Merge branch 'nd/per-worktree-ref-iteration'

The code to traverse objects for reachability, used to decide what
objects are unreferenced and expendable, have been taught to also
consider per-worktree refs of other worktrees as starting points to
prevent data loss.

* nd/per-worktree-ref-iteration:
  git-worktree.txt: correct linkgit command name
  reflog expire: cover reflog from all worktrees
  fsck: check HEAD and reflog from other worktrees
  fsck: move fsck_head_link() to get_default_heads() to avoid some globals
  revision.c: better error reporting on ref from different worktrees
  revision.c: correct a parameter name
  refs: new ref types to make per-worktree refs visible to all worktrees
  Add a place for (not) sharing stuff between worktrees
  refs.c: indent with tabs, not spaces

2 files changed, 89 insertions, 25 deletions

diff --git a/builtin/fsck.c b/builtin/fsck.c
index 06eb421720..3c3e0f06e7 100644
--- a/builtin/fsck.c
+++ b/builtin/fsck.c
@@ -19,6 +19,7 @@
 #include "packfile.h"
 #include "object-store.h"
 #include "run-command.h"
+#include "worktree.h"
 
 #define REACHABLE 0x0001
 #define SEEN      0x0002
@@ -36,8 +37,6 @@ static int check_strict;
 static int keep_cache_objects;
 static struct fsck_options fsck_walk_options = FSCK_OPTIONS_DEFAULT;
 static struct fsck_options fsck_obj_options = FSCK_OPTIONS_DEFAULT;
-static struct object_id head_oid;
-static const char *head_points_at;
 static int errors_found;
 static int write_lost_and_found;
 static int verbose;
@@ -446,7 +445,11 @@ static int fsck_handle_reflog_ent(struct object_id *ooid, struct object_id *noid
 static int fsck_handle_reflog(const char *logname, const struct object_id *oid,
 			      int flag, void *cb_data)
 {
-	for_each_reflog_ent(logname, fsck_handle_reflog_ent, (void *)logname);
+	struct strbuf refname = STRBUF_INIT;
+
+	strbuf_worktree_ref(cb_data, &refname, logname);
+	for_each_reflog_ent(refname.buf, fsck_handle_reflog_ent, refname.buf);
+	strbuf_release(&refname);
 	return 0;
 }
 
@@ -484,13 +487,34 @@ static int fsck_handle_ref(const char *refname, const struct object_id *oid,
 	return 0;
 }
 
+static int fsck_head_link(const char *head_ref_name,
+			  const char **head_points_at,
+			  struct object_id *head_oid);
+
 static void get_default_heads(void)
 {
-	if (head_points_at && !is_null_oid(&head_oid))
-		fsck_handle_ref("HEAD", &head_oid, 0, NULL);
+	struct worktree **worktrees, **p;
+	const char *head_points_at;
+	struct object_id head_oid;
+
 	for_each_rawref(fsck_handle_ref, NULL);
-	if (include_reflogs)
-		for_each_reflog(fsck_handle_reflog, NULL);
+
+	worktrees = get_worktrees(0);
+	for (p = worktrees; *p; p++) {
+		struct worktree *wt = *p;
+		struct strbuf ref = STRBUF_INIT;
+
+		strbuf_worktree_ref(wt, &ref, "HEAD");
+		fsck_head_link(ref.buf, &head_points_at, &head_oid);
+		if (head_points_at && !is_null_oid(&head_oid))
+			fsck_handle_ref(ref.buf, &head_oid, 0, NULL);
+		strbuf_release(&ref);
+
+		if (include_reflogs)
+			refs_for_each_reflog(get_worktree_ref_store(wt),
+					     fsck_handle_reflog, wt);
+	}
+	free_worktrees(worktrees);
 
 	/*
 	 * Not having any default heads isn't really fatal, but
@@ -579,33 +603,36 @@ static void fsck_object_dir(const char *path)
 	stop_progress(&progress);
 }
 
-static int fsck_head_link(void)
+static int fsck_head_link(const char *head_ref_name,
+			  const char **head_points_at,
+			  struct object_id *head_oid)
 {
 	int null_is_error = 0;
 
 	if (verbose)
-		fprintf(stderr, "Checking HEAD link\n");
+		fprintf(stderr, "Checking %s link\n", head_ref_name);
 
-	head_points_at = resolve_ref_unsafe("HEAD", 0, &head_oid, NULL);
-	if (!head_points_at) {
+	*head_points_at = resolve_ref_unsafe(head_ref_name, 0, head_oid, NULL);
+	if (!*head_points_at) {
 		errors_found |= ERROR_REFS;
-		return error("Invalid HEAD");
+		return error("Invalid %s", head_ref_name);
 	}
-	if (!strcmp(head_points_at, "HEAD"))
+	if (!strcmp(*head_points_at, head_ref_name))
 		/* detached HEAD */
 		null_is_error = 1;
-	else if (!starts_with(head_points_at, "refs/heads/")) {
+	else if (!starts_with(*head_points_at, "refs/heads/")) {
 		errors_found |= ERROR_REFS;
-		return error("HEAD points to something strange (%s)",
-			     head_points_at);
+		return error("%s points to something strange (%s)",
+			     head_ref_name, *head_points_at);
 	}
-	if (is_null_oid(&head_oid)) {
+	if (is_null_oid(head_oid)) {
 		if (null_is_error) {
 			errors_found |= ERROR_REFS;
-			return error("HEAD: detached HEAD points at nothing");
+			return error("%s: detached HEAD points at nothing",
+				     head_ref_name);
 		}
-		fprintf(stderr, "notice: HEAD points to an unborn branch (%s)\n",
-			head_points_at + 11);
+		fprintf(stderr, "notice: %s points to an unborn branch (%s)\n",
+			head_ref_name, *head_points_at + 11);
 	}
 	return 0;
 }
@@ -720,7 +747,6 @@ int cmd_fsck(int argc, const char **argv, const char *prefix)
 
 	git_config(fsck_config, NULL);
 
-	fsck_head_link();
 	if (connectivity_only) {
 		for_each_loose_object(mark_loose_for_connectivity, NULL, 0);
 		for_each_packed_object(mark_packed_for_connectivity, NULL, 0);
diff --git a/builtin/reflog.c b/builtin/reflog.c
index b5941c1ff3..7a85e4b164 100644
--- a/builtin/reflog.c
+++ b/builtin/reflog.c
@@ -10,6 +10,7 @@
 #include "diff.h"
 #include "revision.h"
 #include "reachable.h"
+#include "worktree.h"
 
 /* NEEDSWORK: switch to using parse_options */
 static const char reflog_expire_usage[] =
@@ -52,6 +53,7 @@ struct collect_reflog_cb {
 	struct collected_reflog **e;
 	int alloc;
 	int nr;
+	struct worktree *wt;
 };
 
 /* Remember to update object flag allocation in object.h */
@@ -330,13 +332,27 @@ static int push_tip_to_list(const char *refname, const struct object_id *oid,
 	return 0;
 }
 
+static int is_head(const char *refname)
+{
+	switch (ref_type(refname)) {
+	case REF_TYPE_OTHER_PSEUDOREF:
+	case REF_TYPE_MAIN_PSEUDOREF:
+		if (parse_worktree_ref(refname, NULL, NULL, &refname))
+			BUG("not a worktree ref: %s", refname);
+		break;
+	default:
+		break;
+	}
+	return !strcmp(refname, "HEAD");
+}
+
 static void reflog_expiry_prepare(const char *refname,
 				  const struct object_id *oid,
 				  void *cb_data)
 {
 	struct expire_reflog_policy_cb *cb = cb_data;
 
-	if (!cb->cmd.expire_unreachable || !strcmp(refname, "HEAD")) {
+	if (!cb->cmd.expire_unreachable || is_head(refname)) {
 		cb->tip_commit = NULL;
 		cb->unreachable_expire_kind = UE_HEAD;
 	} else {
@@ -388,8 +404,19 @@ static int collect_reflog(const char *ref, const struct object_id *oid, int unus
 {
 	struct collected_reflog *e;
 	struct collect_reflog_cb *cb = cb_data;
+	struct strbuf newref = STRBUF_INIT;
+
+	/*
+	 * Avoid collecting the same shared ref multiple times because
+	 * they are available via all worktrees.
+	 */
+	if (!cb->wt->is_current && ref_type(ref) == REF_TYPE_NORMAL)
+		return 0;
+
+	strbuf_worktree_ref(cb->wt, &newref, ref);
+	FLEX_ALLOC_STR(e, reflog, newref.buf);
+	strbuf_release(&newref);
 
-	FLEX_ALLOC_STR(e, reflog, ref);
 	oidcpy(&e->oid, oid);
 	ALLOC_GROW(cb->e, cb->nr + 1, cb->alloc);
 	cb->e[cb->nr++] = e;
@@ -512,7 +539,7 @@ static int cmd_reflog_expire(int argc, const char **argv, const char *prefix)
 {
 	struct expire_reflog_policy_cb cb;
 	timestamp_t now = time(NULL);
-	int i, status, do_all;
+	int i, status, do_all, all_worktrees = 1;
 	int explicit_expiry = 0;
 	unsigned int flags = 0;
 
@@ -549,6 +576,8 @@ static int cmd_reflog_expire(int argc, const char **argv, const char *prefix)
 			flags |= EXPIRE_REFLOGS_UPDATE_REF;
 		else if (!strcmp(arg, "--all"))
 			do_all = 1;
+		else if (!strcmp(arg, "--single-worktree"))
+			all_worktrees = 0;
 		else if (!strcmp(arg, "--verbose"))
 			flags |= EXPIRE_REFLOGS_VERBOSE;
 		else if (!strcmp(arg, "--")) {
@@ -577,10 +606,19 @@ static int cmd_reflog_expire(int argc, const char **argv, const char *prefix)
 
 	if (do_all) {
 		struct collect_reflog_cb collected;
+		struct worktree **worktrees, **p;
 		int i;
 
 		memset(&collected, 0, sizeof(collected));
-		for_each_reflog(collect_reflog, &collected);
+		worktrees = get_worktrees(0);
+		for (p = worktrees; *p; p++) {
+			if (!all_worktrees && !(*p)->is_current)
+				continue;
+			collected.wt = *p;
+			refs_for_each_reflog(get_worktree_ref_store(*p),
+					     collect_reflog, &collected);
+		}
+		free_worktrees(worktrees);
 		for (i = 0; i < collected.nr; i++) {
 			struct collected_reflog *e = collected.e[i];
 			set_reflog_expiry_param(&cb.cmd, explicit_expiry, e->reflog);