base/location.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "base/location.h"
   6
   7 // location.h is a widely included header and its size can significantly impact
   8 // build time. Try not to raise this limit unless absolutely necessary. See
   9 // https://chromium.googlesource.com/chromium/src/+/HEAD/docs/wmax_tokens.md
  10 #ifndef NACL_TC_REV
  11 #pragma clang max_tokens_here 240000
  12 #endif
  13
  14 #if defined(COMPILER_MSVC)
  15 #include <intrin.h>
  16 #endif
  17
  18 #include "base/compiler_specific.h"
  19 #include "base/strings/string_number_conversions.h"
  20 #include "base/strings/stringprintf.h"
  21 #include "build/build_config.h"
  22
  23 namespace base {
  24
  25 namespace {
  26
  27 // Returns the length of the given null terminated c-string.
  28 constexpr size_t StrLen(const char* str) {
  29   size_t str_len = 0;
  30   for (str_len = 0; str[str_len] != '\0'; ++str_len)
  31     ;
  32   return str_len;
  33 }
  34
  35 // Finds the length of the build folder prefix from the file path.
  36 // TODO(ssid): Strip prefixes from stored strings in the binary. This code only
  37 // skips the prefix while reading the file name strings at runtime.
  38 constexpr size_t StrippedFilePathPrefixLength() {
  39   constexpr char path[] = __FILE__;
  40   // Only keep the file path starting from the src directory.
  41   constexpr char stripped[] = "base/location.cc";
  42   constexpr size_t path_len = StrLen(path);
  43   constexpr size_t stripped_len = StrLen(stripped);
  44   static_assert(path_len >= stripped_len,
  45                 "Invalid file path for base/location.cc.");
  46   return path_len - stripped_len;
  47 }
  48
  49 constexpr size_t kStrippedPrefixLength = StrippedFilePathPrefixLength();
  50
  51 // Returns true if the |name| string has |prefix_len| characters in the prefix
  52 // and the suffix matches the |expected| string.
  53 // TODO(ssid): With C++20 we can make base::EndsWith() constexpr and use it
  54 //  instead.
  55 constexpr bool StrEndsWith(const char* name,
  56                            size_t prefix_len,
  57                            const char* expected) {
  58   const size_t name_len = StrLen(name);
  59   const size_t expected_len = StrLen(expected);
  60   if (name_len != prefix_len + expected_len)
  61     return false;
  62   for (size_t i = 0; i < expected_len; ++i) {
  63     if (name[i + prefix_len] != expected[i])
  64       return false;
  65   }
  66   return true;
  67 }
  68
  69 static_assert(StrEndsWith(__FILE__, kStrippedPrefixLength, "base/location.cc"),
  70               "The file name does not match the expected prefix format.");
  71
  72 }  // namespace
  73
  74 Location::Location() = default;
  75 Location::Location(const Location& other) = default;
  76 Location& Location::operator=(const Location& other) = default;
  77
  78 Location::Location(const char* file_name, const void* program_counter)
  79     : file_name_(file_name), program_counter_(program_counter) {}
  80
  81 Location::Location(const char* function_name,
  82                    const char* file_name,
  83                    int line_number,
  84                    const void* program_counter)
  85     : function_name_(function_name),
  86       file_name_(file_name),
  87       line_number_(line_number),
  88       program_counter_(program_counter) {
  89 #if !defined(OS_NACL)
  90   // The program counter should not be null except in a default constructed
  91   // (empty) Location object. This value is used for identity, so if it doesn't
  92   // uniquely identify a location, things will break.
  93   //
  94   // The program counter isn't supported in NaCl so location objects won't work
  95   // properly in that context.
  96   DCHECK(program_counter);
  97 #endif
  98 }
  99
 100 std::string Location::ToString() const {
 101   if (has_source_info()) {
 102     return std::string(function_name_) + "@" + file_name_ + ":" +
 103            NumberToString(line_number_);
 104   }
 105   return StringPrintf("pc:%p", program_counter_);
 106 }
 107
 108 #if defined(COMPILER_MSVC)
 109 #define RETURN_ADDRESS() _ReturnAddress()
 110 #elif defined(COMPILER_GCC) && !defined(OS_NACL)
 111 #define RETURN_ADDRESS() \
 112   __builtin_extract_return_addr(__builtin_return_address(0))
 113 #else
 114 #define RETURN_ADDRESS() nullptr
 115 #endif
 116
 117 #if !BUILDFLAG(FROM_HERE_USES_LOCATION_BUILTINS)
 118 #if !BUILDFLAG(ENABLE_LOCATION_SOURCE)
 119
 120 // static
 121 NOINLINE Location Location::CreateFromHere(const char* file_name) {
 122   return Location(file_name + kStrippedPrefixLength, RETURN_ADDRESS());
 123 }
 124
 125 #else
 126
 127 // static
 128 NOINLINE Location Location::CreateFromHere(const char* function_name,
 129                                            const char* file_name,
 130                                            int line_number) {
 131   return Location(function_name, file_name + kStrippedPrefixLength, line_number,
 132                   RETURN_ADDRESS());
 133 }
 134
 135 #endif
 136 #endif
 137
 138 #if SUPPORTS_LOCATION_BUILTINS && BUILDFLAG(ENABLE_LOCATION_SOURCE)
 139 // static
 140 NOINLINE Location Location::Current(const char* function_name,
 141                                     const char* file_name,
 142                                     int line_number) {
 143   return Location(function_name, file_name + kStrippedPrefixLength, line_number,
 144                   RETURN_ADDRESS());
 145 }
 146 #elif SUPPORTS_LOCATION_BUILTINS
 147 // static
 148 NOINLINE Location Location::Current(const char* file_name) {
 149   return Location(file_name + kStrippedPrefixLength, RETURN_ADDRESS());
 150 }
 151 #else
 152 // static
 153 NOINLINE Location Location::Current() {
 154   return Location(nullptr, RETURN_ADDRESS());
 155 }
 156 #endif
 157
 158 //------------------------------------------------------------------------------
 159 NOINLINE const void* GetProgramCounter() {
 160   return RETURN_ADDRESS();
 161 }
 162
 163 }  // namespace base