wt-status: introduce wt_status_state_free_buffers()

When we have a `struct wt_status_state`, we manually free its `branch`,
`onto` and `detached_from`, or sometimes just one or two of them.
Provide a function `wt_status_state_free_buffers()` which does the
freeing.

The callers are still aware of these fields, e.g., they check whether
`branch` was populated or not. But this way, they don't need to know
about *all* of them, and if `struct wt_status_state` gets more fields,
they will not need to learn to free them.

Users of `struct wt_status` (which contains a `wt_status_state`) already
have `wt_status_collect_free_buffers()` (corresponding to
`wt_status_collect()`) which we can also teach to use this new helper.

Finally, note that we're currently leaving dangling pointers behind.
Some callers work on a stack-allocated struct, where this is obviously
ok. But for the users of `run_status()` in builtin/commit.c, there are
ample opportunities for someone to mistakenly use those dangling
pointers. We seem to be ok for now, but it's a use-after-free waiting to
happen. Let's leave NULL-pointers behind instead.

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Martin Ågren 2020-09-27 15:15:43 +02:00 коммит произвёл Junio C Hamano
Родитель 8f7e3de097
Коммит 962dd7ebc3
4 изменённых файлов: 18 добавлений и 9 удалений

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@ -1509,9 +1509,7 @@ char *get_head_description(void)
strbuf_addstr(&desc, _("no branch"));
strbuf_addch(&desc, ')');
free(state.branch);
free(state.onto);
free(state.detached_from);
wt_status_state_free_buffers(&state);
return strbuf_detach(&desc, NULL);
}

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@ -357,8 +357,7 @@ int is_worktree_being_rebased(const struct worktree *wt,
state.branch &&
starts_with(target, "refs/heads/") &&
!strcmp(state.branch, target + strlen("refs/heads/")));
free(state.branch);
free(state.onto);
wt_status_state_free_buffers(&state);
return found_rebase;
}
@ -373,7 +372,7 @@ int is_worktree_being_bisected(const struct worktree *wt,
state.branch &&
starts_with(target, "refs/heads/") &&
!strcmp(state.branch, target + strlen("refs/heads/"));
free(state.branch);
wt_status_state_free_buffers(&state);
return found_rebase;
}

Просмотреть файл

@ -778,9 +778,14 @@ void wt_status_collect(struct wt_status *s)
void wt_status_collect_free_buffers(struct wt_status *s)
{
free(s->state.branch);
free(s->state.onto);
free(s->state.detached_from);
wt_status_state_free_buffers(&s->state);
}
void wt_status_state_free_buffers(struct wt_status_state *state)
{
FREE_AND_NULL(state->branch);
FREE_AND_NULL(state->onto);
FREE_AND_NULL(state->detached_from);
}
static void wt_longstatus_print_unmerged(struct wt_status *s)

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@ -151,7 +151,14 @@ void wt_status_add_cut_line(FILE *fp);
void wt_status_prepare(struct repository *r, struct wt_status *s);
void wt_status_print(struct wt_status *s);
void wt_status_collect(struct wt_status *s);
/*
* Frees the buffers allocated by wt_status_collect.
*/
void wt_status_collect_free_buffers(struct wt_status *s);
/*
* Frees the buffers of the wt_status_state.
*/
void wt_status_state_free_buffers(struct wt_status_state *s);
void wt_status_get_state(struct repository *repo,
struct wt_status_state *state,
int get_detached_from);