In a couple of places, we pop objects off an object array `foo` by
decreasing `foo.nr`. We access `foo.nr` in many places, but most if not
all other times we do so read-only, e.g., as we iterate over the array.
But when we change `foo.nr` behind the array's back, it feels a bit
nasty and looks like it might leak memory.
Leaks happen if the popped element has an allocated `name` or `path`.
At the moment, that is not the case. Still, 1) the object array might
gain more fields that want to be freed, 2) a code path where we pop
might start using names or paths, 3) one of these code paths might be
copied to somewhere where we do, and 4) using a dedicated function for
popping is conceptually cleaner.
Introduce and use `object_array_pop()` instead. Release memory in the
new function. Document that popping an object leaves the associated
elements in limbo.
The converted places were identified by grepping for "\.nr\>" and
looking for "--".
Make the new function return NULL on an empty array. This is consistent
with `pop_commit()` and allows the following:
while ((o = object_array_pop(&foo)) != NULL) {
// do something
}
But as noted above, we don't need to go out of our way to avoid reading
`foo.nr`. This is probably more readable:
while (foo.nr) {
... o = object_array_pop(&foo);
// do something
}
The name of `object_array_pop()` does not quite align with
`add_object_array()`. That is unfortunate. On the other hand, it matches
`object_array_clear()`. Arguably it's `add_...` that is the odd one out,
since it reads like it's used to "add" an "object array". For that
reason, side with `object_array_clear()`.
Signed-off-by: Martin Ågren <martin.agren@xxxxxxxxx>
---
builtin/fast-export.c | 3 +--
builtin/fsck.c | 7 +------
builtin/reflog.c | 2 +-
object.c | 13 +++++++++++++
object.h | 7 +++++++
shallow.c | 2 +-
6 files changed, 24 insertions(+), 10 deletions(-)
diff --git a/builtin/fast-export.c b/builtin/fast-export.c
index d412c0a8f..cff8d0fc5 100644
--- a/builtin/fast-export.c
+++ b/builtin/fast-export.c
@@ -634,11 +634,10 @@ static void handle_tail(struct object_array *commits, struct rev_info *revs)
{
struct commit *commit;
while (commits->nr) {
- commit = (struct commit *)commits->objects[commits->nr - 1].item;
+ commit = (struct commit *)object_array_pop(commits);
if (has_unshown_parent(commit))
return;
handle_commit(commit, revs);
- commits->nr--;
}
}
diff --git a/builtin/fsck.c b/builtin/fsck.c
index d18244ab5..7d4ad0273 100644
--- a/builtin/fsck.c
+++ b/builtin/fsck.c
@@ -181,12 +181,7 @@ static int traverse_reachable(void)
if (show_progress)
progress = start_progress_delay(_("Checking connectivity"), 0, 0, 2);
while (pending.nr) {
- struct object_array_entry *entry;
- struct object *obj;
-
- entry = pending.objects + --pending.nr;
- obj = entry->item;
- result |= traverse_one_object(obj);
+ result |= traverse_one_object(object_array_pop(&pending));
display_progress(progress, ++nr);
}
stop_progress(&progress);
diff --git a/builtin/reflog.c b/builtin/reflog.c
index 6b34f23e7..2067cca5b 100644
--- a/builtin/reflog.c
+++ b/builtin/reflog.c
@@ -126,7 +126,7 @@ static int commit_is_complete(struct commit *commit)
struct commit *c;
struct commit_list *parent;
- c = (struct commit *)study.objects[--study.nr].item;
+ c = (struct commit *)object_array_pop(&study);
if (!c->object.parsed && !parse_object(&c->object.oid))
c->object.flags |= INCOMPLETE;
diff --git a/object.c b/object.c
index 321d7e920..b9a4a0e50 100644
--- a/object.c
+++ b/object.c
@@ -353,6 +353,19 @@ static void object_array_release_entry(struct object_array_entry *ent)
free(ent->path);
}
+struct object *object_array_pop(struct object_array *array)
+{
+ struct object *ret;
+
+ if (!array->nr)
+ return NULL;
+
+ ret = array->objects[array->nr - 1].item;
+ object_array_release_entry(&array->objects[array->nr - 1]);
+ array->nr--;
+ return ret;
+}
+
void object_array_filter(struct object_array *array,
object_array_each_func_t want, void *cb_data)
{
diff --git a/object.h b/object.h
index 0a419ba8d..b7629fe92 100644
--- a/object.h
+++ b/object.h
@@ -115,6 +115,13 @@ int object_list_contains(struct object_list *list, struct object *obj);
/* Object array handling .. */
void add_object_array(struct object *obj, const char *name, struct object_array *array);
void add_object_array_with_path(struct object *obj, const char *name, struct object_array *array, unsigned mode, const char *path);
+/*
+ * Returns NULL if the array is empty. Otherwise, returns the last object
+ * after removing its entry from the array. Other resources associated
+ * with that object are left in an unspecified state and should not be
+ * examined.
+ */
+struct object *object_array_pop(struct object_array *array);
typedef int (*object_array_each_func_t)(struct object_array_entry *, void *);
diff --git a/shallow.c b/shallow.c
index 54359d549..901ac9791 100644
--- a/shallow.c
+++ b/shallow.c
@@ -99,7 +99,7 @@ struct commit_list *get_shallow_commits(struct object_array *heads, int depth,
cur_depth = 0;
} else {
commit = (struct commit *)
- stack.objects[--stack.nr].item;
+ object_array_pop(&stack);
cur_depth = *(int *)commit->util;
}
}
--
2.14.1.727.g9ddaf86
