Update the HPSF change properties example to use NPOIFS + in-place writes, and have NPOIFS give a helpful error if you try to in-place write on a read only open

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1590577 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 6 insertions, 0 deletions

diff --git a/src/java/org/apache/poi/poifs/filesystem/NPOIFSFileSystem.java b/src/java/org/apache/poi/poifs/filesystem/NPOIFSFileSystem.java
index 3f60b4bda2..7aea791b3b 100644
--- a/src/java/org/apache/poi/poifs/filesystem/NPOIFSFileSystem.java
+++ b/src/java/org/apache/poi/poifs/filesystem/NPOIFSFileSystem.java
@@ -693,6 +693,12 @@ public class NPOIFSFileSystem extends BlockStore
                 "not be called. Use writeFilesystem(OutputStream) instead"
           );
        }
+       if (! ((FileBackedDataSource)_data).isWriteable()) {
+           throw new IllegalArgumentException(
+                "POIFS opened in read only mode, so writeFilesystem() may " +
+                "not be called. Open the FileSystem in read-write mode first"
+           );
+       }
        syncWithDataSource();
     }