Clean up work-tree handling

The old version of work-tree support was an unholy mess, barely readable,
and not to the point.

For example, why do you have to provide a worktree, when it is not used?
As in "git status".  Now it works.

Another riddle was: if you can have work trees inside the git dir, why
are some programs complaining that they need a work tree?

IOW it is allowed to call

	$ git --git-dir=../ --work-tree=. bla

when you really want to.  In this case, you are both in the git directory
and in the working tree.  So, programs have to actually test for the right
thing, namely if they are inside a working tree, and not if they are
inside a git directory.

Also, GIT_DIR=../.git should behave the same as if no GIT_DIR was
specified, unless there is a repository in the current working directory.
It does now.

The logic to determine if a repository is bare, or has a work tree
(tertium non datur), is this:

--work-tree=bla overrides GIT_WORK_TREE, which overrides core.bare = true,
which overrides core.worktree, which overrides GIT_DIR/.. when GIT_DIR
ends in /.git, which overrides the directory in which .git/ was found.

In related news, a long standing bug was fixed: when in .git/bla/x.git/,
which is a bare repository, git formerly assumed ../.. to be the
appropriate git dir.  This problem was reported by Shawn Pearce to have
caused much pain, where a colleague mistakenly ran "git init" in "/" a
long time ago, and bare repositories just would not work.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 11 insertions, 37 deletions

diff --git a/builtin-init-db.c b/builtin-init-db.c
index 66ddaebcc..0d9b1e055 100644
--- a/builtin-init-db.c
+++ b/builtin-init-db.c
@@ -174,36 +174,7 @@ static void copy_templates(const char *git_dir, int len, const char *template_di
 	closedir(dir);
 }
 
-/*
- * Get the full path to the working tree specified in $GIT_WORK_TREE
- * or NULL if no working tree is specified.
- */
-static const char *get_work_tree(void)
-{
-	const char *git_work_tree;
-	char cwd[PATH_MAX];
-	static char worktree[PATH_MAX];
-
-	git_work_tree = getenv(GIT_WORK_TREE_ENVIRONMENT);
-	if (!git_work_tree)
-		return NULL;
-	if (!getcwd(cwd, sizeof(cwd)))
-		die("Unable to read current working directory");
-	if (chdir(git_work_tree))
-		die("Cannot change directory to specified working tree '%s'",
-			git_work_tree);
-	if (git_work_tree[0] != '/') {
-		if (!getcwd(worktree, sizeof(worktree)))
-			die("Unable to read current working directory");
-		git_work_tree = worktree;
-	}
-	if (chdir(cwd))
-		die("Cannot come back to cwd");
-	return git_work_tree;
-}
-
-static int create_default_files(const char *git_dir, const char *git_work_tree,
-	const char *template_path)
+static int create_default_files(const char *git_dir, const char *template_path)
 {
 	unsigned len = strlen(git_dir);
 	static char path[PATH_MAX];
@@ -282,16 +253,16 @@ static int create_default_files(const char *git_dir, const char *git_work_tree,
 	}
 	git_config_set("core.filemode", filemode ? "true" : "false");
 
-	if (is_bare_repository() && !git_work_tree) {
+	if (is_bare_repository())
 		git_config_set("core.bare", "true");
-	}
 	else {
+		const char *work_tree = get_git_work_tree();
 		git_config_set("core.bare", "false");
 		/* allow template config file to override the default */
 		if (log_all_ref_updates == -1)
 		    git_config_set("core.logallrefupdates", "true");
-		if (git_work_tree)
-			git_config_set("core.worktree", git_work_tree);
+		if (work_tree != git_work_tree_cfg)
+			git_config_set("core.worktree", work_tree);
 	}
 	return reinit;
 }
@@ -308,7 +279,6 @@ static const char init_db_usage[] =
 int cmd_init_db(int argc, const char **argv, const char *prefix)
 {
 	const char *git_dir;
-	const char *git_work_tree;
 	const char *sha1_dir;
 	const char *template_dir = NULL;
 	char *path;
@@ -329,7 +299,11 @@ int cmd_init_db(int argc, const char **argv, const char *prefix)
 			usage(init_db_usage);
 	}
 
-	git_work_tree = get_work_tree();
+	git_work_tree_cfg = xcalloc(PATH_MAX, 1);
+	if (!getcwd(git_work_tree_cfg, PATH_MAX))
+		die ("Cannot access current working directory.");
+	if (access(get_git_work_tree(), X_OK))
+		die ("Cannot access work tree '%s'", get_git_work_tree());
 
 	/*
 	 * Set up the default .git directory contents
@@ -346,7 +320,7 @@ int cmd_init_db(int argc, const char **argv, const char *prefix)
 	 */
 	check_repository_format();
 
-	reinit = create_default_files(git_dir, git_work_tree, template_dir);
+	reinit = create_default_files(git_dir, template_dir);
 
 	/*
 	 * And set up the object store.