1
0
Fork 0
mirror of https://github.com/git/git.git synced 2024-05-21 17:26:09 +02:00
git/object.h
brian m. carlson 64472d15e9 http-push: ensure unforced pushes fail when data would be lost
When we push using the DAV-based protocol, the client is the one that
performs the ref updates and therefore makes the checks to see whether
an unforced push should be allowed.  We make this check by determining
if either (a) we lack the object file for the old value of the ref or
(b) the new value of the ref is not newer than the old value, and in
either case, reject the push.

However, the ref_newer function, which performs this latter check, has
an odd behavior due to the reuse of certain object flags.  Specifically,
it will incorrectly return false in its first invocation and then
correctly return true on a subsequent invocation.  This occurs because
the object flags used by http-push.c are the same as those used by
commit-reach.c, which implements ref_newer, and one piece of code
misinterprets the flags set by the other.

Note that this does not occur in all cases.  For example, if the example
used in the tests is changed to use one repository instead of two and
rewind the head to add a commit, the test passes and we correctly reject
the push.  However, the example provided does trigger this behavior, and
the code has been broken in this way since at least Git 2.0.0.

To solve this problem, let's move the two sets of object flags so that
they don't overlap, since we're clearly using them at the same time.
The new set should not conflict with other usage because other users are
either builtin code (which is not compiled into git http-push) or
upload-pack (which we similarly do not use here).

Reported-by: Michael Ward <mward@smartsoftwareinc.com>
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-23 15:40:59 -07:00

198 lines
6.4 KiB
C

#ifndef OBJECT_H
#define OBJECT_H
#include "cache.h"
struct buffer_slab;
struct parsed_object_pool {
struct object **obj_hash;
int nr_objs, obj_hash_size;
/* TODO: migrate alloc_states to mem-pool? */
struct alloc_state *blob_state;
struct alloc_state *tree_state;
struct alloc_state *commit_state;
struct alloc_state *tag_state;
struct alloc_state *object_state;
unsigned commit_count;
/* parent substitutions from .git/info/grafts and .git/shallow */
struct commit_graft **grafts;
int grafts_alloc, grafts_nr;
int is_shallow;
struct stat_validity *shallow_stat;
char *alternate_shallow_file;
int commit_graft_prepared;
struct buffer_slab *buffer_slab;
};
struct parsed_object_pool *parsed_object_pool_new(void);
void parsed_object_pool_clear(struct parsed_object_pool *o);
struct object_list {
struct object *item;
struct object_list *next;
};
struct object_array {
unsigned int nr;
unsigned int alloc;
struct object_array_entry {
struct object *item;
/*
* name or NULL. If non-NULL, the memory pointed to
* is owned by this object *except* if it points at
* object_array_slopbuf, which is a static copy of the
* empty string.
*/
char *name;
char *path;
unsigned mode;
} *objects;
};
#define OBJECT_ARRAY_INIT { 0, 0, NULL }
/*
* object flag allocation:
* revision.h: 0---------10 25----28
* fetch-pack.c: 01
* negotiator/default.c: 2--5
* walker.c: 0-2
* upload-pack.c: 4 11-----14 16-----19
* builtin/blame.c: 12-13
* bisect.c: 16
* bundle.c: 16
* http-push.c: 11-----14
* commit-graph.c: 15
* commit-reach.c: 16-----19
* sha1-name.c: 20
* list-objects-filter.c: 21
* builtin/fsck.c: 0--3
* builtin/index-pack.c: 2021
* builtin/pack-objects.c: 20
* builtin/reflog.c: 10--12
* builtin/show-branch.c: 0-------------------------------------------26
* builtin/unpack-objects.c: 2021
*/
#define FLAG_BITS 29
/*
* The object type is stored in 3 bits.
*/
struct object {
unsigned parsed : 1;
unsigned type : TYPE_BITS;
unsigned flags : FLAG_BITS;
struct object_id oid;
};
const char *type_name(unsigned int type);
int type_from_string_gently(const char *str, ssize_t, int gentle);
#define type_from_string(str) type_from_string_gently(str, -1, 0)
/*
* Return the current number of buckets in the object hashmap.
*/
unsigned int get_max_object_index(void);
/*
* Return the object from the specified bucket in the object hashmap.
*/
struct object *get_indexed_object(unsigned int);
/*
* This can be used to see if we have heard of the object before, but
* it can return "yes we have, and here is a half-initialised object"
* for an object that we haven't loaded/parsed yet.
*
* When parsing a commit to create an in-core commit object, its
* parents list holds commit objects that represent its parents, but
* they are expected to be lazily initialized and do not know what
* their trees or parents are yet. When this function returns such a
* half-initialised objects, the caller is expected to initialize them
* by calling parse_object() on them.
*/
struct object *lookup_object(struct repository *r, const struct object_id *oid);
void *create_object(struct repository *r, const struct object_id *oid, void *obj);
void *object_as_type(struct repository *r, struct object *obj, enum object_type type, int quiet);
/*
* Returns the object, having parsed it to find out what it is.
*
* Returns NULL if the object is missing or corrupt.
*/
struct object *parse_object(struct repository *r, const struct object_id *oid);
/*
* Like parse_object, but will die() instead of returning NULL. If the
* "name" parameter is not NULL, it is included in the error message
* (otherwise, the hex object ID is given).
*/
struct object *parse_object_or_die(const struct object_id *oid, const char *name);
/* Given the result of read_sha1_file(), returns the object after
* parsing it. eaten_p indicates if the object has a borrowed copy
* of buffer and the caller should not free() it.
*/
struct object *parse_object_buffer(struct repository *r, const struct object_id *oid, enum object_type type, unsigned long size, void *buffer, int *eaten_p);
/** Returns the object, with potentially excess memory allocated. **/
struct object *lookup_unknown_object(const struct object_id *oid);
struct object_list *object_list_insert(struct object *item,
struct object_list **list_p);
int object_list_contains(struct object_list *list, struct object *obj);
void object_list_free(struct object_list **list);
/* 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 *);
/*
* Apply want to each entry in array, retaining only the entries for
* which the function returns true. Preserve the order of the entries
* that are retained.
*/
void object_array_filter(struct object_array *array,
object_array_each_func_t want, void *cb_data);
/*
* Remove from array all but the first entry with a given name.
* Warning: this function uses an O(N^2) algorithm.
*/
void object_array_remove_duplicates(struct object_array *array);
/*
* Remove any objects from the array, freeing all used memory; afterwards
* the array is ready to store more objects with add_object_array().
*/
void object_array_clear(struct object_array *array);
void clear_object_flags(unsigned flags);
/*
* Clear the specified object flags from all in-core commit objects.
*/
void clear_commit_marks_all(unsigned int flags);
#endif /* OBJECT_H */