submodule--helper: move config-sanitizing to submodule.c

These functions should be used by any code which spawns a
submodule process, which may happen in submodule.c (e.g.,
for spawning fetch). Let's move them there and make them
public so that submodule--helper can continue to use them.

Since they're now public, let's also provide a basic overview
of their intended use.

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

builtin/submodule--helper.c

@@ -125,54 +125,6 @@ static int module_name(int argc, const char **argv, const char *prefix)
 	return 0;
 }
 
-/*
- * Rules to sanitize configuration variables that are Ok to be passed into
- * submodule operations from the parent project using "-c". Should only
- * include keys which are both (a) safe and (b) necessary for proper
- * operation.
- */
-static int submodule_config_ok(const char *var)
-{
-	if (starts_with(var, "credential."))
-		return 1;
-	return 0;
-}
-
-static int sanitize_submodule_config(const char *var, const char *value, void *data)
-{
-	struct strbuf *out = data;
-
-	if (submodule_config_ok(var)) {
-		if (out->len)
-			strbuf_addch(out, ' ');
-
-		if (value)
-			sq_quotef(out, "%s=%s", var, value);
-		else
-			sq_quote_buf(out, var);
-	}
-
-	return 0;
-}
-
-static void prepare_submodule_repo_env(struct argv_array *out)
-{
-	const char * const *var;
-
-	for (var = local_repo_env; *var; var++) {
-		if (!strcmp(*var, CONFIG_DATA_ENVIRONMENT)) {
-			struct strbuf sanitized_config = STRBUF_INIT;
-			git_config_from_parameters(sanitize_submodule_config,
-						   &sanitized_config);
-			argv_array_pushf(out, "%s=%s", *var, sanitized_config.buf);
-			strbuf_release(&sanitized_config);
-		} else {
-			argv_array_push(out, *var);
-		}
-	}
-
-}
-
 static int clone_submodule(const char *path, const char *gitdir, const char *url,
 			   const char *depth, const char *reference, int quiet)
 {

submodule.c

@@ -13,6 +13,7 @@
 #include "argv-array.h"
 #include "blob.h"
 #include "thread-utils.h"
+#include "quote.h"
 
 static int config_fetch_recurse_submodules = RECURSE_SUBMODULES_ON_DEMAND;
 static struct string_list changed_submodule_paths;
@@ -1097,3 +1098,50 @@ void connect_work_tree_and_git_dir(const char *work_tree, const char *git_dir)
 	strbuf_release(&rel_path);
 	free((void *)real_work_tree);
 }
+/*
+ * Rules to sanitize configuration variables that are Ok to be passed into
+ * submodule operations from the parent project using "-c". Should only
+ * include keys which are both (a) safe and (b) necessary for proper
+ * operation.
+ */
+static int submodule_config_ok(const char *var)
+{
+	if (starts_with(var, "credential."))
+		return 1;
+	return 0;
+}
+
+int sanitize_submodule_config(const char *var, const char *value, void *data)
+{
+	struct strbuf *out = data;
+
+	if (submodule_config_ok(var)) {
+		if (out->len)
+			strbuf_addch(out, ' ');
+
+		if (value)
+			sq_quotef(out, "%s=%s", var, value);
+		else
+			sq_quote_buf(out, var);
+	}
+
+	return 0;
+}
+
+void prepare_submodule_repo_env(struct argv_array *out)
+{
+	const char * const *var;
+
+	for (var = local_repo_env; *var; var++) {
+		if (!strcmp(*var, CONFIG_DATA_ENVIRONMENT)) {
+			struct strbuf sanitized_config = STRBUF_INIT;
+			git_config_from_parameters(sanitize_submodule_config,
+						   &sanitized_config);
+			argv_array_pushf(out, "%s=%s", *var, sanitized_config.buf);
+			strbuf_release(&sanitized_config);
+		} else {
+			argv_array_push(out, *var);
+		}
+	}
+
+}

submodule.h

@@ -43,4 +43,20 @@ int find_unpushed_submodules(unsigned char new_sha1[20], const char *remotes_nam
 int push_unpushed_submodules(unsigned char new_sha1[20], const char *remotes_name);
 void connect_work_tree_and_git_dir(const char *work_tree, const char *git_dir);
 
+/*
+ * This function is intended as a callback for use with
+ * git_config_from_parameters(). It ignores any config options which
+ * are not suitable for passing along to a submodule, and accumulates the rest
+ * in "data", which must be a pointer to a strbuf. The end result can
+ * be put into $GIT_CONFIG_PARAMETERS for passing to a sub-process.
+ */
+int sanitize_submodule_config(const char *var, const char *value, void *data);
+
+/*
+ * Prepare the "env_array" parameter of a "struct child_process" for executing
+ * a submodule by clearing any repo-specific envirionment variables, but
+ * retaining any config approved by sanitize_submodule_config().
+ */
+void prepare_submodule_repo_env(struct argv_array *out);
+
 #endif