Merge branch 'ah/log-decorate-default-to-auto'
[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 int refs_read_raw_ref(struct ref_store *ref_store,
169 const char *refname, unsigned char *sha1,
170 struct strbuf *referent, unsigned int *type);
171
172 /*
173 * Add a ref_update with the specified properties to transaction, and
174 * return a pointer to the new object. This function does not verify
175 * that refname is well-formed. new_sha1 and old_sha1 are only
176 * dereferenced if the REF_HAVE_NEW and REF_HAVE_OLD bits,
177 * respectively, are set in flags.
178 */
179 struct ref_update *ref_transaction_add_update(
180 struct ref_transaction *transaction,
181 const char *refname, unsigned int flags,
182 const unsigned char *new_sha1,
183 const unsigned char *old_sha1,
184 const char *msg);
185
186 /*
187 * Transaction states.
188 * OPEN: The transaction is in a valid state and can accept new updates.
189 * An OPEN transaction can be committed.
190 * CLOSED: A closed transaction is no longer active and no other operations
191 * than free can be used on it in this state.
192 * A transaction can either become closed by successfully committing
193 * an active transaction or if there is a failure while building
194 * the transaction thus rendering it failed/inactive.
195 */
196 enum ref_transaction_state {
197 REF_TRANSACTION_OPEN = 0,
198 REF_TRANSACTION_CLOSED = 1
199 };
200
201 /*
202 * Data structure for holding a reference transaction, which can
203 * consist of checks and updates to multiple references, carried out
204 * as atomically as possible. This structure is opaque to callers.
205 */
206 struct ref_transaction {
207 struct ref_store *ref_store;
208 struct ref_update **updates;
209 size_t alloc;
210 size_t nr;
211 enum ref_transaction_state state;
212 };
213
214 /*
215 * Check for entries in extras that are within the specified
216 * directory, where dirname is a reference directory name including
217 * the trailing slash (e.g., "refs/heads/foo/"). Ignore any
218 * conflicting references that are found in skip. If there is a
219 * conflicting reference, return its name.
220 *
221 * extras and skip must be sorted lists of reference names. Either one
222 * can be NULL, signifying the empty list.
223 */
224 const char *find_descendant_ref(const char *dirname,
225 const struct string_list *extras,
226 const struct string_list *skip);
227
228 /*
229 * Check whether an attempt to rename old_refname to new_refname would
230 * cause a D/F conflict with any existing reference (other than
231 * possibly old_refname). If there would be a conflict, emit an error
232 * message and return false; otherwise, return true.
233 *
234 * Note that this function is not safe against all races with other
235 * processes (though rename_ref() catches some races that might get by
236 * this check).
237 */
238 int refs_rename_ref_available(struct ref_store *refs,
239 const char *old_refname,
240 const char *new_refname);
241
242 /* We allow "recursive" symbolic refs. Only within reason, though */
243 #define SYMREF_MAXDEPTH 5
244
245 /* Include broken references in a do_for_each_ref*() iteration: */
246 #define DO_FOR_EACH_INCLUDE_BROKEN 0x01
247
248 /*
249 * Reference iterators
250 *
251 * A reference iterator encapsulates the state of an in-progress
252 * iteration over references. Create an instance of `struct
253 * ref_iterator` via one of the functions in this module.
254 *
255 * A freshly-created ref_iterator doesn't yet point at a reference. To
256 * advance the iterator, call ref_iterator_advance(). If successful,
257 * this sets the iterator's refname, oid, and flags fields to describe
258 * the next reference and returns ITER_OK. The data pointed at by
259 * refname and oid belong to the iterator; if you want to retain them
260 * after calling ref_iterator_advance() again or calling
261 * ref_iterator_abort(), you must make a copy. When the iteration has
262 * been exhausted, ref_iterator_advance() releases any resources
263 * assocated with the iteration, frees the ref_iterator object, and
264 * returns ITER_DONE. If you want to abort the iteration early, call
265 * ref_iterator_abort(), which also frees the ref_iterator object and
266 * any associated resources. If there was an internal error advancing
267 * to the next entry, ref_iterator_advance() aborts the iteration,
268 * frees the ref_iterator, and returns ITER_ERROR.
269 *
270 * The reference currently being looked at can be peeled by calling
271 * ref_iterator_peel(). This function is often faster than peel_ref(),
272 * so it should be preferred when iterating over references.
273 *
274 * Putting it all together, a typical iteration looks like this:
275 *
276 * int ok;
277 * struct ref_iterator *iter = ...;
278 *
279 * while ((ok = ref_iterator_advance(iter)) == ITER_OK) {
280 * if (want_to_stop_iteration()) {
281 * ok = ref_iterator_abort(iter);
282 * break;
283 * }
284 *
285 * // Access information about the current reference:
286 * if (!(iter->flags & REF_ISSYMREF))
287 * printf("%s is %s\n", iter->refname, oid_to_hex(&iter->oid));
288 *
289 * // If you need to peel the reference:
290 * ref_iterator_peel(iter, &oid);
291 * }
292 *
293 * if (ok != ITER_DONE)
294 * handle_error();
295 */
296 struct ref_iterator {
297 struct ref_iterator_vtable *vtable;
298 const char *refname;
299 const struct object_id *oid;
300 unsigned int flags;
301 };
302
303 /*
304 * Advance the iterator to the first or next item and return ITER_OK.
305 * If the iteration is exhausted, free the resources associated with
306 * the ref_iterator and return ITER_DONE. On errors, free the iterator
307 * resources and return ITER_ERROR. It is a bug to use ref_iterator or
308 * call this function again after it has returned ITER_DONE or
309 * ITER_ERROR.
310 */
311 int ref_iterator_advance(struct ref_iterator *ref_iterator);
312
313 /*
314 * If possible, peel the reference currently being viewed by the
315 * iterator. Return 0 on success.
316 */
317 int ref_iterator_peel(struct ref_iterator *ref_iterator,
318 struct object_id *peeled);
319
320 /*
321 * End the iteration before it has been exhausted, freeing the
322 * reference iterator and any associated resources and returning
323 * ITER_DONE. If the abort itself failed, return ITER_ERROR.
324 */
325 int ref_iterator_abort(struct ref_iterator *ref_iterator);
326
327 /*
328 * An iterator over nothing (its first ref_iterator_advance() call
329 * returns ITER_DONE).
330 */
331 struct ref_iterator *empty_ref_iterator_begin(void);
332
333 /*
334 * Return true iff ref_iterator is an empty_ref_iterator.
335 */
336 int is_empty_ref_iterator(struct ref_iterator *ref_iterator);
337
338 /*
339 * Return an iterator that goes over each reference in `refs` for
340 * which the refname begins with prefix. If trim is non-zero, then
341 * trim that many characters off the beginning of each refname. flags
342 * can be DO_FOR_EACH_INCLUDE_BROKEN to include broken references in
343 * the iteration.
344 */
345 struct ref_iterator *refs_ref_iterator_begin(
346 struct ref_store *refs,
347 const char *prefix, int trim, int flags);
348
349 /*
350 * A callback function used to instruct merge_ref_iterator how to
351 * interleave the entries from iter0 and iter1. The function should
352 * return one of the constants defined in enum iterator_selection. It
353 * must not advance either of the iterators itself.
354 *
355 * The function must be prepared to handle the case that iter0 and/or
356 * iter1 is NULL, which indicates that the corresponding sub-iterator
357 * has been exhausted. Its return value must be consistent with the
358 * current states of the iterators; e.g., it must not return
359 * ITER_SKIP_1 if iter1 has already been exhausted.
360 */
361 typedef enum iterator_selection ref_iterator_select_fn(
362 struct ref_iterator *iter0, struct ref_iterator *iter1,
363 void *cb_data);
364
365 /*
366 * Iterate over the entries from iter0 and iter1, with the values
367 * interleaved as directed by the select function. The iterator takes
368 * ownership of iter0 and iter1 and frees them when the iteration is
369 * over.
370 */
371 struct ref_iterator *merge_ref_iterator_begin(
372 struct ref_iterator *iter0, struct ref_iterator *iter1,
373 ref_iterator_select_fn *select, void *cb_data);
374
375 /*
376 * An iterator consisting of the union of the entries from front and
377 * back. If there are entries common to the two sub-iterators, use the
378 * one from front. Each iterator must iterate over its entries in
379 * strcmp() order by refname for this to work.
380 *
381 * The new iterator takes ownership of its arguments and frees them
382 * when the iteration is over. As a convenience to callers, if front
383 * or back is an empty_ref_iterator, then abort that one immediately
384 * and return the other iterator directly, without wrapping it.
385 */
386 struct ref_iterator *overlay_ref_iterator_begin(
387 struct ref_iterator *front, struct ref_iterator *back);
388
389 /*
390 * Wrap iter0, only letting through the references whose names start
391 * with prefix. If trim is set, set iter->refname to the name of the
392 * reference with that many characters trimmed off the front;
393 * otherwise set it to the full refname. The new iterator takes over
394 * ownership of iter0 and frees it when iteration is over. It makes
395 * its own copy of prefix.
396 *
397 * As an convenience to callers, if prefix is the empty string and
398 * trim is zero, this function returns iter0 directly, without
399 * wrapping it.
400 */
401 struct ref_iterator *prefix_ref_iterator_begin(struct ref_iterator *iter0,
402 const char *prefix,
403 int trim);
404
405 /* Internal implementation of reference iteration: */
406
407 /*
408 * Base class constructor for ref_iterators. Initialize the
409 * ref_iterator part of iter, setting its vtable pointer as specified.
410 * This is meant to be called only by the initializers of derived
411 * classes.
412 */
413 void base_ref_iterator_init(struct ref_iterator *iter,
414 struct ref_iterator_vtable *vtable);
415
416 /*
417 * Base class destructor for ref_iterators. Destroy the ref_iterator
418 * part of iter and shallow-free the object. This is meant to be
419 * called only by the destructors of derived classes.
420 */
421 void base_ref_iterator_free(struct ref_iterator *iter);
422
423 /* Virtual function declarations for ref_iterators: */
424
425 typedef int ref_iterator_advance_fn(struct ref_iterator *ref_iterator);
426
427 typedef int ref_iterator_peel_fn(struct ref_iterator *ref_iterator,
428 struct object_id *peeled);
429
430 /*
431 * Implementations of this function should free any resources specific
432 * to the derived class, then call base_ref_iterator_free() to clean
433 * up and free the ref_iterator object.
434 */
435 typedef int ref_iterator_abort_fn(struct ref_iterator *ref_iterator);
436
437 struct ref_iterator_vtable {
438 ref_iterator_advance_fn *advance;
439 ref_iterator_peel_fn *peel;
440 ref_iterator_abort_fn *abort;
441 };
442
443 /*
444 * current_ref_iter is a performance hack: when iterating over
445 * references using the for_each_ref*() functions, current_ref_iter is
446 * set to the reference iterator before calling the callback function.
447 * If the callback function calls peel_ref(), then peel_ref() first
448 * checks whether the reference to be peeled is the one referred to by
449 * the iterator (it usually is) and if so, asks the iterator for the
450 * peeled version of the reference if it is available. This avoids a
451 * refname lookup in a common case. current_ref_iter is set to NULL
452 * when the iteration is over.
453 */
454 extern struct ref_iterator *current_ref_iter;
455
456 /*
457 * The common backend for the for_each_*ref* functions. Call fn for
458 * each reference in iter. If the iterator itself ever returns
459 * ITER_ERROR, return -1. If fn ever returns a non-zero value, stop
460 * the iteration and return that value. Otherwise, return 0. In any
461 * case, free the iterator when done. This function is basically an
462 * adapter between the callback style of reference iteration and the
463 * iterator style.
464 */
465 int do_for_each_ref_iterator(struct ref_iterator *iter,
466 each_ref_fn fn, void *cb_data);
467
468 /*
469 * Only include per-worktree refs in a do_for_each_ref*() iteration.
470 * Normally this will be used with a files ref_store, since that's
471 * where all reference backends will presumably store their
472 * per-worktree refs.
473 */
474 #define DO_FOR_EACH_PER_WORKTREE_ONLY 0x02
475
476 struct ref_store;
477
478 /* refs backends */
479
480 /* ref_store_init flags */
481 #define REF_STORE_READ (1 << 0)
482 #define REF_STORE_WRITE (1 << 1) /* can perform update operations */
483 #define REF_STORE_ODB (1 << 2) /* has access to object database */
484 #define REF_STORE_MAIN (1 << 3)
485 #define REF_STORE_ALL_CAPS (REF_STORE_READ | \
486 REF_STORE_WRITE | \
487 REF_STORE_ODB | \
488 REF_STORE_MAIN)
489
490 /*
491 * Initialize the ref_store for the specified gitdir. These functions
492 * should call base_ref_store_init() to initialize the shared part of
493 * the ref_store and to record the ref_store for later lookup.
494 */
495 typedef struct ref_store *ref_store_init_fn(const char *gitdir,
496 unsigned int flags);
497
498 typedef int ref_init_db_fn(struct ref_store *refs, struct strbuf *err);
499
500 typedef int ref_transaction_commit_fn(struct ref_store *refs,
501 struct ref_transaction *transaction,
502 struct strbuf *err);
503
504 typedef int pack_refs_fn(struct ref_store *ref_store, unsigned int flags);
505 typedef int peel_ref_fn(struct ref_store *ref_store,
506 const char *refname, unsigned char *sha1);
507 typedef int create_symref_fn(struct ref_store *ref_store,
508 const char *ref_target,
509 const char *refs_heads_master,
510 const char *logmsg);
511 typedef int delete_refs_fn(struct ref_store *ref_store,
512 struct string_list *refnames, unsigned int flags);
513 typedef int rename_ref_fn(struct ref_store *ref_store,
514 const char *oldref, const char *newref,
515 const char *logmsg);
516
517 /*
518 * Iterate over the references in the specified ref_store that are
519 * within find_containing_dir(prefix). If prefix is NULL or the empty
520 * string, iterate over all references in the submodule.
521 */
522 typedef struct ref_iterator *ref_iterator_begin_fn(
523 struct ref_store *ref_store,
524 const char *prefix, unsigned int flags);
525
526 /* reflog functions */
527
528 /*
529 * Iterate over the references in the specified ref_store that have a
530 * reflog. The refs are iterated over in arbitrary order.
531 */
532 typedef struct ref_iterator *reflog_iterator_begin_fn(
533 struct ref_store *ref_store);
534
535 typedef int for_each_reflog_ent_fn(struct ref_store *ref_store,
536 const char *refname,
537 each_reflog_ent_fn fn,
538 void *cb_data);
539 typedef int for_each_reflog_ent_reverse_fn(struct ref_store *ref_store,
540 const char *refname,
541 each_reflog_ent_fn fn,
542 void *cb_data);
543 typedef int reflog_exists_fn(struct ref_store *ref_store, const char *refname);
544 typedef int create_reflog_fn(struct ref_store *ref_store, const char *refname,
545 int force_create, struct strbuf *err);
546 typedef int delete_reflog_fn(struct ref_store *ref_store, const char *refname);
547 typedef int reflog_expire_fn(struct ref_store *ref_store,
548 const char *refname, const unsigned char *sha1,
549 unsigned int flags,
550 reflog_expiry_prepare_fn prepare_fn,
551 reflog_expiry_should_prune_fn should_prune_fn,
552 reflog_expiry_cleanup_fn cleanup_fn,
553 void *policy_cb_data);
554
555 /*
556 * Read a reference from the specified reference store, non-recursively.
557 * Set type to describe the reference, and:
558 *
559 * - If refname is the name of a normal reference, fill in sha1
560 * (leaving referent unchanged).
561 *
562 * - If refname is the name of a symbolic reference, write the full
563 * name of the reference to which it refers (e.g.
564 * "refs/heads/master") to referent and set the REF_ISSYMREF bit in
565 * type (leaving sha1 unchanged). The caller is responsible for
566 * validating that referent is a valid reference name.
567 *
568 * WARNING: refname might be used as part of a filename, so it is
569 * important from a security standpoint that it be safe in the sense
570 * of refname_is_safe(). Moreover, for symrefs this function sets
571 * referent to whatever the repository says, which might not be a
572 * properly-formatted or even safe reference name. NEITHER INPUT NOR
573 * OUTPUT REFERENCE NAMES ARE VALIDATED WITHIN THIS FUNCTION.
574 *
575 * Return 0 on success. If the ref doesn't exist, set errno to ENOENT
576 * and return -1. If the ref exists but is neither a symbolic ref nor
577 * a sha1, it is broken; set REF_ISBROKEN in type, set errno to
578 * EINVAL, and return -1. If there is another error reading the ref,
579 * set errno appropriately and return -1.
580 *
581 * Backend-specific flags might be set in type as well, regardless of
582 * outcome.
583 *
584 * It is OK for refname to point into referent. If so:
585 *
586 * - if the function succeeds with REF_ISSYMREF, referent will be
587 * overwritten and the memory formerly pointed to by it might be
588 * changed or even freed.
589 *
590 * - in all other cases, referent will be untouched, and therefore
591 * refname will still be valid and unchanged.
592 */
593 typedef int read_raw_ref_fn(struct ref_store *ref_store,
594 const char *refname, unsigned char *sha1,
595 struct strbuf *referent, unsigned int *type);
596
597 struct ref_storage_be {
598 struct ref_storage_be *next;
599 const char *name;
600 ref_store_init_fn *init;
601 ref_init_db_fn *init_db;
602 ref_transaction_commit_fn *transaction_commit;
603 ref_transaction_commit_fn *initial_transaction_commit;
604
605 pack_refs_fn *pack_refs;
606 peel_ref_fn *peel_ref;
607 create_symref_fn *create_symref;
608 delete_refs_fn *delete_refs;
609 rename_ref_fn *rename_ref;
610
611 ref_iterator_begin_fn *iterator_begin;
612 read_raw_ref_fn *read_raw_ref;
613
614 reflog_iterator_begin_fn *reflog_iterator_begin;
615 for_each_reflog_ent_fn *for_each_reflog_ent;
616 for_each_reflog_ent_reverse_fn *for_each_reflog_ent_reverse;
617 reflog_exists_fn *reflog_exists;
618 create_reflog_fn *create_reflog;
619 delete_reflog_fn *delete_reflog;
620 reflog_expire_fn *reflog_expire;
621 };
622
623 extern struct ref_storage_be refs_be_files;
624
625 /*
626 * A representation of the reference store for the main repository or
627 * a submodule. The ref_store instances for submodules are kept in a
628 * linked list.
629 */
630 struct ref_store {
631 /* The backend describing this ref_store's storage scheme: */
632 const struct ref_storage_be *be;
633 };
634
635 /*
636 * Fill in the generic part of refs and add it to our collection of
637 * reference stores.
638 */
639 void base_ref_store_init(struct ref_store *refs,
640 const struct ref_storage_be *be);
641
642 #endif /* REFS_REFS_INTERNAL_H */