[PATCH v2 4/8] read_early_config(): optionally return the worktree's top-level directory

[Johannes Schindelin <johannes.schindelin@gmx.de>]

So far, when we invoked the early config code path, we implicitly
determined the top-level directory of the worktree while discovering the
.git/ directory.

And then we simply forgot that information.

However, when we expand aliases, we very much need that information, as
aliases expanding to shell commands, i.e. whose value starts with an
exclamation point, have to be executed in the top-level directory of the
worktree. There are exceptions abound, not only with non-shell aliases
(which are supposed to be executed in the original working directory
instead), but also when being started inside the .git/ directory or in a
worktree created via `git worktree add`.

In preparation for allowing the alias machinery to make use of the early
config machinery, let's add an optional strbuf parameter to the
read_early_config() function; if not NULL, the path of said top-level
directory is appended to the strbuf. As a special case, nothing is
appended if setup_git_directory() would have restored the original
working directory before returning.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 cache.h                |  5 +++--
 config.c               |  4 ++--
 help.c                 |  2 +-
 pager.c                |  4 ++--
 setup.c                | 12 ++++++++++--
 t/helper/test-config.c |  2 +-
 6 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/cache.h b/cache.h
index 4d92aae0e81..f769ef1779c 100644
--- a/cache.h
+++ b/cache.h
@@ -530,7 +530,7 @@ extern void setup_work_tree(void);
  * appended to gitdir. The return value is either NULL if no repository was
  * found, or pointing to the path inside gitdir's buffer.
  */
-extern const char *discover_git_directory(struct strbuf *gitdir);
+extern const char *discover_git_directory(struct strbuf *gitdir, struct strbuf *cdup_dir);
 extern const char *setup_git_directory_gently(int *);
 extern const char *setup_git_directory(void);
 extern char *prefix_path(const char *prefix, int len, const char *path);
@@ -1913,7 +1913,8 @@ extern int git_config_from_blob_sha1(config_fn_t fn, const char *name,
 				     const unsigned char *sha1, void *data);
 extern void git_config_push_parameter(const char *text);
 extern int git_config_from_parameters(config_fn_t fn, void *data);
-extern void read_early_config(config_fn_t cb, void *data);
+extern void read_early_config(config_fn_t cb, void *data,
+			      struct strbuf *cdup_dir);
 extern void git_config(config_fn_t fn, void *);
 extern int git_config_with_options(config_fn_t fn, void *,
 				   struct git_config_source *config_source,
diff --git a/config.c b/config.c
index 9b88531a70d..5aec6e4c87c 100644
--- a/config.c
+++ b/config.c
@@ -1651,7 +1651,7 @@ static void configset_iter(struct config_set *cs, config_fn_t fn, void *data)
 	}
 }
 
-void read_early_config(config_fn_t cb, void *data)
+void read_early_config(config_fn_t cb, void *data, struct strbuf *cdup_dir)
 {
 	struct config_options opts = {0};
 	struct strbuf buf = STRBUF_INIT;
@@ -1668,7 +1668,7 @@ void read_early_config(config_fn_t cb, void *data)
 	 * notably, the current working directory is still the same after the
 	 * call).
 	 */
-	else if (discover_git_directory(&buf))
+	else if (discover_git_directory(&buf, cdup_dir))
 		opts.git_dir = buf.buf;
 
 	git_config_with_options(cb, data, NULL, &opts);
diff --git a/help.c b/help.c
index b44c55ec2da..f78747e8413 100644
--- a/help.c
+++ b/help.c
@@ -289,7 +289,7 @@ const char *help_unknown_cmd(const char *cmd)
 	memset(&other_cmds, 0, sizeof(other_cmds));
 	memset(&aliases, 0, sizeof(aliases));
 
-	read_early_config(git_unknown_cmd_config, NULL);
+	read_early_config(git_unknown_cmd_config, NULL, NULL);
 
 	load_command_list("git-", &main_cmds, &other_cmds);
 
diff --git a/pager.c b/pager.c
index c113d898a4a..857cf5ecb32 100644
--- a/pager.c
+++ b/pager.c
@@ -53,7 +53,7 @@ const char *git_pager(int stdout_is_tty)
 	pager = getenv("GIT_PAGER");
 	if (!pager) {
 		if (!pager_program)
-			read_early_config(core_pager_config, NULL);
+			read_early_config(core_pager_config, NULL, NULL);
 		pager = pager_program;
 	}
 	if (!pager)
@@ -214,7 +214,7 @@ int check_pager_config(const char *cmd)
 	data.want = -1;
 	data.value = NULL;
 
-	read_early_config(pager_command_config, &data);
+	read_early_config(pager_command_config, &data, NULL);
 
 	if (data.value)
 		pager_program = data.value;
diff --git a/setup.c b/setup.c
index 2435186e448..3f6fc1577b7 100644
--- a/setup.c
+++ b/setup.c
@@ -945,10 +945,11 @@ static enum discovery_result setup_git_directory_gently_1(struct strbuf *dir,
 	}
 }
 
-const char *discover_git_directory(struct strbuf *gitdir)
+const char *discover_git_directory(struct strbuf *gitdir,
+				   struct strbuf *cdup_dir)
 {
 	struct strbuf dir = STRBUF_INIT, err = STRBUF_INIT;
-	size_t gitdir_offset = gitdir->len, cwd_len;
+	size_t gitdir_offset = gitdir->len, cwd_len, cdup_dir_offset;
 	struct repository_format candidate;
 
 	if (strbuf_getcwd(&dir))
@@ -973,6 +974,11 @@ const char *discover_git_directory(struct strbuf *gitdir)
 		strbuf_insert(gitdir, gitdir_offset, dir.buf, dir.len);
 	}
 
+	if (cdup_dir) {
+		cdup_dir_offset = cdup_dir->len;
+		strbuf_addbuf(cdup_dir, &dir);
+	}
+
 	strbuf_reset(&dir);
 	strbuf_addf(&dir, "%s/config", gitdir->buf + gitdir_offset);
 	read_repository_format(&candidate, dir.buf);
@@ -983,6 +989,8 @@ const char *discover_git_directory(struct strbuf *gitdir)
 			gitdir->buf + gitdir_offset, err.buf);
 		strbuf_release(&err);
 		strbuf_setlen(gitdir, gitdir_offset);
+		if (cdup_dir)
+			strbuf_setlen(cdup_dir, cdup_dir_offset);
 		return NULL;
 	}
 
diff --git a/t/helper/test-config.c b/t/helper/test-config.c
index 8e3ed6a76cb..5e1e78f8fa2 100644
--- a/t/helper/test-config.c
+++ b/t/helper/test-config.c
@@ -84,7 +84,7 @@ int cmd_main(int argc, const char **argv)
 	struct config_set cs;
 
 	if (argc == 3 && !strcmp(argv[1], "read_early_config")) {
-		read_early_config(early_config_cb, (void *)argv[2]);
+		read_early_config(early_config_cb, (void *)argv[2], NULL);
 		return 0;
 	}
 
-- 
2.13.0.windows.1.460.g13f583bedb5