Hi,
On Tue, 11 Jul 2006, Linus Torvalds wrote:
> On Tue, 11 Jul 2006, Junio C Hamano wrote:
> >
> > I do not like to rely too heavily on what zlib compression's
> > beginning of stream looks like.
>
> Well, I normally would agree with you if it was a "oh, all our zlib
> objects seem to start with 0x78" thing, but after having dug into both the
> zlib standard (which is actually an RFC, not just some random thing), and
> looked at the sources, it's definitely the case that the "0x78" byte isn't
> just an implementation detail.
>
> It's actually really part of the specs, and not just happenstance.
Good.
> --- a/sha1_file.c
> +++ b/sha1_file.c
> @@ -684,26 +684,74 @@ static void *map_sha1_file_internal(cons
> return map;
> }
>
> -static int unpack_sha1_header(z_stream *stream, void *map, unsigned long mapsize, void *buffer, unsigned long size)
> +static int unpack_sha1_header(z_stream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
> {
> + unsigned char c;
> + unsigned int word, bits;
> + unsigned long size;
> + static const char *typename[8] = {
> + NULL, /* OBJ_EXT */
> + "commit", "tree", "blob", "tag",
> + NULL, NULL, NULL
> + };
I completely forgot to mention that type_names[] is already declared in
object.h. Obviously, it is not really important, but maybe it would be
better to obey the DRY principle (think addition of "bind" object type).
> + while (!(c & 0x80)) {
> + if (bits >= 8*sizeof(long))
Another nit: while it is safe to assume that sizeof(long) ==
sizeof(unsigned long), it was nevertheless a little confusing to yours
truly (especially since you changed it since your last patch).
> static void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size)
> {
> int bytes = strlen(buffer) + 1;
> unsigned char *buf = xmalloc(1+size);
> + unsigned long n;
>
> - memcpy(buf, (char *) buffer + bytes, stream->total_out - bytes);
> - bytes = stream->total_out - bytes;
> + n = stream->total_out - bytes;
> + if (n > size)
> + n = size;
Just out of curiosity: when can this happen? I mean, there is no error or
something which could tell the caller that not the whole object was
copied.
> memset(&stream, 0, sizeof(stream));
> deflateInit(&stream, zlib_compression_level);
> - size = deflateBound(&stream, len+hdrlen);
> + size = 8 + deflateBound(&stream, len+hdrlen);
Again, I had to think why this is correct. I think it should be something
like 2 + sizeof(unsigned long) * 8 / 7, but I did not think all that hard.
It looks good to me, but I did not really test...
Ciao,
Dscho
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