Fixes for xattr on Linux

- A very unlikely failure where getxattr returns an error code the first time
  but succeeds the second time could cause buffer overrun and corruption.

Affecting the tests only:

- On Linux (and presumably Irix) normal users can only modify attributes in
  the 'user.' namespace.
- Some filesystems can have strict limits on value size (eg. 1024 bytes on
  ext3 depending on block size)
- ENOATTR is defined in xattr/xattr.h. This file is an optional install and is
  not needed for the rest of box to use extended attributes. Provide it
  ourselves if not present.

1 files changed, 4 insertions, 1 deletions

diff --git a/lib/backupclient/BackupClientFileAttributes.cpp b/lib/backupclient/BackupClientFileAttributes.cpp
index 70c0d09d..a31cd7b4 100644
--- a/lib/backupclient/BackupClientFileAttributes.cpp
+++ b/lib/backupclient/BackupClientFileAttributes.cpp
@@ -511,6 +511,10 @@ void BackupClientFileAttributes::FillExtendedAttr(StreamableMemBlock &outputBloc
 				// Find size of attribute (must call with buffer and length 0 on some platforms,
 				// as -1 is returned if the data doesn't fit.)
 				int valueSize = ::lgetxattr(Filename, attrKey.c_str(), 0, 0);
+				if(valueSize<0)
+				{
+					THROW_EXCEPTION(CommonException, OSFileError);
+				}
 
 				// Resize block, if needed
 				if(xattrSize+valueSize>xattrBufferSize)
@@ -522,7 +526,6 @@ void BackupClientFileAttributes::FillExtendedAttr(StreamableMemBlock &outputBloc
 
 				// This gets the attribute value (may be text or binary), no termination
 				valueSize = ::lgetxattr(Filename, attrKey.c_str(), buffer+xattrSize, xattrBufferSize-xattrSize);
-
 				if(valueSize<0)
 				{
 					THROW_EXCEPTION(CommonException, OSFileError);