[Lldb-commits] [lldb] [lldb] Change the implementation of Status to store an llvm::Error (NFC) (PR #106774)
Adrian Prantl via lldb-commits
lldb-commits at lists.llvm.org
Wed Sep 11 13:55:16 PDT 2024
https://github.com/adrian-prantl updated https://github.com/llvm/llvm-project/pull/106774
>From 141b8cec8c266c7857c38e5da76ab538ac35c706 Mon Sep 17 00:00:00 2001
From: Pavel Labath <pavel at labath.sk>
Date: Wed, 11 Sep 2024 10:35:37 +0200
Subject: [PATCH 1/2] [lldb] Only send "posix" error codes through the
gdb-remote protocol
The other side has no way of telling which namespace do these codes
belong to, so mashing them all together is not very helpful.
I'm mainly doing this to simplify some code in a pending patch
<https://github.com/llvm/llvm-project/pull/106774/files#r1752628604>,
and I've picked the posix error category semi-randomly. If we wanted to
be serious about assigning meaning to these error codes, we should
create a special error category for "gdb errors".
---
.../Process/gdb-remote/GDBRemoteCommunicationServer.cpp | 7 ++++---
.../gdb-remote/GDBRemoteCommunicationServerTest.cpp | 3 ++-
2 files changed, 6 insertions(+), 4 deletions(-)
diff --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServer.cpp b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServer.cpp
index 9b72cb00352821..d4aa90b2c7731a 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServer.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServer.cpp
@@ -103,13 +103,14 @@ GDBRemoteCommunicationServer::SendErrorResponse(uint8_t err) {
GDBRemoteCommunication::PacketResult
GDBRemoteCommunicationServer::SendErrorResponse(const Status &error) {
+ uint8_t code = error.GetType() == eErrorTypePOSIX ? error.GetError() : 0xff;
if (m_send_error_strings) {
lldb_private::StreamString packet;
- packet.Printf("E%2.2x;", static_cast<uint8_t>(error.GetError()));
+ packet.Printf("E%2.2x;", code);
packet.PutStringAsRawHex8(error.AsCString());
return SendPacketNoLock(packet.GetString());
- } else
- return SendErrorResponse(error.GetError());
+ }
+ return SendErrorResponse(code);
}
GDBRemoteCommunication::PacketResult
diff --git a/lldb/unittests/Process/gdb-remote/GDBRemoteCommunicationServerTest.cpp b/lldb/unittests/Process/gdb-remote/GDBRemoteCommunicationServerTest.cpp
index 69ca1720c04fc9..ba9ca6ea73e3be 100644
--- a/lldb/unittests/Process/gdb-remote/GDBRemoteCommunicationServerTest.cpp
+++ b/lldb/unittests/Process/gdb-remote/GDBRemoteCommunicationServerTest.cpp
@@ -12,6 +12,7 @@
#include "Plugins/Process/gdb-remote/GDBRemoteCommunicationServer.h"
#include "lldb/Utility/Connection.h"
#include "lldb/Utility/UnimplementedError.h"
+#include "lldb/lldb-enumerations.h"
namespace lldb_private {
namespace process_gdb_remote {
@@ -25,7 +26,7 @@ TEST(GDBRemoteCommunicationServerTest, SendErrorResponse_ErrorNumber) {
TEST(GDBRemoteCommunicationServerTest, SendErrorResponse_Status) {
MockServerWithMockConnection server;
- Status status(0x42, lldb::eErrorTypeGeneric, "Test error message");
+ Status status(0x42, lldb::eErrorTypePOSIX, "Test error message");
server.SendErrorResponse(status);
EXPECT_THAT(
>From d82cb1739f1186582719817c9eb83348982d7192 Mon Sep 17 00:00:00 2001
From: Adrian Prantl <aprantl at apple.com>
Date: Wed, 4 Sep 2024 12:50:37 -0700
Subject: [PATCH 2/2] [lldb] Change the implementation of Status to store an
llvm::Error (NFC)
Most APIs that currently vend a Status would be better served by
returning llvm::Expected<> instead. Where possible, APIs should be
refactored to avoid Status. The only legitimate long-term uses of
Status are objects that need to store an error for a long time (which
should be questioned as a design decision, too).
This patch makes the transition to llvm::Error easier by making the
places that cannot switch to llvm::Error explicit: They are marked
with a call to Status::clone(). Every other API can and should be
refactored to use llvm::Expected. In the end Status should only be
used in very few places.
Whenever an unchecked Error is dropped by Status it logs this to the
verbose API channel.
Implementation notes:
This patch introduces two new kinds of error_category as well as new
llvm::Error types. Here is the mapping of lldb::ErrorType to
llvm::Errors:
(eErrorTypeInvalid)
eErrorTypeGeneric llvm::StringError
eErrorTypePOSIX llvm::ECError
eErrorTypeMachKernel MachKernelError
eErrorTypeExpression llvm::ErrorList<ExpressionError>
eErrorTypeWin32 Win32Error
---
lldb/include/lldb/Utility/Status.h | 83 +++++-
.../Python/PythonDataObjects.cpp | 5 +-
lldb/source/Utility/Status.cpp | 246 ++++++++++++------
3 files changed, 244 insertions(+), 90 deletions(-)
diff --git a/lldb/include/lldb/Utility/Status.h b/lldb/include/lldb/Utility/Status.h
index 795c830b965173..64e193f8d84206 100644
--- a/lldb/include/lldb/Utility/Status.h
+++ b/lldb/include/lldb/Utility/Status.h
@@ -28,6 +28,67 @@ namespace lldb_private {
const char *ExpressionResultAsCString(lldb::ExpressionResults result);
+/// Going a bit against the spirit of llvm::Error,
+/// lldb_private::Status need to store errors long-term and sometimes
+/// copy them. This base class defines an interface for this
+/// operation.
+class CloneableError
+ : public llvm::ErrorInfo<CloneableError, llvm::ErrorInfoBase> {
+public:
+ using llvm::ErrorInfo<CloneableError, llvm::ErrorInfoBase>::ErrorInfo;
+ CloneableError() : ErrorInfo() {}
+ virtual std::unique_ptr<CloneableError> Clone() const = 0;
+ static char ID;
+};
+
+/// Common base class for all error-code errors.
+class CloneableECError
+ : public llvm::ErrorInfo<CloneableECError, CloneableError> {
+public:
+ using llvm::ErrorInfo<CloneableECError, CloneableError>::ErrorInfo;
+ CloneableECError(std::error_code ec) : ErrorInfo() {}
+ std::error_code convertToErrorCode() const override { return EC; }
+ void log(llvm::raw_ostream &OS) const override { OS << EC.message(); }
+ static char ID;
+
+protected:
+ std::error_code EC;
+};
+
+/// FIXME: Move these declarations closer to where they're used.
+class MachKernelError
+ : public llvm::ErrorInfo<MachKernelError, CloneableECError> {
+public:
+ using llvm::ErrorInfo<MachKernelError, CloneableECError>::ErrorInfo;
+ MachKernelError(std::error_code ec) : ErrorInfo(ec) {}
+ std::string message() const override;
+ std::unique_ptr<CloneableError> Clone() const override;
+ static char ID;
+};
+
+class Win32Error : public llvm::ErrorInfo<Win32Error, CloneableECError> {
+public:
+ using llvm::ErrorInfo<Win32Error, CloneableECError>::ErrorInfo;
+ Win32Error(std::error_code ec, const llvm::Twine &msg = {}) : ErrorInfo(ec) {}
+ std::string message() const override;
+ std::unique_ptr<CloneableError> Clone() const override;
+ static char ID;
+};
+
+class ExpressionError
+ : public llvm::ErrorInfo<ExpressionError, CloneableECError> {
+public:
+ using llvm::ErrorInfo<ExpressionError, CloneableECError>::ErrorInfo;
+ ExpressionError(std::error_code ec, std::string msg = {})
+ : ErrorInfo(ec), m_string(msg) {}
+ std::unique_ptr<CloneableError> Clone() const override;
+ std::string message() const override { return m_string; }
+ static char ID;
+
+protected:
+ std::string m_string;
+};
+
/// \class Status Status.h "lldb/Utility/Status.h" An error handling class.
///
/// This class is designed to be able to hold any error code that can be
@@ -100,9 +161,7 @@ class Status {
}
static Status FromExpressionError(lldb::ExpressionResults result,
- std::string msg) {
- return Status(result, lldb::eErrorTypeExpression, msg);
- }
+ std::string msg);
/// Set the current error to errno.
///
@@ -115,6 +174,7 @@ class Status {
const Status &operator=(Status &&);
/// Avoid using this in new code. Migrate APIs to llvm::Expected instead.
static Status FromError(llvm::Error error);
+
/// FIXME: Replace this with a takeError() method.
llvm::Error ToError() const;
/// Don't call this function in new code. Instead, redesign the API
@@ -149,12 +209,20 @@ class Status {
/// Access the error value.
///
+ /// If the internally stored \ref llvm::Error is an \ref
+ /// llvm::ErrorList then this returns the error value of the first
+ /// error.
+ ///
/// \return
/// The error value.
ValueType GetError() const;
/// Access the error type.
///
+ /// If the internally stored \ref llvm::Error is an \ref
+ /// llvm::ErrorList then this returns the error value of the first
+ /// error.
+ ///
/// \return
/// The error type enumeration value.
lldb::ErrorType GetType() const;
@@ -170,12 +238,9 @@ class Status {
bool Success() const;
protected:
- Status(llvm::Error error);
- /// Status code as an integer value.
- ValueType m_code = 0;
- /// The type of the above error code.
- lldb::ErrorType m_type = lldb::eErrorTypeInvalid;
- /// A string representation of the error code.
+ Status(llvm::Error error) : m_error(std::move(error)) {}
+ llvm::Error m_error;
+ /// TODO: Replace this with just callling toString(m_error).
mutable std::string m_string;
};
diff --git a/lldb/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.cpp b/lldb/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.cpp
index 24cf3430006329..79e1db9b54e590 100644
--- a/lldb/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.cpp
+++ b/lldb/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.cpp
@@ -973,6 +973,9 @@ PythonException::PythonException(const char *caller) {
PyErr_Clear();
}
Py_XDECREF(repr);
+ Py_INCREF(m_exception);
+ if (m_traceback)
+ Py_INCREF(m_traceback);
} else {
PyErr_Clear();
}
@@ -993,8 +996,8 @@ void PythonException::Restore() {
}
PythonException::~PythonException() {
- Py_XDECREF(m_exception_type);
Py_XDECREF(m_exception);
+ Py_XDECREF(m_exception_type);
Py_XDECREF(m_traceback);
Py_XDECREF(m_repr_bytes);
}
diff --git a/lldb/source/Utility/Status.cpp b/lldb/source/Utility/Status.cpp
index 4af3af5fba0185..b1d7eac0bb8d23 100644
--- a/lldb/source/Utility/Status.cpp
+++ b/lldb/source/Utility/Status.cpp
@@ -8,6 +8,8 @@
#include "lldb/Utility/Status.h"
+#include "lldb/Utility/LLDBLog.h"
+#include "lldb/Utility/Log.h"
#include "lldb/Utility/VASPrintf.h"
#include "lldb/lldb-defines.h"
#include "lldb/lldb-enumerations.h"
@@ -37,48 +39,77 @@ class raw_ostream;
using namespace lldb;
using namespace lldb_private;
-Status::Status() {}
+char CloneableError::ID;
+char CloneableECError::ID;
+char MachKernelError::ID;
+char Win32Error::ID;
+char ExpressionError::ID;
+
+namespace {
+/// A std::error_code category for eErrorTypeGeneric.
+class LLDBGenericCategory : public std::error_category {
+ const char *name() const override { return "LLDBGenericCategory"; }
+ std::string message(int __ev) const override { return "generic LLDB error"; };
+};
+LLDBGenericCategory &lldb_generic_category() {
+ static GenericCategory g_generic_category;
+ return g_generic_category;
+}
+
+/// A std::error_code category for eErrorTypeExpression.
+class ExpressionCategory : public std::error_category {
+ const char *name() const override { return "LLDBExpressionCategory"; }
+ std::string message(int __ev) const override {
+ return ExpressionResultAsCString(
+ static_cast<lldb::ExpressionResults>(__ev));
+ };
+};
+ExpressionCategory &expression_category() {
+ static ExpressionCategory g_expression_category;
+ return g_expression_category;
+}
+} // namespace
+
+Status::Status() : m_error(llvm::Error::success()) {}
+
+static llvm::Error ErrorFromEnums(Status::ValueType err, ErrorType type,
+ std::string msg) {
+ switch (type) {
+ case eErrorTypeMachKernel:
+ return llvm::make_error<MachKernelError>(
+ std::error_code(err, std::system_category()));
+ case eErrorTypeWin32:
+ return llvm::make_error<Win32Error>(
+ std::error_code(err, std::system_category()));
+ case eErrorTypePOSIX:
+ if (msg.empty())
+ return llvm::errorCodeToError(
+ std::error_code(err, std::generic_category()));
+ return llvm::createStringError(
+ std::move(msg), std::error_code(err, std::generic_category()));
+ default:
+ return llvm::createStringError(
+ std::move(msg), std::error_code(err, lldb_generic_category()));
+ }
+}
Status::Status(ValueType err, ErrorType type, std::string msg)
- : m_code(err), m_type(type), m_string(std::move(msg)) {}
+ : m_error(ErrorFromEnums(err, type, msg)) {}
-// This logic is confusing because c++ calls the traditional (posix) errno codes
+// This logic is confusing because C++ calls the traditional (posix) errno codes
// "generic errors", while we use the term "generic" to mean completely
// arbitrary (text-based) errors.
Status::Status(std::error_code EC)
- : m_code(EC.value()),
- m_type(EC.category() == std::generic_category() ? eErrorTypePOSIX
- : eErrorTypeGeneric),
- m_string(EC.message()) {}
+ : m_error(!EC ? llvm::Error::success() : llvm::errorCodeToError(EC)) {}
Status::Status(std::string err_str)
- : m_code(LLDB_GENERIC_ERROR), m_type(eErrorTypeGeneric),
- m_string(std::move(err_str)) {}
-
-Status::Status(llvm::Error error) {
- if (!error) {
- Clear();
- return;
- }
+ : m_error(
+ llvm::createStringError(llvm::inconvertibleErrorCode(), err_str)) {}
- // if the error happens to be a errno error, preserve the error code
- error = llvm::handleErrors(
- std::move(error), [&](std::unique_ptr<llvm::ECError> e) -> llvm::Error {
- std::error_code ec = e->convertToErrorCode();
- if (ec.category() == std::generic_category()) {
- m_code = ec.value();
- m_type = ErrorType::eErrorTypePOSIX;
- return llvm::Error::success();
- }
- return llvm::Error(std::move(e));
- });
-
- // Otherwise, just preserve the message
- if (error) {
- m_code = LLDB_GENERIC_ERROR;
- m_type = eErrorTypeGeneric;
- m_string = llvm::toString(std::move(error));
- }
+const Status &Status::operator=(Status &&other) {
+ Clear();
+ m_error = std::move(other.m_error);
+ return *this;
}
Status Status::FromErrorStringWithFormat(const char *format, ...) {
@@ -94,25 +125,36 @@ Status Status::FromErrorStringWithFormat(const char *format, ...) {
return Status(string);
}
-Status Status::FromError(llvm::Error error) { return Status(std::move(error)); }
+Status Status::FromExpressionError(lldb::ExpressionResults result,
+ std::string msg) {
+ return Status(llvm::make_error<ExpressionError>(
+ std::error_code(result, expression_category()), msg));
+}
-llvm::Error Status::ToError() const {
- if (Success())
+/// Creates a deep copy of all known errors and converts all other
+/// errors to a new llvm::StringError.
+static llvm::Error CloneError(const llvm::Error &error) {
+ std::vector<std::unique_ptr<llvm::ErrorInfoBase>> info;
+ llvm::visitErrors(error, [&](const llvm::ErrorInfoBase &error) {
+ if (error.isA<CloneableError>())
+ info.push_back(static_cast<const CloneableError *>(&error)->Clone());
+ else
+ info.push_back(std::make_unique<llvm::StringError>(
+ error.message(), error.convertToErrorCode(), true));
+ });
+ if (info.size() == 0)
return llvm::Error::success();
- if (m_type == ErrorType::eErrorTypePOSIX)
- return llvm::errorCodeToError(
- std::error_code(m_code, std::generic_category()));
- return llvm::createStringError(AsCString());
+ llvm::Error e(std::move(info.front()));
+ for (auto it = std::next(info.begin()); it != info.end(); ++it)
+ e = llvm::joinErrors(std::move(e), llvm::Error(std::move(*it)));
+ return e;
}
-Status::~Status() = default;
+Status Status::FromError(llvm::Error error) { return Status(std::move(error)); }
-const Status &Status::operator=(Status &&other) {
- m_code = other.m_code;
- m_type = other.m_type;
- m_string = std::move(other.m_string);
- return *this;
-}
+llvm::Error Status::ToError() const { return CloneError(m_error); }
+
+Status::~Status() { llvm::consumeError(std::move(m_error)); }
#ifdef _WIN32
static std::string RetrieveWin32ErrorString(uint32_t error_code) {
@@ -140,6 +182,33 @@ static std::string RetrieveWin32ErrorString(uint32_t error_code) {
}
#endif
+std::string MachKernelError::message() const {
+#if defined(__APPLE__)
+ if (const char *s = ::mach_error_string(convertToErrorCode().value()))
+ return s;
+#endif
+ return "MachKernelError";
+}
+
+std::string Win32Error::message() const {
+#if defined(_WIN32)
+ return RetrieveWin32ErrorString(convertToErrorCode().value());
+#endif
+ return "Win32Error";
+}
+
+std::unique_ptr<CloneableError> MachKernelError::Clone() const {
+ return std::make_unique<MachKernelError>(convertToErrorCode());
+}
+
+std::unique_ptr<CloneableError> Win32Error::Clone() const {
+ return std::make_unique<Win32Error>(convertToErrorCode());
+}
+
+std::unique_ptr<CloneableError> ExpressionError::Clone() const {
+ return std::make_unique<ExpressionError>(convertToErrorCode(), message());
+}
+
// Get the error value as a NULL C string. The error string will be fetched and
// cached on demand. The cached error string value will remain until the error
// value is changed or cleared.
@@ -147,29 +216,12 @@ const char *Status::AsCString(const char *default_error_str) const {
if (Success())
return nullptr;
- if (m_string.empty()) {
- switch (m_type) {
- case eErrorTypeMachKernel:
-#if defined(__APPLE__)
- if (const char *s = ::mach_error_string(m_code))
- m_string.assign(s);
-#endif
- break;
-
- case eErrorTypePOSIX:
- m_string = llvm::sys::StrError(m_code);
- break;
-
- case eErrorTypeWin32:
-#if defined(_WIN32)
- m_string = RetrieveWin32ErrorString(m_code);
-#endif
- break;
+ m_string = llvm::toStringWithoutConsuming(m_error);
+ // Backwards compatibility with older implementations of Status.
+ if (m_error.isA<llvm::ECError>())
+ if (!m_string.empty() && m_string[m_string.size() - 1] == '\n')
+ m_string.pop_back();
- default:
- break;
- }
- }
if (m_string.empty()) {
if (default_error_str)
m_string.assign(default_error_str);
@@ -181,29 +233,63 @@ const char *Status::AsCString(const char *default_error_str) const {
// Clear the error and any cached error string that it might contain.
void Status::Clear() {
- m_code = 0;
- m_type = eErrorTypeInvalid;
- m_string.clear();
+ if (m_error)
+ LLDB_LOG_ERRORV(GetLog(LLDBLog::API), std::move(m_error),
+ "dropping error {0}");
+ m_error = llvm::Error::success();
+ llvm::consumeError(std::move(m_error));
}
-// Access the error value.
-Status::ValueType Status::GetError() const { return m_code; }
+Status::ValueType Status::GetError() const {
+ Status::ValueType result = 0;
+ llvm::visitErrors(m_error, [&](const llvm::ErrorInfoBase &error) {
+ // Return the first only.
+ if (result)
+ return;
+ std::error_code ec = error.convertToErrorCode();
+ result = ec.value();
+ });
+ return result;
+}
// Access the error type.
-ErrorType Status::GetType() const { return m_type; }
+ErrorType Status::GetType() const {
+ ErrorType result = eErrorTypeInvalid;
+ llvm::visitErrors(m_error, [&](const llvm::ErrorInfoBase &error) {
+ // Return the first only.
+ if (result != eErrorTypeInvalid)
+ return;
+ if (error.isA<MachKernelError>())
+ result = eErrorTypeMachKernel;
+ else if (error.isA<Win32Error>())
+ result = eErrorTypeWin32;
+ else if (error.isA<ExpressionError>())
+ result = eErrorTypeExpression;
+ else if (error.convertToErrorCode().category() == std::generic_category())
+ result = eErrorTypePOSIX;
+ else if (error.convertToErrorCode().category() == lldb_generic_category() ||
+ error.convertToErrorCode() == llvm::inconvertibleErrorCode())
+ result = eErrorTypeGeneric;
+ else
+ result = eErrorTypeInvalid;
+ });
+ return result;
+}
-// Returns true if this object contains a value that describes an error or
-// otherwise non-success result.
-bool Status::Fail() const { return m_code != 0; }
+bool Status::Fail() const {
+ // Note that this does not clear the checked flag in
+ // m_error. Otherwise we'd need to make this thread-safe.
+ return m_error.isA<llvm::ErrorInfoBase>();
+}
Status Status::FromErrno() {
// Update the error value to be "errno" and update the type to be "POSIX".
- return Status(errno, eErrorTypePOSIX);
+ return Status(llvm::errorCodeToError(llvm::errnoAsErrorCode()));
}
// Returns true if the error code in this object is considered a successful
// return value.
-bool Status::Success() const { return m_code == 0; }
+bool Status::Success() const { return !Fail(); }
void llvm::format_provider<lldb_private::Status>::format(
const lldb_private::Status &error, llvm::raw_ostream &OS,
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