[v3,2/3] replace-objects: create wrapper around setting

Commit Message

Derrick Stolee June 6, 2023, 1:24 p.m. UTC

From: Derrick Stolee <[e-mail]>

The 'read_replace_objects' constant is initialized by git_default_config
(if core.useReplaceRefs is disabled) and within setup_git_env (if
GIT_NO_REPLACE_OBJECTS) is set. To ensure that this variable cannot be
set accidentally in other places, wrap it in a replace_refs_enabled()
method.

Since we still assign this global in config.c, we are not able to remove
the global scope of this variable and make it a static within
replace-object.c. This will happen in a later change which will also
prevent the variable from being read before it is initialized.

Centralizing read access to the variable is an important first step.

Signed-off-by: Derrick Stolee <[e-mail]>
---
 commit-graph.c   |  4 +---
 log-tree.c       |  2 +-
 replace-object.c |  5 +++++
 replace-object.h | 14 +++++++++++++-
 4 files changed, 20 insertions(+), 5 deletions(-)

Patch

diff --git a/commit-graph.c b/commit-graph.c
index 43558b4d9b0..95873317bf7 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -203,14 +203,12 @@  static struct commit_graph *alloc_commit_graph(void)
 	return g;
 }
 
-extern int read_replace_refs;
-
 static int commit_graph_compatible(struct repository *r)
 {
 	if (!r->gitdir)
 		return 0;
 
-	if (read_replace_refs) {
+	if (replace_refs_enabled(r)) {
 		prepare_replace_object(r);
 		if (hashmap_get_size(&r->objects->replace_map->map))
 			return 0;
diff --git a/log-tree.c b/log-tree.c
index 143b86fecf9..86212af3626 100644
--- a/log-tree.c
+++ b/log-tree.c
@@ -155,7 +155,7 @@  static int add_ref_decoration(const char *refname, const struct object_id *oid,
 
 	if (starts_with(refname, git_replace_ref_base)) {
 		struct object_id original_oid;
-		if (!read_replace_refs)
+		if (!replace_refs_enabled(the_repository))
 			return 0;
 		if (get_oid_hex(refname + strlen(git_replace_ref_base),
 				&original_oid)) {
diff --git a/replace-object.c b/replace-object.c
index ceec81c940c..07cfedd6df4 100644
--- a/replace-object.c
+++ b/replace-object.c
@@ -89,3 +89,8 @@  void disable_replace_refs(void)
 {
 	read_replace_refs = 0;
 }
+
+int replace_refs_enabled(struct repository *r)
+{
+	return read_replace_refs;
+}
diff --git a/replace-object.h b/replace-object.h
index 7786d4152b0..3e9c3516c3c 100644
--- a/replace-object.h
+++ b/replace-object.h
@@ -27,6 +27,18 @@  void prepare_replace_object(struct repository *r);
 const struct object_id *do_lookup_replace_object(struct repository *r,
 						 const struct object_id *oid);
 
+/*
+ * Some commands disable replace-refs unconditionally, and otherwise each
+ * repository could alter the core.useReplaceRefs config value.
+ *
+ * Return 1 if and only if all of the following are true:
+ *
+ *  a. disable_replace_refs() has not been called.
+ *  b. GIT_NO_REPLACE_OBJECTS is unset or zero.
+ *  c. the given repository does not have core.useReplaceRefs=false.
+ */
+int replace_refs_enabled(struct repository *r);
+
 /*
  * If object sha1 should be replaced, return the replacement object's
  * name (replaced recursively, if necessary).  The return value is
@@ -41,7 +53,7 @@  const struct object_id *do_lookup_replace_object(struct repository *r,
 static inline const struct object_id *lookup_replace_object(struct repository *r,
 							    const struct object_id *oid)
 {
-	if (!read_replace_refs ||
+	if (!replace_refs_enabled(r) ||
 	    (r->objects->replace_map_initialized &&
 	     r->objects->replace_map->map.tablesize == 0))
 		return oid;