tools/gn/escape.cc

   1 // Copyright (c) 2013 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 "tools/gn/escape.h"
   6
   7 #include "base/containers/stack_container.h"
   8 #include "base/logging.h"
   9
  10 namespace {
  11
  12 // A "1" in this lookup table means that char is valid in the Posix shell.
  13 const char kShellValid[0x80] = {
  14 // 00-1f: all are invalid
  15     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  16     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  17 // ' ' !  "  #  $  %  &  '  (  )  *  +  ,  -  .  /
  18     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1,
  19 //  0  1  2  3  4  5  6  7  8  9  :  ;  <  =  >  ?
  20     1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 0, 0,
  21 //  @  A  B  C  D  E  F  G  H  I  J  K  L  M  N  O
  22     1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
  23 //  P  Q  R  S  T  U  V  W  X  Y  Z  [  \  ]  ^  _
  24     1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1,
  25 //  `  a  b  c  d  e  f  g  h  i  j  k  l  m  n  o
  26     0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
  27 //  p  q  r  s  t  u  v  w  x  y  z  {  |  }  ~
  28     1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0, 0 };
  29
  30 // Append one character to the given string, escaping it for Ninja.
  31 //
  32 // Ninja's escaping rules are very simple. We always escape colons even
  33 // though they're OK in many places, in case the resulting string is used on
  34 // the left-hand-side of a rule.
  35 template<typename DestString>
  36 inline void NinjaEscapeChar(char ch, DestString* dest) {
  37   if (ch == '$' || ch == ' ' || ch == ':')
  38     dest->push_back('$');
  39   dest->push_back(ch);
  40 }
  41
  42 template<typename DestString>
  43 void EscapeStringToString_Ninja(const base::StringPiece& str,
  44                                 const EscapeOptions& options,
  45                                 DestString* dest,
  46                                 bool* needed_quoting) {
  47   for (const auto& elem : str)
  48     NinjaEscapeChar(elem, dest);
  49 }
  50
  51 template<typename DestString>
  52 void EscapeStringToString_NinjaPreformatted(const base::StringPiece& str,
  53                                             DestString* dest) {
  54   // Only Ninja-escape $.
  55   for (const auto& elem : str) {
  56     if (elem == '$')
  57       dest->push_back('$');
  58     dest->push_back(elem);
  59   }
  60 }
  61
  62 // Escape for CommandLineToArgvW and additionally escape Ninja characters.
  63 //
  64 // The basic algorithm is if the string doesn't contain any parse-affecting
  65 // characters, don't do anything (other than the Ninja processing). If it does,
  66 // quote the string, and backslash-escape all quotes and backslashes.
  67 // See:
  68 //   http://blogs.msdn.com/b/twistylittlepassagesallalike/archive/2011/04/23/everyone-quotes-arguments-the-wrong-way.aspx
  69 //   http://blogs.msdn.com/b/oldnewthing/archive/2010/09/17/10063629.aspx
  70 template<typename DestString>
  71 void EscapeStringToString_WindowsNinjaFork(const base::StringPiece& str,
  72                                            const EscapeOptions& options,
  73                                            DestString* dest,
  74                                            bool* needed_quoting) {
  75   // We assume we don't have any whitespace chars that aren't spaces.
  76   DCHECK(str.find_first_of("\r\n\v\t") == std::string::npos);
  77
  78   if (str.find_first_of(" \"") == std::string::npos) {
  79     // Simple case, don't quote.
  80     EscapeStringToString_Ninja(str, options, dest, needed_quoting);
  81   } else {
  82     if (!options.inhibit_quoting)
  83       dest->push_back('"');
  84
  85     for (size_t i = 0; i < str.size(); i++) {
  86       // Count backslashes in case they're followed by a quote.
  87       size_t backslash_count = 0;
  88       while (i < str.size() && str[i] == '\\') {
  89         i++;
  90         backslash_count++;
  91       }
  92       if (i == str.size()) {
  93         // Backslashes at end of string. Backslash-escape all of them since
  94         // they'll be followed by a quote.
  95         dest->append(backslash_count * 2, '\\');
  96       } else if (str[i] == '"') {
  97         // 0 or more backslashes followed by a quote. Backslash-escape the
  98         // backslashes, then backslash-escape the quote.
  99         dest->append(backslash_count * 2 + 1, '\\');
 100         dest->push_back('"');
 101       } else {
 102         // Non-special Windows character, just escape for Ninja. Also, add any
 103         // backslashes we read previously, these are literals.
 104         dest->append(backslash_count, '\\');
 105         NinjaEscapeChar(str[i], dest);
 106       }
 107     }
 108
 109     if (!options.inhibit_quoting)
 110       dest->push_back('"');
 111     if (needed_quoting)
 112       *needed_quoting = true;
 113   }
 114 }
 115
 116 template<typename DestString>
 117 void EscapeStringToString_PosixNinjaFork(const base::StringPiece& str,
 118                                          const EscapeOptions& options,
 119                                          DestString* dest,
 120                                          bool* needed_quoting) {
 121   for (const auto& elem : str) {
 122     if (elem == '$' || elem == ' ') {
 123       // Space and $ are special to both Ninja and the shell. '$' escape for
 124       // Ninja, then backslash-escape for the shell.
 125       dest->push_back('\\');
 126       dest->push_back('$');
 127       dest->push_back(elem);
 128     } else if (elem == ':') {
 129       // Colon is the only other Ninja special char, which is not special to
 130       // the shell.
 131       dest->push_back('$');
 132       dest->push_back(':');
 133     } else if (static_cast<unsigned>(elem) >= 0x80 ||
 134                !kShellValid[static_cast<int>(elem)]) {
 135       // All other invalid shell chars get backslash-escaped.
 136       dest->push_back('\\');
 137       dest->push_back(elem);
 138     } else {
 139       // Everything else is a literal.
 140       dest->push_back(elem);
 141     }
 142   }
 143 }
 144
 145 template<typename DestString>
 146 void EscapeStringToString(const base::StringPiece& str,
 147                           const EscapeOptions& options,
 148                           DestString* dest,
 149                           bool* needed_quoting) {
 150   switch (options.mode) {
 151     case ESCAPE_NONE:
 152       dest->append(str.data(), str.size());
 153       break;
 154     case ESCAPE_NINJA:
 155       EscapeStringToString_Ninja(str, options, dest, needed_quoting);
 156       break;
 157     case ESCAPE_NINJA_COMMAND:
 158       switch (options.platform) {
 159         case ESCAPE_PLATFORM_CURRENT:
 160 #if defined(OS_WIN)
 161           EscapeStringToString_WindowsNinjaFork(str, options, dest,
 162                                                 needed_quoting);
 163 #else
 164           EscapeStringToString_PosixNinjaFork(str, options, dest,
 165                                               needed_quoting);
 166 #endif
 167           break;
 168         case ESCAPE_PLATFORM_WIN:
 169           EscapeStringToString_WindowsNinjaFork(str, options, dest,
 170                                                 needed_quoting);
 171           break;
 172         case ESCAPE_PLATFORM_POSIX:
 173           EscapeStringToString_PosixNinjaFork(str, options, dest,
 174                                               needed_quoting);
 175           break;
 176         default:
 177           NOTREACHED();
 178       }
 179       break;
 180     case ESCAPE_NINJA_PREFORMATTED_COMMAND:
 181       EscapeStringToString_NinjaPreformatted(str, dest);
 182       break;
 183     default:
 184       NOTREACHED();
 185   }
 186 }
 187
 188 }  // namespace
 189
 190 std::string EscapeString(const base::StringPiece& str,
 191                          const EscapeOptions& options,
 192                          bool* needed_quoting) {
 193   std::string result;
 194   result.reserve(str.size() + 4);  // Guess we'll add a couple of extra chars.
 195   EscapeStringToString(str, options, &result, needed_quoting);
 196   return result;
 197 }
 198
 199 void EscapeStringToStream(std::ostream& out,
 200                           const base::StringPiece& str,
 201                           const EscapeOptions& options) {
 202   base::StackString<256> escaped;
 203   EscapeStringToString(str, options, &escaped.container(), nullptr);
 204   if (!escaped->empty())
 205     out.write(escaped->data(), escaped->size());
 206 }