Re: [PATCH v2] builtin-fast-export: Add importing and exporting of revision marks
- From
Junio C Hamano <gitster@pobox.com>
- Date
- Jun 6, 2008, 23:09 UTC
- Message-ID
- <7v8wxirwi1.fsf@gitster.siamese.dyndns.org>
- In-Reply-To
- <1212663163-43064-1-git-send-email-pdebie@ai.rug.nl>
Pieter de Bie <pdebie@ai.rug.nl> writes:
Show 23 quoted lines
> +static void export_marks(char *file)
> +{
> + unsigned int i;
> + uint32_t mark;
> + struct object_decoration *deco = idnums.hash;
> + FILE *f;
> +
> + f = fopen(file, "w");
> + if (!f)
> + error("Unable to open marks file %s for writing", file);
> +
> + for (i = 0; i < idnums.size; ++i) {
> + deco++;
> ...
> + mark = (uint32_t *)deco->decoration - (uint32_t *)NULL;
> + fprintf(f, ":%u %s\n", mark,
> + sha1_to_hex(deco->base->sha1));
> ...
> +}
> +
> +static void import_marks(char * input_file)
> ...
> + add_decoration(&idnums, object, ((uint32_t *)NULL) + mark);I am confused.
The type of object_decoration.decorattion is a (void*). Why isn't it sufficient to do it in a naïve and straightforward way?
mark = (uint32_t)(deco->decoration);
add_decoration(&idnums, object, (void*) mark);Is this twisted pointer arithmetic done in order to avoid cast between int and pointer of different size in the code? Even if that is the case, doesn't "(uint32_t *)deco->decoration - (uint32_t *)NULL" mean the value range for deco->decoration is one-fourth of U32? What are you gaining from using "uint32_t *" instead of some other pointer types, say "char *"?