Merge branch 'ab/push-cas-doc-n-test'
[git/git.git] / refs / refs-internal.h
1 #ifndef REFS_REFS_INTERNAL_H
2 #define REFS_REFS_INTERNAL_H
3
4 /*
5 * Data structures and functions for the internal use of the refs
6 * module. Code outside of the refs module should use only the public
7 * functions defined in "refs.h", and should *not* include this file.
8 */
9
10 /*
11 * Flag passed to lock_ref_sha1_basic() telling it to tolerate broken
12 * refs (i.e., because the reference is about to be deleted anyway).
13 */
14 #define REF_DELETING 0x02
15
16 /*
17 * Used as a flag in ref_update::flags when a loose ref is being
18 * pruned. This flag must only be used when REF_NODEREF is set.
19 */
20 #define REF_ISPRUNING 0x04
21
22 /*
23 * Used as a flag in ref_update::flags when the reference should be
24 * updated to new_sha1.
25 */
26 #define REF_HAVE_NEW 0x08
27
28 /*
29 * Used as a flag in ref_update::flags when old_sha1 should be
30 * checked.
31 */
32 #define REF_HAVE_OLD 0x10
33
34 /*
35 * Used as a flag in ref_update::flags when the lockfile needs to be
36 * committed.
37 */
38 #define REF_NEEDS_COMMIT 0x20
39
40 /*
41 * 0x40 is REF_FORCE_CREATE_REFLOG, so skip it if you're adding a
42 * value to ref_update::flags
43 */
44
45 /*
46 * Used as a flag in ref_update::flags when we want to log a ref
47 * update but not actually perform it. This is used when a symbolic
48 * ref update is split up.
49 */
50 #define REF_LOG_ONLY 0x80
51
52 /*
53 * Internal flag, meaning that the containing ref_update was via an
54 * update to HEAD.
55 */
56 #define REF_UPDATE_VIA_HEAD 0x100
57
58 /*
59 * Used as a flag in ref_update::flags when the loose reference has
60 * been deleted.
61 */
62 #define REF_DELETED_LOOSE 0x200
63
64 /*
65 * Return true iff refname is minimally safe. "Safe" here means that
66 * deleting a loose reference by this name will not do any damage, for
67 * example by causing a file that is not a reference to be deleted.
68 * This function does not check that the reference name is legal; for
69 * that, use check_refname_format().
70 *
71 * A refname that starts with "refs/" is considered safe iff it
72 * doesn't contain any "." or ".." components or consecutive '/'
73 * characters, end with '/', or (on Windows) contain any '\'
74 * characters. Names that do not start with "refs/" are considered
75 * safe iff they consist entirely of upper case characters and '_'
76 * (like "HEAD" and "MERGE_HEAD" but not "config" or "FOO/BAR").
77 */
78 int refname_is_safe(const char *refname);
79
80 enum peel_status {
81 /* object was peeled successfully: */
82 PEEL_PEELED = 0,
83
84 /*
85 * object cannot be peeled because the named object (or an
86 * object referred to by a tag in the peel chain), does not
87 * exist.
88 */
89 PEEL_INVALID = -1,
90
91 /* object cannot be peeled because it is not a tag: */
92 PEEL_NON_TAG = -2,
93
94 /* ref_entry contains no peeled value because it is a symref: */
95 PEEL_IS_SYMREF = -3,
96
97 /*
98 * ref_entry cannot be peeled because it is broken (i.e., the
99 * symbolic reference cannot even be resolved to an object
100 * name):
101 */
102 PEEL_BROKEN = -4
103 };
104
105 /*
106 * Peel the named object; i.e., if the object is a tag, resolve the
107 * tag recursively until a non-tag is found. If successful, store the
108 * result to sha1 and return PEEL_PEELED. If the object is not a tag
109 * or is not valid, return PEEL_NON_TAG or PEEL_INVALID, respectively,
110 * and leave sha1 unchanged.
111 */
112 enum peel_status peel_object(const unsigned char *name, unsigned char *sha1);
113
114 /*
115 * Copy the reflog message msg to buf, which has been allocated sufficiently
116 * large, while cleaning up the whitespaces. Especially, convert LF to space,
117 * because reflog file is one line per entry.
118 */
119 int copy_reflog_msg(char *buf, const char *msg);
120
121 /**
122 * Information needed for a single ref update. Set new_sha1 to the new
123 * value or to null_sha1 to delete the ref. To check the old value
124 * while the ref is locked, set (flags & REF_HAVE_OLD) and set
125 * old_sha1 to the old value, or to null_sha1 to ensure the ref does
126 * not exist before update.
127 */
128 struct ref_update {
129
130 /*
131 * If (flags & REF_HAVE_NEW), set the reference to this value:
132 */
133 unsigned char new_sha1[20];
134
135 /*
136 * If (flags & REF_HAVE_OLD), check that the reference
137 * previously had this value:
138 */
139 unsigned char old_sha1[20];
140
141 /*
142 * One or more of REF_HAVE_NEW, REF_HAVE_OLD, REF_NODEREF,
143 * REF_DELETING, REF_ISPRUNING, REF_LOG_ONLY,
144 * REF_UPDATE_VIA_HEAD, REF_NEEDS_COMMIT, and
145 * REF_DELETED_LOOSE:
146 */
147 unsigned int flags;
148
149 void *backend_data;
150 unsigned int type;
151 char *msg;
152
153 /*
154 * If this ref_update was split off of a symref update via
155 * split_symref_update(), then this member points at that
156 * update. This is used for two purposes:
157 * 1. When reporting errors, we report the refname under which
158 * the update was originally requested.
159 * 2. When we read the old value of this reference, we
160 * propagate it back to its parent update for recording in
161 * the latter's reflog.
162 */
163 struct ref_update *parent_update;
164
165 const char refname[FLEX_ARRAY];
166 };
167
168 /*
169 * Add a ref_update with the specified properties to transaction, and
170 * return a pointer to the new object. This function does not verify
171 * that refname is well-formed. new_sha1 and old_sha1 are only
172 * dereferenced if the REF_HAVE_NEW and REF_HAVE_OLD bits,
173 * respectively, are set in flags.
174 */
175 struct ref_update *ref_transaction_add_update(
176 struct ref_transaction *transaction,
177 const char *refname, unsigned int flags,
178 const unsigned char *new_sha1,
179 const unsigned char *old_sha1,
180 const char *msg);
181
182 /*
183 * Transaction states.
184 * OPEN: The transaction is in a valid state and can accept new updates.
185 * An OPEN transaction can be committed.
186 * CLOSED: A closed transaction is no longer active and no other operations
187 * than free can be used on it in this state.
188 * A transaction can either become closed by successfully committing
189 * an active transaction or if there is a failure while building
190 * the transaction thus rendering it failed/inactive.
191 */
192 enum ref_transaction_state {
193 REF_TRANSACTION_OPEN = 0,
194 REF_TRANSACTION_CLOSED = 1
195 };
196
197 /*
198 * Data structure for holding a reference transaction, which can
199 * consist of checks and updates to multiple references, carried out
200 * as atomically as possible. This structure is opaque to callers.
201 */
202 struct ref_transaction {
203 struct ref_store *ref_store;
204 struct ref_update **updates;
205 size_t alloc;
206 size_t nr;
207 enum ref_transaction_state state;
208 };
209
210 /*
211 * Check for entries in extras that are within the specified
212 * directory, where dirname is a reference directory name including
213 * the trailing slash (e.g., "refs/heads/foo/"). Ignore any
214 * conflicting references that are found in skip. If there is a
215 * conflicting reference, return its name.
216 *
217 * extras and skip must be sorted lists of reference names. Either one
218 * can be NULL, signifying the empty list.
219 */
220 const char *find_descendant_ref(const char *dirname,
221 const struct string_list *extras,
222 const struct string_list *skip);
223
224 /*
225 * Check whether an attempt to rename old_refname to new_refname would
226 * cause a D/F conflict with any existing reference (other than
227 * possibly old_refname). If there would be a conflict, emit an error
228 * message and return false; otherwise, return true.
229 *
230 * Note that this function is not safe against all races with other
231 * processes (though rename_ref() catches some races that might get by
232 * this check).
233 */
234 int refs_rename_ref_available(struct ref_store *refs,
235 const char *old_refname,
236 const char *new_refname);
237
238 /* We allow "recursive" symbolic refs. Only within reason, though */
239 #define SYMREF_MAXDEPTH 5
240
241 /* Include broken references in a do_for_each_ref*() iteration: */
242 #define DO_FOR_EACH_INCLUDE_BROKEN 0x01
243
244 /*
245 * Reference iterators
246 *
247 * A reference iterator encapsulates the state of an in-progress
248 * iteration over references. Create an instance of `struct
249 * ref_iterator` via one of the functions in this module.
250 *
251 * A freshly-created ref_iterator doesn't yet point at a reference. To
252 * advance the iterator, call ref_iterator_advance(). If successful,
253 * this sets the iterator's refname, oid, and flags fields to describe
254 * the next reference and returns ITER_OK. The data pointed at by
255 * refname and oid belong to the iterator; if you want to retain them
256 * after calling ref_iterator_advance() again or calling
257 * ref_iterator_abort(), you must make a copy. When the iteration has
258 * been exhausted, ref_iterator_advance() releases any resources
259 * assocated with the iteration, frees the ref_iterator object, and
260 * returns ITER_DONE. If you want to abort the iteration early, call
261 * ref_iterator_abort(), which also frees the ref_iterator object and
262 * any associated resources. If there was an internal error advancing
263 * to the next entry, ref_iterator_advance() aborts the iteration,
264 * frees the ref_iterator, and returns ITER_ERROR.
265 *
266 * The reference currently being looked at can be peeled by calling
267 * ref_iterator_peel(). This function is often faster than peel_ref(),
268 * so it should be preferred when iterating over references.
269 *
270 * Putting it all together, a typical iteration looks like this:
271 *
272 * int ok;
273 * struct ref_iterator *iter = ...;
274 *
275 * while ((ok = ref_iterator_advance(iter)) == ITER_OK) {
276 * if (want_to_stop_iteration()) {
277 * ok = ref_iterator_abort(iter);
278 * break;
279 * }
280 *
281 * // Access information about the current reference:
282 * if (!(iter->flags & REF_ISSYMREF))
283 * printf("%s is %s\n", iter->refname, oid_to_hex(&iter->oid));
284 *
285 * // If you need to peel the reference:
286 * ref_iterator_peel(iter, &oid);
287 * }
288 *
289 * if (ok != ITER_DONE)
290 * handle_error();
291 */
292 struct ref_iterator {
293 struct ref_iterator_vtable *vtable;
294 const char *refname;
295 const struct object_id *oid;
296 unsigned int flags;
297 };
298
299 /*
300 * Advance the iterator to the first or next item and return ITER_OK.
301 * If the iteration is exhausted, free the resources associated with
302 * the ref_iterator and return ITER_DONE. On errors, free the iterator
303 * resources and return ITER_ERROR. It is a bug to use ref_iterator or
304 * call this function again after it has returned ITER_DONE or
305 * ITER_ERROR.
306 */
307 int ref_iterator_advance(struct ref_iterator *ref_iterator);
308
309 /*
310 * If possible, peel the reference currently being viewed by the
311 * iterator. Return 0 on success.
312 */
313 int ref_iterator_peel(struct ref_iterator *ref_iterator,
314 struct object_id *peeled);
315
316 /*
317 * End the iteration before it has been exhausted, freeing the
318 * reference iterator and any associated resources and returning
319 * ITER_DONE. If the abort itself failed, return ITER_ERROR.
320 */
321 int ref_iterator_abort(struct ref_iterator *ref_iterator);
322
323 /*
324 * An iterator over nothing (its first ref_iterator_advance() call
325 * returns ITER_DONE).
326 */
327 struct ref_iterator *empty_ref_iterator_begin(void);
328
329 /*
330 * Return true iff ref_iterator is an empty_ref_iterator.
331 */
332 int is_empty_ref_iterator(struct ref_iterator *ref_iterator);
333
334 /*
335 * A callback function used to instruct merge_ref_iterator how to
336 * interleave the entries from iter0 and iter1. The function should
337 * return one of the constants defined in enum iterator_selection. It
338 * must not advance either of the iterators itself.
339 *
340 * The function must be prepared to handle the case that iter0 and/or
341 * iter1 is NULL, which indicates that the corresponding sub-iterator
342 * has been exhausted. Its return value must be consistent with the
343 * current states of the iterators; e.g., it must not return
344 * ITER_SKIP_1 if iter1 has already been exhausted.
345 */
346 typedef enum iterator_selection ref_iterator_select_fn(
347 struct ref_iterator *iter0, struct ref_iterator *iter1,
348 void *cb_data);
349
350 /*
351 * Iterate over the entries from iter0 and iter1, with the values
352 * interleaved as directed by the select function. The iterator takes
353 * ownership of iter0 and iter1 and frees them when the iteration is
354 * over.
355 */
356 struct ref_iterator *merge_ref_iterator_begin(
357 struct ref_iterator *iter0, struct ref_iterator *iter1,
358 ref_iterator_select_fn *select, void *cb_data);
359
360 /*
361 * An iterator consisting of the union of the entries from front and
362 * back. If there are entries common to the two sub-iterators, use the
363 * one from front. Each iterator must iterate over its entries in
364 * strcmp() order by refname for this to work.
365 *
366 * The new iterator takes ownership of its arguments and frees them
367 * when the iteration is over. As a convenience to callers, if front
368 * or back is an empty_ref_iterator, then abort that one immediately
369 * and return the other iterator directly, without wrapping it.
370 */
371 struct ref_iterator *overlay_ref_iterator_begin(
372 struct ref_iterator *front, struct ref_iterator *back);
373
374 /*
375 * Wrap iter0, only letting through the references whose names start
376 * with prefix. If trim is set, set iter->refname to the name of the
377 * reference with that many characters trimmed off the front;
378 * otherwise set it to the full refname. The new iterator takes over
379 * ownership of iter0 and frees it when iteration is over. It makes
380 * its own copy of prefix.
381 *
382 * As an convenience to callers, if prefix is the empty string and
383 * trim is zero, this function returns iter0 directly, without
384 * wrapping it.
385 */
386 struct ref_iterator *prefix_ref_iterator_begin(struct ref_iterator *iter0,
387 const char *prefix,
388 int trim);
389
390 /* Internal implementation of reference iteration: */
391
392 /*
393 * Base class constructor for ref_iterators. Initialize the
394 * ref_iterator part of iter, setting its vtable pointer as specified.
395 * This is meant to be called only by the initializers of derived
396 * classes.
397 */
398 void base_ref_iterator_init(struct ref_iterator *iter,
399 struct ref_iterator_vtable *vtable);
400
401 /*
402 * Base class destructor for ref_iterators. Destroy the ref_iterator
403 * part of iter and shallow-free the object. This is meant to be
404 * called only by the destructors of derived classes.
405 */
406 void base_ref_iterator_free(struct ref_iterator *iter);
407
408 /* Virtual function declarations for ref_iterators: */
409
410 typedef int ref_iterator_advance_fn(struct ref_iterator *ref_iterator);
411
412 typedef int ref_iterator_peel_fn(struct ref_iterator *ref_iterator,
413 struct object_id *peeled);
414
415 /*
416 * Implementations of this function should free any resources specific
417 * to the derived class, then call base_ref_iterator_free() to clean
418 * up and free the ref_iterator object.
419 */
420 typedef int ref_iterator_abort_fn(struct ref_iterator *ref_iterator);
421
422 struct ref_iterator_vtable {
423 ref_iterator_advance_fn *advance;
424 ref_iterator_peel_fn *peel;
425 ref_iterator_abort_fn *abort;
426 };
427
428 /*
429 * current_ref_iter is a performance hack: when iterating over
430 * references using the for_each_ref*() functions, current_ref_iter is
431 * set to the reference iterator before calling the callback function.
432 * If the callback function calls peel_ref(), then peel_ref() first
433 * checks whether the reference to be peeled is the one referred to by
434 * the iterator (it usually is) and if so, asks the iterator for the
435 * peeled version of the reference if it is available. This avoids a
436 * refname lookup in a common case. current_ref_iter is set to NULL
437 * when the iteration is over.
438 */
439 extern struct ref_iterator *current_ref_iter;
440
441 /*
442 * The common backend for the for_each_*ref* functions. Call fn for
443 * each reference in iter. If the iterator itself ever returns
444 * ITER_ERROR, return -1. If fn ever returns a non-zero value, stop
445 * the iteration and return that value. Otherwise, return 0. In any
446 * case, free the iterator when done. This function is basically an
447 * adapter between the callback style of reference iteration and the
448 * iterator style.
449 */
450 int do_for_each_ref_iterator(struct ref_iterator *iter,
451 each_ref_fn fn, void *cb_data);
452
453 /*
454 * Only include per-worktree refs in a do_for_each_ref*() iteration.
455 * Normally this will be used with a files ref_store, since that's
456 * where all reference backends will presumably store their
457 * per-worktree refs.
458 */
459 #define DO_FOR_EACH_PER_WORKTREE_ONLY 0x02
460
461 struct ref_store;
462
463 /* refs backends */
464
465 /* ref_store_init flags */
466 #define REF_STORE_READ (1 << 0)
467 #define REF_STORE_WRITE (1 << 1) /* can perform update operations */
468 #define REF_STORE_ODB (1 << 2) /* has access to object database */
469 #define REF_STORE_MAIN (1 << 3)
470
471 /*
472 * Initialize the ref_store for the specified gitdir. These functions
473 * should call base_ref_store_init() to initialize the shared part of
474 * the ref_store and to record the ref_store for later lookup.
475 */
476 typedef struct ref_store *ref_store_init_fn(const char *gitdir,
477 unsigned int flags);
478
479 typedef int ref_init_db_fn(struct ref_store *refs, struct strbuf *err);
480
481 typedef int ref_transaction_commit_fn(struct ref_store *refs,
482 struct ref_transaction *transaction,
483 struct strbuf *err);
484
485 typedef int pack_refs_fn(struct ref_store *ref_store, unsigned int flags);
486 typedef int peel_ref_fn(struct ref_store *ref_store,
487 const char *refname, unsigned char *sha1);
488 typedef int create_symref_fn(struct ref_store *ref_store,
489 const char *ref_target,
490 const char *refs_heads_master,
491 const char *logmsg);
492 typedef int delete_refs_fn(struct ref_store *ref_store,
493 struct string_list *refnames, unsigned int flags);
494 typedef int rename_ref_fn(struct ref_store *ref_store,
495 const char *oldref, const char *newref,
496 const char *logmsg);
497
498 /*
499 * Iterate over the references in the specified ref_store that are
500 * within find_containing_dir(prefix). If prefix is NULL or the empty
501 * string, iterate over all references in the submodule.
502 */
503 typedef struct ref_iterator *ref_iterator_begin_fn(
504 struct ref_store *ref_store,
505 const char *prefix, unsigned int flags);
506
507 /* reflog functions */
508
509 /*
510 * Iterate over the references in the specified ref_store that have a
511 * reflog. The refs are iterated over in arbitrary order.
512 */
513 typedef struct ref_iterator *reflog_iterator_begin_fn(
514 struct ref_store *ref_store);
515
516 typedef int for_each_reflog_ent_fn(struct ref_store *ref_store,
517 const char *refname,
518 each_reflog_ent_fn fn,
519 void *cb_data);
520 typedef int for_each_reflog_ent_reverse_fn(struct ref_store *ref_store,
521 const char *refname,
522 each_reflog_ent_fn fn,
523 void *cb_data);
524 typedef int reflog_exists_fn(struct ref_store *ref_store, const char *refname);
525 typedef int create_reflog_fn(struct ref_store *ref_store, const char *refname,
526 int force_create, struct strbuf *err);
527 typedef int delete_reflog_fn(struct ref_store *ref_store, const char *refname);
528 typedef int reflog_expire_fn(struct ref_store *ref_store,
529 const char *refname, const unsigned char *sha1,
530 unsigned int flags,
531 reflog_expiry_prepare_fn prepare_fn,
532 reflog_expiry_should_prune_fn should_prune_fn,
533 reflog_expiry_cleanup_fn cleanup_fn,
534 void *policy_cb_data);
535
536 /*
537 * Read a reference from the specified reference store, non-recursively.
538 * Set type to describe the reference, and:
539 *
540 * - If refname is the name of a normal reference, fill in sha1
541 * (leaving referent unchanged).
542 *
543 * - If refname is the name of a symbolic reference, write the full
544 * name of the reference to which it refers (e.g.
545 * "refs/heads/master") to referent and set the REF_ISSYMREF bit in
546 * type (leaving sha1 unchanged). The caller is responsible for
547 * validating that referent is a valid reference name.
548 *
549 * WARNING: refname might be used as part of a filename, so it is
550 * important from a security standpoint that it be safe in the sense
551 * of refname_is_safe(). Moreover, for symrefs this function sets
552 * referent to whatever the repository says, which might not be a
553 * properly-formatted or even safe reference name. NEITHER INPUT NOR
554 * OUTPUT REFERENCE NAMES ARE VALIDATED WITHIN THIS FUNCTION.
555 *
556 * Return 0 on success. If the ref doesn't exist, set errno to ENOENT
557 * and return -1. If the ref exists but is neither a symbolic ref nor
558 * a sha1, it is broken; set REF_ISBROKEN in type, set errno to
559 * EINVAL, and return -1. If there is another error reading the ref,
560 * set errno appropriately and return -1.
561 *
562 * Backend-specific flags might be set in type as well, regardless of
563 * outcome.
564 *
565 * It is OK for refname to point into referent. If so:
566 *
567 * - if the function succeeds with REF_ISSYMREF, referent will be
568 * overwritten and the memory formerly pointed to by it might be
569 * changed or even freed.
570 *
571 * - in all other cases, referent will be untouched, and therefore
572 * refname will still be valid and unchanged.
573 */
574 typedef int read_raw_ref_fn(struct ref_store *ref_store,
575 const char *refname, unsigned char *sha1,
576 struct strbuf *referent, unsigned int *type);
577
578 typedef int verify_refname_available_fn(struct ref_store *ref_store,
579 const char *newname,
580 const struct string_list *extras,
581 const struct string_list *skip,
582 struct strbuf *err);
583
584 struct ref_storage_be {
585 struct ref_storage_be *next;
586 const char *name;
587 ref_store_init_fn *init;
588 ref_init_db_fn *init_db;
589 ref_transaction_commit_fn *transaction_commit;
590 ref_transaction_commit_fn *initial_transaction_commit;
591
592 pack_refs_fn *pack_refs;
593 peel_ref_fn *peel_ref;
594 create_symref_fn *create_symref;
595 delete_refs_fn *delete_refs;
596 rename_ref_fn *rename_ref;
597
598 ref_iterator_begin_fn *iterator_begin;
599 read_raw_ref_fn *read_raw_ref;
600 verify_refname_available_fn *verify_refname_available;
601
602 reflog_iterator_begin_fn *reflog_iterator_begin;
603 for_each_reflog_ent_fn *for_each_reflog_ent;
604 for_each_reflog_ent_reverse_fn *for_each_reflog_ent_reverse;
605 reflog_exists_fn *reflog_exists;
606 create_reflog_fn *create_reflog;
607 delete_reflog_fn *delete_reflog;
608 reflog_expire_fn *reflog_expire;
609 };
610
611 extern struct ref_storage_be refs_be_files;
612
613 /*
614 * A representation of the reference store for the main repository or
615 * a submodule. The ref_store instances for submodules are kept in a
616 * linked list.
617 */
618 struct ref_store {
619 /* The backend describing this ref_store's storage scheme: */
620 const struct ref_storage_be *be;
621 };
622
623 /*
624 * Fill in the generic part of refs and add it to our collection of
625 * reference stores.
626 */
627 void base_ref_store_init(struct ref_store *refs,
628 const struct ref_storage_be *be);
629
630 #endif /* REFS_REFS_INTERNAL_H */