On Sat, Sep 11, 2021 at 10:08:44PM -0400, Eric Sunshine wrote:
> On Sat, Sep 11, 2021 at 12:25 PM Taylor Blau <me@xxxxxxxxxxxx> wrote:
> > On Sat, Sep 11, 2021 at 12:05:05PM +0200, Ævar Arnfjörð Bjarmason wrote:
> > > Before calling string_list_clear(). I.e. we didn't strdup(), but during
> > > free() we pretend that we did, because we did, just not in
> > > string_list_append().
> >
> > Good catch. It's kind of gross, but the result is:
> >
> > static void read_packs_from_stdin(struct string_list *to)
> > {
> > - struct strbuf buf = STRBUF_INIT;
> > + struct strbuf buf = STRBUF_INIT_NODUP;
> > while (strbuf_getline(&buf, stdin) != EOF) {
> > string_list_append(to, strbuf_detach(&buf, NULL));
> > }
> > @@ -107,6 +107,11 @@ static int cmd_multi_pack_index_write(int argc, const char **argv)
> > ret = write_midx_file_only(opts.object_dir, &packs,
> > opts.preferred_pack, opts.flags);
> >
> > + /*
> > + * pretend strings are duplicated to free the memory allocated
> > + * by read_packs_from_stdin()
> > + */
> > + packs.strdup_strings = 1;
> > string_list_clear(&packs, 0);
>
> An alternative is to do this:
>
> struct strbuf buf = STRBUF_INIT;
> ...
> while (...) {
> string_list_append_nodup(to, strbuf_detach(&buf, NULL));
> ...
> }
> ...
> string_list_clear(&packs, 0);
>
> That is, use string_list_append_nodup(), which is documented as
> existing precisely for this sort of use-case:
>
> Like string_list_append(), except string is never copied. When
> list->strdup_strings is set, this function can be used to hand
> ownership of a malloc()ed string to list without making an extra
> copy.
>
> (I mention this only for completeness but don't care strongly which
> approach is used.)
Thanks for a great suggestion; I do prefer using the existing APIs where
possible, and it seems like string_list_append_nodup() was designed
exactly for this case.
Thanks,
Taylor
