[GN] Add support to rebase_path to resolve paths above the source root.

tools/gn/filesystem_utils_unittest.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 "base/files/file_path.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "build/build_config.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "tools/gn/filesystem_utils.h"
@@ skipping 186 matching lines @@
   EXPECT_EQ("//foo", input);
 
   input = "foo/..//bar";
   NormalizePath(&input);
   EXPECT_EQ("bar", input);
 
   input = "foo/../../bar";
   NormalizePath(&input);
   EXPECT_EQ("../bar", input);
 
-  input = "/../foo";  // Don't go aboe the root dir.
+  input = "/../foo";  // Don't go above the root dir.
   NormalizePath(&input);
   EXPECT_EQ("/foo", input);
 
   input = "//../foo";  // Don't go above the root dir.
   NormalizePath(&input);
   EXPECT_EQ("//foo", input);
 
   input = "../foo";
   NormalizePath(&input);
   EXPECT_EQ("../foo", input);
@@ skipping 16 matching lines @@
 
   // Backslash normalization.
   input = "foo\\..\\..\\bar";
   NormalizePath(&input);
   EXPECT_EQ("../bar", input);
 
   // Trailing slashes should get preserved.
   input = "//foo/bar/";
   NormalizePath(&input);
   EXPECT_EQ("//foo/bar/", input);
+
+#if defined(OS_WIN)
+  // Go above and outside of the source root.
+  input = "//../foo";
+  NormalizePath(&input, "/C:/source/root");
+  EXPECT_EQ("/C:/source/foo", input);
+
+  input = "//../foo";
+  NormalizePath(&input, "C:\\source\\root");
+  EXPECT_EQ("/C:/source/foo", input);
+
+  input = "//../";
+  NormalizePath(&input, "/C:/source/root");
+  EXPECT_EQ("/C:/source/", input);
+
+  input = "//../foo.txt";
+  NormalizePath(&input, "/C:/source/root");
+  EXPECT_EQ("/C:/source/foo.txt", input);
+
+  input = "//../foo/bar/";
+  NormalizePath(&input, "/C:/source/root");
+  EXPECT_EQ("/C:/source/foo/bar/", input);
+
+  // Go above and back into the source root. This should return a system-
+  // absolute path. We could arguably return this as a source-absolute path,
+  // but that would require additional handling to account for a rare edge
+  // case.
+  input = "//../root/foo";
+  NormalizePath(&input, "/C:/source/root");
+  EXPECT_EQ("/C:/source/root/foo", input);
+
+  input = "//../root/foo/bar/";
+  NormalizePath(&input, "/C:/source/root");
+  EXPECT_EQ("/C:/source/root/foo/bar/", input);
+
+  // Stay inside the source root
+  input = "//foo/bar";
+  NormalizePath(&input, "/C:/source/root");
+  EXPECT_EQ("//foo/bar", input);
+
+  input = "//foo/bar/";
+  NormalizePath(&input, "/C:/source/root");
+  EXPECT_EQ("//foo/bar/", input);
+
+  // The path should not go above the system root. Note that on Windows, this
+  // will consume the drive (C:).
+  input = "//../../../../../foo/bar";
+  NormalizePath(&input, "/C:/source/root");
+  EXPECT_EQ("/foo/bar", input);
+
+  // Test when the source root is the letter drive.
+  input = "//../foo";
+  NormalizePath(&input, "/C:");
+  EXPECT_EQ("/foo", input);
+
+  input = "//../foo";
+  NormalizePath(&input, "C:");
+  EXPECT_EQ("/foo", input);
+
+  input = "//../foo";
+  NormalizePath(&input, "/");
+  EXPECT_EQ("/foo", input);
+
+  input = "//../";
+  NormalizePath(&input, "\\C:");
+  EXPECT_EQ("/", input);
+
+  input = "//../foo.txt";
+  NormalizePath(&input, "/C:");
+  EXPECT_EQ("/foo.txt", input);
+#else
+  // Go above and outside of the source root.
+  input = "//../foo";
+  NormalizePath(&input, "/source/root");
+  EXPECT_EQ("/source/foo", input);
+
+  input = "//../";
+  NormalizePath(&input, "/source/root");
+  EXPECT_EQ("/source/", input);
+
+  input = "//../foo.txt";
+  NormalizePath(&input, "/source/root");
+  EXPECT_EQ("/source/foo.txt", input);
+
+  input = "//../foo/bar/";
+  NormalizePath(&input, "/source/root");
+  EXPECT_EQ("/source/foo/bar/", input);
+
+  // Go above and back into the source root. This should return a system-
+  // absolute path. We could arguably return this as a source-absolute path,
+  // but that would require additional handling to account for a rare edge
+  // case.
+  input = "//../root/foo";
+  NormalizePath(&input, "/source/root");
+  EXPECT_EQ("/source/root/foo", input);
+
+  input = "//../root/foo/bar/";
+  NormalizePath(&input, "/source/root");
+  EXPECT_EQ("/source/root/foo/bar/", input);
+
+  // Stay inside the source root
+  input = "//foo/bar";
+  NormalizePath(&input, "/source/root");
+  EXPECT_EQ("//foo/bar", input);
+
+  input = "//foo/bar/";
+  NormalizePath(&input, "/source/root");
+  EXPECT_EQ("//foo/bar/", input);
+
+  // The path should not go above the system root.
+  input = "//../../../../../foo/bar";
+  NormalizePath(&input, "/source/root");
+  EXPECT_EQ("/foo/bar", input);
+
+  // Test when the source root is the system root.
+  input = "//../foo/bar/";
+  NormalizePath(&input, "/");
+  EXPECT_EQ("/foo/bar/", input);
+
+  input = "//../";
+  NormalizePath(&input, "/");
+  EXPECT_EQ("/", input);
+
+  input = "//../foo.txt";
+  NormalizePath(&input, "/");
+  EXPECT_EQ("/foo.txt", input);
+
+#endif
 }
 
 TEST(FilesystemUtils, RebasePath) {
   base::StringPiece source_root("/source/root");
 
   // Degenerate case.
   EXPECT_EQ(".", RebasePath("//", SourceDir("//"), source_root));
   EXPECT_EQ(".", RebasePath("//foo/bar/", SourceDir("//foo/bar/"),
                             source_root));
 
@@ skipping 339 matching lines @@
   EXPECT_EQ("gen/", GetToolchainGenDirAsOutputFile(&settings).value());
   EXPECT_EQ("//obj/",
             GetOutputDirForSourceDir(&settings, SourceDir("//")).value());
   EXPECT_EQ("obj/",
             GetOutputDirForSourceDirAsOutputFile(
                 &settings, SourceDir("//")).value());
   EXPECT_EQ("gen/",
             GetGenDirForSourceDirAsOutputFile(
                 &settings, SourceDir("//")).value());
 }