Change FileExists to return tensorflow::Status.

Also done separately by @llhe at github.com/tensorflow/tensorflow/pull/5370. We needed to do this change internally to fix all callers.

Motivation: The existing FileExists interface doesn't allow callers to distinguish between file not found vs. filesystem errors.

Semantics changes:
- gfile.Exists in Python now throws an exception for filesystem errors. It continues to return true/false if it can accurately determine whether a file exists.
- RecursivelyCreateDir now returns errors for filesystem errors when calling FileExists.
Change: 138224013

1 files changed, 4 insertions, 2 deletions

diff --git a/tensorflow/core/platform/file_system.h b/tensorflow/core/platform/file_system.h
index dfaf75be66..78453c4f72 100644
--- a/tensorflow/core/platform/file_system.h
+++ b/tensorflow/core/platform/file_system.h
@@ -61,7 +61,7 @@ class FileSystem {
   virtual Status NewReadOnlyMemoryRegionFromFile(
       const string& fname, std::unique_ptr<ReadOnlyMemoryRegion>* result) = 0;
 
-  virtual bool FileExists(const string& fname) = 0;
+  virtual Status FileExists(const string& fname) = 0;
 
   /// \brief Returns the immediate children in the given directory.
   ///
@@ -178,7 +178,9 @@ class NullFileSystem : public FileSystem {
         "NewReadOnlyMemoryRegionFromFile unimplemented");
   }
 
-  bool FileExists(const string& fname) override { return false; }
+  Status FileExists(const string& fname) override {
+    return errors::Unimplemented("FileExists unimplemented");
+  }
 
   Status GetChildren(const string& dir, std::vector<string>* result) override {
     return errors::Unimplemented("GetChildren unimplemented");