1 files changed, 303 insertions, 0 deletions
diff --git a/worktree.c b/worktree.c
new file mode 100644
index 0000000000..e2a94e0476
--- /dev/null
+++ b/worktree.c
@@ -0,0 +1,303 @@
+#include "cache.h"
+#include "refs.h"
+#include "strbuf.h"
+#include "worktree.h"
+#include "dir.h"
+#include "wt-status.h"
+
+void free_worktrees(struct worktree **worktrees)
+{
+	int i = 0;
+
+	for (i = 0; worktrees[i]; i++) {
+		free(worktrees[i]->path);
+		free(worktrees[i]->id);
+		free(worktrees[i]->head_ref);
+		free(worktrees[i]);
+	}
+	free (worktrees);
+}
+
+/*
+ * read 'path_to_ref' into 'ref'.  Also if is_detached is not NULL,
+ * set is_detached to 1 (0) if the ref is detached (is not detached).
+ *
+ * $GIT_COMMON_DIR/$symref (e.g. HEAD) is practically outside $GIT_DIR so
+ * for linked worktrees, `resolve_ref_unsafe()` won't work (it uses
+ * git_path). Parse the ref ourselves.
+ *
+ * return -1 if the ref is not a proper ref, 0 otherwise (success)
+ */
+static int parse_ref(char *path_to_ref, struct strbuf *ref, int *is_detached)
+{
+	if (is_detached)
+		*is_detached = 0;
+	if (!strbuf_readlink(ref, path_to_ref, 0)) {
+		/* HEAD is symbolic link */
+		if (!starts_with(ref->buf, "refs/") ||
+				check_refname_format(ref->buf, 0))
+			return -1;
+	} else if (strbuf_read_file(ref, path_to_ref, 0) >= 0) {
+		/* textual symref or detached */
+		if (!starts_with(ref->buf, "ref:")) {
+			if (is_detached)
+				*is_detached = 1;
+		} else {
+			strbuf_remove(ref, 0, strlen("ref:"));
+			strbuf_trim(ref);
+			if (check_refname_format(ref->buf, 0))
+				return -1;
+		}
+	} else
+		return -1;
+	return 0;
+}
+
+/**
+ * Add the head_sha1 and head_ref (if not detached) to the given worktree
+ */
+static void add_head_info(struct strbuf *head_ref, struct worktree *worktree)
+{
+	if (head_ref->len) {
+		if (worktree->is_detached) {
+			get_sha1_hex(head_ref->buf, worktree->head_sha1);
+		} else {
+			resolve_ref_unsafe(head_ref->buf, 0, worktree->head_sha1, NULL);
+			worktree->head_ref = strbuf_detach(head_ref, NULL);
+		}
+	}
+}
+
+/**
+ * get the main worktree
+ */
+static struct worktree *get_main_worktree(void)
+{
+	struct worktree *worktree = NULL;
+	struct strbuf path = STRBUF_INIT;
+	struct strbuf worktree_path = STRBUF_INIT;
+	struct strbuf head_ref = STRBUF_INIT;
+	int is_bare = 0;
+	int is_detached = 0;
+
+	strbuf_addstr(&worktree_path, absolute_path(get_git_common_dir()));
+	is_bare = !strbuf_strip_suffix(&worktree_path, "/.git");
+	if (is_bare)
+		strbuf_strip_suffix(&worktree_path, "/.");
+
+	strbuf_addf(&path, "%s/HEAD", get_git_common_dir());
+
+	if (parse_ref(path.buf, &head_ref, &is_detached) < 0)
+		goto done;
+
+	worktree = xmalloc(sizeof(struct worktree));
+	worktree->path = strbuf_detach(&worktree_path, NULL);
+	worktree->id = NULL;
+	worktree->is_bare = is_bare;
+	worktree->head_ref = NULL;
+	worktree->is_detached = is_detached;
+	worktree->is_current = 0;
+	add_head_info(&head_ref, worktree);
+
+done:
+	strbuf_release(&path);
+	strbuf_release(&worktree_path);
+	strbuf_release(&head_ref);
+	return worktree;
+}
+
+static struct worktree *get_linked_worktree(const char *id)
+{
+	struct worktree *worktree = NULL;
+	struct strbuf path = STRBUF_INIT;
+	struct strbuf worktree_path = STRBUF_INIT;
+	struct strbuf head_ref = STRBUF_INIT;
+	int is_detached = 0;
+
+	if (!id)
+		die("Missing linked worktree name");
+
+	strbuf_git_common_path(&path, "worktrees/%s/gitdir", id);
+	if (strbuf_read_file(&worktree_path, path.buf, 0) <= 0)
+		/* invalid gitdir file */
+		goto done;
+
+	strbuf_rtrim(&worktree_path);
+	if (!strbuf_strip_suffix(&worktree_path, "/.git")) {
+		strbuf_reset(&worktree_path);
+		strbuf_addstr(&worktree_path, absolute_path("."));
+		strbuf_strip_suffix(&worktree_path, "/.");
+	}
+
+	strbuf_reset(&path);
+	strbuf_addf(&path, "%s/worktrees/%s/HEAD", get_git_common_dir(), id);
+
+	if (parse_ref(path.buf, &head_ref, &is_detached) < 0)
+		goto done;
+
+	worktree = xmalloc(sizeof(struct worktree));
+	worktree->path = strbuf_detach(&worktree_path, NULL);
+	worktree->id = xstrdup(id);
+	worktree->is_bare = 0;
+	worktree->head_ref = NULL;
+	worktree->is_detached = is_detached;
+	worktree->is_current = 0;
+	add_head_info(&head_ref, worktree);
+
+done:
+	strbuf_release(&path);
+	strbuf_release(&worktree_path);
+	strbuf_release(&head_ref);
+	return worktree;
+}
+
+static void mark_current_worktree(struct worktree **worktrees)
+{
+	char *git_dir = xstrdup(absolute_path(get_git_dir()));
+	int i;
+
+	for (i = 0; worktrees[i]; i++) {
+		struct worktree *wt = worktrees[i];
+		const char *wt_git_dir = get_worktree_git_dir(wt);
+
+		if (!fspathcmp(git_dir, absolute_path(wt_git_dir))) {
+			wt->is_current = 1;
+			break;
+		}
+	}
+	free(git_dir);
+}
+
+struct worktree **get_worktrees(void)
+{
+	struct worktree **list = NULL;
+	struct strbuf path = STRBUF_INIT;
+	DIR *dir;
+	struct dirent *d;
+	int counter = 0, alloc = 2;
+
+	list = xmalloc(alloc * sizeof(struct worktree *));
+
+	if ((list[counter] = get_main_worktree()))
+		counter++;
+
+	strbuf_addf(&path, "%s/worktrees", get_git_common_dir());
+	dir = opendir(path.buf);
+	strbuf_release(&path);
+	if (dir) {
+		while ((d = readdir(dir)) != NULL) {
+			struct worktree *linked = NULL;
+			if (is_dot_or_dotdot(d->d_name))
+				continue;
+
+			if ((linked = get_linked_worktree(d->d_name))) {
+				ALLOC_GROW(list, counter + 1, alloc);
+				list[counter++] = linked;
+			}
+		}
+		closedir(dir);
+	}
+	ALLOC_GROW(list, counter + 1, alloc);
+	list[counter] = NULL;
+
+	mark_current_worktree(list);
+	return list;
+}
+
+const char *get_worktree_git_dir(const struct worktree *wt)
+{
+	if (!wt)
+		return get_git_dir();
+	else if (!wt->id)
+		return get_git_common_dir();
+	else
+		return git_common_path("worktrees/%s", wt->id);
+}
+
+int is_worktree_being_rebased(const struct worktree *wt,
+			      const char *target)
+{
+	struct wt_status_state state;
+	int found_rebase;
+
+	memset(&state, 0, sizeof(state));
+	found_rebase = wt_status_check_rebase(wt, &state) &&
+		((state.rebase_in_progress ||
+		  state.rebase_interactive_in_progress) &&
+		 state.branch &&
+		 starts_with(target, "refs/heads/") &&
+		 !strcmp(state.branch, target + strlen("refs/heads/")));
+	free(state.branch);
+	free(state.onto);
+	return found_rebase;
+}
+
+int is_worktree_being_bisected(const struct worktree *wt,
+			       const char *target)
+{
+	struct wt_status_state state;
+	int found_rebase;
+
+	memset(&state, 0, sizeof(state));
+	found_rebase = wt_status_check_bisect(wt, &state) &&
+		state.branch &&
+		starts_with(target, "refs/heads/") &&
+		!strcmp(state.branch, target + strlen("refs/heads/"));
+	free(state.branch);
+	return found_rebase;
+}
+
+/*
+ * note: this function should be able to detect shared symref even if
+ * HEAD is temporarily detached (e.g. in the middle of rebase or
+ * bisect). New commands that do similar things should update this
+ * function as well.
+ */
+const struct worktree *find_shared_symref(const char *symref,
+					  const char *target)
+{
+	const struct worktree *existing = NULL;
+	struct strbuf path = STRBUF_INIT;
+	struct strbuf sb = STRBUF_INIT;
+	static struct worktree **worktrees;
+	int i = 0;
+
+	if (worktrees)
+		free_worktrees(worktrees);
+	worktrees = get_worktrees();
+
+	for (i = 0; worktrees[i]; i++) {
+		struct worktree *wt = worktrees[i];
+
+		if (wt->is_detached && !strcmp(symref, "HEAD")) {
+			if (is_worktree_being_rebased(wt, target)) {
+				existing = wt;
+				break;
+			}
+			if (is_worktree_being_bisected(wt, target)) {
+				existing = wt;
+				break;
+			}
+		}
+
+		strbuf_reset(&path);
+		strbuf_reset(&sb);
+		strbuf_addf(&path, "%s/%s",
+			    get_worktree_git_dir(wt),
+			    symref);
+
+		if (parse_ref(path.buf, &sb, NULL)) {
+			continue;
+		}
+
+		if (!strcmp(sb.buf, target)) {
+			existing = wt;
+			break;
+		}
+	}
+
+	strbuf_release(&path);
+	strbuf_release(&sb);
+
+	return existing;
+}