setup: suppress implicit "." work-tree for bare repos

If an explicit GIT_DIR is given without a working tree, we
implicitly assume that the current working directory should
be used as the working tree. E.g.,:

GIT_DIR=/some/repo.git git status

would compare against the cwd.

Unfortunately, we fool this rule for sub-invocations of git
by setting GIT_DIR internally ourselves. For example:

git init foo
cd foo/.git
git status ;# fails, as we expect
git config alias.st status
git status ;# does not fail, but should

What happens is that we run setup_git_directory when doing
alias lookup (since we need to see the config), set GIT_DIR
as a result, and then leave GIT_WORK_TREE blank (because we
do not have one). Then when we actually run the status
command, we do setup_git_directory again, which sees our
explicit GIT_DIR and uses the cwd as an implicit worktree.

It's tempting to argue that we should be suppressing that
second invocation of setup_git_directory, as it could use
the values we already found in memory. However, the problem
still exists for sub-processes (e.g., if "git status" were
an external command).

You can see another example with the "--bare" option, which
sets GIT_DIR explicitly. For example:

git init foo
cd foo/.git
git status ;# fails
git --bare status ;# does NOT fail

We need some way of telling sub-processes "even though
GIT_DIR is set, do not use cwd as an implicit working tree".
We could do it by putting a special token into
GIT_WORK_TREE, but the obvious choice (an empty string) has
some portability problems.

Instead, we add a new boolean variable, GIT_IMPLICIT_WORK_TREE,
which suppresses the use of cwd as a working tree when
GIT_DIR is set. We trigger the new variable when we know we
are in a bare setting.

The variable is left intentionally undocumented, as this is
an internal detail (for now, anyway). If somebody comes up
with a good alternate use for it, and once we are confident
we have shaken any bugs out of it, we can consider promoting
it further.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/cache.h b/cache.h
index 3c6b677418a1db5fd6cd74f1e9cb16b6b8f29ddf..c1fe67ffcfb1e792658d8d2c889e21f28ea78a94 100644 (file)
--- a/cache.h
+++ b/cache.h
@@ -365,6 +365,18 @@ static inline enum object_type object_type(unsigned int mode)
 #define GIT_NOTES_REWRITE_REF_ENVIRONMENT "GIT_NOTES_REWRITE_REF"
 #define GIT_NOTES_REWRITE_MODE_ENVIRONMENT "GIT_NOTES_REWRITE_MODE"
 
+/*
+ * This environment variable is expected to contain a boolean indicating
+ * whether we should or should not treat:
+ *
+ *   GIT_DIR=foo.git git ...
+ *
+ * as if GIT_WORK_TREE=. was given. It's not expected that users will make use
+ * of this, but we use it internally to communicate to sub-processes that we
+ * are in a bare repo. If not set, defaults to true.
+ */
+#define GIT_IMPLICIT_WORK_TREE_ENVIRONMENT "GIT_IMPLICIT_WORK_TREE"
+
 /*
  * Repository-local GIT_* environment variables; these will be cleared
  * when git spawns a sub-process that runs inside another repository.

diff --git a/environment.c b/environment.c
index 4fb7ceac3aec94ca2c1ab2e5d94e54ff3f1bcf53..92c5dff008b591e66f47678f21ba5442fde43593 100644 (file)
--- a/environment.c
+++ b/environment.c
@@ -85,6 +85,7 @@ const char * const local_repo_env[] = {
        DB_ENVIRONMENT,
        GIT_DIR_ENVIRONMENT,
        GIT_WORK_TREE_ENVIRONMENT,
+       GIT_IMPLICIT_WORK_TREE_ENVIRONMENT,
        GRAFT_ENVIRONMENT,
        INDEX_ENVIRONMENT,
        NO_REPLACE_OBJECTS_ENVIRONMENT,

diff --git a/git.c b/git.c
index d33f9b32a2895ef9f062f9fda487588daac6f5bc..0ffea570c71cfc4619dc42f20c5ee7f4d72c6499 100644 (file)
--- a/git.c
+++ b/git.c
@@ -125,6 +125,7 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
                        static char git_dir[PATH_MAX+1];
                        is_bare_repository_cfg = 1;
                        setenv(GIT_DIR_ENVIRONMENT, getcwd(git_dir, sizeof(git_dir)), 0);
+                       setenv(GIT_IMPLICIT_WORK_TREE_ENVIRONMENT, "0", 1);
                        if (envchanged)
                                *envchanged = 1;
                } else if (!strcmp(cmd, "-c")) {

diff --git a/setup.c b/setup.c
index d0e3ecdcd4222a3287cbca9b48f9fa04ca4765a8..01c5476eb771f13df0e1ace0066a2213d3aaa290 100644 (file)
--- a/setup.c
+++ b/setup.c
@@ -497,6 +497,12 @@ static const char *setup_explicit_git_dir(const char *gitdirenv,
                        set_git_work_tree(core_worktree);
                }
        }
+       else if (!git_env_bool(GIT_IMPLICIT_WORK_TREE_ENVIRONMENT, 1)) {
+               /* #16d */
+               set_git_dir(gitdirenv);
+               free(gitfile);
+               return NULL;
+       }
        else /* #2, #10 */
                set_git_work_tree(".");
 
@@ -575,6 +581,8 @@ static const char *setup_bare_git_dir(char *cwd, int offset, int len, int *nongi
        if (check_repository_format_gently(".", nongit_ok))
                return NULL;
 
+       setenv(GIT_IMPLICIT_WORK_TREE_ENVIRONMENT, "0", 1);
+
        /* --work-tree is set without --git-dir; use discovered one */
        if (getenv(GIT_WORK_TREE_ENVIRONMENT) || git_work_tree_cfg) {
                const char *gitdir;

diff --git a/t/t1510-repo-setup.sh b/t/t1510-repo-setup.sh
index 80aedfca8c15bea1104b4985023f338059ae751c..cf2ee7885ac9c2172deccc27dfb994546593e842 100755 (executable)
--- a/t/t1510-repo-setup.sh
+++ b/t/t1510-repo-setup.sh
@@ -517,6 +517,25 @@ test_expect_success '#16c: bare .git has no worktree' '
                "$here/16c/.git" "(null)" "$here/16c/sub" "(null)"
 '
 
+test_expect_success '#16d: bareness preserved across alias' '
+       setup_repo 16d unset "" unset &&
+       (
+               cd 16d/.git &&
+               test_must_fail git status &&
+               git config alias.st status &&
+               test_must_fail git st
+       )
+'
+
+test_expect_success '#16e: bareness preserved by --bare' '
+       setup_repo 16e unset "" unset &&
+       (
+               cd 16e/.git &&
+               test_must_fail git status &&
+               test_must_fail git --bare status
+       )
+'
+
 test_expect_success '#17: GIT_WORK_TREE without explicit GIT_DIR is accepted (bare case)' '
        # Just like #16.
        setup_repo 17a unset "" true &&