Fix Downloads Windows Zone identifier test.

Changes the setting of the Zone Identifier to not include an unnecessary  trailing null byte, modifies the test to check for any of a range of options known to be acceptable to Windows, and makes explicit the restriction the utility test function works under.

BUG=20809
TEST=Test run on windows and successful try bot run (with test enabled).

Review URL: http://codereview.chromium.org/6541003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@75762 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 23 insertions, 34 deletions

diff --git a/base/test/test_file_util.h b/base/test/test_file_util.h
index 2de74e7..6a6ae7d 100644
--- a/base/test/test_file_util.h
+++ b/base/test/test_file_util.h
@@ -35,6 +35,9 @@ bool CopyRecursiveDirNoCache(const FilePath& source_dir,
 bool VolumeSupportsADS(const FilePath& path);
 
 // Returns true if the ZoneIdentifier is correctly set to "Internet" (3).
+// Note that this function must be called from the same process as
+// the one that set the zone identifier.  I.e. don't use it in UI/automation
+// based tests.
 bool HasInternetZoneIdentifier(const FilePath& full_path);
 #endif  // defined(OS_WIN)
 
diff --git a/base/test/test_file_util_win.cc b/base/test/test_file_util_win.cc
index 7ca7e84..9820c42 100644
--- a/base/test/test_file_util_win.cc
+++ b/base/test/test_file_util_win.cc
@@ -194,41 +194,27 @@ bool VolumeSupportsADS(const FilePath& path) {
 }
 
 // Return whether the ZoneIdentifier is correctly set to "Internet" (3)
+// Only returns a valid result when called from same process as the
+// one that (was supposed to have) set the zone identifier.
 bool HasInternetZoneIdentifier(const FilePath& full_path) {
-  std::wstring path = full_path.value() + L":Zone.Identifier";
-
-  // This polling and sleeping here is a very bad pattern. But due to how
-  // Windows file semantics work it's really hard to do it other way. We are
-  // reading a file written by a different process, using a different handle.
-  // Windows does not guarantee that we will get the same contents even after
-  // the other process closes the handle, flushes the buffers, etc.
-  for (int i = 0; i < 20; i++) {
-    base::PlatformThread::Sleep(1000);
-
-    const DWORD kShare = FILE_SHARE_READ |
-        FILE_SHARE_WRITE |
-        FILE_SHARE_DELETE;
-    HANDLE file = CreateFile(path.c_str(), GENERIC_READ, kShare, NULL,
-                             OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
-    if (file == INVALID_HANDLE_VALUE)
-      continue;
-
-    char buffer[100] = {0};
-    DWORD read = 0;
-    BOOL read_result = ::ReadFile(file, buffer, 100, &read, NULL);
-    CloseHandle(file);
-
-    if (!read_result)
-      continue;
-
-    const char kIdentifier[] = "[ZoneTransfer]\nZoneId=3";
-    if (read != arraysize(kIdentifier))
-      continue;
-
-    if (strcmp(kIdentifier, buffer) == 0)
-      return true;
-  }
-  return false;
+  FilePath zone_path(full_path.value() + L":Zone.Identifier");
+  std::string zone_path_contents;
+  if (!file_util::ReadFileToString(zone_path, &zone_path_contents))
+    return false;
+
+  static const char kInternetIdentifier[] = "[ZoneTransfer]\nZoneId=3";
+  static const size_t kInternetIdentifierSize =
+      // Don't include null byte in size of identifier.
+      arraysize(kInternetIdentifier) - 1;
+
+  // Our test is that the initial characters match the above, and that
+  // the character after the end of the string is eof, null, or newline; any
+  // of those three will invoke the Window Finder cautionary dialog.
+  return ((zone_path_contents.compare(0, kInternetIdentifierSize,
+                                      kInternetIdentifier) == 0) &&
+          (kInternetIdentifierSize == zone_path_contents.length() ||
+           zone_path_contents[kInternetIdentifierSize] == '\0' ||
+           zone_path_contents[kInternetIdentifierSize] == '\n'));
 }
 
 }  // namespace file_util