Re: [PATCH RFC] parse_object: pass on the original sha1, not the replaced one

[Christian Couder <chriscool@tuxfamily.org>]

On Thursday 05 August 2010 00:07:45 Nguyen Thai Ngoc Duy wrote:
> On Wed, Aug 4, 2010 at 10:57 PM, Christian Couder
> 
> <chriscool@tuxfamily.org> wrote:
> > On Wednesday 04 August 2010 14:42:50 Nguyen Thai Ngoc Duy wrote:
> >> On Wed, Aug 4, 2010 at 9:58 PM, Christian Couder
> >> 
> >> <chriscool@tuxfamily.org> wrote:
> >> >> > I will
> >> >> > try to have a deeper look at that, but it would help if you could
> >> >> > give an example of a command that triggers this behavior.
> >> >> 
> >> >> The following patch add "sha1" command. These commands give different
> >> >> sha1:
> >> >> 
> >> >> git sha1 `git rev-parse HEAD` `git rev-parse HEAD^` A
> >> >> git sha1 `git rev-parse HEAD` `git rev-parse HEAD^` B
> >> > 
> >> > Yes, but that does not mean that the content of the object returned by
> >> > lookup_commit(A) is not the content of A.
> >> > 
> >> > Or do you have an example where the content of the object returned by
> >> > lookup_commit(A) is not the content of A?
> >> 
> >> Both return the content of B. I modified my patch a bit to also show
> >> the content, ((struct commit*)obj)->buffer.
> > 
> > I also modified your patch but I don't get any content shown when using
> > lookup_commit()
> > 
> > I use:
> > 
> > diff --git a/builtin/sha1.c b/builtin/sha1.c
> > new file mode 100644
> > index 0000000..8e081b2
> > --- /dev/null
> > +++ b/builtin/sha1.c
> > @@ -0,0 +1,27 @@
> > +#include "cache.h"
> > +#include "commit.h"
> > +
> > +int cmd_sha1(int argc, char **argv)
> > +{
> > +       unsigned char old[20];
> > +       unsigned char new[20];
> > +       struct object *obj;
> > +
> > +       get_sha1_hex(argv[1], old);
> > +       get_sha1_hex(argv[2], new);
> > +       printf("old  = %s\nnew  = %s\n", argv[1], argv[2]);
> > +       replace_pair(old, new);
> > +       if (argv[3][0] == 'A')
> > +              obj = parse_object(old);
> > +       else {
> > +              struct commit *com = lookup_commit(old);
> > +              if (com->buffer)
> > +                      printf("commit buffer:\n%s", com->buffer);
> > +              else
> > +                      printf("no commit buffer\n");
> > +              obj = (struct object *)com;
> > +       }
> > +
> > +       printf("sha1 = %s\n", sha1_to_hex(obj->sha1));
> > +       return 0;
> > +}
> > 
> > and I get:
> > 
> > $ git sha1 `git rev-parse HEAD` `git rev-parse HEAD^` B
> > old  = 5b4585a035e2ba61573273dacc6d17d7e8fcbc7d
> > new  = c9b402bd93105f80f3c5d67ecfccc8ba36810613
> > no commit buffer
> > sha1 = 5b4585a035e2ba61573273dacc6d17d7e8fcbc7d
> > 
> > Could you show what code you use?
> 
> You need parse_commit() (unless somebody already did that before
> lookup_commit()).

It looks like parse_commit() is buggy regarding replaced objects. But I am not 
sure how it should be fixed.

Anyway if you use parse_object(), then you don't need parse_commit(). So if 
possible you should use parse_object() instead of both lookup_commit() and 
parse_commit().

Best regards,
Christian.