[PATCH v5 21/27] refs: check submodules' ref storage config

[David Turner]

All submodules must have the same ref storage (for now).  Confirm that
this is so before attempting to do anything with submodule refs.

Signed-off-by: David Turner <dtur...@twopensource.com>
---
 refs.c               | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 refs.h               |  2 +-
 refs/files-backend.c |  8 ++------
 3 files changed, 57 insertions(+), 7 deletions(-)

diff --git a/refs.c b/refs.c
index 64d4150..ea7e0eb 100644
--- a/refs.c
+++ b/refs.c
@@ -308,6 +308,54 @@ int for_each_tag_ref(each_ref_fn fn, void *cb_data)
        return for_each_ref_in("refs/tags/", fn, cb_data);
 }
 
+static int submodule_backend(const char *key, const char *value, void *data)
+{
+       const char **path = data;
+       char **old_path = data;
+       if (!strcmp(key, "extensions.refstorage") &&
+           !git_config_string(path, key, "extensions.refstorage"))
+                       free(*old_path);
+
+       return 0;
+}
+
+/*
+ * Check that a submodule exists. If its ref storage backend differs
+ * from the current backend, die.  If the submodule exists, return
+ * 0. Else return -1.
+ */
+static int check_submodule_backend(const char *submodule)
+{
+       struct strbuf sb = STRBUF_INIT;
+       char *submodule_storage_backend;
+       int result = -1;
+
+       if (!submodule)
+               return 0;
+
+       submodule_storage_backend = xstrdup("files");
+
+       strbuf_addstr(&sb, submodule);
+       if (!is_nonbare_repository_dir(&sb))
+               goto done;
+
+       strbuf_reset(&sb);
+       strbuf_git_path_submodule(&sb, submodule, "config");
+
+       git_config_from_file(submodule_backend, sb.buf,
+                            &submodule_storage_backend);
+       if (strcmp(submodule_storage_backend, ref_storage_backend))
+               die(_("Ref storage '%s' for submodule '%s' does not match our 
storage, '%s'"),
+                   submodule_storage_backend, submodule, ref_storage_backend);
+
+       result = 0;
+done:
+       free(submodule_storage_backend);
+       strbuf_release(&sb);
+
+       return result;
+}
+
 int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void 
*cb_data)
 {
        return for_each_ref_in_submodule(submodule, "refs/tags/", fn, cb_data);
@@ -320,6 +368,7 @@ int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 
 int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void 
*cb_data)
 {
+       check_submodule_backend(submodule);
        return for_each_ref_in_submodule(submodule, "refs/heads/", fn, cb_data);
 }
 
@@ -330,6 +379,7 @@ int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 
 int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void 
*cb_data)
 {
+       check_submodule_backend(submodule);
        return for_each_ref_in_submodule(submodule, "refs/remotes/", fn, 
cb_data);
 }
 
@@ -1141,6 +1191,7 @@ int head_ref_submodule(const char *submodule, each_ref_fn 
fn, void *cb_data)
        int flag;
 
        if (submodule) {
+               check_submodule_backend(submodule);
                if (resolve_gitlink_ref(submodule, "HEAD", oid.hash) == 0)
                        return fn("HEAD", &oid, 0, cb_data);
 
@@ -1447,6 +1498,9 @@ int create_symref(const char *ref_target, const char 
*refs_heads_master,
 int resolve_gitlink_ref(const char *path, const char *refname,
                        unsigned char *sha1)
 {
+       if (check_submodule_backend(path))
+               return -1;
+
        return the_refs_backend->resolve_gitlink_ref(path, refname, sha1);
 }
 
diff --git a/refs.h b/refs.h
index 4992aa4..e659882 100644
--- a/refs.h
+++ b/refs.h
@@ -511,7 +511,7 @@ extern int reflog_expire(const char *refname, const 
unsigned char *sha1,
                         void *policy_cb_data);
 
 /*
- * Read the refdb storage backend name out of the config file
+ * Read the ref storage backend name out of the config file
  */
 int ref_storage_backend_config(const char *var, const char *value, void *ptr);
 
diff --git a/refs/files-backend.c b/refs/files-backend.c
index b3cca8e..4bddfb3 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -1357,13 +1357,9 @@ static int files_resolve_gitlink_ref(const char *path, 
const char *refname,
 
        strbuf_add(&submodule, path, len);
        refs = lookup_ref_cache(submodule.buf);
-       if (!refs) {
-               if (!is_nonbare_repository_dir(&submodule)) {
-                       strbuf_release(&submodule);
-                       return -1;
-               }
+       if (!refs)
                refs = create_ref_cache(submodule.buf);
-       }
+
        strbuf_release(&submodule);
 
        retval = resolve_gitlink_ref_recursive(refs, refname, sha1, 0);
-- 
2.4.2.767.g62658d5-twtrsrc

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