In what way is /cygdrive special WRT to permissions?

Andy Hall fixpertise-consulting@comcast.net
Wed Oct 6 20:20:00 GMT 2010


Corinna -

Thanks for the reply and clarification.  I have made the obvious change in
my mounts to get around this problem.   However, there has been a change in
behavior between 1.5 and 1.7.   I have 1.7.7 installed on Windows Server
2003 SP2.

The mount table shows

$ mount
//vega/repository on /repos type smbfs (binary,noacl)
C:/cygwin/bin on /usr/bin type ntfs (binary,auto)
C:/cygwin/lib on /usr/lib type ntfs (binary,auto)
C:/cygwin on / type ntfs (binary,auto)
C: on /cygdrive/c type ntfs (binary,posix=0,user,noumount,auto)
D: on /cygdrive/d type iso9660 (binary,posix=0,user,noumount,auto)
F: on /cygdrive/f type smbfs (binary,posix=0,user,noumount,auto)
H: on /cygdrive/h type smbfs (binary,posix=0,user,noumount,auto)

F: also happens to be mapped to //vega/repository via the normal Windows
mechanisms.   

When signed on to the Administrator account you have:

Administrator@taurus ~
$ ls -l /repos
total 2048
drwxr-xr-x 36 Administrator None 0 2010-10-04 19:30 builds
drwxr-xr-x 17 Administrator None 0 2010-10-04 18:23 releases

Administrator@taurus ~
$ test -w /repos/builds && echo writeable
writeable

Administrator@taurus ~
$ ls -l /cygdrive/f
total 2048
drwxrwxr-x 36 ???????? ???????? 0 2010-10-04 19:30 builds
drwxrwxr-x 17 ???????? ???????? 0 2010-10-04 18:23 releases

Administrator@taurus ~
$ test -w /repos/builds && echo writeable
Writeable

When logged on as the non-admistrative user build you have:

build@taurus ~
$ ls -l /repos
total 2048
drwxr-xr-x 36 build None 0 2010-10-04 19:30 builds
drwxr-xr-x 17 build None 0 2010-10-04 18:23 releases

build@taurus ~
$ test -w /repos/builds && echo writeable
writeable

build@taurus ~
$ ls -l /cygdrive/f
total 2048
drwxrwxr-x 36 ???????? ???????? 0 2010-10-04 19:30 builds
drwxrwxr-x 17 ???????? ???????? 0 2010-10-04 18:23 releases

build@taurus ~
$ test -w /cygdrive/f/builds && echo writeable

build@taurus ~
$ echo test >/cygdrive/f/builds/zap

build@taurus ~
$ ls -l /cygdrive/f/builds/zap
-rwxrwxr-x 1 ???????? ???????? 5 2010-10-06 16:11 /cygdrive/f/builds/zap

Notice that the test -w /cygdrive/f/builds reports that /cygdrive/f/builds
is not writeable, yet you can create and write files in /cygdrive/f/builds!
THIS IS INCONSTENT BEHAVIOR.  Cygwin 1.5 did not have this behavior.

Regarding the mount of drive letters via /etc/fstab. I am not sure what the
documentation should say about this.  Overriding the default mount of a
single drive letter in fstab actually seems to work, although it simply
reproduces the same behavior as the default.    
  
Even if I understood the actual behavior, I regret that am not familiar with
the ways of Cygwin source maintenance to make the documentation changes.  I
have to leave this to somebody else more qualified.  

Cheers, Andy


> On Oct  6  1:48 Corinna Vischen wrote:
> 
> 
> On Oct  5 15:40, Andy Hall wrote:
> > If instead, I map F: to /cygdrive/c with the following entry in
> /etc/fstab
> >
> > F: /cygdrive/f smbfs binary,noacl 0 0
> >
> > mount shows
> >
> > $ mount
> > C:/cygwin/bin on /usr/bin type ntfs (binary,auto)
> > C:/cygwin/lib on /usr/lib type ntfs (binary,auto)
> > C:/cygwin on / type ntfs (binary,auto)
> > F: on /cygdrive/f type smbfs (binary,noacl)
> > C: on /cygdrive/c type ntfs (binary,posix=0,user,noumount,auto)
> >
> > And ls -l of /cygdrive/f shows
> >
> > $ ls -l /cygdrive/f
> > total 2048
> > drwxrwxr-x 36 ???????? ???????? 0 2010-10-04 16:30 builds
> > drwxrwxr-x 17 ???????? ???????? 0 2010-10-04 15:23 releases
> > [...]
> > Why am I getting -1 for the uid and gid when I mount to /cygdrive/f but
> not
> > to /repos1?
> 
> That's a restriction of the cygdrive prefix handling.  You can't
> override the cygdrive mount options for a single drive.  It's an
> all or nothing thingy.  I guess it would help to refuse such paths
> in /etc/fstab or mount(1), or at least improve the documentation,
> but, well, http://cygwin.com/acronyms/#SHTDI.
> 
> 
> Corinna
> 
> --
> Corinna Vinschen                  Please, send mails regarding Cygwin to
> Cygwin Project Co-Leader          cygwin AT cygwin DOT com
> Red Hat
> 
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