setup: introduce startup_info->original_cwd

Removing the current working directory causes all subsequent git
commands run from that directory to get confused and fail with a message
about being unable to read the current working directory:

    $ git status
    fatal: Unable to read current working directory: No such file or directory

Non-git commands likely have similar warnings or even errors, e.g.

    $ bash -c 'echo hello'
    shell-init: error retrieving current directory: getcwd: cannot access parent directories: No such file or directory
    hello

This confuses end users, particularly since the command they get the
error from is not the one that caused the problem; the problem came from
the side-effect of some previous command.

We would like to avoid removing the current working directory of our
parent process; towards this end, introduce a new variable,
startup_info->original_cwd, that tracks the current working directory
that we inherited from our parent process.  For convenience of later
comparisons, we prefer that this new variable store a path relative to
the toplevel working directory (thus much like 'prefix'), except without
the trailing slash.

Subsequent commits will make use of this new variable.

Acked-by: Derrick Stolee <stolee@gmail.com>
Acked-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/cache.h b/cache.h
index eba12487b9..92e181ea75 100644
--- a/cache.h
+++ b/cache.h
@@ -1834,8 +1834,10 @@ void overlay_tree_on_index(struct index_state *istate,
 struct startup_info {
 	int have_repository;
 	const char *prefix;
+	const char *original_cwd;
 };
 extern struct startup_info *startup_info;
+extern const char *tmp_original_cwd;
 
 /* merge.c */
 struct commit_list;