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      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/ninja_copy_target_writer.h"
      6 
      7 #include "base/strings/string_util.h"
      8 #include "tools/gn/ninja_utils.h"
      9 #include "tools/gn/output_file.h"
     10 #include "tools/gn/scheduler.h"
     11 #include "tools/gn/string_utils.h"
     12 #include "tools/gn/substitution_list.h"
     13 #include "tools/gn/substitution_writer.h"
     14 #include "tools/gn/target.h"
     15 #include "tools/gn/toolchain.h"
     16 
     17 NinjaCopyTargetWriter::NinjaCopyTargetWriter(const Target* target,
     18                                              std::ostream& out)
     19     : NinjaTargetWriter(target, out) {
     20 }
     21 
     22 NinjaCopyTargetWriter::~NinjaCopyTargetWriter() {
     23 }
     24 
     25 void NinjaCopyTargetWriter::Run() {
     26   const Tool* copy_tool = target_->toolchain()->GetTool(Toolchain::TYPE_COPY);
     27   if (!copy_tool) {
     28     g_scheduler->FailWithError(Err(NULL,
     29         "Copy tool not defined",
     30         "The toolchain " +
     31         target_->toolchain()->label().GetUserVisibleName(false) +
     32         "\n used by target " + target_->label().GetUserVisibleName(false) +
     33         "\n doesn't define a \"copy\" tool."));
     34     return;
     35   }
     36 
     37   const Tool* stamp_tool = target_->toolchain()->GetTool(Toolchain::TYPE_STAMP);
     38   if (!stamp_tool) {
     39     g_scheduler->FailWithError(Err(NULL,
     40         "Copy tool not defined",
     41         "The toolchain " +
     42         target_->toolchain()->label().GetUserVisibleName(false) +
     43         "\n used by target " + target_->label().GetUserVisibleName(false) +
     44         "\n doesn't define a \"stamp\" tool."));
     45     return;
     46   }
     47 
     48   // Figure out the substitutions used by the copy and stamp tools.
     49   SubstitutionBits required_bits = copy_tool->substitution_bits();
     50   required_bits.MergeFrom(stamp_tool->substitution_bits());
     51 
     52   // General target-related substitutions needed by both tools.
     53   WriteSharedVars(required_bits);
     54 
     55   std::vector<OutputFile> output_files;
     56   WriteCopyRules(&output_files);
     57   out_ << std::endl;
     58   WriteStampForTarget(output_files, std::vector<OutputFile>());
     59 }
     60 
     61 void NinjaCopyTargetWriter::WriteCopyRules(
     62     std::vector<OutputFile>* output_files) {
     63   CHECK(target_->action_values().outputs().list().size() == 1);
     64   const SubstitutionList& output_subst_list =
     65       target_->action_values().outputs();
     66   CHECK_EQ(1u, output_subst_list.list().size())
     67       << "Should have one entry exactly.";
     68   const SubstitutionPattern& output_subst = output_subst_list.list()[0];
     69 
     70   std::string tool_name =
     71       GetNinjaRulePrefixForToolchain(settings_) +
     72       Toolchain::ToolTypeToName(Toolchain::TYPE_COPY);
     73 
     74   // Note that we don't write implicit deps for copy steps. "copy" only
     75   // depends on the output files themselves, rather than having includes
     76   // (the possibility of generated #includes is the main reason for implicit
     77   // dependencies).
     78   //
     79   // It would seem that specifying implicit dependencies on the deps of the
     80   // copy command would still be harmeless. But Chrome implements copy tools
     81   // as hard links (much faster) which don't change the timestamp. If the
     82   // ninja rule looks like this:
     83   //   output: copy input | foo.stamp
     84   // The copy will not make a new timestamp on the output file, but the
     85   // foo.stamp file generated from a previous step will have a new timestamp.
     86   // The copy rule will therefore look out-of-date to Ninja and the rule will
     87   // get rebuilt.
     88   //
     89   // If this copy is copying a generated file, not listing the implicit
     90   // dependency will be fine as long as the input to the copy is properly
     91   // listed as the output from the step that generated it.
     92   //
     93   // Moreover, doing this assumes that the copy step is always a simple
     94   // locally run command, so there is no need for a toolchain dependency.
     95   for (size_t i = 0; i < target_->sources().size(); i++) {
     96     const SourceFile& input_file = target_->sources()[i];
     97 
     98     OutputFile output_file =
     99         SubstitutionWriter::ApplyPatternToSourceAsOutputFile(
    100             target_->settings(), output_subst, input_file);
    101     output_files->push_back(output_file);
    102 
    103     out_ << "build ";
    104     path_output_.WriteFile(out_, output_file);
    105     out_ << ": " << tool_name << " ";
    106     path_output_.WriteFile(out_, input_file);
    107     out_ << std::endl;
    108   }
    109 }
    110