tor-browser

The Tor Browser
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location.h (4593B)

      1 // Copyright 2012 The Chromium Authors
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef BASE_LOCATION_H_
      6 #define BASE_LOCATION_H_
      7 
      8 #include <string>
      9 
     10 #include "base/base_export.h"
     11 #include "base/memory/raw_ptr_exclusion.h"
     12 #include "base/trace_event/base_tracing_forward.h"
     13 #include "build/build_config.h"
     14 
     15 namespace base {
     16 
     17 #if defined(__has_builtin)
     18 // Clang allows detection of these builtins.
     19 #  define SUPPORTS_LOCATION_BUILTINS                                       \
     20    (__has_builtin(__builtin_FUNCTION) && __has_builtin(__builtin_FILE) && \
     21     __has_builtin(__builtin_LINE))
     22 #elif defined(COMPILER_GCC) && __GNUC__ >= 7
     23 // GCC has supported these for a long time, but they point at the function
     24 // declaration in the case of default arguments, rather than at the call site.
     25 #  define SUPPORTS_LOCATION_BUILTINS 1
     26 #else
     27 #  define SUPPORTS_LOCATION_BUILTINS 0
     28 #endif
     29 
     30 // Location provides basic info where of an object was constructed, or was
     31 // significantly brought to life.
     32 class BASE_EXPORT Location {
     33 public:
     34  Location();
     35  Location(const Location& other);
     36  Location(Location&& other) noexcept;
     37  Location& operator=(const Location& other);
     38 
     39  static Location CreateForTesting(const char* function_name,
     40                                   const char* file_name,
     41                                   int line_number,
     42                                   const void* program_counter) {
     43    return Location(function_name, file_name, line_number, program_counter);
     44  }
     45 
     46  // Comparator for testing. The program counter should uniquely
     47  // identify a location.
     48  bool operator==(const Location& other) const {
     49    return program_counter_ == other.program_counter_;
     50  }
     51 
     52  // Comparator is necessary to use location object within an ordered container
     53  // type (eg. std::map).
     54  bool operator<(const Location& other) const {
     55    return program_counter_ < other.program_counter_;
     56  }
     57 
     58  // Returns true if there is source code location info. If this is false,
     59  // the Location object only contains a program counter or is
     60  // default-initialized (the program counter is also null).
     61  bool has_source_info() const { return function_name_ && file_name_; }
     62 
     63  // Will be nullptr for default initialized Location objects and when source
     64  // names are disabled.
     65  const char* function_name() const { return function_name_; }
     66 
     67  // Will be nullptr for default initialized Location objects and when source
     68  // names are disabled.
     69  const char* file_name() const { return file_name_; }
     70 
     71  // Will be -1 for default initialized Location objects and when source names
     72  // are disabled.
     73  int line_number() const { return line_number_; }
     74 
     75  // The address of the code generating this Location object. Should always be
     76  // valid except for default initialized Location objects, which will be
     77  // nullptr.
     78  const void* program_counter() const { return program_counter_; }
     79 
     80  // Converts to the most user-readable form possible. If function and filename
     81  // are not available, this will return "pc:<hex address>".
     82  std::string ToString() const;
     83 
     84  // Write a representation of this object into a trace.
     85  void WriteIntoTrace(perfetto::TracedValue context) const;
     86 
     87 #if SUPPORTS_LOCATION_BUILTINS
     88  static Location Current(const char* function_name = __builtin_FUNCTION(),
     89                          const char* file_name = __builtin_FILE(),
     90                          int line_number = __builtin_LINE());
     91 #else
     92  static Location Current();
     93 #endif
     94 
     95 private:
     96  // Only initializes the file name and program counter, the source information
     97  // will be null for the strings, and -1 for the line number.
     98  // TODO(http://crbug.com/760702) remove file name from this constructor.
     99  Location(const char* file_name, const void* program_counter);
    100 
    101  // Constructor should be called with a long-lived char*, such as __FILE__.
    102  // It assumes the provided value will persist as a global constant, and it
    103  // will not make a copy of it.
    104  Location(const char* function_name,
    105           const char* file_name,
    106           int line_number,
    107           const void* program_counter);
    108 
    109  const char* function_name_ = nullptr;
    110  const char* file_name_ = nullptr;
    111  int line_number_ = -1;
    112 
    113  // `program_counter_` is not a raw_ptr<...> for performance reasons (based on
    114  // analysis of sampling profiler data and tab_search:top100:2020).
    115  RAW_PTR_EXCLUSION const void* program_counter_ = nullptr;
    116 };
    117 
    118 BASE_EXPORT const void* GetProgramCounter();
    119 
    120 #define FROM_HERE ::base::Location::Current()
    121 
    122 }  // namespace base
    123 
    124 #endif  // BASE_LOCATION_H_