Fix the case where the browser livelocks if we cannot open a file.

If one tries to upload a file that one doesn't have read access to,
the browser livelocks. It tries to read from the file, gets nothing
but spins forever because it knows that it hasn't finished reading.

To address this, firstly we add a check at stat() time to make sure
that we can read the file. However, this doesn't take care of the case
where the access() call was incorrect, or the permissions have changed
under us. In this case, we replace the missing file with NULs.

(Land attempt three: first in r39446, reverted in r39448. Second in
r39899, reverted in r39901.)

http://codereview.chromium.org/541022
BUG=30850
TEST=Try to upload a file that isn't readable (i.e. /etc/shadow). The resulting upload should be a 0 byte file.

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@40146 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 12 insertions, 1 deletions

diff --git a/net/base/file_stream.h b/net/base/file_stream.h
index 6b7f3dc..def87bc 100644
--- a/net/base/file_stream.h
+++ b/net/base/file_stream.h
@@ -43,13 +43,24 @@ class FileStream {
   // Note that if there are any pending async operations, they'll be aborted.
   void Close();
 
+  // Release performs the same actions as Close, but doesn't actually close the
+  // underlying PlatformFile.
+  void Release();
+
   // Call this method to open the FileStream.  The remaining methods
   // cannot be used unless this method returns OK.  If the file cannot be
   // opened then an error code is returned.
   // open_flags is a bitfield of base::PlatformFileFlags
   int Open(const FilePath& path, int open_flags);
 
-  // Returns true if Open succeeded and Close has not been called.
+  // Calling this method is functionally the same as constructing the object
+  // with the non-default constructor. This method can only be used if the
+  // FileSteam isn't currently open (i.e. was constructed with the default
+  // constructor).
+  int Open(base::PlatformFile file, int open_flags);
+
+  // Returns true if Open succeeded and neither Close nor Release have been
+  // called.
   bool IsOpen() const;
 
   // Adjust the position from where data is read.  Upon success, the stream