Re: Re: [PATCH v2] config: preserve config file permissions on edits

> On Mon, May 19, 2014 at 9:44 AM, Erik Faye-Lund <kusmabite@gmail.com> wrote:
> > On Mon, May 19, 2014 at 9:13 AM, Johannes Sixt <j.sixt@viscovery.net> wrote:
> >> Am 5/6/2014 2:17, schrieb Eric Wong:
> >>> Users may already store sensitive data such as imap.pass in
> >>> ..git/config; making the file world-readable when "git config"
> >>> is called to edit means their password would be compromised
> >>> on a shared system.
> >>>
> >>> [v2: updated for section renames, as noted by Junio]
> >>>
> >>> Signed-off-by: Eric Wong <normalperson@yhbt.net>
> >>> ---
> >>>  config.c               | 16 ++++++++++++++++
> >>>  t/t1300-repo-config.sh | 10 ++++++++++
> >>>  2 files changed, 26 insertions(+)
> >>>
> >>> diff --git a/config.c b/config.c
> >>> index a30cb5c..c227aa8 100644
> >>> --- a/config.c
> >>> +++ b/config.c
> >>> @@ -1636,6 +1636,13 @@ int git_config_set_multivar_in_file(const char *config_filename,
> >>>                       MAP_PRIVATE, in_fd, 0);
> >>>               close(in_fd);
> >>>
> >>> +             if (fchmod(fd, st.st_mode & 07777) < 0) {
> >>> +                     error("fchmod on %s failed: %s",
> >>> +                             lock->filename, strerror(errno));
> >>> +                     ret = CONFIG_NO_WRITE;
> >>> +                     goto out_free;
> >>> +             }
> >>
> >> This introduces a severe failure in the Windows port because we do not
> >> implement fchmod. Existing fchmod invocations do not check the return
> >> value, and they are only interested in removing the write bits, and we
> >> generally don't care a lot if files remain writable.
> >>
> >> I'm not proficient enough to add any ACL fiddling to fchmod that would be
> >> required by the above change, whose purpose is to be strict about
> >> permissions. Nor am I interested (who the heck is sharing a Windows box
> >> anyway? ;-)
> >>
> >> Therefore, here's just a work-around patch to keep things going on
> >> Windows. Any opinions from the Windows corner?
> >>
> >
> > Since we use MSVCRT's chmod implementation directly which only checks
> > for S_IWRITE,and Get/SetFileAttributes to simply set or clear the
> > FILE_ATTRIBUTE_READONLY-flag, perhaps we could do the same except
> > using Get/SetFileInformationByHandle instead? That takes us in a
> > better direction, IMO. Adding full ACL support seems like a bigger
> > project.
> >
> > If there's no objection, I'll sketch up a patch for that...
> 
> OK, this turned out a bit more yucky than I assumed, because
> SetFileInformationByHandle is only available on Windows Vista and up.
> There's a static library (FileExtd.lib) that ships with MSVC that
> emulates it for legacy support, I guess I should have a look at what
> that does.