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[PATCH 3/3] repository: create read_replace_refs setting

From
Derrick Stolee via GitGitGadget <gitgitgadget@gmail.com>
Date
May 26, 2023, 18:43 UTC
Message-ID
<481a81a515efb29bc4eb0b1a09b7d1df3f3c074b.1685126618.git.gitgitgadget@gmail.com>
In-Reply-To
<pull.1537.git.1685126617.gitgitgadget@gmail.com>
From: Derrick Stolee <derrickstolee@github.com>

The 'read_replace_refs' global specifies whether or not we should respect the references of the form 'refs/replace/<oid>' to replace which object we look up when asking for '<oid>'. This global has caused issues when it is not initialized properly, such as in b6551feadfd (merge-tree: load default git config, 2023-05-10).

To make this more robust, move its config-based initialization out of git_default_config and into prepare_repo_settings(). This provides a repository-scoped version of the 'read_replace_refs' global.

The global still has its purpose: it is disabled process-wide by the GIT_NO_REPLACE_OBJECTS environment variable or by a call to disable_replace_refs() in some specific Git commands.

Since we already encapsulated the use of the constant inside replace_refs_enabled(), we can perform the initialization inside that method, if necessary. This solves the problem of forgetting to check the config, as we will check it before returning this value.

There is an interesting behavior change possible here: we now have a repository-scoped understanding of this config value. Thus, if there was a command that recurses into submodules and might follow replace refs, then it would now respect the core.useReplaceRefs config value in each repository.

Unfortunately, the existing processes that recurse into submodules do not appear to follow object IDs to their contents, so this behavior change is not visible in the current implementation. It is something valuable for future behavior changes.

Signed-off-by: Derrick Stolee <derrickstolee@github.com>
---
 config.c         |  5 -----
 replace-object.c | 13 +++++++++++--
 replace-object.h |  8 --------
 repo-settings.c  |  1 +
 repository.h     |  8 ++++++++
 5 files changed, 20 insertions(+), 15 deletions(-)
diff --git a/config.c b/config.c
index 43b0d3fb573..d0ce902af39 100644
--- a/config.c
+++ b/config.c
@@ -1838,11 +1838,6 @@ static int git_default_core_config(const char *var, const char *value, void *cb)
 		return 0;
 	}
 
-	if (!strcmp(var, "core.usereplacerefs")) {
-		read_replace_refs = git_config_bool(var, value);
-		return 0;
-	}
-
 	/* Add other config variables here and to Documentation/config.txt. */
 	return platform_core_config(var, value, cb);
 }
diff --git a/replace-object.c b/replace-object.c
index cf91c3ba456..c599729a281 100644
--- a/replace-object.c
+++ b/replace-object.c
@@ -64,7 +64,7 @@ void prepare_replace_object(struct repository *r)
  * replacement object's name (replaced recursively, if necessary).
  * The return value is either oid or a pointer to a
  * permanently-allocated value.  This function always respects replace
- * references, regardless of the value of read_replace_refs.
+ * references, regardless of the value of r->settings.read_replace_refs.
  */
 const struct object_id *do_lookup_replace_object(struct repository *r,
 						 const struct object_id *oid)
@@ -94,5 +94,14 @@ void disable_replace_refs(void)
 
 int replace_refs_enabled(struct repository *r)
 {
-	return read_replace_refs;
+	if (!read_replace_refs)
+		return 0;
+
+	if (r->gitdir) {
+		prepare_repo_settings(r);
+		return r->settings.read_replace_refs;
+	}
+
+	/* repository has no objects or refs. */
+	return 0;
 }
diff --git a/replace-object.h b/replace-object.h
index b141075023e..8813a75b96e 100644
--- a/replace-object.h
+++ b/replace-object.h
@@ -5,14 +5,6 @@
 #include "repository.h"
 #include "object-store.h"
 
-/*
- * Do replace refs need to be checked this run?  This variable is
- * initialized to true unless --no-replace-object is used or
- * $GIT_NO_REPLACE_OBJECTS is set, but is set to false by some
- * commands that do not want replace references to be active.
- */
-extern int read_replace_refs;
-
 struct replace_object {
 	struct oidmap_entry original;
 	struct object_id replacement;
diff --git a/repo-settings.c b/repo-settings.c
index 1df0320bf33..5a7c990300d 100644
--- a/repo-settings.c
+++ b/repo-settings.c
@@ -68,6 +68,7 @@ void prepare_repo_settings(struct repository *r)
 	repo_cfg_bool(r, "pack.usebitmapboundarytraversal",
 		      &r->settings.pack_use_bitmap_boundary_traversal,
 		      r->settings.pack_use_bitmap_boundary_traversal);
+	repo_cfg_bool(r, "core.usereplacerefs", &r->settings.read_replace_refs, 1);
 
 	/*
 	 * The GIT_TEST_MULTI_PACK_INDEX variable is special in that
diff --git a/repository.h b/repository.h
index c42f7ab6bdc..13fefa540bc 100644
--- a/repository.h
+++ b/repository.h
@@ -39,6 +39,14 @@ struct repo_settings {
 	int pack_read_reverse_index;
 	int pack_use_bitmap_boundary_traversal;
 
+	/*
+	 * Do replace refs need to be checked this run?  This variable is
+	 * initialized to true unless --no-replace-object is used or
+	 * $GIT_NO_REPLACE_OBJECTS is set, but is set to false by some
+	 * commands that do not want replace references to be active.
+	 */
+	int read_replace_refs;
+
 	struct fsmonitor_settings *fsmonitor; /* lazily loaded */
 
 	int index_version;
-- 
gitgitgadget
Previous: Derrick StoleeNext: Victoria Dye
Message 15 of 32 in “Create stronger guard rails on replace refs”
  1. 0/3 Create stronger guard rails on replace refsDerrick Stolee via GitGitGadget, May 26, 2023
  2. 1/3 repository: create disable_replace_refs()Derrick Stolee via GitGitGadget, May 26, 2023
  3. Elijah NewrenMay 31, 2023
  4. Derrick StoleeMay 31, 2023
  5. Jeff KingJun 1, 2023
  6. Junio C HamanoJun 3, 2023
  7. Jeff KingJun 4, 2023
  8. Junio C HamanoJun 1, 2023
  9. Victoria DyeJun 1, 2023
  10. 2/3 replace-objects: create wrapper around settingDerrick Stolee via GitGitGadget, May 26, 2023
  11. Victoria DyeJun 1, 2023
  12. Derrick StoleeJun 1, 2023
  13. Elijah NewrenJun 3, 2023
  14. Derrick StoleeJun 5, 2023
  15. 3/3 repository: create read_replace_refs settingDerrick Stolee via GitGitGadget, May 26, 2023
  16. Victoria DyeJun 1, 2023
  17. Derrick StoleeJun 1, 2023
  18. Elijah NewrenMay 31, 2023
  19. 0/3 Create stronger guard rails on replace refsDerrick Stolee via GitGitGadget, Jun 2, 2023
  20. 1/3 repository: create disable_replace_refs()Derrick Stolee via GitGitGadget, Jun 2, 2023
  21. 2/3 replace-objects: create wrapper around settingDerrick Stolee via GitGitGadget, Jun 2, 2023
  22. René ScharfeJun 3, 2023
  23. Derrick StoleeJun 5, 2023
  24. 3/3 repository: create read_replace_refs settingDerrick Stolee via GitGitGadget, Jun 2, 2023
  25. Victoria DyeJun 5, 2023
  26. Elijah NewrenJun 3, 2023
  27. 0/3 Create stronger guard rails on replace refsDerrick Stolee via GitGitGadget, Jun 6, 2023
  28. 1/3 repository: create disable_replace_refs()Derrick Stolee via GitGitGadget, Jun 6, 2023
  29. 2/3 replace-objects: create wrapper around settingDerrick Stolee via GitGitGadget, Jun 6, 2023
  30. 3/3 repository: create read_replace_refs settingDerrick Stolee via GitGitGadget, Jun 6, 2023
  31. Victoria DyeJun 6, 2023
  32. Junio C HamanoJun 12, 2023

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