diff options
Diffstat (limited to 'refs/files-backend.c')
| -rw-r--r-- | refs/files-backend.c | 3201 |
1 files changed, 3201 insertions, 0 deletions
diff --git a/refs/files-backend.c b/refs/files-backend.c new file mode 100644 index 000000000000..d60767ab739f --- /dev/null +++ b/refs/files-backend.c @@ -0,0 +1,3201 @@ +#include "../cache.h" +#include "../config.h" +#include "../refs.h" +#include "refs-internal.h" +#include "ref-cache.h" +#include "packed-backend.h" +#include "../iterator.h" +#include "../dir-iterator.h" +#include "../lockfile.h" +#include "../object.h" +#include "../dir.h" +#include "../chdir-notify.h" +#include "worktree.h" + +/* + * This backend uses the following flags in `ref_update::flags` for + * internal bookkeeping purposes. Their numerical values must not + * conflict with REF_NO_DEREF, REF_FORCE_CREATE_REFLOG, REF_HAVE_NEW, + * REF_HAVE_OLD, or REF_IS_PRUNING, which are also stored in + * `ref_update::flags`. + */ + +/* + * Used as a flag in ref_update::flags when a loose ref is being + * pruned. This flag must only be used when REF_NO_DEREF is set. + */ +#define REF_IS_PRUNING (1 << 4) + +/* + * Flag passed to lock_ref_sha1_basic() telling it to tolerate broken + * refs (i.e., because the reference is about to be deleted anyway). + */ +#define REF_DELETING (1 << 5) + +/* + * Used as a flag in ref_update::flags when the lockfile needs to be + * committed. + */ +#define REF_NEEDS_COMMIT (1 << 6) + +/* + * Used as a flag in ref_update::flags when we want to log a ref + * update but not actually perform it. This is used when a symbolic + * ref update is split up. + */ +#define REF_LOG_ONLY (1 << 7) + +/* + * Used as a flag in ref_update::flags when the ref_update was via an + * update to HEAD. + */ +#define REF_UPDATE_VIA_HEAD (1 << 8) + +/* + * Used as a flag in ref_update::flags when the loose reference has + * been deleted. + */ +#define REF_DELETED_LOOSE (1 << 9) + +struct ref_lock { + char *ref_name; + struct lock_file lk; + struct object_id old_oid; +}; + +struct files_ref_store { + struct ref_store base; + unsigned int store_flags; + + char *gitdir; + char *gitcommondir; + + struct ref_cache *loose; + + struct ref_store *packed_ref_store; +}; + +static void clear_loose_ref_cache(struct files_ref_store *refs) +{ + if (refs->loose) { + free_ref_cache(refs->loose); + refs->loose = NULL; + } +} + +/* + * Create a new submodule ref cache and add it to the internal + * set of caches. + */ +static struct ref_store *files_ref_store_create(const char *gitdir, + unsigned int flags) +{ + struct files_ref_store *refs = xcalloc(1, sizeof(*refs)); + struct ref_store *ref_store = (struct ref_store *)refs; + struct strbuf sb = STRBUF_INIT; + + base_ref_store_init(ref_store, &refs_be_files); + refs->store_flags = flags; + + refs->gitdir = xstrdup(gitdir); + get_common_dir_noenv(&sb, gitdir); + refs->gitcommondir = strbuf_detach(&sb, NULL); + strbuf_addf(&sb, "%s/packed-refs", refs->gitcommondir); + refs->packed_ref_store = packed_ref_store_create(sb.buf, flags); + strbuf_release(&sb); + + chdir_notify_reparent("files-backend $GIT_DIR", + &refs->gitdir); + chdir_notify_reparent("files-backend $GIT_COMMONDIR", + &refs->gitcommondir); + + return ref_store; +} + +/* + * Die if refs is not the main ref store. caller is used in any + * necessary error messages. + */ +static void files_assert_main_repository(struct files_ref_store *refs, + const char *caller) +{ + if (refs->store_flags & REF_STORE_MAIN) + return; + + BUG("operation %s only allowed for main ref store", caller); +} + +/* + * Downcast ref_store to files_ref_store. Die if ref_store is not a + * files_ref_store. required_flags is compared with ref_store's + * store_flags to ensure the ref_store has all required capabilities. + * "caller" is used in any necessary error messages. + */ +static struct files_ref_store *files_downcast(struct ref_store *ref_store, + unsigned int required_flags, + const char *caller) +{ + struct files_ref_store *refs; + + if (ref_store->be != &refs_be_files) + BUG("ref_store is type \"%s\" not \"files\" in %s", + ref_store->be->name, caller); + + refs = (struct files_ref_store *)ref_store; + + if ((refs->store_flags & required_flags) != required_flags) + BUG("operation %s requires abilities 0x%x, but only have 0x%x", + caller, required_flags, refs->store_flags); + + return refs; +} + +static void files_reflog_path_other_worktrees(struct files_ref_store *refs, + struct strbuf *sb, + const char *refname) +{ + const char *real_ref; + const char *worktree_name; + int length; + + if (parse_worktree_ref(refname, &worktree_name, &length, &real_ref)) + BUG("refname %s is not a other-worktree ref", refname); + + if (worktree_name) + strbuf_addf(sb, "%s/worktrees/%.*s/logs/%s", refs->gitcommondir, + length, worktree_name, real_ref); + else + strbuf_addf(sb, "%s/logs/%s", refs->gitcommondir, + real_ref); +} + +static void files_reflog_path(struct files_ref_store *refs, + struct strbuf *sb, + const char *refname) +{ + switch (ref_type(refname)) { + case REF_TYPE_PER_WORKTREE: + case REF_TYPE_PSEUDOREF: + strbuf_addf(sb, "%s/logs/%s", refs->gitdir, refname); + break; + case REF_TYPE_OTHER_PSEUDOREF: + case REF_TYPE_MAIN_PSEUDOREF: + files_reflog_path_other_worktrees(refs, sb, refname); + break; + case REF_TYPE_NORMAL: + strbuf_addf(sb, "%s/logs/%s", refs->gitcommondir, refname); + break; + default: + BUG("unknown ref type %d of ref %s", + ref_type(refname), refname); + } +} + +static void files_ref_path(struct files_ref_store *refs, + struct strbuf *sb, + const char *refname) +{ + switch (ref_type(refname)) { + case REF_TYPE_PER_WORKTREE: + case REF_TYPE_PSEUDOREF: + strbuf_addf(sb, "%s/%s", refs->gitdir, refname); + break; + case REF_TYPE_MAIN_PSEUDOREF: + if (!skip_prefix(refname, "main-worktree/", &refname)) + BUG("ref %s is not a main pseudoref", refname); + /* fallthrough */ + case REF_TYPE_OTHER_PSEUDOREF: + case REF_TYPE_NORMAL: + strbuf_addf(sb, "%s/%s", refs->gitcommondir, refname); + break; + default: + BUG("unknown ref type %d of ref %s", + ref_type(refname), refname); + } +} + +/* + * Manually add refs/bisect, refs/rewritten and refs/worktree, which, being + * per-worktree, might not appear in the directory listing for + * refs/ in the main repo. + */ +static void add_per_worktree_entries_to_dir(struct ref_dir *dir, const char *dirname) +{ + const char *prefixes[] = { "refs/bisect/", "refs/worktree/", "refs/rewritten/" }; + int ip; + + if (strcmp(dirname, "refs/")) + return; + + for (ip = 0; ip < ARRAY_SIZE(prefixes); ip++) { + const char *prefix = prefixes[ip]; + int prefix_len = strlen(prefix); + struct ref_entry *child_entry; + int pos; + + pos = search_ref_dir(dir, prefix, prefix_len); + if (pos >= 0) + continue; + child_entry = create_dir_entry(dir->cache, prefix, prefix_len, 1); + add_entry_to_dir(dir, child_entry); + } +} + +/* + * Read the loose references from the namespace dirname into dir + * (without recursing). dirname must end with '/'. dir must be the + * directory entry corresponding to dirname. + */ +static void loose_fill_ref_dir(struct ref_store *ref_store, + struct ref_dir *dir, const char *dirname) +{ + struct files_ref_store *refs = + files_downcast(ref_store, REF_STORE_READ, "fill_ref_dir"); + DIR *d; + struct dirent *de; + int dirnamelen = strlen(dirname); + struct strbuf refname; + struct strbuf path = STRBUF_INIT; + size_t path_baselen; + + files_ref_path(refs, &path, dirname); + path_baselen = path.len; + + d = opendir(path.buf); + if (!d) { + strbuf_release(&path); + return; + } + + strbuf_init(&refname, dirnamelen + 257); + strbuf_add(&refname, dirname, dirnamelen); + + while ((de = readdir(d)) != NULL) { + struct object_id oid; + struct stat st; + int flag; + + if (de->d_name[0] == '.') + continue; + if (ends_with(de->d_name, ".lock")) + continue; + strbuf_addstr(&refname, de->d_name); + strbuf_addstr(&path, de->d_name); + if (stat(path.buf, &st) < 0) { + ; /* silently ignore */ + } else if (S_ISDIR(st.st_mode)) { + strbuf_addch(&refname, '/'); + add_entry_to_dir(dir, + create_dir_entry(dir->cache, refname.buf, + refname.len, 1)); + } else { + if (!refs_resolve_ref_unsafe(&refs->base, + refname.buf, + RESOLVE_REF_READING, + &oid, &flag)) { + oidclr(&oid); + flag |= REF_ISBROKEN; + } else if (is_null_oid(&oid)) { + /* + * It is so astronomically unlikely + * that null_oid is the OID of an + * actual object that we consider its + * appearance in a loose reference + * file to be repo corruption + * (probably due to a software bug). + */ + flag |= REF_ISBROKEN; + } + + if (check_refname_format(refname.buf, + REFNAME_ALLOW_ONELEVEL)) { + if (!refname_is_safe(refname.buf)) + die("loose refname is dangerous: %s", refname.buf); + oidclr(&oid); + flag |= REF_BAD_NAME | REF_ISBROKEN; + } + add_entry_to_dir(dir, + create_ref_entry(refname.buf, &oid, flag)); + } + strbuf_setlen(&refname, dirnamelen); + strbuf_setlen(&path, path_baselen); + } + strbuf_release(&refname); + strbuf_release(&path); + closedir(d); + + add_per_worktree_entries_to_dir(dir, dirname); +} + +static struct ref_cache *get_loose_ref_cache(struct files_ref_store *refs) +{ + if (!refs->loose) { + /* + * Mark the top-level directory complete because we + * are about to read the only subdirectory that can + * hold references: + */ + refs->loose = create_ref_cache(&refs->base, loose_fill_ref_dir); + + /* We're going to fill the top level ourselves: */ + refs->loose->root->flag &= ~REF_INCOMPLETE; + + /* + * Add an incomplete entry for "refs/" (to be filled + * lazily): + */ + add_entry_to_dir(get_ref_dir(refs->loose->root), + create_dir_entry(refs->loose, "refs/", 5, 1)); + } + return refs->loose; +} + +static int files_read_raw_ref(struct ref_store *ref_store, + const char *refname, struct object_id *oid, + struct strbuf *referent, unsigned int *type) +{ + struct files_ref_store *refs = + files_downcast(ref_store, REF_STORE_READ, "read_raw_ref"); + struct strbuf sb_contents = STRBUF_INIT; + struct strbuf sb_path = STRBUF_INIT; + const char *path; + const char *buf; + const char *p; + struct stat st; + int fd; + int ret = -1; + int save_errno; + int remaining_retries = 3; + + *type = 0; + strbuf_reset(&sb_path); + + files_ref_path(refs, &sb_path, refname); + + path = sb_path.buf; + +stat_ref: + /* + * We might have to loop back here to avoid a race + * condition: first we lstat() the file, then we try + * to read it as a link or as a file. But if somebody + * changes the type of the file (file <-> directory + * <-> symlink) between the lstat() and reading, then + * we don't want to report that as an error but rather + * try again starting with the lstat(). + * + * We'll keep a count of the retries, though, just to avoid + * any confusing situation sending us into an infinite loop. + */ + + if (remaining_retries-- <= 0) + goto out; + + if (lstat(path, &st) < 0) { + if (errno != ENOENT) + goto out; + if (refs_read_raw_ref(refs->packed_ref_store, refname, + oid, referent, type)) { + errno = ENOENT; + goto out; + } + ret = 0; + goto out; + } + + /* Follow "normalized" - ie "refs/.." symlinks by hand */ + if (S_ISLNK(st.st_mode)) { + strbuf_reset(&sb_contents); + if (strbuf_readlink(&sb_contents, path, st.st_size) < 0) { + if (errno == ENOENT || errno == EINVAL) + /* inconsistent with lstat; retry */ + goto stat_ref; + else + goto out; + } + if (starts_with(sb_contents.buf, "refs/") && + !check_refname_format(sb_contents.buf, 0)) { + strbuf_swap(&sb_contents, referent); + *type |= REF_ISSYMREF; + ret = 0; + goto out; + } + /* + * It doesn't look like a refname; fall through to just + * treating it like a non-symlink, and reading whatever it + * points to. + */ + } + + /* Is it a directory? */ + if (S_ISDIR(st.st_mode)) { + /* + * Even though there is a directory where the loose + * ref is supposed to be, there could still be a + * packed ref: + */ + if (refs_read_raw_ref(refs->packed_ref_store, refname, + oid, referent, type)) { + errno = EISDIR; + goto out; + } + ret = 0; + goto out; + } + + /* + * Anything else, just open it and try to use it as + * a ref + */ + fd = open(path, O_RDONLY); + if (fd < 0) { + if (errno == ENOENT && !S_ISLNK(st.st_mode)) + /* inconsistent with lstat; retry */ + goto stat_ref; + else + goto out; + } + strbuf_reset(&sb_contents); + if (strbuf_read(&sb_contents, fd, 256) < 0) { + int save_errno = errno; + close(fd); + errno = save_errno; + goto out; + } + close(fd); + strbuf_rtrim(&sb_contents); + buf = sb_contents.buf; + if (starts_with(buf, "ref:")) { + buf += 4; + while (isspace(*buf)) + buf++; + + strbuf_reset(referent); + strbuf_addstr(referent, buf); + *type |= REF_ISSYMREF; + ret = 0; + goto out; + } + + /* + * Please note that FETCH_HEAD has additional + * data after the sha. + */ + if (parse_oid_hex(buf, oid, &p) || + (*p != '\0' && !isspace(*p))) { + *type |= REF_ISBROKEN; + errno = EINVAL; + goto out; + } + + ret = 0; + +out: + save_errno = errno; + strbuf_release(&sb_path); + strbuf_release(&sb_contents); + errno = save_errno; + return ret; +} + +static void unlock_ref(struct ref_lock *lock) +{ + rollback_lock_file(&lock->lk); + free(lock->ref_name); + free(lock); +} + +/* + * Lock refname, without following symrefs, and set *lock_p to point + * at a newly-allocated lock object. Fill in lock->old_oid, referent, + * and type similarly to read_raw_ref(). + * + * The caller must verify that refname is a "safe" reference name (in + * the sense of refname_is_safe()) before calling this function. + * + * If the reference doesn't already exist, verify that refname doesn't + * have a D/F conflict with any existing references. extras and skip + * are passed to refs_verify_refname_available() for this check. + * + * If mustexist is not set and the reference is not found or is + * broken, lock the reference anyway but clear old_oid. + * + * Return 0 on success. On failure, write an error message to err and + * return TRANSACTION_NAME_CONFLICT or TRANSACTION_GENERIC_ERROR. + * + * Implementation note: This function is basically + * + * lock reference + * read_raw_ref() + * + * but it includes a lot more code to + * - Deal with possible races with other processes + * - Avoid calling refs_verify_refname_available() when it can be + * avoided, namely if we were successfully able to read the ref + * - Generate informative error messages in the case of failure + */ +static int lock_raw_ref(struct files_ref_store *refs, + const char *refname, int mustexist, + const struct string_list *extras, + const struct string_list *skip, + struct ref_lock **lock_p, + struct strbuf *referent, + unsigned int *type, + struct strbuf *err) +{ + struct ref_lock *lock; + struct strbuf ref_file = STRBUF_INIT; + int attempts_remaining = 3; + int ret = TRANSACTION_GENERIC_ERROR; + + assert(err); + files_assert_main_repository(refs, "lock_raw_ref"); + + *type = 0; + + /* First lock the file so it can't change out from under us. */ + + *lock_p = lock = xcalloc(1, sizeof(*lock)); + + lock->ref_name = xstrdup(refname); + files_ref_path(refs, &ref_file, refname); + +retry: + switch (safe_create_leading_directories(ref_file.buf)) { + case SCLD_OK: + break; /* success */ + case SCLD_EXISTS: + /* + * Suppose refname is "refs/foo/bar". We just failed + * to create the containing directory, "refs/foo", + * because there was a non-directory in the way. This + * indicates a D/F conflict, probably because of + * another reference such as "refs/foo". There is no + * reason to expect this error to be transitory. + */ + if (refs_verify_refname_available(&refs->base, refname, + extras, skip, err)) { + if (mustexist) { + /* + * To the user the relevant error is + * that the "mustexist" reference is + * missing: + */ + strbuf_reset(err); + strbuf_addf(err, "unable to resolve reference '%s'", + refname); + } else { + /* + * The error message set by + * refs_verify_refname_available() is + * OK. + */ + ret = TRANSACTION_NAME_CONFLICT; + } + } else { + /* + * The file that is in the way isn't a loose + * reference. Report it as a low-level + * failure. + */ + strbuf_addf(err, "unable to create lock file %s.lock; " + "non-directory in the way", + ref_file.buf); + } + goto error_return; + case SCLD_VANISHED: + /* Maybe another process was tidying up. Try again. */ + if (--attempts_remaining > 0) + goto retry; + /* fall through */ + default: + strbuf_addf(err, "unable to create directory for %s", + ref_file.buf); + goto error_return; + } + + if (hold_lock_file_for_update_timeout( + &lock->lk, ref_file.buf, LOCK_NO_DEREF, + get_files_ref_lock_timeout_ms()) < 0) { + if (errno == ENOENT && --attempts_remaining > 0) { + /* + * Maybe somebody just deleted one of the + * directories leading to ref_file. Try + * again: + */ + goto retry; + } else { + unable_to_lock_message(ref_file.buf, errno, err); + goto error_return; + } + } + + /* + * Now we hold the lock and can read the reference without + * fear that its value will change. + */ + + if (files_read_raw_ref(&refs->base, refname, + &lock->old_oid, referent, type)) { + if (errno == ENOENT) { + if (mustexist) { + /* Garden variety missing reference. */ + strbuf_addf(err, "unable to resolve reference '%s'", + refname); + goto error_return; + } else { + /* + * Reference is missing, but that's OK. We + * know that there is not a conflict with + * another loose reference because + * (supposing that we are trying to lock + * reference "refs/foo/bar"): + * + * - We were successfully able to create + * the lockfile refs/foo/bar.lock, so we + * know there cannot be a loose reference + * named "refs/foo". + * + * - We got ENOENT and not EISDIR, so we + * know that there cannot be a loose + * reference named "refs/foo/bar/baz". + */ + } + } else if (errno == EISDIR) { + /* + * There is a directory in the way. It might have + * contained references that have been deleted. If + * we don't require that the reference already + * exists, try to remove the directory so that it + * doesn't cause trouble when we want to rename the + * lockfile into place later. + */ + if (mustexist) { + /* Garden variety missing reference. */ + strbuf_addf(err, "unable to resolve reference '%s'", + refname); + goto error_return; + } else if (remove_dir_recursively(&ref_file, + REMOVE_DIR_EMPTY_ONLY)) { + if (refs_verify_refname_available( + &refs->base, refname, + extras, skip, err)) { + /* + * The error message set by + * verify_refname_available() is OK. + */ + ret = TRANSACTION_NAME_CONFLICT; + goto error_return; + } else { + /* + * We can't delete the directory, + * but we also don't know of any + * references that it should + * contain. + */ + strbuf_addf(err, "there is a non-empty directory '%s' " + "blocking reference '%s'", + ref_file.buf, refname); + goto error_return; + } + } + } else if (errno == EINVAL && (*type & REF_ISBROKEN)) { + strbuf_addf(err, "unable to resolve reference '%s': " + "reference broken", refname); + goto error_return; + } else { + strbuf_addf(err, "unable to resolve reference '%s': %s", + refname, strerror(errno)); + goto error_return; + } + + /* + * If the ref did not exist and we are creating it, + * make sure there is no existing packed ref that + * conflicts with refname: + */ + if (refs_verify_refname_available( + refs->packed_ref_store, refname, + extras, skip, err)) + goto error_return; + } + + ret = 0; + goto out; + +error_return: + unlock_ref(lock); + *lock_p = NULL; + +out: + strbuf_release(&ref_file); + return ret; +} + +struct files_ref_iterator { + struct ref_iterator base; + + struct ref_iterator *iter0; + unsigned int flags; +}; + +static int files_ref_iterator_advance(struct ref_iterator *ref_iterator) +{ + struct files_ref_iterator *iter = + (struct files_ref_iterator *)ref_iterator; + int ok; + + while ((ok = ref_iterator_advance(iter->iter0)) == ITER_OK) { + if (iter->flags & DO_FOR_EACH_PER_WORKTREE_ONLY && + ref_type(iter->iter0->refname) != REF_TYPE_PER_WORKTREE) + continue; + + if (!(iter->flags & DO_FOR_EACH_INCLUDE_BROKEN) && + !ref_resolves_to_object(iter->iter0->refname, + iter->iter0->oid, + iter->iter0->flags)) + continue; + + iter->base.refname = iter->iter0->refname; + iter->base.oid = iter->iter0->oid; + iter->base.flags = iter->iter0->flags; + return ITER_OK; + } + + iter->iter0 = NULL; + if (ref_iterator_abort(ref_iterator) != ITER_DONE) + ok = ITER_ERROR; + + return ok; +} + +static int files_ref_iterator_peel(struct ref_iterator *ref_iterator, + struct object_id *peeled) +{ + struct files_ref_iterator *iter = + (struct files_ref_iterator *)ref_iterator; + + return ref_iterator_peel(iter->iter0, peeled); +} + +static int files_ref_iterator_abort(struct ref_iterator *ref_iterator) +{ + struct files_ref_iterator *iter = + (struct files_ref_iterator *)ref_iterator; + int ok = ITER_DONE; + + if (iter->iter0) + ok = ref_iterator_abort(iter->iter0); + + base_ref_iterator_free(ref_iterator); + return ok; +} + +static struct ref_iterator_vtable files_ref_iterator_vtable = { + files_ref_iterator_advance, + files_ref_iterator_peel, + files_ref_iterator_abort +}; + +static struct ref_iterator *files_ref_iterator_begin( + struct ref_store *ref_store, + const char *prefix, unsigned int flags) +{ + struct files_ref_store *refs; + struct ref_iterator *loose_iter, *packed_iter, *overlay_iter; + struct files_ref_iterator *iter; + struct ref_iterator *ref_iterator; + unsigned int required_flags = REF_STORE_READ; + + if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN)) + required_flags |= REF_STORE_ODB; + + refs = files_downcast(ref_store, required_flags, "ref_iterator_begin"); + + /* + * We must make sure that all loose refs are read before + * accessing the packed-refs file; this avoids a race + * condition if loose refs are migrated to the packed-refs + * file by a simultaneous process, but our in-memory view is + * from before the migration. We ensure this as follows: + * First, we call start the loose refs iteration with its + * `prime_ref` argument set to true. This causes the loose + * references in the subtree to be pre-read into the cache. + * (If they've already been read, that's OK; we only need to + * guarantee that they're read before the packed refs, not + * *how much* before.) After that, we call + * packed_ref_iterator_begin(), which internally checks + * whether the packed-ref cache is up to date with what is on + * disk, and re-reads it if not. + */ + + loose_iter = cache_ref_iterator_begin(get_loose_ref_cache(refs), + prefix, 1); + + /* + * The packed-refs file might contain broken references, for + * example an old version of a reference that points at an + * object that has since been garbage-collected. This is OK as + * long as there is a corresponding loose reference that + * overrides it, and we don't want to emit an error message in + * this case. So ask the packed_ref_store for all of its + * references, and (if needed) do our own check for broken + * ones in files_ref_iterator_advance(), after we have merged + * the packed and loose references. + */ + packed_iter = refs_ref_iterator_begin( + refs->packed_ref_store, prefix, 0, + DO_FOR_EACH_INCLUDE_BROKEN); + + overlay_iter = overlay_ref_iterator_begin(loose_iter, packed_iter); + + iter = xcalloc(1, sizeof(*iter)); + ref_iterator = &iter->base; + base_ref_iterator_init(ref_iterator, &files_ref_iterator_vtable, + overlay_iter->ordered); + iter->iter0 = overlay_iter; + iter->flags = flags; + + return ref_iterator; +} + +/* + * Verify that the reference locked by lock has the value old_oid + * (unless it is NULL). Fail if the reference doesn't exist and + * mustexist is set. Return 0 on success. On error, write an error + * message to err, set errno, and return a negative value. + */ +static int verify_lock(struct ref_store *ref_store, struct ref_lock *lock, + const struct object_id *old_oid, int mustexist, + struct strbuf *err) +{ + assert(err); + + if (refs_read_ref_full(ref_store, lock->ref_name, + mustexist ? RESOLVE_REF_READING : 0, + &lock->old_oid, NULL)) { + if (old_oid) { + int save_errno = errno; + strbuf_addf(err, "can't verify ref '%s'", lock->ref_name); + errno = save_errno; + return -1; + } else { + oidclr(&lock->old_oid); + return 0; + } + } + if (old_oid && !oideq(&lock->old_oid, old_oid)) { + strbuf_addf(err, "ref '%s' is at %s but expected %s", + lock->ref_name, + oid_to_hex(&lock->old_oid), + oid_to_hex(old_oid)); + errno = EBUSY; + return -1; + } + return 0; +} + +static int remove_empty_directories(struct strbuf *path) +{ + /* + * we want to create a file but there is a directory there; + * if that is an empty directory (or a directory that contains + * only empty directories), remove them. + */ + return remove_dir_recursively(path, REMOVE_DIR_EMPTY_ONLY); +} + +static int create_reflock(const char *path, void *cb) +{ + struct lock_file *lk = cb; + + return hold_lock_file_for_update_timeout( + lk, path, LOCK_NO_DEREF, + get_files_ref_lock_timeout_ms()) < 0 ? -1 : 0; +} + +/* + * Locks a ref returning the lock on success and NULL on failure. + * On failure errno is set to something meaningful. + */ +static struct ref_lock *lock_ref_oid_basic(struct files_ref_store *refs, + const char *refname, + const struct object_id *old_oid, + const struct string_list *extras, + const struct string_list *skip, + unsigned int flags, int *type, + struct strbuf *err) +{ + struct strbuf ref_file = STRBUF_INIT; + struct ref_lock *lock; + int last_errno = 0; + int mustexist = (old_oid && !is_null_oid(old_oid)); + int resolve_flags = RESOLVE_REF_NO_RECURSE; + int resolved; + + files_assert_main_repository(refs, "lock_ref_oid_basic"); + assert(err); + + lock = xcalloc(1, sizeof(struct ref_lock)); + + if (mustexist) + resolve_flags |= RESOLVE_REF_READING; + if (flags & REF_DELETING) + resolve_flags |= RESOLVE_REF_ALLOW_BAD_NAME; + + files_ref_path(refs, &ref_file, refname); + resolved = !!refs_resolve_ref_unsafe(&refs->base, + refname, resolve_flags, + &lock->old_oid, type); + if (!resolved && errno == EISDIR) { + /* + * we are trying to lock foo but we used to + * have foo/bar which now does not exist; + * it is normal for the empty directory 'foo' + * to remain. + */ + if (remove_empty_directories(&ref_file)) { + last_errno = errno; + if (!refs_verify_refname_available( + &refs->base, + refname, extras, skip, err)) + strbuf_addf(err, "there are still refs under '%s'", + refname); + goto error_return; + } + resolved = !!refs_resolve_ref_unsafe(&refs->base, + refname, resolve_flags, + &lock->old_oid, type); + } + if (!resolved) { + last_errno = errno; + if (last_errno != ENOTDIR || + !refs_verify_refname_available(&refs->base, refname, + extras, skip, err)) + strbuf_addf(err, "unable to resolve reference '%s': %s", + refname, strerror(last_errno)); + + goto error_return; + } + + /* + * If the ref did not exist and we are creating it, make sure + * there is no existing packed ref whose name begins with our + * refname, nor a packed ref whose name is a proper prefix of + * our refname. + */ + if (is_null_oid(&lock->old_oid) && + refs_verify_refname_available(refs->packed_ref_store, refname, + extras, skip, err)) { + last_errno = ENOTDIR; + goto error_return; + } + + lock->ref_name = xstrdup(refname); + + if (raceproof_create_file(ref_file.buf, create_reflock, &lock->lk)) { + last_errno = errno; + unable_to_lock_message(ref_file.buf, errno, err); + goto error_return; + } + + if (verify_lock(&refs->base, lock, old_oid, mustexist, err)) { + last_errno = errno; + goto error_return; + } + goto out; + + error_return: + unlock_ref(lock); + lock = NULL; + + out: + strbuf_release(&ref_file); + errno = last_errno; + return lock; +} + +struct ref_to_prune { + struct ref_to_prune *next; + struct object_id oid; + char name[FLEX_ARRAY]; +}; + +enum { + REMOVE_EMPTY_PARENTS_REF = 0x01, + REMOVE_EMPTY_PARENTS_REFLOG = 0x02 +}; + +/* + * Remove empty parent directories associated with the specified + * reference and/or its reflog, but spare [logs/]refs/ and immediate + * subdirs. flags is a combination of REMOVE_EMPTY_PARENTS_REF and/or + * REMOVE_EMPTY_PARENTS_REFLOG. + */ +static void try_remove_empty_parents(struct files_ref_store *refs, + const char *refname, + unsigned int flags) +{ + struct strbuf buf = STRBUF_INIT; + struct strbuf sb = STRBUF_INIT; + char *p, *q; + int i; + + strbuf_addstr(&buf, refname); + p = buf.buf; + for (i = 0; i < 2; i++) { /* refs/{heads,tags,...}/ */ + while (*p && *p != '/') + p++; + /* tolerate duplicate slashes; see check_refname_format() */ + while (*p == '/') + p++; + } + q = buf.buf + buf.len; + while (flags & (REMOVE_EMPTY_PARENTS_REF | REMOVE_EMPTY_PARENTS_REFLOG)) { + while (q > p && *q != '/') + q--; + while (q > p && *(q-1) == '/') + q--; + if (q == p) + break; + strbuf_setlen(&buf, q - buf.buf); + + strbuf_reset(&sb); + files_ref_path(refs, &sb, buf.buf); + if ((flags & REMOVE_EMPTY_PARENTS_REF) && rmdir(sb.buf)) + flags &= ~REMOVE_EMPTY_PARENTS_REF; + + strbuf_reset(&sb); + files_reflog_path(refs, &sb, buf.buf); + if ((flags & REMOVE_EMPTY_PARENTS_REFLOG) && rmdir(sb.buf)) + flags &= ~REMOVE_EMPTY_PARENTS_REFLOG; + } + strbuf_release(&buf); + strbuf_release(&sb); +} + +/* make sure nobody touched the ref, and unlink */ +static void prune_ref(struct files_ref_store *refs, struct ref_to_prune *r) +{ + struct ref_transaction *transaction; + struct strbuf err = STRBUF_INIT; + int ret = -1; + + if (check_refname_format(r->name, 0)) + return; + + transaction = ref_store_transaction_begin(&refs->base, &err); + if (!transaction) + goto cleanup; + ref_transaction_add_update( + transaction, r->name, + REF_NO_DEREF | REF_HAVE_NEW | REF_HAVE_OLD | REF_IS_PRUNING, + &null_oid, &r->oid, NULL); + if (ref_transaction_commit(transaction, &err)) + goto cleanup; + + ret = 0; + +cleanup: + if (ret) + error("%s", err.buf); + strbuf_release(&err); + ref_transaction_free(transaction); + return; +} + +/* + * Prune the loose versions of the references in the linked list + * `*refs_to_prune`, freeing the entries in the list as we go. + */ +static void prune_refs(struct files_ref_store *refs, struct ref_to_prune **refs_to_prune) +{ + while (*refs_to_prune) { + struct ref_to_prune *r = *refs_to_prune; + *refs_to_prune = r->next; + prune_ref(refs, r); + free(r); + } +} + +/* + * Return true if the specified reference should be packed. + */ +static int should_pack_ref(const char *refname, + const struct object_id *oid, unsigned int ref_flags, + unsigned int pack_flags) +{ + /* Do not pack per-worktree refs: */ + if (ref_type(refname) != REF_TYPE_NORMAL) + return 0; + + /* Do not pack non-tags unless PACK_REFS_ALL is set: */ + if (!(pack_flags & PACK_REFS_ALL) && !starts_with(refname, "refs/tags/")) + return 0; + + /* Do not pack symbolic refs: */ + if (ref_flags & REF_ISSYMREF) + return 0; + + /* Do not pack broken refs: */ + if (!ref_resolves_to_object(refname, oid, ref_flags)) + return 0; + + return 1; +} + +static int files_pack_refs(struct ref_store *ref_store, unsigned int flags) +{ + struct files_ref_store *refs = + files_downcast(ref_store, REF_STORE_WRITE | REF_STORE_ODB, + "pack_refs"); + struct ref_iterator *iter; + int ok; + struct ref_to_prune *refs_to_prune = NULL; + struct strbuf err = STRBUF_INIT; + struct ref_transaction *transaction; + + transaction = ref_store_transaction_begin(refs->packed_ref_store, &err); + if (!transaction) + return -1; + + packed_refs_lock(refs->packed_ref_store, LOCK_DIE_ON_ERROR, &err); + + iter = cache_ref_iterator_begin(get_loose_ref_cache(refs), NULL, 0); + while ((ok = ref_iterator_advance(iter)) == ITER_OK) { + /* + * If the loose reference can be packed, add an entry + * in the packed ref cache. If the reference should be + * pruned, also add it to refs_to_prune. + */ + if (!should_pack_ref(iter->refname, iter->oid, iter->flags, + flags)) + continue; + + /* + * Add a reference creation for this reference to the + * packed-refs transaction: + */ + if (ref_transaction_update(transaction, iter->refname, + iter->oid, NULL, + REF_NO_DEREF, NULL, &err)) + die("failure preparing to create packed reference %s: %s", + iter->refname, err.buf); + + /* Schedule the loose reference for pruning if requested. */ + if ((flags & PACK_REFS_PRUNE)) { + struct ref_to_prune *n; + FLEX_ALLOC_STR(n, name, iter->refname); + oidcpy(&n->oid, iter->oid); + n->next = refs_to_prune; + refs_to_prune = n; + } + } + if (ok != ITER_DONE) + die("error while iterating over references"); + + if (ref_transaction_commit(transaction, &err)) + die("unable to write new packed-refs: %s", err.buf); + + ref_transaction_free(transaction); + + packed_refs_unlock(refs->packed_ref_store); + + prune_refs(refs, &refs_to_prune); + strbuf_release(&err); + return 0; +} + +static int files_delete_refs(struct ref_store *ref_store, const char *msg, + struct string_list *refnames, unsigned int flags) +{ + struct files_ref_store *refs = + files_downcast(ref_store, REF_STORE_WRITE, "delete_refs"); + struct strbuf err = STRBUF_INIT; + int i, result = 0; + + if (!refnames->nr) + return 0; + + if (packed_refs_lock(refs->packed_ref_store, 0, &err)) + goto error; + + if (refs_delete_refs(refs->packed_ref_store, msg, refnames, flags)) { + packed_refs_unlock(refs->packed_ref_store); + goto error; + } + + packed_refs_unlock(refs->packed_ref_store); + + for (i = 0; i < refnames->nr; i++) { + const char *refname = refnames->items[i].string; + + if (refs_delete_ref(&refs->base, msg, refname, NULL, flags)) + result |= error(_("could not remove reference %s"), refname); + } + + strbuf_release(&err); + return result; + +error: + /* + * If we failed to rewrite the packed-refs file, then it is + * unsafe to try to remove loose refs, because doing so might + * expose an obsolete packed value for a reference that might + * even point at an object that has been garbage collected. + */ + if (refnames->nr == 1) + error(_("could not delete reference %s: %s"), + refnames->items[0].string, err.buf); + else + error(_("could not delete references: %s"), err.buf); + + strbuf_release(&err); + return -1; +} + +/* + * People using contrib's git-new-workdir have .git/logs/refs -> + * /some/other/path/.git/logs/refs, and that may live on another device. + * + * IOW, to avoid cross device rename errors, the temporary renamed log must + * live into logs/refs. + */ +#define TMP_RENAMED_LOG "refs/.tmp-renamed-log" + +struct rename_cb { + const char *tmp_renamed_log; + int true_errno; +}; + +static int rename_tmp_log_callback(const char *path, void *cb_data) +{ + struct rename_cb *cb = cb_data; + + if (rename(cb->tmp_renamed_log, path)) { + /* + * rename(a, b) when b is an existing directory ought + * to result in ISDIR, but Solaris 5.8 gives ENOTDIR. + * Sheesh. Record the true errno for error reporting, + * but report EISDIR to raceproof_create_file() so + * that it knows to retry. + */ + cb->true_errno = errno; + if (errno == ENOTDIR) + errno = EISDIR; + return -1; + } else { + return 0; + } +} + +static int rename_tmp_log(struct files_ref_store *refs, const char *newrefname) +{ + struct strbuf path = STRBUF_INIT; + struct strbuf tmp = STRBUF_INIT; + struct rename_cb cb; + int ret; + + files_reflog_path(refs, &path, newrefname); + files_reflog_path(refs, &tmp, TMP_RENAMED_LOG); + cb.tmp_renamed_log = tmp.buf; + ret = raceproof_create_file(path.buf, rename_tmp_log_callback, &cb); + if (ret) { + if (errno == EISDIR) + error("directory not empty: %s", path.buf); + else + error("unable to move logfile %s to %s: %s", + tmp.buf, path.buf, + strerror(cb.true_errno)); + } + + strbuf_release(&path); + strbuf_release(&tmp); + return ret; +} + +static int write_ref_to_lockfile(struct ref_lock *lock, + const struct object_id *oid, struct strbuf *err); +static int commit_ref_update(struct files_ref_store *refs, + struct ref_lock *lock, + const struct object_id *oid, const char *logmsg, + struct strbuf *err); + +static int files_copy_or_rename_ref(struct ref_store *ref_store, + const char *oldrefname, const char *newrefname, + const char *logmsg, int copy) +{ + struct files_ref_store *refs = + files_downcast(ref_store, REF_STORE_WRITE, "rename_ref"); + struct object_id oid, orig_oid; + int flag = 0, logmoved = 0; + struct ref_lock *lock; + struct stat loginfo; + struct strbuf sb_oldref = STRBUF_INIT; + struct strbuf sb_newref = STRBUF_INIT; + struct strbuf tmp_renamed_log = STRBUF_INIT; + int log, ret; + struct strbuf err = STRBUF_INIT; + + files_reflog_path(refs, &sb_oldref, oldrefname); + files_reflog_path(refs, &sb_newref, newrefname); + files_reflog_path(refs, &tmp_renamed_log, TMP_RENAMED_LOG); + + log = !lstat(sb_oldref.buf, &loginfo); + if (log && S_ISLNK(loginfo.st_mode)) { + ret = error("reflog for %s is a symlink", oldrefname); + goto out; + } + + if (!refs_resolve_ref_unsafe(&refs->base, oldrefname, + RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE, + &orig_oid, &flag)) { + ret = error("refname %s not found", oldrefname); + goto out; + } + + if (flag & REF_ISSYMREF) { + if (copy) + ret = error("refname %s is a symbolic ref, copying it is not supported", + oldrefname); + else + ret = error("refname %s is a symbolic ref, renaming it is not supported", + oldrefname); + goto out; + } + if (!refs_rename_ref_available(&refs->base, oldrefname, newrefname)) { + ret = 1; + goto out; + } + + if (!copy && log && rename(sb_oldref.buf, tmp_renamed_log.buf)) { + ret = error("unable to move logfile logs/%s to logs/"TMP_RENAMED_LOG": %s", + oldrefname, strerror(errno)); + goto out; + } + + if (copy && log && copy_file(tmp_renamed_log.buf, sb_oldref.buf, 0644)) { + ret = error("unable to copy logfile logs/%s to logs/"TMP_RENAMED_LOG": %s", + oldrefname, strerror(errno)); + goto out; + } + + if (!copy && refs_delete_ref(&refs->base, logmsg, oldrefname, + &orig_oid, REF_NO_DEREF)) { + error("unable to delete old %s", oldrefname); + goto rollback; + } + + /* + * Since we are doing a shallow lookup, oid is not the + * correct value to pass to delete_ref as old_oid. But that + * doesn't matter, because an old_oid check wouldn't add to + * the safety anyway; we want to delete the reference whatever + * its current value. + */ + if (!copy && !refs_read_ref_full(&refs->base, newrefname, + RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE, + &oid, NULL) && + refs_delete_ref(&refs->base, NULL, newrefname, + NULL, REF_NO_DEREF)) { + if (errno == EISDIR) { + struct strbuf path = STRBUF_INIT; + int result; + + files_ref_path(refs, &path, newrefname); + result = remove_empty_directories(&path); + strbuf_release(&path); + + if (result) { + error("Directory not empty: %s", newrefname); + goto rollback; + } + } else { + error("unable to delete existing %s", newrefname); + goto rollback; + } + } + + if (log && rename_tmp_log(refs, newrefname)) + goto rollback; + + logmoved = log; + + lock = lock_ref_oid_basic(refs, newrefname, NULL, NULL, NULL, + REF_NO_DEREF, NULL, &err); + if (!lock) { + if (copy) + error("unable to copy '%s' to '%s': %s", oldrefname, newrefname, err.buf); + else + error("unable to rename '%s' to '%s': %s", oldrefname, newrefname, err.buf); + strbuf_release(&err); + goto rollback; + } + oidcpy(&lock->old_oid, &orig_oid); + + if (write_ref_to_lockfile(lock, &orig_oid, &err) || + commit_ref_update(refs, lock, &orig_oid, logmsg, &err)) { + error("unable to write current sha1 into %s: %s", newrefname, err.buf); + strbuf_release(&err); + goto rollback; + } + + ret = 0; + goto out; + + rollback: + lock = lock_ref_oid_basic(refs, oldrefname, NULL, NULL, NULL, + REF_NO_DEREF, NULL, &err); + if (!lock) { + error("unable to lock %s for rollback: %s", oldrefname, err.buf); + strbuf_release(&err); + goto rollbacklog; + } + + flag = log_all_ref_updates; + log_all_ref_updates = LOG_REFS_NONE; + if (write_ref_to_lockfile(lock, &orig_oid, &err) || + commit_ref_update(refs, lock, &orig_oid, NULL, &err)) { + error("unable to write current sha1 into %s: %s", oldrefname, err.buf); + strbuf_release(&err); + } + log_all_ref_updates = flag; + + rollbacklog: + if (logmoved && rename(sb_newref.buf, sb_oldref.buf)) + error("unable to restore logfile %s from %s: %s", + oldrefname, newrefname, strerror(errno)); + if (!logmoved && log && + rename(tmp_renamed_log.buf, sb_oldref.buf)) + error("unable to restore logfile %s from logs/"TMP_RENAMED_LOG": %s", + oldrefname, strerror(errno)); + ret = 1; + out: + strbuf_release(&sb_newref); + strbuf_release(&sb_oldref); + strbuf_release(&tmp_renamed_log); + + return ret; +} + +static int files_rename_ref(struct ref_store *ref_store, + const char *oldrefname, const char *newrefname, + const char *logmsg) +{ + return files_copy_or_rename_ref(ref_store, oldrefname, + newrefname, logmsg, 0); +} + +static int files_copy_ref(struct ref_store *ref_store, + const char *oldrefname, const char *newrefname, + const char *logmsg) +{ + return files_copy_or_rename_ref(ref_store, oldrefname, + newrefname, logmsg, 1); +} + +static int close_ref_gently(struct ref_lock *lock) +{ + if (close_lock_file_gently(&lock->lk)) + return -1; + return 0; +} + +static int commit_ref(struct ref_lock *lock) +{ + char *path = get_locked_file_path(&lock->lk); + struct stat st; + + if (!lstat(path, &st) && S_ISDIR(st.st_mode)) { + /* + * There is a directory at the path we want to rename + * the lockfile to. Hopefully it is empty; try to + * delete it. + */ + size_t len = strlen(path); + struct strbuf sb_path = STRBUF_INIT; + + strbuf_attach(&sb_path, path, len, len); + + /* + * If this fails, commit_lock_file() will also fail + * and will report the problem. + */ + remove_empty_directories(&sb_path); + strbuf_release(&sb_path); + } else { + free(path); + } + + if (commit_lock_file(&lock->lk)) + return -1; + return 0; +} + +static int open_or_create_logfile(const char *path, void *cb) +{ + int *fd = cb; + + *fd = open(path, O_APPEND | O_WRONLY | O_CREAT, 0666); + return (*fd < 0) ? -1 : 0; +} + +/* + * Create a reflog for a ref. If force_create = 0, only create the + * reflog for certain refs (those for which should_autocreate_reflog + * returns non-zero). Otherwise, create it regardless of the reference + * name. If the logfile already existed or was created, return 0 and + * set *logfd to the file descriptor opened for appending to the file. + * If no logfile exists and we decided not to create one, return 0 and + * set *logfd to -1. On failure, fill in *err, set *logfd to -1, and + * return -1. + */ +static int log_ref_setup(struct files_ref_store *refs, + const char *refname, int force_create, + int *logfd, struct strbuf *err) +{ + struct strbuf logfile_sb = STRBUF_INIT; + char *logfile; + + files_reflog_path(refs, &logfile_sb, refname); + logfile = strbuf_detach(&logfile_sb, NULL); + + if (force_create || should_autocreate_reflog(refname)) { + if (raceproof_create_file(logfile, open_or_create_logfile, logfd)) { + if (errno == ENOENT) + strbuf_addf(err, "unable to create directory for '%s': " + "%s", logfile, strerror(errno)); + else if (errno == EISDIR) + strbuf_addf(err, "there are still logs under '%s'", + logfile); + else + strbuf_addf(err, "unable to append to '%s': %s", + logfile, strerror(errno)); + + goto error; + } + } else { + *logfd = open(logfile, O_APPEND | O_WRONLY, 0666); + if (*logfd < 0) { + if (errno == ENOENT || errno == EISDIR) { + /* + * The logfile doesn't already exist, + * but that is not an error; it only + * means that we won't write log + * entries to it. + */ + ; + } else { + strbuf_addf(err, "unable to append to '%s': %s", + logfile, strerror(errno)); + goto error; + } + } + } + + if (*logfd >= 0) + adjust_shared_perm(logfile); + + free(logfile); + return 0; + +error: + free(logfile); + return -1; +} + +static int files_create_reflog(struct ref_store *ref_store, + const char *refname, int force_create, + struct strbuf *err) +{ + struct files_ref_store *refs = + files_downcast(ref_store, REF_STORE_WRITE, "create_reflog"); + int fd; + + if (log_ref_setup(refs, refname, force_create, &fd, err)) + return -1; + + if (fd >= 0) + close(fd); + + return 0; +} + +static int log_ref_write_fd(int fd, const struct object_id *old_oid, + const struct object_id *new_oid, + const char *committer, const char *msg) +{ + struct strbuf sb = STRBUF_INIT; + int ret = 0; + + strbuf_addf(&sb, "%s %s %s", oid_to_hex(old_oid), oid_to_hex(new_oid), committer); + if (msg && *msg) + copy_reflog_msg(&sb, msg); + strbuf_addch(&sb, '\n'); + if (write_in_full(fd, sb.buf, sb.len) < 0) + ret = -1; + strbuf_release(&sb); + return ret; +} + +static int files_log_ref_write(struct files_ref_store *refs, + const char *refname, const struct object_id *old_oid, + const struct object_id *new_oid, const char *msg, + int flags, struct strbuf *err) +{ + int logfd, result; + + if (log_all_ref_updates == LOG_REFS_UNSET) + log_all_ref_updates = is_bare_repository() ? LOG_REFS_NONE : LOG_REFS_NORMAL; + + result = log_ref_setup(refs, refname, + flags & REF_FORCE_CREATE_REFLOG, + &logfd, err); + + if (result) + return result; + + if (logfd < 0) + return 0; + result = log_ref_write_fd(logfd, old_oid, new_oid, + git_committer_info(0), msg); + if (result) { + struct strbuf sb = STRBUF_INIT; + int save_errno = errno; + + files_reflog_path(refs, &sb, refname); + strbuf_addf(err, "unable to append to '%s': %s", + sb.buf, strerror(save_errno)); + strbuf_release(&sb); + close(logfd); + return -1; + } + if (close(logfd)) { + struct strbuf sb = STRBUF_INIT; + int save_errno = errno; + + files_reflog_path(refs, &sb, refname); + strbuf_addf(err, "unable to append to '%s': %s", + sb.buf, strerror(save_errno)); + strbuf_release(&sb); + return -1; + } + return 0; +} + +/* + * Write oid into the open lockfile, then close the lockfile. On + * errors, rollback the lockfile, fill in *err and return -1. + */ +static int write_ref_to_lockfile(struct ref_lock *lock, + const struct object_id *oid, struct strbuf *err) +{ + static char term = '\n'; + struct object *o; + int fd; + + o = parse_object(the_repository, oid); + if (!o) { + strbuf_addf(err, + "trying to write ref '%s' with nonexistent object %s", + lock->ref_name, oid_to_hex(oid)); + unlock_ref(lock); + return -1; + } + if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) { + strbuf_addf(err, + "trying to write non-commit object %s to branch '%s'", + oid_to_hex(oid), lock->ref_name); + unlock_ref(lock); + return -1; + } + fd = get_lock_file_fd(&lock->lk); + if (write_in_full(fd, oid_to_hex(oid), the_hash_algo->hexsz) < 0 || + write_in_full(fd, &term, 1) < 0 || + close_ref_gently(lock) < 0) { + strbuf_addf(err, + "couldn't write '%s'", get_lock_file_path(&lock->lk)); + unlock_ref(lock); + return -1; + } + return 0; +} + +/* + * Commit a change to a loose reference that has already been written + * to the loose reference lockfile. Also update the reflogs if + * necessary, using the specified lockmsg (which can be NULL). + */ +static int commit_ref_update(struct files_ref_store *refs, + struct ref_lock *lock, + const struct object_id *oid, const char *logmsg, + struct strbuf *err) +{ + files_assert_main_repository(refs, "commit_ref_update"); + + clear_loose_ref_cache(refs); + if (files_log_ref_write(refs, lock->ref_name, + &lock->old_oid, oid, + logmsg, 0, err)) { + char *old_msg = strbuf_detach(err, NULL); + strbuf_addf(err, "cannot update the ref '%s': %s", + lock->ref_name, old_msg); + free(old_msg); + unlock_ref(lock); + return -1; + } + + if (strcmp(lock->ref_name, "HEAD") != 0) { + /* + * Special hack: If a branch is updated directly and HEAD + * points to it (may happen on the remote side of a push + * for example) then logically the HEAD reflog should be + * updated too. + * A generic solution implies reverse symref information, + * but finding all symrefs pointing to the given branch + * would be rather costly for this rare event (the direct + * update of a branch) to be worth it. So let's cheat and + * check with HEAD only which should cover 99% of all usage + * scenarios (even 100% of the default ones). + */ + int head_flag; + const char *head_ref; + + head_ref = refs_resolve_ref_unsafe(&refs->base, "HEAD", + RESOLVE_REF_READING, + NULL, &head_flag); + if (head_ref && (head_flag & REF_ISSYMREF) && + !strcmp(head_ref, lock->ref_name)) { + struct strbuf log_err = STRBUF_INIT; + if (files_log_ref_write(refs, "HEAD", + &lock->old_oid, oid, + logmsg, 0, &log_err)) { + error("%s", log_err.buf); + strbuf_release(&log_err); + } + } + } + + if (commit_ref(lock)) { + strbuf_addf(err, "couldn't set '%s'", lock->ref_name); + unlock_ref(lock); + return -1; + } + + unlock_ref(lock); + return 0; +} + +static int create_ref_symlink(struct ref_lock *lock, const char *target) +{ + int ret = -1; +#ifndef NO_SYMLINK_HEAD + char *ref_path = get_locked_file_path(&lock->lk); + unlink(ref_path); + ret = symlink(target, ref_path); + free(ref_path); + + if (ret) + fprintf(stderr, "no symlink - falling back to symbolic ref\n"); +#endif + return ret; +} + +static void update_symref_reflog(struct files_ref_store *refs, + struct ref_lock *lock, const char *refname, + const char *target, const char *logmsg) +{ + struct strbuf err = STRBUF_INIT; + struct object_id new_oid; + if (logmsg && + !refs_read_ref_full(&refs->base, target, + RESOLVE_REF_READING, &new_oid, NULL) && + files_log_ref_write(refs, refname, &lock->old_oid, + &new_oid, logmsg, 0, &err)) { + error("%s", err.buf); + strbuf_release(&err); + } +} + +static int create_symref_locked(struct files_ref_store *refs, + struct ref_lock *lock, const char *refname, + const char *target, const char *logmsg) +{ + if (prefer_symlink_refs && !create_ref_symlink(lock, target)) { + update_symref_reflog(refs, lock, refname, target, logmsg); + return 0; + } + + if (!fdopen_lock_file(&lock->lk, "w")) + return error("unable to fdopen %s: %s", + lock->lk.tempfile->filename.buf, strerror(errno)); + + update_symref_reflog(refs, lock, refname, target, logmsg); + + /* no error check; commit_ref will check ferror */ + fprintf(lock->lk.tempfile->fp, "ref: %s\n", target); + if (commit_ref(lock) < 0) + return error("unable to write symref for %s: %s", refname, + strerror(errno)); + return 0; +} + +static int files_create_symref(struct ref_store *ref_store, + const char *refname, const char *target, + const char *logmsg) +{ + struct files_ref_store *refs = + files_downcast(ref_store, REF_STORE_WRITE, "create_symref"); + struct strbuf err = STRBUF_INIT; + struct ref_lock *lock; + int ret; + + lock = lock_ref_oid_basic(refs, refname, NULL, + NULL, NULL, REF_NO_DEREF, NULL, + &err); + if (!lock) { + error("%s", err.buf); + strbuf_release(&err); + return -1; + } + + ret = create_symref_locked(refs, lock, refname, target, logmsg); + unlock_ref(lock); + return ret; +} + +static int files_reflog_exists(struct ref_store *ref_store, + const char *refname) +{ + struct files_ref_store *refs = + files_downcast(ref_store, REF_STORE_READ, "reflog_exists"); + struct strbuf sb = STRBUF_INIT; + struct stat st; + int ret; + + files_reflog_path(refs, &sb, refname); + ret = !lstat(sb.buf, &st) && S_ISREG(st.st_mode); + strbuf_release(&sb); + return ret; +} + +static int files_delete_reflog(struct ref_store *ref_store, + const char *refname) +{ + struct files_ref_store *refs = + files_downcast(ref_store, REF_STORE_WRITE, "delete_reflog"); + struct strbuf sb = STRBUF_INIT; + int ret; + + files_reflog_path(refs, &sb, refname); + ret = remove_path(sb.buf); + strbuf_release(&sb); + return ret; +} + +static int show_one_reflog_ent(struct strbuf *sb, each_reflog_ent_fn fn, void *cb_data) +{ + struct object_id ooid, noid; + char *email_end, *message; + timestamp_t timestamp; + int tz; + const char *p = sb->buf; + + /* old SP new SP name <email> SP time TAB msg LF */ + if (!sb->len || sb->buf[sb->len - 1] != '\n' || + parse_oid_hex(p, &ooid, &p) || *p++ != ' ' || + parse_oid_hex(p, &noid, &p) || *p++ != ' ' || + !(email_end = strchr(p, '>')) || + email_end[1] != ' ' || + !(timestamp = parse_timestamp(email_end + 2, &message, 10)) || + !message || message[0] != ' ' || + (message[1] != '+' && message[1] != '-') || + !isdigit(message[2]) || !isdigit(message[3]) || + !isdigit(message[4]) || !isdigit(message[5])) + return 0; /* corrupt? */ + email_end[1] = '\0'; + tz = strtol(message + 1, NULL, 10); + if (message[6] != '\t') + message += 6; + else + message += 7; + return fn(&ooid, &noid, p, timestamp, tz, message, cb_data); +} + +static char *find_beginning_of_line(char *bob, char *scan) +{ + while (bob < scan && *(--scan) != '\n') + ; /* keep scanning backwards */ + /* + * Return either beginning of the buffer, or LF at the end of + * the previous line. + */ + return scan; +} + +static int files_for_each_reflog_ent_reverse(struct ref_store *ref_store, + const char *refname, + each_reflog_ent_fn fn, + void *cb_data) +{ + struct files_ref_store *refs = + files_downcast(ref_store, REF_STORE_READ, + "for_each_reflog_ent_reverse"); + struct strbuf sb = STRBUF_INIT; + FILE *logfp; + long pos; + int ret = 0, at_tail = 1; + + files_reflog_path(refs, &sb, refname); + logfp = fopen(sb.buf, "r"); + strbuf_release(&sb); + if (!logfp) + return -1; + + /* Jump to the end */ + if (fseek(logfp, 0, SEEK_END) < 0) + ret = error("cannot seek back reflog for %s: %s", + refname, strerror(errno)); + pos = ftell(logfp); + while (!ret && 0 < pos) { + int cnt; + size_t nread; + char buf[BUFSIZ]; + char *endp, *scanp; + + /* Fill next block from the end */ + cnt = (sizeof(buf) < pos) ? sizeof(buf) : pos; + if (fseek(logfp, pos - cnt, SEEK_SET)) { + ret = error("cannot seek back reflog for %s: %s", + refname, strerror(errno)); + break; + } + nread = fread(buf, cnt, 1, logfp); + if (nread != 1) { + ret = error("cannot read %d bytes from reflog for %s: %s", + cnt, refname, strerror(errno)); + break; + } + pos -= cnt; + + scanp = endp = buf + cnt; + if (at_tail && scanp[-1] == '\n') + /* Looking at the final LF at the end of the file */ + scanp--; + at_tail = 0; + + while (buf < scanp) { + /* + * terminating LF of the previous line, or the beginning + * of the buffer. + */ + char *bp; + + bp = find_beginning_of_line(buf, scanp); + + if (*bp == '\n') { + /* + * The newline is the end of the previous line, + * so we know we have complete line starting + * at (bp + 1). Prefix it onto any prior data + * we collected for the line and process it. + */ + strbuf_splice(&sb, 0, 0, bp + 1, endp - (bp + 1)); + scanp = bp; + endp = bp + 1; + ret = show_one_reflog_ent(&sb, fn, cb_data); + strbuf_reset(&sb); + if (ret) + break; + } else if (!pos) { + /* + * We are at the start of the buffer, and the + * start of the file; there is no previous + * line, and we have everything for this one. + * Process it, and we can end the loop. + */ + strbuf_splice(&sb, 0, 0, buf, endp - buf); + ret = show_one_reflog_ent(&sb, fn, cb_data); + strbuf_reset(&sb); + break; + } + + if (bp == buf) { + /* + * We are at the start of the buffer, and there + * is more file to read backwards. Which means + * we are in the middle of a line. Note that we + * may get here even if *bp was a newline; that + * just means we are at the exact end of the + * previous line, rather than some spot in the + * middle. + * + * Save away what we have to be combined with + * the data from the next read. + */ + strbuf_splice(&sb, 0, 0, buf, endp - buf); + break; + } + } + + } + if (!ret && sb.len) + BUG("reverse reflog parser had leftover data"); + + fclose(logfp); + strbuf_release(&sb); + return ret; +} + +static int files_for_each_reflog_ent(struct ref_store *ref_store, + const char *refname, + each_reflog_ent_fn fn, void *cb_data) +{ + struct files_ref_store *refs = + files_downcast(ref_store, REF_STORE_READ, + "for_each_reflog_ent"); + FILE *logfp; + struct strbuf sb = STRBUF_INIT; + int ret = 0; + + files_reflog_path(refs, &sb, refname); + logfp = fopen(sb.buf, "r"); + strbuf_release(&sb); + if (!logfp) + return -1; + + while (!ret && !strbuf_getwholeline(&sb, logfp, '\n')) + ret = show_one_reflog_ent(&sb, fn, cb_data); + fclose(logfp); + strbuf_release(&sb); + return ret; +} + +struct files_reflog_iterator { + struct ref_iterator base; + + struct ref_store *ref_store; + struct dir_iterator *dir_iterator; + struct object_id oid; +}; + +static int files_reflog_iterator_advance(struct ref_iterator *ref_iterator) +{ + struct files_reflog_iterator *iter = + (struct files_reflog_iterator *)ref_iterator; + struct dir_iterator *diter = iter->dir_iterator; + int ok; + + while ((ok = dir_iterator_advance(diter)) == ITER_OK) { + int flags; + + if (!S_ISREG(diter->st.st_mode)) + continue; + if (diter->basename[0] == '.') + continue; + if (ends_with(diter->basename, ".lock")) + continue; + + if (refs_read_ref_full(iter->ref_store, + diter->relative_path, 0, + &iter->oid, &flags)) { + error("bad ref for %s", diter->path.buf); + continue; + } + + iter->base.refname = diter->relative_path; + iter->base.oid = &iter->oid; + iter->base.flags = flags; + return ITER_OK; + } + + iter->dir_iterator = NULL; + if (ref_iterator_abort(ref_iterator) == ITER_ERROR) + ok = ITER_ERROR; + return ok; +} + +static int files_reflog_iterator_peel(struct ref_iterator *ref_iterator, + struct object_id *peeled) +{ + BUG("ref_iterator_peel() called for reflog_iterator"); +} + +static int files_reflog_iterator_abort(struct ref_iterator *ref_iterator) +{ + struct files_reflog_iterator *iter = + (struct files_reflog_iterator *)ref_iterator; + int ok = ITER_DONE; + + if (iter->dir_iterator) + ok = dir_iterator_abort(iter->dir_iterator); + + base_ref_iterator_free(ref_iterator); + return ok; +} + +static struct ref_iterator_vtable files_reflog_iterator_vtable = { + files_reflog_iterator_advance, + files_reflog_iterator_peel, + files_reflog_iterator_abort +}; + +static struct ref_iterator *reflog_iterator_begin(struct ref_store *ref_store, + const char *gitdir) +{ + struct dir_iterator *diter; + struct files_reflog_iterator *iter; + struct ref_iterator *ref_iterator; + struct strbuf sb = STRBUF_INIT; + + strbuf_addf(&sb, "%s/logs", gitdir); + + diter = dir_iterator_begin(sb.buf, 0); + if (!diter) { + strbuf_release(&sb); + return empty_ref_iterator_begin(); + } + + iter = xcalloc(1, sizeof(*iter)); + ref_iterator = &iter->base; + + base_ref_iterator_init(ref_iterator, &files_reflog_iterator_vtable, 0); + iter->dir_iterator = diter; + iter->ref_store = ref_store; + strbuf_release(&sb); + + return ref_iterator; +} + +static enum iterator_selection reflog_iterator_select( + struct ref_iterator *iter_worktree, + struct ref_iterator *iter_common, + void *cb_data) +{ + if (iter_worktree) { + /* + * We're a bit loose here. We probably should ignore + * common refs if they are accidentally added as + * per-worktree refs. + */ + return ITER_SELECT_0; + } else if (iter_common) { + if (ref_type(iter_common->refname) == REF_TYPE_NORMAL) + return ITER_SELECT_1; + + /* + * The main ref store may contain main worktree's + * per-worktree refs, which should be ignored + */ + return ITER_SKIP_1; + } else + return ITER_DONE; +} + +static struct ref_iterator *files_reflog_iterator_begin(struct ref_store *ref_store) +{ + struct files_ref_store *refs = + files_downcast(ref_store, REF_STORE_READ, + "reflog_iterator_begin"); + + if (!strcmp(refs->gitdir, refs->gitcommondir)) { + return reflog_iterator_begin(ref_store, refs->gitcommondir); + } else { + return merge_ref_iterator_begin( + 0, + reflog_iterator_begin(ref_store, refs->gitdir), + reflog_iterator_begin(ref_store, refs->gitcommondir), + reflog_iterator_select, refs); + } +} + +/* + * If update is a direct update of head_ref (the reference pointed to + * by HEAD), then add an extra REF_LOG_ONLY update for HEAD. + */ +static int split_head_update(struct ref_update *update, + struct ref_transaction *transaction, + const char *head_ref, + struct string_list *affected_refnames, + struct strbuf *err) +{ + struct string_list_item *item; + struct ref_update *new_update; + + if ((update->flags & REF_LOG_ONLY) || + (update->flags & REF_IS_PRUNING) || + (update->flags & REF_UPDATE_VIA_HEAD)) + return 0; + + if (strcmp(update->refname, head_ref)) + return 0; + + /* + * First make sure that HEAD is not already in the + * transaction. This check is O(lg N) in the transaction + * size, but it happens at most once per transaction. + */ + if (string_list_has_string(affected_refnames, "HEAD")) { + /* An entry already existed */ + strbuf_addf(err, + "multiple updates for 'HEAD' (including one " + "via its referent '%s') are not allowed", + update->refname); + return TRANSACTION_NAME_CONFLICT; + } + + new_update = ref_transaction_add_update( + transaction, "HEAD", + update->flags | REF_LOG_ONLY | REF_NO_DEREF, + &update->new_oid, &update->old_oid, + update->msg); + + /* + * Add "HEAD". This insertion is O(N) in the transaction + * size, but it happens at most once per transaction. + * Add new_update->refname instead of a literal "HEAD". + */ + if (strcmp(new_update->refname, "HEAD")) + BUG("%s unexpectedly not 'HEAD'", new_update->refname); + item = string_list_insert(affected_refnames, new_update->refname); + item->util = new_update; + + return 0; +} + +/* + * update is for a symref that points at referent and doesn't have + * REF_NO_DEREF set. Split it into two updates: + * - The original update, but with REF_LOG_ONLY and REF_NO_DEREF set + * - A new, separate update for the referent reference + * Note that the new update will itself be subject to splitting when + * the iteration gets to it. + */ +static int split_symref_update(struct ref_update *update, + const char *referent, + struct ref_transaction *transaction, + struct string_list *affected_refnames, + struct strbuf *err) +{ + struct string_list_item *item; + struct ref_update *new_update; + unsigned int new_flags; + + /* + * First make sure that referent is not already in the + * transaction. This check is O(lg N) in the transaction + * size, but it happens at most once per symref in a + * transaction. + */ + if (string_list_has_string(affected_refnames, referent)) { + /* An entry already exists */ + strbuf_addf(err, + "multiple updates for '%s' (including one " + "via symref '%s') are not allowed", + referent, update->refname); + return TRANSACTION_NAME_CONFLICT; + } + + new_flags = update->flags; + if (!strcmp(update->refname, "HEAD")) { + /* + * Record that the new update came via HEAD, so that + * when we process it, split_head_update() doesn't try + * to add another reflog update for HEAD. Note that + * this bit will be propagated if the new_update + * itself needs to be split. + */ + new_flags |= REF_UPDATE_VIA_HEAD; + } + + new_update = ref_transaction_add_update( + transaction, referent, new_flags, + &update->new_oid, &update->old_oid, + update->msg); + + new_update->parent_update = update; + + /* + * Change the symbolic ref update to log only. Also, it + * doesn't need to check its old OID value, as that will be + * done when new_update is processed. + */ + update->flags |= REF_LOG_ONLY | REF_NO_DEREF; + update->flags &= ~REF_HAVE_OLD; + + /* + * Add the referent. This insertion is O(N) in the transaction + * size, but it happens at most once per symref in a + * transaction. Make sure to add new_update->refname, which will + * be valid as long as affected_refnames is in use, and NOT + * referent, which might soon be freed by our caller. + */ + item = string_list_insert(affected_refnames, new_update->refname); + if (item->util) + BUG("%s unexpectedly found in affected_refnames", + new_update->refname); + item->util = new_update; + + return 0; +} + +/* + * Return the refname under which update was originally requested. + */ +static const char *original_update_refname(struct ref_update *update) +{ + while (update->parent_update) + update = update->parent_update; + + return update->refname; +} + +/* + * Check whether the REF_HAVE_OLD and old_oid values stored in update + * are consistent with oid, which is the reference's current value. If + * everything is OK, return 0; otherwise, write an error message to + * err and return -1. + */ +static int check_old_oid(struct ref_update *update, struct object_id *oid, + struct strbuf *err) +{ + if (!(update->flags & REF_HAVE_OLD) || + oideq(oid, &update->old_oid)) + return 0; + + if (is_null_oid(&update->old_oid)) + strbuf_addf(err, "cannot lock ref '%s': " + "reference already exists", + original_update_refname(update)); + else if (is_null_oid(oid)) + strbuf_addf(err, "cannot lock ref '%s': " + "reference is missing but expected %s", + original_update_refname(update), + oid_to_hex(&update->old_oid)); + else + strbuf_addf(err, "cannot lock ref '%s': " + "is at %s but expected %s", + original_update_refname(update), + oid_to_hex(oid), + oid_to_hex(&update->old_oid)); + + return -1; +} + +/* + * Prepare for carrying out update: + * - Lock the reference referred to by update. + * - Read the reference under lock. + * - Check that its old OID value (if specified) is correct, and in + * any case record it in update->lock->old_oid for later use when + * writing the reflog. + * - If it is a symref update without REF_NO_DEREF, split it up into a + * REF_LOG_ONLY update of the symref and add a separate update for + * the referent to transaction. + * - If it is an update of head_ref, add a corresponding REF_LOG_ONLY + * update of HEAD. + */ +static int lock_ref_for_update(struct files_ref_store *refs, + struct ref_update *update, + struct ref_transaction *transaction, + const char *head_ref, + struct string_list *affected_refnames, + struct strbuf *err) +{ + struct strbuf referent = STRBUF_INIT; + int mustexist = (update->flags & REF_HAVE_OLD) && + !is_null_oid(&update->old_oid); + int ret = 0; + struct ref_lock *lock; + + files_assert_main_repository(refs, "lock_ref_for_update"); + + if ((update->flags & REF_HAVE_NEW) && is_null_oid(&update->new_oid)) + update->flags |= REF_DELETING; + + if (head_ref) { + ret = split_head_update(update, transaction, head_ref, + affected_refnames, err); + if (ret) + goto out; + } + + ret = lock_raw_ref(refs, update->refname, mustexist, + affected_refnames, NULL, + &lock, &referent, + &update->type, err); + if (ret) { + char *reason; + + reason = strbuf_detach(err, NULL); + strbuf_addf(err, "cannot lock ref '%s': %s", + original_update_refname(update), reason); + free(reason); + goto out; + } + + update->backend_data = lock; + + if (update->type & REF_ISSYMREF) { + if (update->flags & REF_NO_DEREF) { + /* + * We won't be reading the referent as part of + * the transaction, so we have to read it here + * to record and possibly check old_oid: + */ + if (refs_read_ref_full(&refs->base, + referent.buf, 0, + &lock->old_oid, NULL)) { + if (update->flags & REF_HAVE_OLD) { + strbuf_addf(err, "cannot lock ref '%s': " + "error reading reference", + original_update_refname(update)); + ret = TRANSACTION_GENERIC_ERROR; + goto out; + } + } else if (check_old_oid(update, &lock->old_oid, err)) { + ret = TRANSACTION_GENERIC_ERROR; + goto out; + } + } else { + /* + * Create a new update for the reference this + * symref is pointing at. Also, we will record + * and verify old_oid for this update as part + * of processing the split-off update, so we + * don't have to do it here. + */ + ret = split_symref_update(update, + referent.buf, transaction, + affected_refnames, err); + if (ret) + goto out; + } + } else { + struct ref_update *parent_update; + + if (check_old_oid(update, &lock->old_oid, err)) { + ret = TRANSACTION_GENERIC_ERROR; + goto out; + } + + /* + * If this update is happening indirectly because of a + * symref update, record the old OID in the parent + * update: + */ + for (parent_update = update->parent_update; + parent_update; + parent_update = parent_update->parent_update) { + struct ref_lock *parent_lock = parent_update->backend_data; + oidcpy(&parent_lock->old_oid, &lock->old_oid); + } + } + + if ((update->flags & REF_HAVE_NEW) && + !(update->flags & REF_DELETING) && + !(update->flags & REF_LOG_ONLY)) { + if (!(update->type & REF_ISSYMREF) && + oideq(&lock->old_oid, &update->new_oid)) { + /* + * The reference already has the desired + * value, so we don't need to write it. + */ + } else if (write_ref_to_lockfile(lock, &update->new_oid, + err)) { + char *write_err = strbuf_detach(err, NULL); + + /* + * The lock was freed upon failure of + * write_ref_to_lockfile(): + */ + update->backend_data = NULL; + strbuf_addf(err, + "cannot update ref '%s': %s", + update->refname, write_err); + free(write_err); + ret = TRANSACTION_GENERIC_ERROR; + goto out; + } else { + update->flags |= REF_NEEDS_COMMIT; + } + } + if (!(update->flags & REF_NEEDS_COMMIT)) { + /* + * We didn't call write_ref_to_lockfile(), so + * the lockfile is still open. Close it to + * free up the file descriptor: + */ + if (close_ref_gently(lock)) { + strbuf_addf(err, "couldn't close '%s.lock'", + update->refname); + ret = TRANSACTION_GENERIC_ERROR; + goto out; + } + } + +out: + strbuf_release(&referent); + return ret; +} + +struct files_transaction_backend_data { + struct ref_transaction *packed_transaction; + int packed_refs_locked; +}; + +/* + * Unlock any references in `transaction` that are still locked, and + * mark the transaction closed. + */ +static void files_transaction_cleanup(struct files_ref_store *refs, + struct ref_transaction *transaction) +{ + size_t i; + struct files_transaction_backend_data *backend_data = + transaction->backend_data; + struct strbuf err = STRBUF_INIT; + + for (i = 0; i < transaction->nr; i++) { + struct ref_update *update = transaction->updates[i]; + struct ref_lock *lock = update->backend_data; + + if (lock) { + unlock_ref(lock); + update->backend_data = NULL; + } + } + + if (backend_data->packed_transaction && + ref_transaction_abort(backend_data->packed_transaction, &err)) { + error("error aborting transaction: %s", err.buf); + strbuf_release(&err); + } + + if (backend_data->packed_refs_locked) + packed_refs_unlock(refs->packed_ref_store); + + free(backend_data); + + transaction->state = REF_TRANSACTION_CLOSED; +} + +static int files_transaction_prepare(struct ref_store *ref_store, + struct ref_transaction *transaction, + struct strbuf *err) +{ + struct files_ref_store *refs = + files_downcast(ref_store, REF_STORE_WRITE, + "ref_transaction_prepare"); + size_t i; + int ret = 0; + struct string_list affected_refnames = STRING_LIST_INIT_NODUP; + char *head_ref = NULL; + int head_type; + struct files_transaction_backend_data *backend_data; + struct ref_transaction *packed_transaction = NULL; + + assert(err); + + if (!transaction->nr) + goto cleanup; + + backend_data = xcalloc(1, sizeof(*backend_data)); + transaction->backend_data = backend_data; + + /* + * Fail if a refname appears more than once in the + * transaction. (If we end up splitting up any updates using + * split_symref_update() or split_head_update(), those + * functions will check that the new updates don't have the + * same refname as any existing ones.) Also fail if any of the + * updates use REF_IS_PRUNING without REF_NO_DEREF. + */ + for (i = 0; i < transaction->nr; i++) { + struct ref_update *update = transaction->updates[i]; + struct string_list_item *item = + string_list_append(&affected_refnames, update->refname); + + if ((update->flags & REF_IS_PRUNING) && + !(update->flags & REF_NO_DEREF)) + BUG("REF_IS_PRUNING set without REF_NO_DEREF"); + + /* + * We store a pointer to update in item->util, but at + * the moment we never use the value of this field + * except to check whether it is non-NULL. + */ + item->util = update; + } + string_list_sort(&affected_refnames); + if (ref_update_reject_duplicates(&affected_refnames, err)) { + ret = TRANSACTION_GENERIC_ERROR; + goto cleanup; + } + + /* + * Special hack: If a branch is updated directly and HEAD + * points to it (may happen on the remote side of a push + * for example) then logically the HEAD reflog should be + * updated too. + * + * A generic solution would require reverse symref lookups, + * but finding all symrefs pointing to a given branch would be + * rather costly for this rare event (the direct update of a + * branch) to be worth it. So let's cheat and check with HEAD + * only, which should cover 99% of all usage scenarios (even + * 100% of the default ones). + * + * So if HEAD is a symbolic reference, then record the name of + * the reference that it points to. If we see an update of + * head_ref within the transaction, then split_head_update() + * arranges for the reflog of HEAD to be updated, too. + */ + head_ref = refs_resolve_refdup(ref_store, "HEAD", + RESOLVE_REF_NO_RECURSE, + NULL, &head_type); + + if (head_ref && !(head_type & REF_ISSYMREF)) { + FREE_AND_NULL(head_ref); + } + + /* + * Acquire all locks, verify old values if provided, check + * that new values are valid, and write new values to the + * lockfiles, ready to be activated. Only keep one lockfile + * open at a time to avoid running out of file descriptors. + * Note that lock_ref_for_update() might append more updates + * to the transaction. + */ + for (i = 0; i < transaction->nr; i++) { + struct ref_update *update = transaction->updates[i]; + + ret = lock_ref_for_update(refs, update, transaction, + head_ref, &affected_refnames, err); + if (ret) + goto cleanup; + + if (update->flags & REF_DELETING && + !(update->flags & REF_LOG_ONLY) && + !(update->flags & REF_IS_PRUNING)) { + /* + * This reference has to be deleted from + * packed-refs if it exists there. + */ + if (!packed_transaction) { + packed_transaction = ref_store_transaction_begin( + refs->packed_ref_store, err); + if (!packed_transaction) { + ret = TRANSACTION_GENERIC_ERROR; + goto cleanup; + } + + backend_data->packed_transaction = + packed_transaction; + } + + ref_transaction_add_update( + packed_transaction, update->refname, + REF_HAVE_NEW | REF_NO_DEREF, + &update->new_oid, NULL, + NULL); + } + } + + if (packed_transaction) { + if (packed_refs_lock(refs->packed_ref_store, 0, err)) { + ret = TRANSACTION_GENERIC_ERROR; + goto cleanup; + } + backend_data->packed_refs_locked = 1; + + if (is_packed_transaction_needed(refs->packed_ref_store, + packed_transaction)) { + ret = ref_transaction_prepare(packed_transaction, err); + /* + * A failure during the prepare step will abort + * itself, but not free. Do that now, and disconnect + * from the files_transaction so it does not try to + * abort us when we hit the cleanup code below. + */ + if (ret) { + ref_transaction_free(packed_transaction); + backend_data->packed_transaction = NULL; + } + } else { + /* + * We can skip rewriting the `packed-refs` + * file. But we do need to leave it locked, so + * that somebody else doesn't pack a reference + * that we are trying to delete. + * + * We need to disconnect our transaction from + * backend_data, since the abort (whether successful or + * not) will free it. + */ + backend_data->packed_transaction = NULL; + if (ref_transaction_abort(packed_transaction, err)) { + ret = TRANSACTION_GENERIC_ERROR; + goto cleanup; + } + } + } + +cleanup: + free(head_ref); + string_list_clear(&affected_refnames, 0); + + if (ret) + files_transaction_cleanup(refs, transaction); + else + transaction->state = REF_TRANSACTION_PREPARED; + + return ret; +} + +static int files_transaction_finish(struct ref_store *ref_store, + struct ref_transaction *transaction, + struct strbuf *err) +{ + struct files_ref_store *refs = + files_downcast(ref_store, 0, "ref_transaction_finish"); + size_t i; + int ret = 0; + struct strbuf sb = STRBUF_INIT; + struct files_transaction_backend_data *backend_data; + struct ref_transaction *packed_transaction; + + + assert(err); + + if (!transaction->nr) { + transaction->state = REF_TRANSACTION_CLOSED; + return 0; + } + + backend_data = transaction->backend_data; + packed_transaction = backend_data->packed_transaction; + + /* Perform updates first so live commits remain referenced */ + for (i = 0; i < transaction->nr; i++) { + struct ref_update *update = transaction->updates[i]; + struct ref_lock *lock = update->backend_data; + + if (update->flags & REF_NEEDS_COMMIT || + update->flags & REF_LOG_ONLY) { + if (files_log_ref_write(refs, + lock->ref_name, + &lock->old_oid, + &update->new_oid, + update->msg, update->flags, + err)) { + char *old_msg = strbuf_detach(err, NULL); + + strbuf_addf(err, "cannot update the ref '%s': %s", + lock->ref_name, old_msg); + free(old_msg); + unlock_ref(lock); + update->backend_data = NULL; + ret = TRANSACTION_GENERIC_ERROR; + goto cleanup; + } + } + if (update->flags & REF_NEEDS_COMMIT) { + clear_loose_ref_cache(refs); + if (commit_ref(lock)) { + strbuf_addf(err, "couldn't set '%s'", lock->ref_name); + unlock_ref(lock); + update->backend_data = NULL; + ret = TRANSACTION_GENERIC_ERROR; + goto cleanup; + } + } + } + + /* + * Now that updates are safely completed, we can perform + * deletes. First delete the reflogs of any references that + * will be deleted, since (in the unexpected event of an + * error) leaving a reference without a reflog is less bad + * than leaving a reflog without a reference (the latter is a + * mildly invalid repository state): + */ + for (i = 0; i < transaction->nr; i++) { + struct ref_update *update = transaction->updates[i]; + if (update->flags & REF_DELETING && + !(update->flags & REF_LOG_ONLY) && + !(update->flags & REF_IS_PRUNING)) { + strbuf_reset(&sb); + files_reflog_path(refs, &sb, update->refname); + if (!unlink_or_warn(sb.buf)) + try_remove_empty_parents(refs, update->refname, + REMOVE_EMPTY_PARENTS_REFLOG); + } + } + + /* + * Perform deletes now that updates are safely completed. + * + * First delete any packed versions of the references, while + * retaining the packed-refs lock: + */ + if (packed_transaction) { + ret = ref_transaction_commit(packed_transaction, err); + ref_transaction_free(packed_transaction); + packed_transaction = NULL; + backend_data->packed_transaction = NULL; + if (ret) + goto cleanup; + } + + /* Now delete the loose versions of the references: */ + for (i = 0; i < transaction->nr; i++) { + struct ref_update *update = transaction->updates[i]; + struct ref_lock *lock = update->backend_data; + + if (update->flags & REF_DELETING && + !(update->flags & REF_LOG_ONLY)) { + if (!(update->type & REF_ISPACKED) || + update->type & REF_ISSYMREF) { + /* It is a loose reference. */ + strbuf_reset(&sb); + files_ref_path(refs, &sb, lock->ref_name); + if (unlink_or_msg(sb.buf, err)) { + ret = TRANSACTION_GENERIC_ERROR; + goto cleanup; + } + update->flags |= REF_DELETED_LOOSE; + } + } + } + + clear_loose_ref_cache(refs); + +cleanup: + files_transaction_cleanup(refs, transaction); + + for (i = 0; i < transaction->nr; i++) { + struct ref_update *update = transaction->updates[i]; + + if (update->flags & REF_DELETED_LOOSE) { + /* + * The loose reference was deleted. Delete any + * empty parent directories. (Note that this + * can only work because we have already + * removed the lockfile.) + */ + try_remove_empty_parents(refs, update->refname, + REMOVE_EMPTY_PARENTS_REF); + } + } + + strbuf_release(&sb); + return ret; +} + +static int files_transaction_abort(struct ref_store *ref_store, + struct ref_transaction *transaction, + struct strbuf *err) +{ + struct files_ref_store *refs = + files_downcast(ref_store, 0, "ref_transaction_abort"); + + files_transaction_cleanup(refs, transaction); + return 0; +} + +static int ref_present(const char *refname, + const struct object_id *oid, int flags, void *cb_data) +{ + struct string_list *affected_refnames = cb_data; + + return string_list_has_string(affected_refnames, refname); +} + +static int files_initial_transaction_commit(struct ref_store *ref_store, + struct ref_transaction *transaction, + struct strbuf *err) +{ + struct files_ref_store *refs = + files_downcast(ref_store, REF_STORE_WRITE, + "initial_ref_transaction_commit"); + size_t i; + int ret = 0; + struct string_list affected_refnames = STRING_LIST_INIT_NODUP; + struct ref_transaction *packed_transaction = NULL; + + assert(err); + + if (transaction->state != REF_TRANSACTION_OPEN) + BUG("commit called for transaction that is not open"); + + /* Fail if a refname appears more than once in the transaction: */ + for (i = 0; i < transaction->nr; i++) + string_list_append(&affected_refnames, + transaction->updates[i]->refname); + string_list_sort(&affected_refnames); + if (ref_update_reject_duplicates(&affected_refnames, err)) { + ret = TRANSACTION_GENERIC_ERROR; + goto cleanup; + } + + /* + * It's really undefined to call this function in an active + * repository or when there are existing references: we are + * only locking and changing packed-refs, so (1) any + * simultaneous processes might try to change a reference at + * the same time we do, and (2) any existing loose versions of + * the references that we are setting would have precedence + * over our values. But some remote helpers create the remote + * "HEAD" and "master" branches before calling this function, + * so here we really only check that none of the references + * that we are creating already exists. + */ + if (refs_for_each_rawref(&refs->base, ref_present, + &affected_refnames)) + BUG("initial ref transaction called with existing refs"); + + packed_transaction = ref_store_transaction_begin(refs->packed_ref_store, err); + if (!packed_transaction) { + ret = TRANSACTION_GENERIC_ERROR; + goto cleanup; + } + + for (i = 0; i < transaction->nr; i++) { + struct ref_update *update = transaction->updates[i]; + + if ((update->flags & REF_HAVE_OLD) && + !is_null_oid(&update->old_oid)) + BUG("initial ref transaction with old_sha1 set"); + if (refs_verify_refname_available(&refs->base, update->refname, + &affected_refnames, NULL, + err)) { + ret = TRANSACTION_NAME_CONFLICT; + goto cleanup; + } + + /* + * Add a reference creation for this reference to the + * packed-refs transaction: + */ + ref_transaction_add_update(packed_transaction, update->refname, + update->flags & ~REF_HAVE_OLD, + &update->new_oid, &update->old_oid, + NULL); + } + + if (packed_refs_lock(refs->packed_ref_store, 0, err)) { + ret = TRANSACTION_GENERIC_ERROR; + goto cleanup; + } + + if (initial_ref_transaction_commit(packed_transaction, err)) { + ret = TRANSACTION_GENERIC_ERROR; + } + + packed_refs_unlock(refs->packed_ref_store); +cleanup: + if (packed_transaction) + ref_transaction_free(packed_transaction); + transaction->state = REF_TRANSACTION_CLOSED; + string_list_clear(&affected_refnames, 0); + return ret; +} + +struct expire_reflog_cb { + unsigned int flags; + reflog_expiry_should_prune_fn *should_prune_fn; + void *policy_cb; + FILE *newlog; + struct object_id last_kept_oid; +}; + +static int expire_reflog_ent(struct object_id *ooid, struct object_id *noid, + const char *email, timestamp_t timestamp, int tz, + const char *message, void *cb_data) +{ + struct expire_reflog_cb *cb = cb_data; + struct expire_reflog_policy_cb *policy_cb = cb->policy_cb; + + if (cb->flags & EXPIRE_REFLOGS_REWRITE) + ooid = &cb->last_kept_oid; + + if ((*cb->should_prune_fn)(ooid, noid, email, timestamp, tz, + message, policy_cb)) { + if (!cb->newlog) + printf("would prune %s", message); + else if (cb->flags & EXPIRE_REFLOGS_VERBOSE) + printf("prune %s", message); + } else { + if (cb->newlog) { + fprintf(cb->newlog, "%s %s %s %"PRItime" %+05d\t%s", + oid_to_hex(ooid), oid_to_hex(noid), + email, timestamp, tz, message); + oidcpy(&cb->last_kept_oid, noid); + } + if (cb->flags & EXPIRE_REFLOGS_VERBOSE) + printf("keep %s", message); + } + return 0; +} + +static int files_reflog_expire(struct ref_store *ref_store, + const char *refname, const struct object_id *oid, + unsigned int flags, + reflog_expiry_prepare_fn prepare_fn, + reflog_expiry_should_prune_fn should_prune_fn, + reflog_expiry_cleanup_fn cleanup_fn, + void *policy_cb_data) +{ + struct files_ref_store *refs = + files_downcast(ref_store, REF_STORE_WRITE, "reflog_expire"); + struct lock_file reflog_lock = LOCK_INIT; + struct expire_reflog_cb cb; + struct ref_lock *lock; + struct strbuf log_file_sb = STRBUF_INIT; + char *log_file; + int status = 0; + int type; + struct strbuf err = STRBUF_INIT; + + memset(&cb, 0, sizeof(cb)); + cb.flags = flags; + cb.policy_cb = policy_cb_data; + cb.should_prune_fn = should_prune_fn; + + /* + * The reflog file is locked by holding the lock on the + * reference itself, plus we might need to update the + * reference if --updateref was specified: + */ + lock = lock_ref_oid_basic(refs, refname, oid, + NULL, NULL, REF_NO_DEREF, + &type, &err); + if (!lock) { + error("cannot lock ref '%s': %s", refname, err.buf); + strbuf_release(&err); + return -1; + } + if (!refs_reflog_exists(ref_store, refname)) { + unlock_ref(lock); + return 0; + } + + files_reflog_path(refs, &log_file_sb, refname); + log_file = strbuf_detach(&log_file_sb, NULL); + if (!(flags & EXPIRE_REFLOGS_DRY_RUN)) { + /* + * Even though holding $GIT_DIR/logs/$reflog.lock has + * no locking implications, we use the lock_file + * machinery here anyway because it does a lot of the + * work we need, including cleaning up if the program + * exits unexpectedly. + */ + if (hold_lock_file_for_update(&reflog_lock, log_file, 0) < 0) { + struct strbuf err = STRBUF_INIT; + unable_to_lock_message(log_file, errno, &err); + error("%s", err.buf); + strbuf_release(&err); + goto failure; + } + cb.newlog = fdopen_lock_file(&reflog_lock, "w"); + if (!cb.newlog) { + error("cannot fdopen %s (%s)", + get_lock_file_path(&reflog_lock), strerror(errno)); + goto failure; + } + } + + (*prepare_fn)(refname, oid, cb.policy_cb); + refs_for_each_reflog_ent(ref_store, refname, expire_reflog_ent, &cb); + (*cleanup_fn)(cb.policy_cb); + + if (!(flags & EXPIRE_REFLOGS_DRY_RUN)) { + /* + * It doesn't make sense to adjust a reference pointed + * to by a symbolic ref based on expiring entries in + * the symbolic reference's reflog. Nor can we update + * a reference if there are no remaining reflog + * entries. + */ + int update = (flags & EXPIRE_REFLOGS_UPDATE_REF) && + !(type & REF_ISSYMREF) && + !is_null_oid(&cb.last_kept_oid); + + if (close_lock_file_gently(&reflog_lock)) { + status |= error("couldn't write %s: %s", log_file, + strerror(errno)); + rollback_lock_file(&reflog_lock); + } else if (update && + (write_in_full(get_lock_file_fd(&lock->lk), + oid_to_hex(&cb.last_kept_oid), the_hash_algo->hexsz) < 0 || + write_str_in_full(get_lock_file_fd(&lock->lk), "\n") < 0 || + close_ref_gently(lock) < 0)) { + status |= error("couldn't write %s", + get_lock_file_path(&lock->lk)); + rollback_lock_file(&reflog_lock); + } else if (commit_lock_file(&reflog_lock)) { + status |= error("unable to write reflog '%s' (%s)", + log_file, strerror(errno)); + } else if (update && commit_ref(lock)) { + status |= error("couldn't set %s", lock->ref_name); + } + } + free(log_file); + unlock_ref(lock); + return status; + + failure: + rollback_lock_file(&reflog_lock); + free(log_file); + unlock_ref(lock); + return -1; +} + +static int files_init_db(struct ref_store *ref_store, struct strbuf *err) +{ + struct files_ref_store *refs = + files_downcast(ref_store, REF_STORE_WRITE, "init_db"); + struct strbuf sb = STRBUF_INIT; + + /* + * Create .git/refs/{heads,tags} + */ + files_ref_path(refs, &sb, "refs/heads"); + safe_create_dir(sb.buf, 1); + + strbuf_reset(&sb); + files_ref_path(refs, &sb, "refs/tags"); + safe_create_dir(sb.buf, 1); + + strbuf_release(&sb); + return 0; +} + +struct ref_storage_be refs_be_files = { + NULL, + "files", + files_ref_store_create, + files_init_db, + files_transaction_prepare, + files_transaction_finish, + files_transaction_abort, + files_initial_transaction_commit, + + files_pack_refs, + files_create_symref, + files_delete_refs, + files_rename_ref, + files_copy_ref, + + files_ref_iterator_begin, + files_read_raw_ref, + + files_reflog_iterator_begin, + files_for_each_reflog_ent, + files_for_each_reflog_ent_reverse, + files_reflog_exists, + files_create_reflog, + files_delete_reflog, + files_reflog_expire +}; |