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The "struct object" type implements basic object polymorphism. Individual instances are allocated as concrete types (or as a union type that can store any object), and a "struct object *" can be cast into its real type after examining its "type" enum. This means it is dangerous to have a type field that does not match the allocation (e.g., setting the type field of a "struct blob" to "OBJ_COMMIT" would mean that a reader might read past the allocated memory). In most of the current code this is not a problem; the first thing we do after allocating an object is usually to set its type field by passing it to create_object. However, the virtual commits we create in merge-recursive.c do not ever get their type set. This does not seem to have caused problems in practice, though (presumably because we always pass around a "struct commit" pointer and never even look at the type). We can fix this oversight and also make it harder for future code to get it wrong by setting the type directly in the object allocation functions. This will also make it easier to fix problems with commit index allocation, as we know that any object allocated by alloc_commit_node will meet the invariant that an object with an OBJ_COMMIT type field will have a unique index number. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
136 lines
4.3 KiB
C
136 lines
4.3 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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unsigned mode;
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struct object_context *context;
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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---4
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* walker.c: 0-2
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* upload-pack.c: 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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*/
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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 used : 1;
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unsigned type : TYPE_BITS;
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unsigned flags : FLAG_BITS;
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unsigned char sha1[20];
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};
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extern const char *typename(unsigned int type);
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extern int type_from_string(const char *str);
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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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/*
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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 unsigned char *sha1);
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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 sha1 hex is given).
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*/
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struct object *parse_object_or_die(const unsigned char *sha1, 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 unsigned char *sha1, 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_mode(struct object *obj, const char *name, struct object_array *array, unsigned mode);
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void add_object_array_with_context(struct object *obj, const char *name, struct object_array *array, struct object_context *context);
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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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void clear_object_flags(unsigned flags);
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#endif /* OBJECT_H */
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