[PATCH] Support working directory located at root

Git should work regardless where the working directory is located,
even at root. This patch fixes two places where it assumes working
directory always have parent directory.

In setup_git_directory_gently(), when Git goes up to root and finds
.git there, it happily sets worktree to "".

In prefix_path(), loosen the outside repo check a little bit. Usually
when a path XXX is inside worktree /foo, it must be either "/foo", or
"/foo/...". When worktree is simply "/", we can safely ignore the
check: we have a slash at the beginning already.

Not related to worktree, but also set gitdir correctly if a bare repo
is placed (insanely?) at root.

Thanks João Carlos Mendes Luís for pointing out this problem.

Signed-off-by: Nguyễn Thái Ngọc Duy <redacted>
---
 Tell me if this patch is rejected, I'll send another one that makes
 setup_git_* die() if worktree/gitdir is to be set empty. I don't think we
 expect gitdir or worktree to be empty anywhere.

 setup.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/setup.c b/setup.c
index b38cbee..0fcd2fd 100644
--- a/setup.c
+++ b/setup.c

@@ -25,7 +25,7 @@ const char *prefix_path(const char *prefix, int len, const char *path)
 		len = strlen(work_tree);
 		total = strlen(sanitized) + 1;
 		if (strncmp(sanitized, work_tree, len) ||
-		    (sanitized[len] != '\0' && sanitized[len] != '/')) {
+		    (len > 1 && sanitized[len] != '\0' && sanitized[len] != '/')) {
 		error_out:
 			die("'%s' is outside repository", orig);
 		}

@@ -403,7 +403,7 @@ const char *setup_git_directory_gently(int *nongit_ok)
 			if (!work_tree_env)
 				inside_work_tree = 0;
 			if (offset != len) {
-				cwd[offset] = '\0';
+				cwd[offset ? offset : 1] = '\0';
 				set_git_dir(cwd);
 			} else
 				set_git_dir(".");

@@ -427,6 +427,8 @@ const char *setup_git_directory_gently(int *nongit_ok)
 	inside_git_dir = 0;
 	if (!work_tree_env)
 		inside_work_tree = 1;
+	if (offset == 0) /* reached root, set worktree to '/' */
+		offset = 1;
 	git_work_tree_cfg = xstrndup(cwd, offset);
 	if (check_repository_format_gently(nongit_ok))
 		return NULL;

-- 
1.7.0.rc0.54.gd33ef

Nguyễn Thái Ngọc Duy [off-list ref] writes:

Git should work regardless where the working directory is located,
even at root. This patch fixes two places where it assumes working
directory always have parent directory.

In setup_git_directory_gently(), when Git goes up to root and finds
.git there, it happily sets worktree to "".

If you mean "instead set it to "/" and things will work much better."
I agree with the reasoning (not suggesting to reword---just trying to
make sure I understood what you meant).

In prefix_path(), loosen the outside repo check a little bit. Usually
when a path XXX is inside worktree /foo, it must be either "/foo", or
"/foo/...". When worktree is simply "/", we can safely ignore the
check: we have a slash at the beginning already.

The logic for the "are we inside?" check above sounds correct.  When
work_tree is at root, have "/" in it, and len inside the "if orig is
absolute" block is 1, so memmove() strips out the leading '/' and makes
the result relative to the root level.  Am I reading the code right?

Not related to worktree, but also set gitdir correctly if a bare repo
is placed (insanely?) at root.

Yuck, but looks correct.

On Montag, 8. Februar 2010, Nguyễn Thái Ngọc Duy wrote:

Does not work:

etc@master:1028> ~/Src/git/git/git add resolv.conf
fatal: pathspec 'tc/resolv.conf' did not match any files

I wonder how this works on Windows where we do not want to strip the slash 
from C:/ either.

-- Hannes

2010/2/9 Junio C Hamano [off-list ref]:

Nguyễn Thái Ngọc Duy [off-list ref] writes:

quoted

Git should work regardless where the working directory is located,
even at root. This patch fixes two places where it assumes working
directory always have parent directory.

In setup_git_directory_gently(), when Git goes up to root and finds
.git there, it happily sets worktree to "".

If you mean "instead set it to "/" and things will work much better."
I agree with the reasoning (not suggesting to reword---just trying to
make sure I understood what you meant).

Yes.

quoted

In prefix_path(), loosen the outside repo check a little bit. Usually
when a path XXX is inside worktree /foo, it must be either "/foo", or
"/foo/...". When worktree is simply "/", we can safely ignore the
check: we have a slash at the beginning already.

The logic for the "are we inside?" check above sounds correct.  When
work_tree is at root, have "/" in it, and len inside the "if orig is
absolute" block is 1, so memmove() strips out the leading '/' and makes
the result relative to the root level.  Am I reading the code right?

You are. But I suspect my change in this code is not enough and caused
the problem (on msys?) for Hannes. If the worktree somehow is '//' and
sanitized is '/etc/resolv.conf', then we could end up eating two
chars, leading to "'tc/resolv.conf' not match" error.

Hannes, can you put a "printf("%s\n", work_tree);" in prefix_path() to
see if it's the case?
-- 
Duy

2010/2/9 Nguyen Thai Ngoc Duy [off-list ref]:

But I suspect my change in this code is not enough and caused
the problem (on msys?) for Hannes. If the worktree somehow is '//' and
sanitized is '/etc/resolv.conf', then we could end up eating two
chars, leading to "'tc/resolv.conf' not match" error.

Hannes, can you put a "printf("%s\n", work_tree);" in prefix_path() to
see if it's the case?

Silly me. You used relative path, so that code path was untouched.
-- 
Duy