git: submodule honor -c credential.* from command line

Due to the way that the git-submodule code works, it clears all local
git environment variables before entering submodules. This is normally
a good thing since we want to clear settings such as GIT_WORKTREE and
other variables which would affect the operation of submodule commands.
However, GIT_CONFIG_PARAMETERS is special, and we actually do want to
preserve these settings. However, we do not want to preserve all
configuration as many things should be left specific to the parent
project.

Add a git submodule--helper function, sanitize-config, which shall be
used to sanitize GIT_CONFIG_PARAMETERS, removing all key/value pairs
except a small subset that are known to be safe and necessary.

Replace all the calls to clear_local_git_env with a wrapped function
that filters GIT_CONFIG_PARAMETERS using the new helper and then
restores it to the filtered subset after clearing the rest of the
environment.

Signed-off-by: Jacob Keller <jacob.keller@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 67 insertions, 1 deletions

diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index 35ae85a7e..3d37c3f18 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -124,6 +124,55 @@ 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)
 {
@@ -145,7 +194,7 @@ static int clone_submodule(const char *path, const char *gitdir, const char *url
 	argv_array_push(&cp.args, path);
 
 	cp.git_cmd = 1;
-	cp.env = local_repo_env;
+	prepare_submodule_repo_env(&cp.env_array);
 	cp.no_stdin = 1;
 
 	return run_command(&cp);
@@ -259,6 +308,22 @@ static int module_clone(int argc, const char **argv, const char *prefix)
 	return 0;
 }
 
+static int module_sanitize_config(int argc, const char **argv, const char *prefix)
+{
+	struct strbuf sanitized_config = STRBUF_INIT;
+
+	if (argc > 1)
+		usage(_("git submodule--helper sanitize-config"));
+
+	git_config_from_parameters(sanitize_submodule_config, &sanitized_config);
+	if (sanitized_config.len)
+		printf("%s\n", sanitized_config.buf);
+
+	strbuf_release(&sanitized_config);
+
+	return 0;
+}
+
 struct cmd_struct {
 	const char *cmd;
 	int (*fn)(int, const char **, const char *);
@@ -268,6 +333,7 @@ static struct cmd_struct commands[] = {
 	{"list", module_list},
 	{"name", module_name},
 	{"clone", module_clone},
+	{"sanitize-config", module_sanitize_config},
 };
 
 int cmd_submodule__helper(int argc, const char **argv, const char *prefix)