Fix initialization of a bare repository

Here is my attempt to fix this with a minimally intrusive patch.

 * As "git --bare init" cannot tell if it was called with --bare or
   just "GIT_DIR=. git init", I added an explicit assignment of
   is_bare_repository_cfg on the codepath for "git --bare".

 * GIT_WORK_TREE alone without GIT_DIR does not make any sense,
   nor GIT_WORK_TREE with an explicit "git --bare".  Catch that
   mistake.  It might make sense to move this check to "git.c"
   side as well, but I tried to shoot for the minimum change for
   now.

 * Some scripts, especially from the olden days, rely on
   traditional GIT_DIR behaviour in "git init".  Namely, these
   are some notable patterns:

   (create a bare repository)
   - mkdir some.git && cd some.git && GIT_DIR=. git init
   - mkdir some.git && cd some.git && git --bare init

   (create a non-bare repository)
   - mkdir .git && GIT_DIR=.git git init
   - mkdir .git && GIT_DIR=`pwd`/.git git init

This comes with a new test script and also passes the existing
test suite, but there may be cases that are still broken with
the current tip of master and this patch does not yet fix.  I'd
appreciate help in straightening this mess out.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-init-db.c

@@ -267,6 +267,44 @@ static int create_default_files(const char *git_dir, const char *template_path)
 	return reinit;
 }
 
+static void guess_repository_type(const char *git_dir)
+{
+	char cwd[PATH_MAX];
+	const char *slash;
+
+	if (0 <= is_bare_repository_cfg)
+		return;
+	if (!git_dir)
+		return;
+
+	/*
+	 * "GIT_DIR=. git init" is always bare.
+	 * "GIT_DIR=`pwd` git init" too.
+	 */
+	if (!strcmp(".", git_dir))
+		goto force_bare;
+	if (!getcwd(cwd, sizeof(cwd)))
+		die("cannot tell cwd");
+	if (!strcmp(git_dir, cwd))
+		goto force_bare;
+	/*
+	 * "GIT_DIR=.git or GIT_DIR=something/.git is usually not.
+	 */
+	if (!strcmp(git_dir, ".git"))
+		return;
+	slash = strrchr(git_dir, '/');
+	if (slash && !strcmp(slash, "/.git"))
+		return;
+
+	/*
+	 * Otherwise it is often bare.  At this point
+	 * we are just guessing.
+	 */
+ force_bare:
+	is_bare_repository_cfg = 1;
+	return;
+}
+
 static const char init_db_usage[] =
 "git-init [-q | --quiet] [--template=<template-directory>] [--shared]";
 
@@ -299,11 +337,28 @@ int cmd_init_db(int argc, const char **argv, const char *prefix)
 			usage(init_db_usage);
 	}
 
-	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());
+	/*
+	 * GIT_WORK_TREE makes sense only in conjunction with GIT_DIR
+	 * without --bare.  Catch the error early.
+	 */
+	git_dir = getenv(GIT_DIR_ENVIRONMENT);
+	if ((!git_dir || is_bare_repository_cfg == 1)
+	    && getenv(GIT_WORK_TREE_ENVIRONMENT))
+		die("%s (or --work-tree=<directory>) not allowed without "
+		    "specifying %s (or --git-dir=<directory>)",
+		    GIT_WORK_TREE_ENVIRONMENT,
+		    GIT_DIR_ENVIRONMENT);
+
+	guess_repository_type(git_dir);
+
+	if (is_bare_repository_cfg <= 0) {
+		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

git.c

@@ -93,6 +93,7 @@ static int handle_options(const char*** argv, int* argc, int* envchanged)
 				*envchanged = 1;
 		} else if (!strcmp(cmd, "--bare")) {
 			static char git_dir[PATH_MAX+1];
+			is_bare_repository_cfg = 1;
 			setenv(GIT_DIR_ENVIRONMENT, getcwd(git_dir, sizeof(git_dir)), 1);
 			if (envchanged)
 				*envchanged = 1;

t/t0001-init.sh

@@ -0,0 +1,116 @@
+#!/bin/sh
+
+test_description='git init'
+
+. ./test-lib.sh
+
+check_config () {
+	if test -d "$1" && test -f "$1/config" && test -d "$1/refs"
+	then
+		: happy
+	else
+		echo "expected a directory $1, a file $1/config and $1/refs"
+		return 1
+	fi
+	bare=$(GIT_CONFIG="$1/config" git config --bool core.bare)
+	worktree=$(GIT_CONFIG="$1/config" git config core.worktree) ||
+	worktree=unset
+
+	test "$bare" = "$2" && test "$worktree" = "$3" || {
+		echo "expected bare=$2 worktree=$3"
+		echo "     got bare=$bare worktree=$worktree"
+		return 1
+	}
+}
+
+test_expect_success 'plain' '
+	(
+		unset GIT_DIR GIT_WORK_TREE &&
+		mkdir plain &&
+		cd plain &&
+		git init
+	) &&
+	check_config plain/.git false unset
+'
+
+test_expect_success 'plain with GIT_WORK_TREE' '
+	if (
+		unset GIT_DIR &&
+		mkdir plain-wt &&
+		cd plain-wt &&
+		GIT_WORK_TREE=$(pwd) git init
+	)
+	then
+		echo Should have failed -- GIT_WORK_TREE should not be used
+		false
+	fi
+'
+
+test_expect_success 'plain bare' '
+	(
+		unset GIT_DIR GIT_WORK_TREE GIT_CONFIG &&
+		mkdir plain-bare-1 &&
+		cd plain-bare-1 &&
+		git --bare init
+	) &&
+	check_config plain-bare-1 true unset
+'
+
+test_expect_success 'plain bare with GIT_WORK_TREE' '
+	if (
+		unset GIT_DIR GIT_CONFIG &&
+		mkdir plain-bare-2 &&
+		cd plain-bare-2 &&
+		GIT_WORK_TREE=$(pwd) git --bare init
+	)
+	then
+		echo Should have failed -- GIT_WORK_TREE should not be used
+		false
+	fi
+'
+
+test_expect_success 'GIT_DIR bare' '
+
+	(
+		unset GIT_CONFIG &&
+		mkdir git-dir-bare.git &&
+		GIT_DIR=git-dir-bare.git git init
+	) &&
+	check_config git-dir-bare.git true unset
+'
+
+test_expect_success 'GIT_DIR non-bare' '
+
+	(
+		unset GIT_CONFIG &&
+		mkdir non-bare &&
+		cd non-bare &&
+		GIT_DIR=.git git init
+	) &&
+	check_config non-bare/.git false unset
+'
+
+test_expect_success 'GIT_DIR & GIT_WORK_TREE (1)' '
+
+	(
+		unset GIT_CONFIG &&
+		mkdir git-dir-wt-1.git &&
+		GIT_WORK_TREE=$(pwd) GIT_DIR=git-dir-wt-1.git git init
+	) &&
+	check_config git-dir-wt-1.git false "$(pwd)"
+'
+
+test_expect_success 'GIT_DIR & GIT_WORK_TREE (2)' '
+
+	if (
+		unset GIT_CONFIG &&
+		mkdir git-dir-wt-2.git &&
+		GIT_WORK_TREE=$(pwd) GIT_DIR=git-dir-wt-2.git git --bare init
+	)
+	then
+		echo Should have failed -- --bare should not be used
+		false
+	fi
+'
+
+test_done