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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@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
152 lines
4.8 KiB
C
152 lines
4.8 KiB
C
#ifndef OBJECT_H
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#define OBJECT_H
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struct object_list {
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struct object *item;
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struct object_list *next;
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};
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struct object_array {
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unsigned int nr;
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unsigned int alloc;
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struct object_array_entry {
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struct object *item;
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/*
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* name or NULL. If non-NULL, the memory pointed to
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* is owned by this object *except* if it points at
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* object_array_slopbuf, which is a static copy of the
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* empty string.
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*/
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char *name;
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char *path;
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unsigned mode;
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} *objects;
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};
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#define OBJECT_ARRAY_INIT { 0, 0, NULL }
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#define TYPE_BITS 3
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/*
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* object flag allocation:
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* revision.h: 0---------10 26
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* fetch-pack.c: 0---5
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* walker.c: 0-2
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* upload-pack.c: 4 11----------------19
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* builtin/blame.c: 12-13
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* bisect.c: 16
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* bundle.c: 16
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* http-push.c: 16-----19
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* commit.c: 16-----19
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* sha1_name.c: 20
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* builtin/fsck.c: 0--3
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*/
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#define FLAG_BITS 27
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/*
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* The object type is stored in 3 bits.
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*/
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struct object {
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unsigned parsed : 1;
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unsigned type : TYPE_BITS;
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unsigned flags : FLAG_BITS;
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struct object_id oid;
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};
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extern const char *typename(unsigned int type);
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extern int type_from_string_gently(const char *str, ssize_t, int gentle);
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#define type_from_string(str) type_from_string_gently(str, -1, 0)
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/*
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* Return the current number of buckets in the object hashmap.
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*/
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extern unsigned int get_max_object_index(void);
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/*
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* Return the object from the specified bucket in the object hashmap.
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*/
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extern struct object *get_indexed_object(unsigned int);
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/*
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* This can be used to see if we have heard of the object before, but
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* it can return "yes we have, and here is a half-initialised object"
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* for an object that we haven't loaded/parsed yet.
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*
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* When parsing a commit to create an in-core commit object, its
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* parents list holds commit objects that represent its parents, but
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* they are expected to be lazily initialized and do not know what
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* their trees or parents are yet. When this function returns such a
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* half-initialised objects, the caller is expected to initialize them
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* by calling parse_object() on them.
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*/
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struct object *lookup_object(const unsigned char *sha1);
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extern void *create_object(const unsigned char *sha1, void *obj);
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void *object_as_type(struct object *obj, enum object_type type, int quiet);
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/*
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* Returns the object, having parsed it to find out what it is.
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*
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* Returns NULL if the object is missing or corrupt.
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*/
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struct object *parse_object(const struct object_id *oid);
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/*
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* Like parse_object, but will die() instead of returning NULL. If the
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* "name" parameter is not NULL, it is included in the error message
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* (otherwise, the hex object ID is given).
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*/
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struct object *parse_object_or_die(const struct object_id *oid, const char *name);
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/* Given the result of read_sha1_file(), returns the object after
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* parsing it. eaten_p indicates if the object has a borrowed copy
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* of buffer and the caller should not free() it.
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*/
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struct object *parse_object_buffer(const struct object_id *oid, enum object_type type, unsigned long size, void *buffer, int *eaten_p);
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/** Returns the object, with potentially excess memory allocated. **/
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struct object *lookup_unknown_object(const unsigned char *sha1);
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struct object_list *object_list_insert(struct object *item,
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struct object_list **list_p);
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int object_list_contains(struct object_list *list, struct object *obj);
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/* Object array handling .. */
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void add_object_array(struct object *obj, const char *name, struct object_array *array);
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void add_object_array_with_path(struct object *obj, const char *name, struct object_array *array, unsigned mode, const char *path);
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/*
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* Returns NULL if the array is empty. Otherwise, returns the last object
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* after removing its entry from the array. Other resources associated
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* with that object are left in an unspecified state and should not be
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* examined.
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*/
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struct object *object_array_pop(struct object_array *array);
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typedef int (*object_array_each_func_t)(struct object_array_entry *, void *);
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/*
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* Apply want to each entry in array, retaining only the entries for
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* which the function returns true. Preserve the order of the entries
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* that are retained.
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*/
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void object_array_filter(struct object_array *array,
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object_array_each_func_t want, void *cb_data);
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/*
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* Remove from array all but the first entry with a given name.
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* Warning: this function uses an O(N^2) algorithm.
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*/
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void object_array_remove_duplicates(struct object_array *array);
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/*
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* Remove any objects from the array, freeing all used memory; afterwards
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* the array is ready to store more objects with add_object_array().
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*/
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void object_array_clear(struct object_array *array);
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void clear_object_flags(unsigned flags);
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#endif /* OBJECT_H */
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