Re: [PATCH 1/1] fat: fix listing the root directory

[Heinrich Schuchardt]

On 1/22/22 10:07, Vladimir 'phcoder' Serbinenko wrote:
> Inserting dummy date of 1970-1-1 is a bad idea. Can we rather allow
> timestamp to be missing instead of throwing error?

This function seems only to be used for validation of the timestamp.
I never have seen the ls command in GRUB actually display a timestamp.

If you use ls -la in Linux it will display 1970-01-01. Wouldn't this be 
what a user would expect to see in GRUB too?

Anyway the filtering would have to be done in a different function than 
the one corrected here.

Best regards

Heinrich

> On Fri, Jan 21, 2022 at 8:33 PM Heinrich Schuchardt
> <heinrich.schuchardt@canonical.com> wrote:
> > ls / for a FAT partition leads to
> >
> >     error: invalid modification timestamp for /.
> >
> > Not all entries of the directory are displayed.
> >
> > Linux never updates the modification timestamp of the /. directory entry.
> > The FAT specification allows the access and creation date fields to be
> > zero.
> >
> > We should follow Linux and render initial FAT timestamps as start of
> > the epoch.
> >
> > Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
> > ---
> >   grub-core/fs/fat.c | 12 ++++++++++++
> >   1 file changed, 12 insertions(+)
> >
> > diff --git a/grub-core/fs/fat.c b/grub-core/fs/fat.c
> > index dd82e4ee3..35ff0b27c 100644
> > --- a/grub-core/fs/fat.c
> > +++ b/grub-core/fs/fat.c
> > @@ -901,6 +901,18 @@ grub_fat_timestamp (grub_uint16_t time, grub_uint16_t 
> > date, grub_int64_t *nix) {
> >       .second = (time & 0x001F) * 2,
> >     };
> >
> > +  /*
> > +   * The modification time of the root directory is never set by Linux.
> > +   * Creation and access time are optional and can be zero.
> > +   * Follow Linux and render FAT initial timestamps as the start of the epoch.
> > +   */
> > +  if (date == 0 && time == 0)
> > +    {
> > +      datetime.year = 1970;
> > +      datetime.month = 1;
> > +      datetime.day = 1;
> > +    }
> > +
> >     /* The conversion below allows seconds=60, so don't trust its validation. */
> >     if ((time & 0x1F) > 29)
> >       return 0;
> > --
> > 2.33.1
> >
> >
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