[systemd-devel] [PATCH] tmpfiles: try to handle read-only file systems gracefully

[Michael Olbrich]

On Wed, May 06, 2015 at 04:11:57AM +0000, Zbigniew Jędrzejewski-Szmek wrote:
> On Thu, Apr 30, 2015 at 08:50:38PM +0200, Michael Olbrich wrote:
> > On read-only filesystems trying to create the target will not fail with
> > EEXIST but with EROFS. Handle EROFS by checking if the target already
> > exists, and if empty when truncating.
> > This avoids reporting errors if tmpfiles doesn't actually needs to do
> > anything.
> > ---
> > 
> > This is a rework of a patch I wrote some time ago[1]. This time reacting to
> > EROFS instead of preempting it.
> Applied, with some small changes, see below.
> 
> > 
> > Michael
> > 
> > [1] http://lists.freedesktop.org/archives/systemd-devel/2014-August/022158.html
> > 
> >  src/tmpfiles/tmpfiles.c | 12 +++++++++---
> >  1 file changed, 9 insertions(+), 3 deletions(-)
> > 
> > diff --git a/src/tmpfiles/tmpfiles.c b/src/tmpfiles/tmpfiles.c
> > index 218d55051410..4473bf019911 100644
> > --- a/src/tmpfiles/tmpfiles.c
> > +++ b/src/tmpfiles/tmpfiles.c
> > @@ -983,9 +983,11 @@ static int write_one_file(Item *i, const char *path) {
> >                          log_debug_errno(errno, "Not writing \"%s\": %m", path);
> >                          return 0;
> >                  }
> > -
> > -                log_error_errno(errno, "Failed to create file %s: %m", path);
> > -                return -errno;
> > +                r = -errno;
> > +                if (i->argument || r != -EROFS || stat(path, &st) < 0 || (i->type == TRUNCATE_FILE && st.st_size > 0)) {
> > +                        log_error_errno(r, "Failed to create file %s: %m", path);
> > +                        return r;
> > +                }
> I reverted the condition, because it seems safer to whitelist instead of
> blacklisting. Also, if the condition didn't succeed, we'd do stat twice.
> Please check that it still works as intended.

Looks good here.

Michael

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