up;
+ // If a url is supplied then use it
+ if (shared_fd_t *comm_fd = std::get_if<shared_fd_t>(&comm)) {
+ LLDB_LOG(log, "debugserver communicates over fd {0}", comm_fd);
+ assert(*comm_fd != SharedSocket::kInvalidFD);
+ debugserver_args.AppendArgument(llvm::formatv("--fd={0}", *comm_fd).str());
+ // Send "comm_fd" down to the inferior so it can use it to communicate back
+ // with this process.
+ launch_info.AppendDuplicateFileAction((int64_t)*comm_fd,
(int64_t)*comm_fd);
+ } else {
+ llvm::StringRef url = std::get<llvm::StringRef>(comm);
+ LLDB_LOG(log, "debugserver listens on: {0}", url);
+ debugserver_args.AppendArgument(url);
- // port is null when debug server should listen on domain socket - we're
- // not interested in port value but rather waiting for debug server to
- // become available.
- if (pass_comm_fd == SharedSocket::kInvalidFD) {
- if (url) {
-// Create a temporary file to get the stdout/stderr and redirect the output of
-// the command into this file. We will later read this file if all goes well
-// and fill the data into "command_output_ptr"
#if defined(__APPLE__)
- // Binding to port zero, we need to figure out what port it ends up
- // using using a named pipe...
- Status error = socket_pipe.CreateWithUniqueName("debugserver-named-pipe",
- false, named_pipe_path);
- if (error.Fail()) {
- LLDB_LOG(log, "named pipe creation failed: {0}", error);
- return error;
- }
- debugserver_args.AppendArgument(llvm::StringRef("--named-pipe"));
- debugserver_args.AppendArgument(named_pipe_path);
+ // Using a named pipe as debugserver does not support --pipe.
+ Status error = socket_pipe.CreateWithUniqueName("debugserver-named-pipe",
+ false, named_pipe_path);
+ if (error.Fail()) {
+ LLDB_LOG(log, "named pipe creation failed: {0}", error);
+ return error;
+ }
+ debugserver_args.AppendArgument(llvm::StringRef("--named-pipe"));
+ debugserver_args.AppendArgument(named_pipe_path);
#else
- // Binding to port zero, we need to figure out what port it ends up
- // using using an unnamed pipe...
- Status error = socket_pipe.CreateNew(true);
- if (error.Fail()) {
- LLDB_LOG(log, "unnamed pipe creation failed: {0}", error);
- return error;
- }
- pipe_t write = socket_pipe.GetWritePipe();
- debugserver_args.AppendArgument(llvm::StringRef("--pipe"));
- debugserver_args.AppendArgument(llvm::to_string(write));
- launch_info.AppendCloseFileAction(socket_pipe.GetReadFileDescriptor());
-#endif
- } else {
- // No host and port given, so lets listen on our end and make the
- // debugserver connect to us..
- if (llvm::Expected<std::unique_ptr<TCPSocket>> expected_sock =
- Socket::TcpListen("127.0.0.1:0"))
- sock_up = std::move(*expected_sock);
- else
- return Status::FromError(expected_sock.takeError());
-
- uint16_t port_ = sock_up->GetLocalPortNumber();
- // Send the host and port down that debugserver and specify an option
- // so that it connects back to the port we are listening to in this
- // process
- debugserver_args.AppendArgument(llvm::StringRef("--reverse-connect"));
- debugserver_args.AppendArgument(
- llvm::formatv("127.0.0.1:{0}", port_).str());
- if (port)
- *port = port_;
+ // Using an unnamed pipe as it's simpler.
+ Status error = socket_pipe.CreateNew(true);
+ if (error.Fail()) {
+ LLDB_LOG(log, "unnamed pipe creation failed: {0}", error);
+ return error;
}
+ pipe_t write = socket_pipe.GetWritePipe();
+ debugserver_args.AppendArgument(llvm::StringRef("--pipe"));
+ debugserver_args.AppendArgument(llvm::to_string(write));
+ launch_info.AppendCloseFileAction(socket_pipe.GetReadFileDescriptor());
+#endif
}
Environment host_env = Host::GetEnvironment();
@@ -1070,7 +1038,7 @@ Status GDBRemoteCommunication::StartDebugserverProcess(
return error;
}
- if (pass_comm_fd != SharedSocket::kInvalidFD)
+ if (std::holds_alternative<shared_fd_t>(comm))
return Status();
Status error;
@@ -1084,55 +1052,30 @@ Status GDBRemoteCommunication::StartDebugserverProcess(
if (socket_pipe.CanWrite())
socket_pipe.CloseWriteFileDescriptor();
- if (socket_pipe.CanRead()) {
- // Read port from pipe with 10 second timeout.
- std::string port_str;
- while (error.Success()) {
- char buf[10];
- if (llvm::Expected<size_t> num_bytes =
- socket_pipe.Read(buf, std::size(buf), std::chrono::seconds(10)))
{
- if (*num_bytes == 0)
- break;
- port_str.append(buf, *num_bytes);
- } else {
- error = Status::FromError(num_bytes.takeError());
- }
- }
- if (error.Success() && (port != nullptr)) {
- // NB: Deliberately using .c_str() to stop at embedded '\0's
- llvm::StringRef port_ref = port_str.c_str();
- uint16_t child_port = 0;
- // FIXME: improve error handling
- llvm::to_integer(port_ref, child_port);
- if (*port == 0 || *port == child_port) {
- *port = child_port;
- LLDB_LOG(log, "debugserver listens on port {0}", *port);
- } else {
- LLDB_LOG(log,
- "debugserver listening on port {0} but requested port was
{1}",
- child_port, (*port));
- }
+ assert(socket_pipe.CanRead());
+
+ // Read data from the pipe -- and ignore it (see comment above).
+ while (error.Success()) {
+ char buf[10];
+ if (llvm::Expected<size_t> num_bytes =
+ socket_pipe.Read(buf, std::size(buf), std::chrono::seconds(10))) {
+ if (*num_bytes == 0)
+ break;
} else {
- LLDB_LOG(log, "failed to read a port value from pipe {0}: {1}",
- named_pipe_path, error);
+ error = Status::FromError(num_bytes.takeError());
}
- socket_pipe.Close();
}
+ if (error.Fail()) {
+ LLDB_LOG(log, "failed to synchronize on pipe {0}: {1}", named_pipe_path,
+ error);
+ }
+ socket_pipe.Close();
if (named_pipe_path.size() > 0) {
if (Status err = socket_pipe.Delete(named_pipe_path); err.Fail())
LLDB_LOG(log, "failed to delete pipe {0}: {1}", named_pipe_path, err);
}
- if (error.Success() && sock_up) {
- Socket *accepted_socket = nullptr;
- error = sock_up->Accept(/*timeout=*/std::nullopt, accepted_socket);
- if (accepted_socket) {
- SetConnection(std::make_unique<ConnectionFileDescriptor>(
- std::unique_ptr<Socket>(accepted_socket)));
- }
- }
-
return error;
}
diff --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.h
b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.h
index fc86f801f0d8a..31f8edf715a3a 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.h
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.h
@@ -135,17 +135,15 @@ class GDBRemoteCommunication : public Communication {
std::chrono::seconds GetPacketTimeout() const { return m_packet_timeout; }
// Get the debugserver path and check that it exist.
- FileSpec GetDebugserverPath(Platform *platform);
+ static FileSpec GetDebugserverPath(Platform *platform);
// Start a debugserver instance on the current host using the
// supplied connection URL.
- Status StartDebugserverProcess(
- const char *url,
+ static Status StartDebugserverProcess(
+ std::variant<llvm::StringRef, shared_fd_t> comm,
Platform *platform, // If non nullptr, then check with the platform for
// the GDB server binary if it can't be located
- ProcessLaunchInfo &launch_info, uint16_t *port, const Args
*inferior_args,
- shared_fd_t pass_comm_fd); // Communication file descriptor to pass
during
- // fork/exec to avoid having to connect/accept
+ ProcessLaunchInfo &launch_info, const Args *inferior_args);
void DumpHistory(Stream &strm);
diff --git
a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerPlatform.cpp
b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerPlatform.cpp
index 89fdfa74bc025..7506cf64def38 100644
---
a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerPlatform.cpp
+++
b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerPlatform.cpp
@@ -94,7 +94,16 @@
GDBRemoteCommunicationServerPlatform::~GDBRemoteCommunicationServerPlatform() =
Status GDBRemoteCommunicationServerPlatform::LaunchGDBServer(
const lldb_private::Args &args, lldb::pid_t &pid, std::string &socket_name,
shared_fd_t fd) {
- std::ostringstream url;
+ Log *log = GetLog(LLDBLog::Platform);
+
+ ProcessLaunchInfo debugserver_launch_info;
+ // Do not run in a new session so that it can not linger after the platform
+ // closes.
+ debugserver_launch_info.SetLaunchInSeparateProcessGroup(false);
+ debugserver_launch_info.SetMonitorProcessCallback(
+ [](lldb::pid_t, int, int) {});
+
+ Status error;
if (fd == SharedSocket::kInvalidFD) {
if (m_socket_protocol == Socket::ProtocolTcp) {
// Just check that GDBServer exists. GDBServer must be launched after
@@ -104,31 +113,22 @@ Status
GDBRemoteCommunicationServerPlatform::LaunchGDBServer(
return Status();
}
+ std::ostringstream url;
// debugserver does not accept the URL scheme prefix.
#if !defined(__APPLE__)
url << Socket::FindSchemeByProtocol(m_socket_protocol) << "://";
#endif
socket_name = GetDomainSocketPath("gdbserver").GetPath();
url << socket_name;
+ error = StartDebugserverProcess(url.str(), nullptr,
debugserver_launch_info,
+ &args);
} else {
if (m_socket_protocol != Socket::ProtocolTcp)
return Status::FromErrorString("protocol must be tcp");
+ error =
+ StartDebugserverProcess(fd, nullptr, debugserver_launch_info, &args);
}
- // Spawn a debugserver and try to get the port it listens to.
- ProcessLaunchInfo debugserver_launch_info;
- Log *log = GetLog(LLDBLog::Platform);
- LLDB_LOG(log, "Launching debugserver url='{0}', fd={1}...", url.str(), fd);
-
- // Do not run in a new session so that it can not linger after the platform
- // closes.
- debugserver_launch_info.SetLaunchInSeparateProcessGroup(false);
- debugserver_launch_info.SetMonitorProcessCallback(
- [](lldb::pid_t, int, int) {});
-
- Status error = StartDebugserverProcess(
- url.str().c_str(), nullptr, debugserver_launch_info, nullptr, &args, fd);
-
if (error.Success()) {
pid = debugserver_launch_info.GetProcessID();
AddSpawnedProcess(pid);
diff --git a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
index 4e70fe8ac1595..3f9c4ddc60a25 100644
--- a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
@@ -3494,9 +3494,9 @@ Status ProcessGDBRemote::LaunchAndConnectToDebugserver(
if (error.Fail())
return error;
- error = m_gdb_comm.StartDebugserverProcess(
- nullptr, GetTarget().GetPlatform().get(), debugserver_launch_info,
- nullptr, nullptr, shared_socket.GetSendableFD());
+ error = m_gdb_comm.StartDebugserverProcess(shared_socket.GetSendableFD(),
+ GetTarget().GetPlatform().get(),
+ debugserver_launch_info, nullptr);
if (error.Fail()) {
Log *log = GetLog(GDBRLog::Process);
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