samba - Feb 1999 - Unix permission problems with 'attrib'

Hi,

	I'm been using Samba for some time and I have been bugged by a problem with
SourceSafe. I finally took some time to see what is going on and found the
source of the problem (well, not in the source code though).
	I'm partially responsible, I have Unix files with the following rights
"r--rw---" and Samba does not deal with these very well. I am now
makind sure that this case does not happen but still, I think Samba's
behavior is incorrect.

	Here is what happens:

$ cat /dev/null >foo
$ chmod 460 foo
$ ls -l foo
-r--rw----   1 me     me           0 Feb  2 11:01 foo

	M:\> attrib foo
           R     M:\foo

Up to here everything is fine. foo is not writable on Unix so attrib returns
that it is read-only. Let's continue...

	M:\> attrib -r foo	
	M:\> attrib foo
           R     M:\foo

$ ls -l foo
-r--rw----   1 me     me           0 Feb  2 11:01 foo


	Here it's wrong. "attrib -r" is supposed to make the file
writable but it did not change anything. I think that's what caused the
problem I had in SourceSafe. When I do a "Get Latest Version"
SourceSafe is supposed to remove the read-only flag, update the file, put back
the read-only file. Of course if step 1 fails... Let's try the opposite
operation.

	M:\> attrib +r foo
	M:\> attrib foo
           R     M:\foo

$ ls -l foo
-r--r-----   1 me     me           0 Feb  2 11:01 foo

	Should Samba do this ? The file is already read-only after all. See more about
that on the last part.

	M:\> attrib -r foo
	M:\> attrib foo
	           M:\foo

$ ls -l foo
-rw-rw----   1 me     me           0 Feb  2 11:01 foo

	This last part proves that 'attrib' does work, some times :-). The
other thing is that it seems that normally it modifies both the user and group
permissions. I'm not sure this should always be the case. Maybe this could
be an option of the share. For instance in user home directories you may not
want to make files writable by everyone in the same group ! In my case this is
what I want though.


	By the way, I'm running Samba 2.0.0 on Solaris 2.5 but I had the same
symptom with "1.9.18p3". The share I tested this on is a share that is
"guest only" with guest being "me/me". I also have "Map
archive", "Map System", and "Map Hidden" disabled. Here
is swat's view of this share:

# Global parameters
[...]
          map archive = No

[Shared]
          path = /shared
          guest account = me
          read only = No
          create mask = 0774
          guest only = Yes
          guest ok = Yes
          hide dot files = No

-- 
Fran?ois Gouget

Looking at the source I found something suspicious in
"sources/smbd/dosmode.c" in file_chmod.

  /* if we previously had any w bits set then leave them alone 
   if the new mode is not rdonly */
  if (!IS_DOS_READONLY(dosmode) &&
      (tmp = st->st_mode & (S_IWUSR|S_IWGRP|S_IWOTH))) {
    unixmode &= ~(S_IWUSR|S_IWGRP|S_IWOTH);
    unixmode |= tmp;
  }

	So if we do an "attrib -r" I guess this function would get called (I
did not check), IS_DOS_READONLY would be false and thus we would preserve the
write permissions of the file. This means we would still not be able to write to
it.

	Would that be it ? Why does it work the second time then ???

-- 
Fran?ois Gouget
fgouget@multimania.com -- http://www.multimania.com/fgouget/