3 files changed, 45 insertions, 0 deletions

diff --git a/base/mac_util.h b/base/mac_util.h
index a65576d..ed49e2f 100644
--- a/base/mac_util.h
+++ b/base/mac_util.h
@@ -89,6 +89,9 @@ void GrabWindowSnapshot(NSWindow* window,
 //   returns - path to the application bundle, or empty on error
 FilePath GetAppBundlePath(const FilePath& exec_name);
 
+// Set the Time Machine exclusion property for the given file.
+bool SetFileBackupExclusion(const FilePath& file_path, bool exclude);
+
 }  // namespace mac_util
 
 #endif  // BASE_MAC_UTIL_H_
diff --git a/base/mac_util.mm b/base/mac_util.mm
index 0eee0e2..1418453 100644
--- a/base/mac_util.mm
+++ b/base/mac_util.mm
@@ -237,4 +237,22 @@ FilePath GetAppBundlePath(const FilePath& exec_name) {
   return FilePath();
 }
 
+bool SetFileBackupExclusion(const FilePath& file_path, bool exclude) {
+  NSString* filePath =
+      [NSString stringWithUTF8String:file_path.value().c_str()];
+  NSURL* url = [NSURL fileURLWithPath:filePath];
+  // Note that we always set CSBackupSetItemExcluded's excludeByPath param
+  // to true.  This prevents a problem with toggling the setting: if the file
+  // is excluded with excludeByPath set to true then excludeByPath must
+  // also be true when un-excluding the file, otherwise the un-excluding
+  // will be ignored.
+  bool success =
+      CSBackupSetItemExcluded((CFURLRef)url, exclude, true) == noErr;
+  if (!success)
+    LOG(WARNING) << "Failed to set backup excluson for file '"
+                 << file_path.value().c_str() << "'.  Continuing.";
+  return success;
+}
+
+
 }  // namespace mac_util
diff --git a/base/mac_util_unittest.mm b/base/mac_util_unittest.mm
index 0abdee7..5e97356 100644
--- a/base/mac_util_unittest.mm
+++ b/base/mac_util_unittest.mm
@@ -8,6 +8,7 @@
 #include "base/mac_util.h"
 
 #include "base/file_path.h"
+#include "base/file_util.h"
 #include "base/scoped_nsobject.h"
 #include "base/scoped_ptr.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -101,3 +102,26 @@ TEST_F(MacUtilTest, TestGetAppBundlePath) {
         out.value().c_str()) << "loop: " << i;
   }
 }
+
+TEST_F(MacUtilTest, TestExcludeFileFromBackups) {
+  NSString* homeDirectory = NSHomeDirectory();
+  NSString* dummyFilePath =
+      [homeDirectory stringByAppendingPathComponent:@"DummyFile"];
+  const char* dummy_file_path = [dummyFilePath fileSystemRepresentation];
+  ASSERT_TRUE(dummy_file_path);
+  FilePath file_path(dummy_file_path);
+  // It is not actually necessary to have a physical file in order to
+  // set its exclusion property.
+  NSURL* fileURL = [NSURL URLWithString:dummyFilePath];
+  // Reset the exclusion in case it was set previously.
+  mac_util::SetFileBackupExclusion(file_path, false);
+  Boolean excludeByPath;
+  // Initial state should be non-excluded.
+  EXPECT_FALSE(CSBackupIsItemExcluded((CFURLRef)fileURL, &excludeByPath));
+  // Exclude the file.
+  EXPECT_TRUE(mac_util::SetFileBackupExclusion(file_path, true));
+  EXPECT_TRUE(CSBackupIsItemExcluded((CFURLRef)fileURL, &excludeByPath));
+  // Un-exclude the file.
+  EXPECT_TRUE(mac_util::SetFileBackupExclusion(file_path, false));
+  EXPECT_FALSE(CSBackupIsItemExcluded((CFURLRef)fileURL, &excludeByPath));
+}