Merge branch 'js/early-config'

The start-up sequence of "git" needs to figure out some configured
settings before it finds and set itself up in the location of the
repository and was quite messy due to its "chicken-and-egg" nature.
The code has been restructured.

* js/early-config:
  setup.c: mention unresolved problems
  t1309: document cases where we would want early config not to die()
  setup_git_directory_gently_1(): avoid die()ing
  t1309: test read_early_config()
  read_early_config(): really discover .git/
  read_early_config(): avoid .git/config hack when unneeded
  setup: make read_early_config() reusable
  setup: introduce the discover_git_directory() function
  setup_git_directory_1(): avoid changing global state
  setup: prepare setup_discovered_git_dir() for the root directory
  setup_git_directory(): use is_dir_sep() helper
  t7006: replace dubious test

Author: gitster

cache.h

@@ -518,6 +518,13 @@ extern void set_git_work_tree(const char *tree);
 #define ALTERNATE_DB_ENVIRONMENT "GIT_ALTERNATE_OBJECT_DIRECTORIES"
 
 extern void setup_work_tree(void);
+/*
+ * Find GIT_DIR of the repository that contains the current working directory,
+ * without changing the working directory or other global state. The result is
+ * 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 *setup_git_directory_gently(int *);
 extern const char *setup_git_directory(void);
 extern char *prefix_path(const char *prefix, int len, const char *path);
@@ -1842,6 +1849,7 @@ 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 git_config(config_fn_t fn, void *);
 extern int git_config_with_options(config_fn_t fn, void *,
 				   struct git_config_source *config_source,

config.c

@@ -1503,6 +1503,31 @@ static void configset_iter(struct config_set *cs, config_fn_t fn, void *data)
 	}
 }
 
+void read_early_config(config_fn_t cb, void *data)
+{
+	struct strbuf buf = STRBUF_INIT;
+
+	git_config_with_options(cb, data, NULL, 1);
+
+	/*
+	 * When setup_git_directory() was not yet asked to discover the
+	 * GIT_DIR, we ask discover_git_directory() to figure out whether there
+	 * is any repository config we should use (but unlike
+	 * setup_git_directory_gently(), no global state is changed, most
+	 * notably, the current working directory is still the same after the
+	 * call).
+	 */
+	if (!have_git_dir() && discover_git_directory(&buf)) {
+		struct git_config_source repo_config;
+
+		memset(&repo_config, 0, sizeof(repo_config));
+		strbuf_addstr(&buf, "/config");
+		repo_config.file = buf.buf;
+		git_config_with_options(cb, data, &repo_config, 1);
+	}
+	strbuf_release(&buf);
+}
+
 static void git_config_check_init(void);
 
 void git_config(config_fn_t fn, void *data)

pager.c

@@ -43,37 +43,6 @@ static int core_pager_config(const char *var, const char *value, void *data)
 	return 0;
 }
 
-static void read_early_config(config_fn_t cb, void *data)
-{
-	git_config_with_options(cb, data, NULL, 1);
-
-	/*
-	 * Note that this is a really dirty hack that does the wrong thing in
-	 * many cases. The crux of the problem is that we cannot run
-	 * setup_git_directory() early on in git's setup, so we have no idea if
-	 * we are in a repository or not, and therefore are not sure whether
-	 * and how to read repository-local config.
-	 *
-	 * So if we _aren't_ in a repository (or we are but we would reject its
-	 * core.repositoryformatversion), we'll read whatever is in .git/config
-	 * blindly. Similarly, if we _are_ in a repository, but not at the
-	 * root, we'll fail to find .git/config (because it's really
-	 * ../.git/config, etc). See t7006 for a complete set of failures.
-	 *
-	 * However, we have historically provided this hack because it does
-	 * work some of the time (namely when you are at the top-level of a
-	 * valid repository), and would rarely make things worse (i.e., you do
-	 * not generally have a .git/config file sitting around).
-	 */
-	if (!startup_info->have_repository) {
-		struct git_config_source repo_config;
-
-		memset(&repo_config, 0, sizeof(repo_config));
-		repo_config.file = ".git/config";
-		git_config_with_options(cb, data, &repo_config, 1);
-	}
-}
-
 const char *git_pager(int stdout_is_tty)
 {
 	const char *pager;