[bug #25904] NSData writeToFile ignores existing protected file

[Tim Kack]

URL:
  <http://savannah.gnu.org/bugs/?25904>

                 Summary: NSData writeToFile ignores existing protected file
                 Project: GNUstep
            Submitted by: tkack
            Submitted on: Wed 18 Mar 2009 12:24:32 AM CET
                Category: Base/Foundation
                Severity: 3 - Normal
              Item Group: Bug
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any

    _______________________________________________________

Details:

It seems that we are using rename() in NSData.m:1054.
GLibc function rename will first delete the oldfile before renaming the
newfile to the old name.
If a file is readonly, it can still be overwritten by the writeToFile as long
as the containing directory is writable and that the file is owned by the same
owner that executes the tool.

I have attached some simple code to demonstrate this.
Here is the steps:

1. Create a file in /tmp/ called permissionstestFile.txt
2, Add some text in the file
3. chmod 000 /tmp/permissionstestFile.txt
4. Compile testFilePerms tool attached.
5. Run it with './obj/testFilePerms'
6. chmod u+rw /tmp/permissionstestFile.txt
7. cat /tmp/permissionstestFile.txt

Note that this behavior is noted in
http://www.gnu.org/software/libc/manual/html_node/Renaming-Files.html#Renaming-Files
as follows for the rename() function:
"If oldname is not a directory, then any existing file named newname is
removed during the renaming operation. However, if newname is the name of a
directory, rename fails in this case. "

Perhaps there should have a check before renaming if the file is writeable or
not. File attributes are already collected at that point so it shouldn't be
much overhead with the test. 



    _______________________________________________________

File Attachments:


-------------------------------------------------------
Date: Wed 18 Mar 2009 12:24:32 AM CET  Name: GNUmakefile  Size: 437B   By:
tkack

<http://savannah.gnu.org/bugs/download.php?file_id=17722>
-------------------------------------------------------
Date: Wed 18 Mar 2009 12:24:32 AM CET  Name: issue.m  Size: 314B   By: tkack

<http://savannah.gnu.org/bugs/download.php?file_id=17723>

    _______________________________________________________

Reply to this item at:

  <http://savannah.gnu.org/bugs/?25904>

_______________________________________________
  Message sent via/by Savannah
  http://savannah.gnu.org/