Add initial prototype for the GN meta-buildsystem.

tools/gn/function_exec_script.cc

Index: tools/gn/function_exec_script.cc
diff --git a/tools/gn/function_exec_script.cc b/tools/gn/function_exec_script.cc
new file mode 100644
index 0000000000000000000000000000000000000000..a950909e25cb06ef48523fa899014b93c154fc20
--- /dev/null
+++ b/tools/gn/function_exec_script.cc
@@ -0,0 +1,254 @@
+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/command_line.h"
+#include "base/file_util.h"
+#include "base/strings/string_number_conversions.h"
+#include "build/build_config.h"
+#include "tools/gn/err.h"
+#include "tools/gn/filesystem_utils.h"
+#include "tools/gn/functions.h"
+#include "tools/gn/input_conversion.h"
+#include "tools/gn/input_file.h"
+#include "tools/gn/parse_tree.h"
+#include "tools/gn/scheduler.h"
+#include "tools/gn/value.h"
+
+#if defined(OS_WIN)
+#include <windows.h>
+
+#include "base/win/scoped_handle.h"
+#include "base/win/scoped_process_information.h"
+#endif
+
+/*
+exec_script: Synchronously run a script and return the output.
+
+  exec_script(filename, arguments, input_conversion, [file_dependencies])
+
+  Runs the given script, returning the stdout of the script. The build
+  generation will fail if the script does not exist or returns a nonzero
+  exit code.
+
+Arguments:
+
+  filename:
+      File name of python script to execute, relative to the build file.
+
+  arguments:
+      A list of strings to be passed to the scripe as arguments.
+
+  input_conversion:
+      Controls how the file is read and parsed. See "help input_conversion".
+
+  dependencies:
+      (Optional) A list of files that this script reads or otherwise depends
+      on. These dependencies will be added to the build result such that if
+      any of them change, the build will be regenerated and the script will
+      be re-run.
+
+      The script itself will be an implicit dependency so you do not need to
+      list it.
+
+Example:
+
+  all_lines = exec_script("myscript.py", [some_input], "list lines",
+                          ["data_file.txt"])
+*/
+
+namespace {
+
+#if defined(OS_WIN)
+bool ExecProcess(const CommandLine& cmdline,
+                 const base::FilePath& startup_dir,
+                 std::string* std_out,
+                 std::string* std_err,
+                 int* exit_code) {
+  SECURITY_ATTRIBUTES sa_attr;
+  // Set the bInheritHandle flag so pipe handles are inherited.
+  sa_attr.nLength = sizeof(SECURITY_ATTRIBUTES);
+  sa_attr.bInheritHandle = TRUE;
+  sa_attr.lpSecurityDescriptor = NULL;
+
+  // Create the pipe for the child process's STDOUT.
+  HANDLE out_read = NULL;
+  HANDLE out_write = NULL;
+  if (!CreatePipe(&out_read, &out_write, &sa_attr, 0)) {
+    NOTREACHED() << "Failed to create pipe";
+    return false;
+  }
+  base::win::ScopedHandle scoped_out_read(out_read);
+  base::win::ScopedHandle scoped_out_write(out_write);
+
+  // Create the pipe for the child process's STDERR.
+  HANDLE err_read = NULL;
+  HANDLE err_write = NULL;
+  if (!CreatePipe(&err_read, &err_write, &sa_attr, 0)) {
+    NOTREACHED() << "Failed to create pipe";
+    return false;
+  }
+  base::win::ScopedHandle scoped_err_read(err_read);
+  base::win::ScopedHandle scoped_err_write(err_write);
+
+  // Ensure the read handle to the pipe for STDOUT/STDERR is not inherited.
+  if (!SetHandleInformation(out_read, HANDLE_FLAG_INHERIT, 0)) {
+    NOTREACHED() << "Failed to disabled pipe inheritance";
+    return false;
+  }
+  if (!SetHandleInformation(err_read, HANDLE_FLAG_INHERIT, 0)) {
+    NOTREACHED() << "Failed to disabled pipe inheritance";
+    return false;
+  }
+
+  base::FilePath::StringType cmdline_str(cmdline.GetCommandLineString());
+
+  base::win::ScopedProcessInformation proc_info;
+  STARTUPINFO start_info = { 0 };
+
+  start_info.cb = sizeof(STARTUPINFO);
+  start_info.hStdOutput = out_write;
+  // Keep the normal stdin.
+  start_info.hStdInput = GetStdHandle(STD_INPUT_HANDLE);
+  // FIXME(brettw) set stderr here when we actually read it below.
+  //start_info.hStdError = err_write;
+  start_info.hStdError = GetStdHandle(STD_ERROR_HANDLE);
+  start_info.dwFlags |= STARTF_USESTDHANDLES;
+
+  // Create the child process.
+  if (!CreateProcess(NULL,
+                     &cmdline_str[0],
+                     NULL, NULL,
+                     TRUE,  // Handles are inherited.
+                     0, NULL,
+                     startup_dir.value().c_str(),
+                     &start_info, proc_info.Receive())) {
+    return false;
+  }
+
+  // Close our writing end of pipes now. Otherwise later read would not be able
+  // to detect end of child's output.
+  scoped_out_write.Close();
+  scoped_err_write.Close();
+
+  // Read output from the child process's pipe for STDOUT
+  const int kBufferSize = 1024;
+  char buffer[kBufferSize];
+
+  // FIXME(brettw) read from stderr here! This is complicated because we want
+  // to read both of them at the same time, probably need overlapped I/O.
+  // Also uncomment start_info code above.
+  for (;;) {
+    DWORD bytes_read = 0;
+    BOOL success = ReadFile(out_read, buffer, kBufferSize, &bytes_read, NULL);
+    if (!success || bytes_read == 0)
+      break;
+    std_out->append(buffer, bytes_read);
+  }
+
+  // Let's wait for the process to finish.
+  WaitForSingleObject(proc_info.process_handle(), INFINITE);
+
+  DWORD dw_exit_code;
+  GetExitCodeProcess(proc_info.process_handle(), &dw_exit_code);
+  *exit_code = static_cast<int>(dw_exit_code);
+
+  return true;
+}
+#else
+bool ExecProcess(const CommandLine& cmdline,
+                 const base::FilePath& startup_dir,
+                 std::string* std_out,
+                 std::string* std_err,
+                 int* exit_code) {
+  //NOTREACHED() << "Implement me.";
+  return false;
+}
+#endif
+
+}  // namespace
+
+Value ExecuteExecScript(Scope* scope,
+                        const FunctionCallNode* function,
+                        const std::vector<Value>& args,
+                        Err* err) {
+  if (args.size() != 3 && args.size() != 4) {
+    *err = Err(function->function(), "Wrong number of args to write_file",
+               "I expected three or four arguments.");
+    return Value();
+  }
+
+  const Settings* settings = scope->settings();
+  const BuildSettings* build_settings = settings->build_settings();
+  const SourceDir& cur_dir = SourceDirForFunctionCall(function);
+
+  // Find the python script to run.
+  if (!args[0].VerifyTypeIs(Value::STRING, err))
+    return Value();
+  SourceFile script_source =
+      cur_dir.ResolveRelativeFile(args[0].string_value());
+  base::FilePath script_path = build_settings->GetFullPath(script_source);
+  if (!build_settings->secondary_source_path().empty() &&
+      !base::PathExists(script_path)) {
+    // Fall back to secondary source root when the file doesn't exist.
+    script_path = build_settings->GetFullPathSecondary(script_source);
+  }
+
+  // Add all dependencies of this script, including the script itself, to the
+  // build deps.
+  g_scheduler->AddGenDependency(script_source);
+  if (args.size() == 4) {
+    const Value& deps_value = args[3];
+    if (!deps_value.VerifyTypeIs(Value::LIST, err))
+      return Value();
+
+    for (size_t i = 0; i < deps_value.list_value().size(); i++) {
+      if (!deps_value.list_value()[0].VerifyTypeIs(Value::STRING, err))
+        return Value();
+      g_scheduler->AddGenDependency(cur_dir.ResolveRelativeFile(
+          deps_value.list_value()[0].string_value()));
+    }
+  }
+
+  // Make the command line.
+  const base::FilePath& python_path = build_settings->python_path();
+  CommandLine cmdline(python_path);
+  cmdline.AppendArgPath(script_path);
+
+  const Value& script_args = args[1];
+  if (!script_args.VerifyTypeIs(Value::LIST, err))
+    return Value();
+  for (size_t i = 0; i < script_args.list_value().size(); i++) {
+    if (!script_args.list_value()[i].VerifyTypeIs(Value::STRING, err))
+      return Value();
+    cmdline.AppendArg(script_args.list_value()[i].string_value());
+  }
+
+  // Execute the process.
+  // TODO(brettw) set the environment block.
+  std::string output;
+  std::string stderr_output;  // TODO(brettw) not hooked up, see above.
+  int exit_code = 0;
+  if (!ExecProcess(cmdline, build_settings->GetFullPath(cur_dir),
+                   &output, &stderr_output, &exit_code)) {
+    *err = Err(function->function(), "Could not execute python.",
+        "I was trying to execute \"" + FilePathToUTF8(python_path) + "\".");
+    return Value();
+  }
+
+  // TODO(brettw) maybe we need stderr also for reasonable stack dumps.
+  if (exit_code != 0) {
+    std::string msg =
+        std::string("I was running \"") + FilePathToUTF8(script_path) + "\"\n"
+        "and it returned " + base::IntToString(exit_code);
+    if (!output.empty())
+      msg += " and printed out:\n\n" + output;
+    else
+      msg += ".";
+    *err = Err(function->function(), "Script returned non-zero exit code.",
+               msg);
+    return Value();
+  }
+
+  return ConvertInputToValue(output, function, args[2], err);
+}