tools/gn/function_write_file.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 <iostream>
   6 #include <sstream>
   7
   8 #include "base/files/file_util.h"
   9 #include "base/strings/string_split.h"
  10 #include "base/strings/string_util.h"
  11 #include "base/strings/utf_string_conversions.h"
  12 #include "tools/gn/err.h"
  13 #include "tools/gn/filesystem_utils.h"
  14 #include "tools/gn/functions.h"
  15 #include "tools/gn/input_file.h"
  16 #include "tools/gn/parse_tree.h"
  17 #include "tools/gn/scheduler.h"
  18
  19 namespace functions {
  20
  21 namespace {
  22
  23 // On Windows, provide a custom implementation of base::WriteFile. Sometimes
  24 // the base version fails, especially on the bots. The guess is that Windows
  25 // Defender or other antivirus programs still have the file open (after
  26 // checking for the read) when the write happens immediately after. This
  27 // version opens with FILE_SHARE_READ (normally not what you want when
  28 // replacing the entire contents of the file) which lets us continue even if
  29 // another program has the file open for reading. See http://crbug.com/468437
  30 #if defined(OS_WIN)
  31 int DoWriteFile(const base::FilePath& filename, const char* data, int size) {
  32   base::win::ScopedHandle file(::CreateFile(
  33       filename.value().c_str(),
  34       GENERIC_WRITE,
  35       FILE_SHARE_READ,
  36       NULL,
  37       CREATE_ALWAYS,
  38       0,
  39       NULL));
  40   if (!file.IsValid()) {
  41     PLOG(ERROR) << "CreateFile failed for path "
  42                   << base::UTF16ToUTF8(filename.value());
  43     return -1;
  44   }
  45
  46   DWORD written;
  47   BOOL result = ::WriteFile(file.Get(), data, size, &written, NULL);
  48   if (result && static_cast<int>(written) == size)
  49     return written;
  50
  51   if (!result) {
  52     // WriteFile failed.
  53     PLOG(ERROR) << "writing file " << base::UTF16ToUTF8(filename.value())
  54                 << " failed";
  55   } else {
  56     // Didn't write all the bytes.
  57     LOG(ERROR) << "wrote" << written << " bytes to "
  58                << base::UTF16ToUTF8(filename.value()) << " expected " << size;
  59   }
  60   return -1;
  61 }
  62 #else
  63 int DoWriteFile(const base::FilePath& filename, const char* data, int size) {
  64   return base::WriteFile(filename, data, size);
  65 }
  66 #endif
  67
  68 }  // namespace
  69
  70 const char kWriteFile[] = "write_file";
  71 const char kWriteFile_HelpShort[] =
  72     "write_file: Write a file to disk.";
  73 const char kWriteFile_Help[] =
  74     "write_file: Write a file to disk.\n"
  75     "\n"
  76     "  write_file(filename, data)\n"
  77     "\n"
  78     "  If data is a list, the list will be written one-item-per-line with no\n"
  79     "  quoting or brackets.\n"
  80     "\n"
  81     "  If the file exists and the contents are identical to that being\n"
  82     "  written, the file will not be updated. This will prevent unnecessary\n"
  83     "  rebuilds of targets that depend on this file.\n"
  84     "\n"
  85     "  TODO(brettw) we probably need an optional third argument to control\n"
  86     "  list formatting.\n"
  87     "\n"
  88     "Arguments:\n"
  89     "\n"
  90     "  filename\n"
  91     "      Filename to write. This must be within the output directory.\n"
  92     "\n"
  93     "  data:\n"
  94     "      The list or string to write.\n";
  95
  96 Value RunWriteFile(Scope* scope,
  97                    const FunctionCallNode* function,
  98                    const std::vector<Value>& args,
  99                    Err* err) {
 100   if (args.size() != 2) {
 101     *err = Err(function->function(), "Wrong number of arguments to write_file",
 102                "I expected two arguments.");
 103     return Value();
 104   }
 105
 106   // Compute the file name and make sure it's in the output dir.
 107   const SourceDir& cur_dir = scope->GetSourceDir();
 108   SourceFile source_file = cur_dir.ResolveRelativeFile(args[0], err,
 109       scope->settings()->build_settings()->root_path_utf8());
 110   if (err->has_error())
 111     return Value();
 112   if (!EnsureStringIsInOutputDir(
 113           scope->settings()->build_settings()->build_dir(),
 114           source_file.value(), args[0].origin(), err))
 115     return Value();
 116   g_scheduler->AddWrittenFile(source_file);  // Track that we wrote this file.
 117
 118   // Track how to recreate this file, since we write it a gen time.
 119   // Note this is a hack since the correct output is not a dependency proper,
 120   // but an addition of this file to the output of the gn rule that writes it.
 121   // This dependency will, however, cause the gen step to be re-run and the
 122   // build restarted if the file is missing.
 123   g_scheduler->AddGenDependency(
 124       scope->settings()->build_settings()->GetFullPath(source_file));
 125
 126   // Compute output.
 127   std::ostringstream contents;
 128   if (args[1].type() == Value::LIST) {
 129     const std::vector<Value>& list = args[1].list_value();
 130     for (const auto& cur : list)
 131       contents << cur.ToString(false) << std::endl;
 132   } else {
 133     contents << args[1].ToString(false);
 134   }
 135   const std::string& new_contents = contents.str();
 136   base::FilePath file_path =
 137       scope->settings()->build_settings()->GetFullPath(source_file);
 138
 139   // Make sure we're not replacing the same contents.
 140   std::string existing_contents;
 141   if (base::ReadFileToString(file_path, &existing_contents) &&
 142       existing_contents == new_contents)
 143     return Value();  // Nothing to do.
 144
 145   // Write file, creating the directory if necessary.
 146   if (!base::CreateDirectory(file_path.DirName())) {
 147     *err = Err(function->function(), "Unable to create directory.",
 148                "I was using \"" + FilePathToUTF8(file_path.DirName()) + "\".");
 149     return Value();
 150   }
 151
 152   int int_size = static_cast<int>(new_contents.size());
 153   if (DoWriteFile(file_path, new_contents.c_str(), int_size)
 154       != int_size) {
 155     *err = Err(function->function(), "Unable to write file.",
 156                "I was writing \"" + FilePathToUTF8(file_path) + "\".");
 157     return Value();
 158   }
 159   return Value();
 160 }
 161
 162 }  // namespace functions