[pull] master from git:master

Documentation/MyFirstContribution.adoc

@@ -52,6 +52,15 @@ respond to you. It's better to ask your questions in the channel so that you
 can be answered if you disconnect and so that others can learn from the
 conversation.
 
+==== https://discord.gg/GRFVkzgxRd[#discord] on Discord
+This is an unofficial Git Discord server for everyone, from people just
+starting out with Git to those who develop it. It's a great place to ask
+questions, share tips, and connect with the broader Git community in real time.
+
+The server has channels for general discussions and specific channels for those
+who use Git and those who develop it. The server's search functionality also
+allows you to find previous conversations and answers to common questions.
+
 [[getting-started]]
 == Getting Started
 

Documentation/RelNotes/2.52.0.adoc

@@ -37,6 +37,9 @@ Performance, Internal Implementation, Development Support etc.
  * Remove dependency on the_repository and other globals from the
    commit-graph code, and other changes unrelated to de-globaling.
 
+ * Discord has been added to the first contribution documentation as
+   another way to ask for help.
+
 
 Fixes since v2.51
 -----------------
@@ -110,6 +113,18 @@ including security updates, are included in this release.
    been corrected.
    (merge 8f32a5a6c0 jk/fetch-check-graph-objects-fix later to maint).
 
+ * "git fetch" can clobber a symref that is dangling when the
+   remote-tracking HEAD is set to auto update, which has been
+   corrected.
+
+ * "git describe <blob>" misbehaves and/or crashes in some corner
+   cases, which has been taught to exit with failure gracefully.
+   (merge 7c10e48e81 jk/describe-blob later to maint).
+
+ * Manual page for "gitk" is updated with the current maintainer's
+   name.
+   (merge bcb20dda83 js/doc-gitk-history later to maint).
+
  * Other code cleanup, docfix, build fix, etc.
    (merge 823d537fa7 kh/doc-git-log-markup-fix later to maint).
    (merge cf7efa4f33 rj/t6137-cygwin-fix later to maint).
@@ -118,3 +133,4 @@ including security updates, are included in this release.
    (merge 741f36c7d9 kr/clone-synopsis-fix later to maint).
    (merge a60203a015 dk/t7005-editor-updates later to maint).
    (merge 7d4a5fef7d ds/doc-count-objects-fix later to maint).
+   (merge 16684b6fae ps/reftable-libgit2-cleanup later to maint).

Documentation/gitk.adoc

@@ -163,16 +163,16 @@ used by default. If '$XDG_CONFIG_HOME' is not set it defaults to
 
 History
 -------
-Gitk was the first graphical repository browser. It's written in
-tcl/tk.
+Gitk was the first graphical repository browser, written by
+Paul Mackerras in Tcl/Tk.
 
 'gitk' is actually maintained as an independent project, but stable
 versions are distributed as part of the Git suite for the convenience
 of end users.
 
-gitk-git/ comes from Paul Mackerras's gitk project:
+`gitk-git/` comes from Johannes Sixt's gitk project:
 
-	git://ozlabs.org/~paulus/gitk
+	https://github.com/j6t/gitk
 
 SEE ALSO
 --------

builtin/describe.c

@@ -352,26 +352,24 @@ static void append_suffix(int depth, const struct object_id *oid, struct strbuf
 		    repo_find_unique_abbrev(the_repository, oid, abbrev));
 }
 
-static void describe_commit(struct object_id *oid, struct strbuf *dst)
+static void describe_commit(struct commit *cmit, struct strbuf *dst)
 {
-	struct commit *cmit, *gave_up_on = NULL;
+	struct commit *gave_up_on = NULL;
 	struct lazy_queue queue = LAZY_QUEUE_INIT;
 	struct commit_name *n;
 	struct possible_tag all_matches[MAX_TAGS];
 	unsigned int match_cnt = 0, annotated_cnt = 0, cur_match;
 	unsigned long seen_commits = 0;
 	unsigned int unannotated_cnt = 0;
 
-	cmit = lookup_commit_reference(the_repository, oid);
-
 	n = find_commit_name(&cmit->object.oid);
 	if (n && (tags || all || n->prio == 2)) {
 		/*
 		 * Exact match to an existing ref.
 		 */
 		append_name(n, dst);
 		if (n->misnamed || longformat)
-			append_suffix(0, n->tag ? get_tagged_oid(n->tag) : oid, dst);
+			append_suffix(0, n->tag ? get_tagged_oid(n->tag) : &cmit->object.oid, dst);
 		if (suffix)
 			strbuf_addstr(dst, suffix);
 		return;
@@ -528,39 +526,47 @@ static void describe_commit(struct object_id *oid, struct strbuf *dst)
 }
 
 struct process_commit_data {
-	struct object_id current_commit;
-	struct object_id looking_for;
+	struct commit *current_commit;
+	const struct object_id *looking_for;
 	struct strbuf *dst;
 	struct rev_info *revs;
 };
 
 static void process_commit(struct commit *commit, void *data)
 {
 	struct process_commit_data *pcd = data;
-	pcd->current_commit = commit->object.oid;
+	pcd->current_commit = commit;
 }
 
 static void process_object(struct object *obj, const char *path, void *data)
 {
 	struct process_commit_data *pcd = data;
 
-	if (oideq(&pcd->looking_for, &obj->oid) && !pcd->dst->len) {
+	if (oideq(pcd->looking_for, &obj->oid) && !pcd->dst->len) {
 		reset_revision_walk();
-		describe_commit(&pcd->current_commit, pcd->dst);
-		strbuf_addf(pcd->dst, ":%s", path);
+		if (pcd->current_commit) {
+			describe_commit(pcd->current_commit, pcd->dst);
+			strbuf_addf(pcd->dst, ":%s", path);
+		}
 		free_commit_list(pcd->revs->commits);
 		pcd->revs->commits = NULL;
 	}
 }
 
-static void describe_blob(struct object_id oid, struct strbuf *dst)
+static void describe_blob(const struct object_id *oid, struct strbuf *dst)
 {
 	struct rev_info revs;
 	struct strvec args = STRVEC_INIT;
-	struct process_commit_data pcd = { *null_oid(the_hash_algo), oid, dst, &revs};
+	struct object_id head_oid;
+	struct process_commit_data pcd = { NULL, oid, dst, &revs};
+
+	if (repo_get_oid(the_repository, "HEAD", &head_oid))
+		die(_("cannot search for blob '%s' on an unborn branch"),
+		    oid_to_hex(oid));
 
 	strvec_pushl(&args, "internal: The first arg is not parsed",
-		     "--objects", "--in-commit-order", "--reverse", "HEAD",
+		     "--objects", "--in-commit-order", "--reverse",
+		     oid_to_hex(&head_oid),
 		     NULL);
 
 	repo_init_revisions(the_repository, &revs, NULL);
@@ -574,6 +580,9 @@ static void describe_blob(struct object_id oid, struct strbuf *dst)
 	reset_revision_walk();
 	release_revisions(&revs);
 	strvec_clear(&args);
+
+	if (!dst->len)
+		die(_("blob '%s' not reachable from HEAD"), oid_to_hex(oid));
 }
 
 static void describe(const char *arg, int last_one)
@@ -590,10 +599,10 @@ static void describe(const char *arg, int last_one)
 	cmit = lookup_commit_reference_gently(the_repository, &oid, 1);
 
 	if (cmit)
-		describe_commit(&oid, &sb);
+		describe_commit(cmit, &sb);
 	else if (odb_read_object_info(the_repository->objects,
 				      &oid, NULL) == OBJ_BLOB)
-		describe_blob(oid, &sb);
+		describe_blob(&oid, &sb);
 	else
 		die(_("%s is neither a commit nor blob"), arg);
 

refs/files-backend.c

@@ -2515,13 +2515,37 @@ static enum ref_transaction_error split_symref_update(struct ref_update *update,
  */
 static enum ref_transaction_error check_old_oid(struct ref_update *update,
 						struct object_id *oid,
+						struct strbuf *referent,
 						struct strbuf *err)
 {
 	if (update->flags & REF_LOG_ONLY ||
-	    !(update->flags & REF_HAVE_OLD) ||
-	    oideq(oid, &update->old_oid))
+	    !(update->flags & REF_HAVE_OLD))
 		return 0;
 
+	if (oideq(oid, &update->old_oid)) {
+		/*
+		 * Normally matching the expected old oid is enough. Either we
+		 * found the ref at the expected state, or we are creating and
+		 * expect the null oid (and likewise found nothing).
+		 *
+		 * But there is one exception for the null oid: if we found a
+		 * symref pointing to nothing we'll also get the null oid. In
+		 * regular recursive mode, that's good (we'll write to what the
+		 * symref points to, which doesn't exist). But in no-deref
+		 * mode, it means we'll clobber the symref, even though the
+		 * caller asked for this to be a creation event. So flag
+		 * that case to preserve the dangling symref.
+		 */
+		if ((update->flags & REF_NO_DEREF) && referent->len &&
+		    is_null_oid(oid)) {
+			strbuf_addf(err, "cannot lock ref '%s': "
+				    "dangling symref already exists",
+				    ref_update_original_update_refname(update));
+			return REF_TRANSACTION_ERROR_CREATE_EXISTS;
+		}
+		return 0;
+	}
+
 	if (is_null_oid(&update->old_oid)) {
 		strbuf_addf(err, "cannot lock ref '%s': "
 			    "reference already exists",
@@ -2661,7 +2685,8 @@ static enum ref_transaction_error lock_ref_for_update(struct files_ref_store *re
 			if (update->old_target)
 				ret = ref_update_check_old_target(referent.buf, update, err);
 			else
-				ret = check_old_oid(update, &lock->old_oid, err);
+				ret = check_old_oid(update, &lock->old_oid,
+						    &referent, err);
 			if (ret)
 				goto out;
 		} else {
@@ -2693,7 +2718,8 @@ static enum ref_transaction_error lock_ref_for_update(struct files_ref_store *re
 			ret = REF_TRANSACTION_ERROR_EXPECTED_SYMREF;
 			goto out;
 		} else {
-			ret = check_old_oid(update, &lock->old_oid, err);
+			ret = check_old_oid(update, &lock->old_oid,
+					    &referent, err);
 			if  (ret) {
 				goto out;
 			}

refs/reftable-backend.c

@@ -1012,10 +1012,6 @@ static int prepare_transaction_update(struct write_transaction_table_arg **out,
 	if (!arg) {
 		struct reftable_addition *addition;
 
-		ret = reftable_stack_reload(be->stack);
-		if (ret)
-			return ret;
-
 		ret = reftable_stack_new_addition(&addition, be->stack,
 						  REFTABLE_STACK_NEW_ADDITION_RELOAD);
 		if (ret) {
@@ -1278,9 +1274,33 @@ static enum ref_transaction_error prepare_single_update(struct reftable_ref_stor
 		ret = ref_update_check_old_target(referent->buf, u, err);
 		if (ret)
 			return ret;
-	} else if ((u->flags & (REF_LOG_ONLY | REF_HAVE_OLD)) == REF_HAVE_OLD &&
-		   !oideq(&current_oid, &u->old_oid)) {
-		if (is_null_oid(&u->old_oid)) {
+	} else if ((u->flags & (REF_LOG_ONLY | REF_HAVE_OLD)) == REF_HAVE_OLD) {
+		if (oideq(&current_oid, &u->old_oid)) {
+			/*
+			 * Normally matching the expected old oid is enough. Either we
+			 * found the ref at the expected state, or we are creating and
+			 * expect the null oid (and likewise found nothing).
+			 *
+			 * But there is one exception for the null oid: if we found a
+			 * symref pointing to nothing we'll also get the null oid. In
+			 * regular recursive mode, that's good (we'll write to what the
+			 * symref points to, which doesn't exist). But in no-deref
+			 * mode, it means we'll clobber the symref, even though the
+			 * caller asked for this to be a creation event. So flag
+			 * that case to preserve the dangling symref.
+			 *
+			 * Everything else is OK and we can fall through to the
+			 * end of the conditional chain.
+			 */
+			if ((u->flags & REF_NO_DEREF) &&
+			    referent->len &&
+			    is_null_oid(&u->old_oid)) {
+				strbuf_addf(err, _("cannot lock ref '%s': "
+					    "dangling symref already exists"),
+					    ref_update_original_update_refname(u));
+				return REF_TRANSACTION_ERROR_CREATE_EXISTS;
+			}
+		} else if (is_null_oid(&u->old_oid)) {
 			strbuf_addf(err, _("cannot lock ref '%s': "
 					   "reference already exists"),
 				    ref_update_original_update_refname(u));
@@ -1974,7 +1994,8 @@ static int reftable_be_rename_ref(struct ref_store *ref_store,
 	ret = backend_for(&arg.be, refs, newrefname, &newrefname, 1);
 	if (ret)
 		goto done;
-	ret = reftable_stack_add(arg.be->stack, &write_copy_table, &arg);
+	ret = reftable_stack_add(arg.be->stack, &write_copy_table, &arg,
+				 REFTABLE_STACK_NEW_ADDITION_RELOAD);
 
 done:
 	assert(ret != REFTABLE_API_ERROR);
@@ -2003,7 +2024,8 @@ static int reftable_be_copy_ref(struct ref_store *ref_store,
 	ret = backend_for(&arg.be, refs, newrefname, &newrefname, 1);
 	if (ret)
 		goto done;
-	ret = reftable_stack_add(arg.be->stack, &write_copy_table, &arg);
+	ret = reftable_stack_add(arg.be->stack, &write_copy_table, &arg,
+				 REFTABLE_STACK_NEW_ADDITION_RELOAD);
 
 done:
 	assert(ret != REFTABLE_API_ERROR);
@@ -2375,7 +2397,8 @@ static int reftable_be_create_reflog(struct ref_store *ref_store,
 		goto done;
 	arg.stack = be->stack;
 
-	ret = reftable_stack_add(be->stack, &write_reflog_existence_table, &arg);
+	ret = reftable_stack_add(be->stack, &write_reflog_existence_table, &arg,
+				 REFTABLE_STACK_NEW_ADDITION_RELOAD);
 
 done:
 	return ret;
@@ -2446,7 +2469,8 @@ static int reftable_be_delete_reflog(struct ref_store *ref_store,
 		return ret;
 	arg.stack = be->stack;
 
-	ret = reftable_stack_add(be->stack, &write_reflog_delete_table, &arg);
+	ret = reftable_stack_add(be->stack, &write_reflog_delete_table, &arg,
+				 REFTABLE_STACK_NEW_ADDITION_RELOAD);
 
 	assert(ret != REFTABLE_API_ERROR);
 	return ret;
@@ -2567,15 +2591,16 @@ static int reftable_be_reflog_expire(struct ref_store *ref_store,
 	if (ret < 0)
 		goto done;
 
-	ret = reftable_stack_init_log_iterator(be->stack, &it);
+	ret = reftable_stack_new_addition(&add, be->stack,
+					  REFTABLE_STACK_NEW_ADDITION_RELOAD);
 	if (ret < 0)
 		goto done;
 
-	ret = reftable_iterator_seek_log(&it, refname);
+	ret = reftable_stack_init_log_iterator(be->stack, &it);
 	if (ret < 0)
 		goto done;
 
-	ret = reftable_stack_new_addition(&add, be->stack, 0);
+	ret = reftable_iterator_seek_log(&it, refname);
 	if (ret < 0)
 		goto done;
 

reftable/reftable-stack.h

@@ -68,12 +68,15 @@ int reftable_addition_commit(struct reftable_addition *add);
  * transaction. Releases the lock if held. */
 void reftable_addition_destroy(struct reftable_addition *add);
 
-/* add a new table to the stack. The write_table function must call
- * reftable_writer_set_limits, add refs and return an error value. */
+/*
+ * Add a new table to the stack. The write_table function must call
+ * reftable_writer_set_limits, add refs and return an error value.
+ * The flags are passed through to `reftable_stack_new_addition()`.
+ */
 int reftable_stack_add(struct reftable_stack *st,
 		       int (*write_table)(struct reftable_writer *wr,
 					  void *write_arg),
-		       void *write_arg);
+		       void *write_arg, unsigned flags);
 
 struct reftable_iterator;
 

reftable/reftable-writer.h

@@ -156,7 +156,7 @@ int reftable_writer_add_ref(struct reftable_writer *w,
   the records before adding them, reordering the records array passed in.
 */
 int reftable_writer_add_refs(struct reftable_writer *w,
-			     struct reftable_ref_record *refs, int n);
+			     struct reftable_ref_record *refs, size_t n);
 
 /*
   adds reftable_log_records. Log records are keyed by (refname, decreasing
@@ -171,7 +171,7 @@ int reftable_writer_add_log(struct reftable_writer *w,
   the records before adding them, reordering records array passed in.
 */
 int reftable_writer_add_logs(struct reftable_writer *w,
-			     struct reftable_log_record *logs, int n);
+			     struct reftable_log_record *logs, size_t n);
 
 /* reftable_writer_close finalizes the reftable. The writer is retained so
  * statistics can be inspected. */