@matheusbsbs / matheus-bagliano / commits / 4468d4435c

object_as_type: initialize commit-graph-related fields of 'struct commit'

When the commit graph and generation numbers were introduced in commits 177722b344 (commit: integrate commit graph with commit parsing, 2018-04-10) and 83073cc994 (commit: add generation number to struct commit, 2018-04-25), they tried to make sure that the corresponding 'graph_pos' and 'generation' fields of 'struct commit' are initialized conservatively, as if the commit were not included in the commit-graph file. Alas, initializing those fields only in alloc_commit_node() missed the case when an object that happens to be a commit is first looked up via lookup_unknown_object(), and is then later converted to a 'struct commit' via the object_as_type() helper function (either calling it directly, or as part of a subsequent lookup_commit() call). Consequently, both of those fields incorrectly remain set to zero, which means e.g. that the commit is present in and is the first entry of the commit-graph file. This will result in wrong timestamp, parent and root tree hashes, if such a 'struct commit' instance is later filled from the commit-graph. Extract the initialization of 'struct commit's fields from alloc_commit_node() into a helper function, and call it from object_as_type() as well, to make sure that it properly initializes the two commit-graph-related fields, too. With this helper function it is hopefully less likely that any new fields added to 'struct commit' in the future would remain uninitialized. With this change alloc_commit_index() won't have any remaining callers outside of 'alloc.c', so mark it as static. Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

SZEDER Gábor committed Jan 27, 2019 at 14:08 UTC 4468d4435c44d50723e96e3416f8b5da97a1806f

3 files changed +12 -6

alloc.c

+8 -3

@@ -99,18 +99,23 @@ void *alloc_object_node(struct repository *r)

99 return obj;

100 }

101

102 -unsigned int alloc_commit_index(struct repository *r)

102 +static unsigned int alloc_commit_index(struct repository *r)

103 {

104 return r->parsed_objects->commit_count++;

105 }

106

107 -void *alloc_commit_node(struct repository *r)

107 +void init_commit_node(struct repository *r, struct commit *c)

108 {

109 - struct commit *c = alloc_node(r->parsed_objects->commit_state, sizeof(struct commit));

109 c->object.type = OBJ_COMMIT;

110 c->index = alloc_commit_index(r);

111 c->graph_pos = COMMIT_NOT_FROM_GRAPH;

112 c->generation = GENERATION_NUMBER_INFINITY;

113 +}

114 +

115 +void *alloc_commit_node(struct repository *r)

116 +{

117 + struct commit *c = alloc_node(r->parsed_objects->commit_state, sizeof(struct commit));

118 + init_commit_node(r, c);

119 return c;

120 }

121

alloc.h

+1 -1

@@ -9,11 +9,11 @@ struct repository;

10 void *alloc_blob_node(struct repository *r);

11 void *alloc_tree_node(struct repository *r);

12 +void init_commit_node(struct repository *r, struct commit *c);

13 void *alloc_commit_node(struct repository *r);

14 void *alloc_tag_node(struct repository *r);

15 void *alloc_object_node(struct repository *r);

16 void alloc_report(struct repository *r);

16 -unsigned int alloc_commit_index(struct repository *r);

18 struct alloc_state *allocate_alloc_state(void);

19 void clear_alloc_state(struct alloc_state *s);

object.c

+3 -2

@@ -164,8 +164,9 @@ void *object_as_type(struct repository *r, struct object *obj, enum object_type

164 return obj;

165 else if (obj->type == OBJ_NONE) {

166 if (type == OBJ_COMMIT)

167 - ((struct commit *)obj)->index = alloc_commit_index(r);

168 - obj->type = type;

167 + init_commit_node(r, (struct commit *) obj);

168 + else

169 + obj->type = type;

170 return obj;

171 }

172 else {