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alloc: fix dangling pointer in alloc_state cleanup

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All callers of clear_alloc_state() immediately free what they
cleared, so currently it does not hurt anybody that the
alloc_state is left in an unreusable state, but it is an
error-prone API. Replace it with a new function that clears but
in addition frees the structure, as well as NULLing the pointer
that points at it and adjust existing callers.

As it is a moral equivalent of FREE_AND_NULL(), except that what it
frees has internal structure that needs to be cleaned, allow the
helper to be called twice in a row, by making a call with a pointer
to a pointer variable that already is NULLed.

While at it, rename allocate_alloc_state() and name the new
function alloc_state_free_and_null(), to follow more closely the
function naming convention specified in the CodingGuidelines
(namely, functions about S are named with S_ prefix and then
verb).

Signed-off-by: ノウラ | Flare <nouraellm@gmail.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
ノウラ | Flare
2025-09-04 17:44:16 +00:00
committed by Junio C Hamano
parent 42bc224495
commit 5e2feb5ca6
3 changed files with 20 additions and 20 deletions
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10
alloc.c
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@@ -36,19 +36,25 @@ struct alloc_state {
int slab_nr, slab_alloc;
};
struct alloc_state *allocate_alloc_state(void)
struct alloc_state *alloc_state_alloc(void)
{
return xcalloc(1, sizeof(struct alloc_state));
}
void clear_alloc_state(struct alloc_state *s)
void alloc_state_free_and_null(struct alloc_state **s_)
{
struct alloc_state *s = *s_;
if (!s)
return;
while (s->slab_nr > 0) {
s->slab_nr--;
free(s->slabs[s->slab_nr]);
}
FREE_AND_NULL(s->slabs);
FREE_AND_NULL(*s_);
}
static inline void *alloc_node(struct alloc_state *s, size_t node_size)