alloc: fix dangling pointer in alloc_state cleanup

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>

diff --git a/alloc.c b/alloc.c
index 377e80f5dda2f80e6222f4eb2fa8c607d708cc9d..533a045c2a8bdf9f4c55301c3946be54bd6b8eba 100644 (file)
--- a/alloc.c
+++ b/alloc.c
@@ -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)

diff --git a/alloc.h b/alloc.h
index 3f4a0ad310a94bd026f48f48491985e3e2053ee2..87a47a970954c10e52e25a2bd3176e593a831cdb 100644 (file)
--- a/alloc.h
+++ b/alloc.h
@@ -14,7 +14,7 @@ void *alloc_commit_node(struct repository *r);
 void *alloc_tag_node(struct repository *r);
 void *alloc_object_node(struct repository *r);
 
-struct alloc_state *allocate_alloc_state(void);
-void clear_alloc_state(struct alloc_state *s);
+struct alloc_state *alloc_state_alloc(void);
+void alloc_state_free_and_null(struct alloc_state **s_);
 
 #endif

diff --git a/object.c b/object.c
index c1553ee4330c89533f4e09f842f40264777e1372..986114a6dba843ea412123dc9035bf67693a6afd 100644 (file)
--- a/object.c
+++ b/object.c
@@ -517,12 +517,11 @@ struct parsed_object_pool *parsed_object_pool_new(struct repository *repo)
        memset(o, 0, sizeof(*o));
 
        o->repo = repo;
-       o->blob_state = allocate_alloc_state();
-       o->tree_state = allocate_alloc_state();
-       o->commit_state = allocate_alloc_state();
-       o->tag_state = allocate_alloc_state();
-       o->object_state = allocate_alloc_state();
-
+       o->blob_state = alloc_state_alloc();
+       o->tree_state = alloc_state_alloc();
+       o->commit_state = alloc_state_alloc();
+       o->tag_state = alloc_state_alloc();
+       o->object_state = alloc_state_alloc();
        o->is_shallow = -1;
        CALLOC_ARRAY(o->shallow_stat, 1);
 
@@ -573,16 +572,11 @@ void parsed_object_pool_clear(struct parsed_object_pool *o)
        o->buffer_slab = NULL;
 
        parsed_object_pool_reset_commit_grafts(o);
-       clear_alloc_state(o->blob_state);
-       clear_alloc_state(o->tree_state);
-       clear_alloc_state(o->commit_state);
-       clear_alloc_state(o->tag_state);
-       clear_alloc_state(o->object_state);
+       alloc_state_free_and_null(&o->blob_state);
+       alloc_state_free_and_null(&o->tree_state);
+       alloc_state_free_and_null(&o->commit_state);
+       alloc_state_free_and_null(&o->tag_state);
+       alloc_state_free_and_null(&o->object_state);
        stat_validity_clear(o->shallow_stat);
-       FREE_AND_NULL(o->blob_state);
-       FREE_AND_NULL(o->tree_state);
-       FREE_AND_NULL(o->commit_state);
-       FREE_AND_NULL(o->tag_state);
-       FREE_AND_NULL(o->object_state);
        FREE_AND_NULL(o->shallow_stat);
 }