GN: Normalize the build directory path

tools/gn/setup.cc

 // 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 "tools/gn/setup.h"
 
 #include <stdlib.h>
 #include <algorithm>
 #include <sstream>
 #include <utility>
@@ skipping 208 matching lines @@
     if (base::PathExists(candidate_bat)) {
       base::FilePath python_exe = PythonBatToExe(candidate_bat);
       if (!python_exe.empty())
         return python_exe;
     }
   }
   return base::FilePath();
 }
 #endif
 
+// Expands all ./, ../, and symbolic links in the given path.
+bool GetRealPath(const base::FilePath& path, base::FilePath* out) {

[hashimoto, 2016/02/23 10:17:31]

Renamed this function to GetRealPath() as filesystem_utils.h also has
NormalizePath() and it can be confusing.

+#if defined(OS_POSIX)
+  char buf[PATH_MAX];
+  if (!realpath(path.value().c_str(), buf)) {
+    return false;
+  }
+  *out = base::FilePath(buf);
+#else
+  // Do nothing on a non-POSIX system.
+  *out = path;
+#endif
+  return true;
+}
+
 }  // namespace
 
 const char Setup::kBuildArgFileName[] = "args.gn";
 
 Setup::Setup()
     : build_settings_(),
       loader_(new LoaderImpl(&build_settings_)),
       builder_(new Builder(loader_.get())),
       root_build_file_("//BUILD.gn"),
       check_public_headers_(false),
@@ skipping 267 matching lines @@
     if (dotfile_name_.empty()) {
       Err(Location(), "Can't find source root.",
           "I could not find a \".gn\" file in the current directory or any "
           "parent,\nand the --root command-line argument was not specified.")
           .PrintToStdout();
       return false;
     }
     root_path = dotfile_name_.DirName();
   }
 
+  base::FilePath root_realpath;
+  if (!GetRealPath(root_path, &root_realpath)) {
+    Err(Location(), "Can't get the real root path.",
+        "I could not get the real path of \"" + FilePathToUTF8(root_path) +
+        "\".").PrintToStdout();
+    return false;
+  }
   if (scheduler_.verbose_logging())
-    scheduler_.Log("Using source root", FilePathToUTF8(root_path));
-  build_settings_.SetRootPath(root_path);
+    scheduler_.Log("Using source root", FilePathToUTF8(root_realpath));
+  build_settings_.SetRootPath(root_realpath);
 
   return true;
 }
 
 bool Setup::FillBuildDir(const std::string& build_dir, bool require_exists) {
   Err err;
   SourceDir resolved =
       SourceDirForCurrentDirectory(build_settings_.root_path()).
     ResolveRelativeDir(Value(nullptr, build_dir), &err,
         build_settings_.root_path_utf8());
   if (err.has_error()) {
     err.PrintToStdout();
     return false;
   }
 
+  base::FilePath build_dir_path = build_settings_.GetFullPath(resolved);
+  if (!base::CreateDirectory(build_dir_path)) {
+    Err(Location(), "Can't create the build dir.",
+        "I could not create the build dir \"" + FilePathToUTF8(build_dir_path) +
+        "\".").PrintToStdout();
+    return false;
+  }
+  base::FilePath build_dir_realpath;
+  if (!GetRealPath(build_dir_path, &build_dir_realpath)) {
+    Err(Location(), "Can't get the real build dir path.",
+        "I could not get the real path of \"" + FilePathToUTF8(build_dir_path) +
+        "\".").PrintToStdout();
+    return false;
+  }
+  resolved = SourceDirForPath(build_settings_.root_path(),
+                              build_dir_realpath);
+
   if (scheduler_.verbose_logging())
     scheduler_.Log("Using build dir", resolved.value());
 
   if (require_exists) {
-    base::FilePath build_dir_path = build_settings_.GetFullPath(resolved);
     if (!base::PathExists(build_dir_path.Append(
             FILE_PATH_LITERAL("build.ninja")))) {
       Err(Location(), "Not a build directory.",
           "This command requires an existing build directory. I interpreted "
           "your input\n\"" + build_dir + "\" as:\n  " +
           FilePathToUTF8(build_dir_path) +
           "\nwhich doesn't seem to contain a previously-generated build.")
           .PrintToStdout();
       return false;
     }
@@ skipping 135 matching lines @@
       if (err.has_error()) {
         err.PrintToStdout();
         return false;
       }
     }
     build_settings_.set_exec_script_whitelist(std::move(whitelist));
   }
 
   return true;
 }