Fix Mac sandbox meta data access

Sandbox::AllowMetadataForPath() currently allow all metadata access due to
https://codereview.chromium.org/10539009/ made the for loop comparison
in Sandbox::AllowMetadataForPath() always false, when we actually only
want to allow access to the path and all its parent path until root.

Turn the for loop to a do/while loop instead as it's a better fit, also
add a test case for Sandbox::AllowMetadataForPath().

It should only affect component builds on OS X 10.6 and utility process
as no other process is using this mechanism.

Review URL: https://codereview.chromium.org/472513002

Cr-Commit-Position: refs/heads/master@{#289526}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@289526 0039d316-1c4b-4281-b951-d872f2087c98

content/common/sandbox_mac.h

@@ -160,6 +160,7 @@ class CONTENT_EXPORT Sandbox {
   FRIEND_TEST_ALL_PREFIXES(MacDirAccessSandboxTest, StringEscape);
   FRIEND_TEST_ALL_PREFIXES(MacDirAccessSandboxTest, RegexEscape);
   FRIEND_TEST_ALL_PREFIXES(MacDirAccessSandboxTest, SandboxAccess);
+  FRIEND_TEST_ALL_PREFIXES(MacDirAccessSandboxTest, AllowMetadataForPath);
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(Sandbox);
 };

content/common/sandbox_mac.mm

@@ -114,12 +114,14 @@ NSString* Sandbox::AllowMetadataForPath(const base::FilePath& allowed_path) {
   // Collect a list of all parent directories.
   base::FilePath last_path = allowed_path;
   std::vector<base::FilePath> subpaths;
-  for (base::FilePath path = allowed_path;
-       path.value() != last_path.value();
-       path = path.DirName()) {
+
+  base::FilePath path = allowed_path;
+  do {
     subpaths.push_back(path);
+
     last_path = path;
-  }
+    path = path.DirName();
+  } while (path.value() != last_path.value());
 
   // Iterate through all parents and allow stat() on them explicitly.
   NSString* sandbox_command = @"(allow file-read-metadata ";

content/common/sandbox_mac_diraccess_unittest.mm

@@ -127,7 +127,6 @@ TEST_F(MacDirAccessSandboxTest, RegexEscape) {
     std::string out;
     EXPECT_TRUE(Sandbox::QuoteStringForRegex(in_utf8, &out));
     EXPECT_EQ(expected, out);
-
   }
 }
 
@@ -178,6 +177,18 @@ TEST_F(MacDirAccessSandboxTest, SandboxAccess) {
   }
 }
 
+TEST_F(MacDirAccessSandboxTest, AllowMetadataForPath) {
+  {
+    std::string expected(
+        "(allow file-read-metadata (literal \"/\")(literal \"/System\")"
+        "(literal \"/System/Library\")"
+        "(literal \"/System/Library/Frameworks\"))");
+    NSString* sandbox_command = Sandbox::AllowMetadataForPath(
+        base::FilePath("/System/Library/Frameworks"));
+    EXPECT_EQ(base::SysNSStringToUTF8(sandbox_command), expected);
+  }
+}
+
 MULTIPROCESS_TEST_MAIN(mac_sandbox_path_access) {
   char *sandbox_allowed_dir = getenv(kSandboxAccessPathKey);
   if (!sandbox_allowed_dir)