Re: [PATCH] Don't pre-create read-only files with --extract --xattrs

[Pavel Raiskup]

Ping, I can see there's 1.34 release now, thank you!

But the git isn't updated yet so I'm not sure this has been fixed or not.

Pavel

On Tuesday, February 9, 2021 5:06:31 PM CET Pavel Raiskup wrote:
> Gently ping on this.  This is easily reproducible, so I am re-attaching
> the patch including a new test-case that fails with the current code:
> 
>     $ tar --xattrs -xf tar
>     tar: setxattrat: Cannot set 'user.attr' extended attribute for file 
> 'file': Permission denied
>     tar: file: Cannot open: Permission denied
>     tar: Exiting with failure status due to previous errors
> 
> Pavel
> 
> On Friday, October 9, 2020 1:39:11 PM CET Pavel Raiskup wrote:
> > We used to respect the target file mode when pre-creating files in
> > set_xattr, so we also pre-created read-only files that we were not able
> > to open later for writing.  This is now fixed, and we always create the
> > file with S_IWUSR.
> > 
> > Fixes the original bug report https://bugzilla.redhat.com/1886540
> > 
> > * src/extract.c (set_xattr): Blindly add S_IWUSR flag to pre-created
> > files, to avoid openat failures later.
> > ---
> >  src/extract.c | 8 +++++++-
> >  1 file changed, 7 insertions(+), 1 deletion(-)
> > 
> > diff --git a/src/extract.c b/src/extract.c
> > index b73a591..2e650ad 100644
> > --- a/src/extract.c
> > +++ b/src/extract.c
> > @@ -865,7 +865,13 @@ set_xattr (char const *file_name, struct tar_stat_info 
> > const *st,
> >  
> >        for (;;)
> >          {
> > -          if (!mknodat (chdir_fd, file_name, mode ^ invert_permissions, 0))
> > +          /* We'll open the file with O_WRONLY later by open_output_file,
> > +             therefore we need to give us the S_IWUSR bit.  If the file was
> > +             meant to be user-read-only, the permissions will be corrected 
> > by
> > +             the set_stat call. */
> > +          mode_t initial_mode = mode ^ invert_permissions | S_IWUSR;
> > +
> > +          if (!mknodat (chdir_fd, file_name, initial_mode, 0))
> >              {
> >                /* Successfully created file */
> >                xattrs_xattrs_set (st, file_name, typeflag, 0);
> > 
> 
>