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[vscode] Improve runInTerminal and support linux
Depends on D93874. runInTerminal was using --wait-for, but it was some problems because it uses process polling looking for a single instance of the debuggee: - it gets to know of the target late, which renders breakpoints in the main function almost impossible - polling might fail if there are already other processes with the same name - polling might also fail on some linux machine, as it's implemented with the ps command, and the ps command's args and output are not standard everywhere As a better way to implement this so that it works well on Darwin and Linux, I'm using now the following process: - lldb-vscode notices the runInTerminal, so it spawns lldb-vscode with a special flag --launch-target <target>. This flags tells lldb-vscode to wait to be attached and then it execs the target program. I'm using lldb-vscode itself to do this, because it makes finding the launcher program easier. Also no CMAKE INSTALL scripts are needed. - Besides this, the debugger creates a temporary FIFO file where the launcher program will write its pid to. That way the debugger will be sure of which program to attach. - Once attach happend, the debugger creates a second temporary file to notify the launcher program that it has been attached, so that it can then exec. I'm using this instead of using a signal or a similar mechanism because I don't want the launcher program to wait indefinitely to be attached in case the debugger crashed. That would pollute the process list with a lot of hanging processes. Instead, I'm setting a 20 seconds timeout (that's an overkill) and the launcher program seeks in intervals the second tepmorary file. Some notes: - I preferred not to use sockets because it requires a lot of code and I only need a pid. It would also require a lot of code when windows support is implemented. - I didn't add Windows support, as I don't have a windows machine, but adding support for it should be easy, as the FIFO file can be implemented with a named pipe, which is standard on Windows and works pretty much the same way. The existing test which didn't pass on Linux, now passes. Differential Revision: https://reviews.llvm.org/D93951
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,91 @@ | ||
| //===-- FifoFiles.cpp -------------------------------------------*- C++ -*-===// | ||
| // | ||
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. | ||
| // See https://llvm.org/LICENSE.txt for license information. | ||
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception | ||
| // | ||
| //===----------------------------------------------------------------------===// | ||
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| #if !defined(WIN32) | ||
| #include <sys/stat.h> | ||
| #include <sys/types.h> | ||
| #include <unistd.h> | ||
| #endif | ||
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| #include <chrono> | ||
| #include <fstream> | ||
| #include <future> | ||
| #include <thread> | ||
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| #include "llvm/Support/FileSystem.h" | ||
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| #include "lldb/lldb-defines.h" | ||
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| #include "FifoFiles.h" | ||
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| using namespace llvm; | ||
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| namespace lldb_vscode { | ||
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| FifoFile::FifoFile(StringRef path) : m_path(path) {} | ||
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| FifoFile::~FifoFile() { | ||
| #if !defined(WIN32) | ||
| unlink(m_path.c_str()); | ||
| #endif | ||
| }; | ||
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| Expected<std::shared_ptr<FifoFile>> CreateFifoFile(StringRef path) { | ||
| #if defined(WIN32) | ||
| return createStringError(inconvertibleErrorCode(), "Unimplemented"); | ||
| #else | ||
| if (int err = mkfifo(path.data(), 0600)) | ||
| return createStringError(std::error_code(err, std::generic_category()), | ||
| "Couldn't create fifo file: %s", path.data()); | ||
| return std::make_shared<FifoFile>(path); | ||
| #endif | ||
| } | ||
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| FifoFileIO::FifoFileIO(StringRef fifo_file, StringRef other_endpoint_name) | ||
| : m_fifo_file(fifo_file), m_other_endpoint_name(other_endpoint_name) {} | ||
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| Expected<json::Value> FifoFileIO::ReadJSON(std::chrono::milliseconds timeout) { | ||
| // We use a pointer for this future, because otherwise its normal destructor | ||
| // would wait for the getline to end, rendering the timeout useless. | ||
| Optional<std::string> line; | ||
| std::future<void> *future = | ||
| new std::future<void>(std::async(std::launch::async, [&]() { | ||
| std::ifstream reader(m_fifo_file, std::ifstream::in); | ||
| std::string buffer; | ||
| std::getline(reader, buffer); | ||
| if (!buffer.empty()) | ||
| line = buffer; | ||
| })); | ||
| if (future->wait_for(timeout) == std::future_status::timeout || | ||
| !line.hasValue()) | ||
| return createStringError(inconvertibleErrorCode(), | ||
| "Timed out trying to get messages from the " + | ||
| m_other_endpoint_name); | ||
| delete future; | ||
| return json::parse(*line); | ||
| } | ||
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| Error FifoFileIO::SendJSON(const json::Value &json, | ||
| std::chrono::milliseconds timeout) { | ||
| bool done = false; | ||
| std::future<void> *future = | ||
| new std::future<void>(std::async(std::launch::async, [&]() { | ||
| std::ofstream writer(m_fifo_file, std::ofstream::out); | ||
| writer << JSONToString(json) << std::endl; | ||
| done = true; | ||
| })); | ||
| if (future->wait_for(timeout) == std::future_status::timeout || !done) { | ||
| return createStringError(inconvertibleErrorCode(), | ||
| "Timed out trying to send messages to the " + | ||
| m_other_endpoint_name); | ||
| } | ||
| delete future; | ||
| return Error::success(); | ||
| } | ||
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| } // namespace lldb_vscode |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,84 @@ | ||
| //===-- FifoFiles.h ---------------------------------------------*- C++ -*-===// | ||
| // | ||
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. | ||
| // See https://llvm.org/LICENSE.txt for license information. | ||
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception | ||
| // | ||
| //===----------------------------------------------------------------------===// | ||
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| #ifndef LLDB_TOOLS_LLDB_VSCODE_FIFOFILES_H | ||
| #define LLDB_TOOLS_LLDB_VSCODE_FIFOFILES_H | ||
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| #include "llvm/Support/Error.h" | ||
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| #include "JSONUtils.h" | ||
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| namespace lldb_vscode { | ||
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| /// Struct that controls the life of a fifo file in the filesystem. | ||
| /// | ||
| /// The file is destroyed when the destructor is invoked. | ||
| struct FifoFile { | ||
| FifoFile(llvm::StringRef path); | ||
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| ~FifoFile(); | ||
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| std::string m_path; | ||
| }; | ||
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| /// Create a fifo file in the filesystem. | ||
| /// | ||
| /// \param[in] path | ||
| /// The path for the fifo file. | ||
| /// | ||
| /// \return | ||
| /// A \a std::shared_ptr<FifoFile> if the file could be created, or an | ||
| /// \a llvm::Error in case of failures. | ||
| llvm::Expected<std::shared_ptr<FifoFile>> CreateFifoFile(llvm::StringRef path); | ||
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| class FifoFileIO { | ||
| public: | ||
| /// \param[in] fifo_file | ||
| /// The path to an input fifo file that exists in the file system. | ||
| /// | ||
| /// \param[in] other_endpoint_name | ||
| /// A human readable name for the other endpoint that will communicate | ||
| /// using this file. This is used for error messages. | ||
| FifoFileIO(llvm::StringRef fifo_file, llvm::StringRef other_endpoint_name); | ||
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| /// Read the next JSON object from the underlying input fifo file. | ||
| /// | ||
| /// The JSON object is expected to be a single line delimited with \a | ||
| /// std::endl. | ||
| /// | ||
| /// \return | ||
| /// An \a llvm::Error object indicating the success or failure of this | ||
| /// operation. Failures arise if the timeout is hit, the next line of text | ||
| /// from the fifo file is not a valid JSON object, or is it impossible to | ||
| /// read from the file. | ||
| llvm::Expected<llvm::json::Value> ReadJSON(std::chrono::milliseconds timeout); | ||
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| /// Serialize a JSON object and write it to the underlying output fifo file. | ||
| /// | ||
| /// \param[in] json | ||
| /// The JSON object to send. It will be printed as a single line delimited | ||
| /// with \a std::endl. | ||
| /// | ||
| /// \param[in] timeout | ||
| /// A timeout for how long we should until for the data to be consumed. | ||
| /// | ||
| /// \return | ||
| /// An \a llvm::Error object indicating whether the data was consumed by | ||
| /// a reader or not. | ||
| llvm::Error SendJSON( | ||
| const llvm::json::Value &json, | ||
| std::chrono::milliseconds timeout = std::chrono::milliseconds(20000)); | ||
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| private: | ||
| std::string m_fifo_file; | ||
| std::string m_other_endpoint_name; | ||
| }; | ||
|
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| } // namespace lldb_vscode | ||
|
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| #endif // LLDB_TOOLS_LLDB_VSCODE_FIFOFILES_H |
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