llvm-project/lldb/source/Utility/Error.cpp

//===-- Error.cpp -----------------------------------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

// C Includes
#ifdef __APPLE__
#include <mach/mach.h>
#endif

// C++ Includes
#include <cerrno>
#include <cstdarg>

// Other libraries and framework includes
#include "llvm/ADT/SmallVector.h"

// Project includes
#include "lldb/Host/PosixApi.h"
#include "lldb/Utility/Error.h"

using namespace lldb;
using namespace lldb_private;

Error::Error() : m_code(0), m_type(eErrorTypeInvalid), m_string() {}

Error::Error(ValueType err, ErrorType type)
    : m_code(err), m_type(type), m_string() {}

Error::Error(const Error &rhs) = default;

Error::Error(const char *format, ...)
    : m_code(0), m_type(eErrorTypeInvalid), m_string() {
  va_list args;
  va_start(args, format);
  SetErrorToGenericError();
  SetErrorStringWithVarArg(format, args);
  va_end(args);
}

//----------------------------------------------------------------------
// Assignment operator
//----------------------------------------------------------------------
const Error &Error::operator=(const Error &rhs) {
  if (this != &rhs) {
    m_code = rhs.m_code;
    m_type = rhs.m_type;
    m_string = rhs.m_string;
  }
  return *this;
}

//----------------------------------------------------------------------
// Assignment operator
//----------------------------------------------------------------------
const Error &Error::operator=(uint32_t err) {
  m_code = err;
  m_type = eErrorTypeMachKernel;
  m_string.clear();
  return *this;
}

Error::~Error() = default;

//----------------------------------------------------------------------
// 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.
//----------------------------------------------------------------------
const char *Error::AsCString(const char *default_error_str) const {
  if (Success())
    return nullptr;

  if (m_string.empty()) {
    const char *s = nullptr;
    switch (m_type) {
    case eErrorTypeMachKernel:
#if defined(__APPLE__)
      s = ::mach_error_string(m_code);
#endif
      break;

    case eErrorTypePOSIX:
      s = ::strerror(m_code);
      break;

    default:
      break;
    }
    if (s != nullptr)
      m_string.assign(s);
  }
  if (m_string.empty()) {
    if (default_error_str)
      m_string.assign(default_error_str);
    else
      return nullptr; // User wanted a nullptr string back...
  }
  return m_string.c_str();
}

//----------------------------------------------------------------------
// Clear the error and any cached error string that it might contain.
//----------------------------------------------------------------------
void Error::Clear() {
  m_code = 0;
  m_type = eErrorTypeInvalid;
  m_string.clear();
}

//----------------------------------------------------------------------
// Access the error value.
//----------------------------------------------------------------------
Error::ValueType Error::GetError() const { return m_code; }

//----------------------------------------------------------------------
// Access the error type.
//----------------------------------------------------------------------
ErrorType Error::GetType() const { return m_type; }

//----------------------------------------------------------------------
// Returns true if this object contains a value that describes an
// error or otherwise non-success result.
//----------------------------------------------------------------------
bool Error::Fail() const { return m_code != 0; }

//----------------------------------------------------------------------
// Set accesssor for the error value to "err" and the type to
// "eErrorTypeMachKernel"
//----------------------------------------------------------------------
void Error::SetMachError(uint32_t err) {
  m_code = err;
  m_type = eErrorTypeMachKernel;
  m_string.clear();
}

void Error::SetExpressionError(lldb::ExpressionResults result,
                               const char *mssg) {
  m_code = result;
  m_type = eErrorTypeExpression;
  m_string = mssg;
}

int Error::SetExpressionErrorWithFormat(lldb::ExpressionResults result,
                                        const char *format, ...) {
  int length = 0;

  if (format != nullptr && format[0]) {
    va_list args;
    va_start(args, format);
    length = SetErrorStringWithVarArg(format, args);
    va_end(args);
  } else {
    m_string.clear();
  }
  m_code = result;
  m_type = eErrorTypeExpression;
  return length;
}

//----------------------------------------------------------------------
// Set accesssor for the error value and type.
//----------------------------------------------------------------------
void Error::SetError(ValueType err, ErrorType type) {
  m_code = err;
  m_type = type;
  m_string.clear();
}

//----------------------------------------------------------------------
// Update the error value to be "errno" and update the type to
// be "POSIX".
//----------------------------------------------------------------------
void Error::SetErrorToErrno() {
  m_code = errno;
  m_type = eErrorTypePOSIX;
  m_string.clear();
}

//----------------------------------------------------------------------
// Update the error value to be LLDB_GENERIC_ERROR and update the type
// to be "Generic".
//----------------------------------------------------------------------
void Error::SetErrorToGenericError() {
  m_code = LLDB_GENERIC_ERROR;
  m_type = eErrorTypeGeneric;
  m_string.clear();
}

//----------------------------------------------------------------------
// Set accessor for the error string value for a specific error.
// This allows any string to be supplied as an error explanation.
// The error string value will remain until the error value is
// cleared or a new error value/type is assigned.
//----------------------------------------------------------------------
void Error::SetErrorString(llvm::StringRef err_str) {
  if (!err_str.empty()) {
    // If we have an error string, we should always at least have an error
    // set to a generic value.
    if (Success())
      SetErrorToGenericError();
  }
  m_string = err_str;
}

//------------------------------------------------------------------
/// Set the current error string to a formatted error string.
///
/// @param format
///     A printf style format string
//------------------------------------------------------------------
int Error::SetErrorStringWithFormat(const char *format, ...) {
  if (format != nullptr && format[0]) {
    va_list args;
    va_start(args, format);
    int length = SetErrorStringWithVarArg(format, args);
    va_end(args);
    return length;
  } else {
    m_string.clear();
  }
  return 0;
}

int Error::SetErrorStringWithVarArg(const char *format, va_list args) {
  if (format != nullptr && format[0]) {
    // If we have an error string, we should always at least have
    // an error set to a generic value.
    if (Success())
      SetErrorToGenericError();

    // Try and fit our error into a 1024 byte buffer first...
    llvm::SmallVector<char, 1024> buf;
    buf.resize(1024);
    // Copy in case our first call to vsnprintf doesn't fit into our
    // allocated buffer above
    va_list copy_args;
    va_copy(copy_args, args);
    unsigned length = ::vsnprintf(buf.data(), buf.size(), format, args);
    if (length >= buf.size()) {
      // The error formatted string didn't fit into our buffer, resize it
      // to the exact needed size, and retry
      buf.resize(length + 1);
      length = ::vsnprintf(buf.data(), buf.size(), format, copy_args);
      va_end(copy_args);
      assert(length < buf.size());
    }
    m_string.assign(buf.data(), length);
    va_end(args);
    return length;
  } else {
    m_string.clear();
  }
  return 0;
}

//----------------------------------------------------------------------
// Returns true if the error code in this object is considered a
// successful return value.
//----------------------------------------------------------------------
bool Error::Success() const { return m_code == 0; }

bool Error::WasInterrupted() const {
  return (m_type == eErrorTypePOSIX && m_code == EINTR);
}

void llvm::format_provider<lldb_private::Error>::format(
    const lldb_private::Error &error, llvm::raw_ostream &OS,
    llvm::StringRef Options) {
  llvm::format_provider<llvm::StringRef>::format(error.AsCString(), OS,
                                                 Options);
}