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wed 2026-10-07 17:27 UTC

[PATCH v2 04/17] odb: move reparenting logic into respective subsystems

From
Patrick Steinhardt <ps@pks.im>
Date
Mar 5, 2026, 14:19 UTC
Message-ID
<20260305-b4-pks-odb-source-pluggable-v2-4-3290bfd1f444@pks.im>
In-Reply-To
<20260305-b4-pks-odb-source-pluggable-v2-0-3290bfd1f444@pks.im>

The primary object database source may be initialized with a relative path. When the process changes its current working directory we thus have to update this path and have it point to the same path, but relative to the new working directory.

This logic is handled in the object database layer. It consists of three steps:

  1. We undo any potential temporary object directory, which are used
     for transactions. This is done so that we don't end up modifying
     the temporary object database source that got applied for the
     transaction.
  2. We then iterate through the non-transactional sources and reparent
     their respective paths.
  3. We reapply the temporary object directory, but update its path.

All of this logic is heavily tied to how the object database source handles paths in the first place. It's an internal implementation detail, and as sources may not even use an on-disk path at all it is not a mechanism that applies to all potential sources.

Refactor the code so that the logic to reparent the sources is hosted by the "files" source and the temporary object directory subsystems, respectively. This logic is easier to reason about, but it also ensures that this logic is handled at the correct level.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 odb.c              | 37 -------------------------------------
 odb/source-files.c | 23 +++++++++++++++++++++++
 tmp-objdir.c       | 42 +++++++++++++++++++-----------------------
 tmp-objdir.h       | 15 ---------------
 4 files changed, 42 insertions(+), 75 deletions(-)
diff --git a/odb.c b/odb.c
index e5aa8deb88..86f7cf70a8 100644
--- a/odb.c
+++ b/odb.c
@@ -1,6 +1,5 @@
 #include "git-compat-util.h"
 #include "abspath.h"
-#include "chdir-notify.h"
 #include "commit-graph.h"
 #include "config.h"
 #include "dir.h"
@@ -1037,38 +1036,6 @@ int odb_write_object_stream(struct object_database *odb,
 	return odb_source_loose_write_stream(odb->sources, stream, len, oid);
 }
 
-static void odb_update_commondir(const char *name UNUSED,
-				 const char *old_cwd,
-				 const char *new_cwd,
-				 void *cb_data)
-{
-	struct object_database *odb = cb_data;
-	struct tmp_objdir *tmp_objdir;
-	struct odb_source *source;
-
-	tmp_objdir = tmp_objdir_unapply_primary_odb();
-
-	/*
-	 * In theory, we only have to do this for the primary object source, as
-	 * alternates' paths are always resolved to an absolute path.
-	 */
-	for (source = odb->sources; source; source = source->next) {
-		char *path;
-
-		if (is_absolute_path(source->path))
-			continue;
-
-		path = reparent_relative_path(old_cwd, new_cwd,
-					      source->path);
-
-		free(source->path);
-		source->path = path;
-	}
-
-	if (tmp_objdir)
-		tmp_objdir_reapply_primary_odb(tmp_objdir, old_cwd, new_cwd);
-}
-
 struct object_database *odb_new(struct repository *repo,
 				const char *primary_source,
 				const char *secondary_sources)
@@ -1089,8 +1056,6 @@ struct object_database *odb_new(struct repository *repo,
 
 	free(to_free);
 
-	chdir_notify_register(NULL, odb_update_commondir, o);
-
 	return o;
 }
 
@@ -1136,8 +1101,6 @@ void odb_free(struct object_database *o)
 
 	string_list_clear(&o->submodule_source_paths, 0);
 
-	chdir_notify_unregister(NULL, odb_update_commondir, o);
-
 	free(o);
 }
 
diff --git a/odb/source-files.c b/odb/source-files.c
index a43a197157..df0ea9ee62 100644
--- a/odb/source-files.c
+++ b/odb/source-files.c
@@ -1,13 +1,28 @@
 #include "git-compat-util.h"
+#include "abspath.h"
+#include "chdir-notify.h"
 #include "object-file.h"
 #include "odb/source.h"
 #include "odb/source-files.h"
 #include "packfile.h"
 
+static void odb_source_files_reparent(const char *name UNUSED,
+				      const char *old_cwd,
+				      const char *new_cwd,
+				      void *cb_data)
+{
+	struct odb_source_files *files = cb_data;
+	char *path = reparent_relative_path(old_cwd, new_cwd,
+					    files->base.path);
+	free(files->base.path);
+	files->base.path = path;
+}
+
 void odb_source_files_free(struct odb_source_files *files)
 {
 	if (!files)
 		return;
+	chdir_notify_unregister(NULL, odb_source_files_reparent, files);
 	odb_source_loose_free(files->loose);
 	packfile_store_free(files->packed);
 	odb_source_release(&files->base);
@@ -25,5 +40,13 @@ struct odb_source_files *odb_source_files_new(struct object_database *odb,
 	files->loose = odb_source_loose_new(&files->base);
 	files->packed = packfile_store_new(&files->base);
 
+	/*
+	 * Ideally, we would only ever store absolute paths in the source. This
+	 * is not (yet) possible though because we access and assume relative
+	 * paths in the primary ODB source in some user-facing functionality.
+	 */
+	if (!is_absolute_path(path))
+		chdir_notify_register(NULL, odb_source_files_reparent, files);
+
 	return files;
 }
diff --git a/tmp-objdir.c b/tmp-objdir.c
index 9f5a1788cd..e436eed07e 100644
--- a/tmp-objdir.c
+++ b/tmp-objdir.c
@@ -36,6 +36,21 @@ static void tmp_objdir_free(struct tmp_objdir *t)
 	free(t);
 }
 
+static void tmp_objdir_reparent(const char *name UNUSED,
+				const char *old_cwd,
+				const char *new_cwd,
+				void *cb_data)
+{
+	struct tmp_objdir *t = cb_data;
+	char *path;
+
+	path = reparent_relative_path(old_cwd, new_cwd,
+				      t->path.buf);
+	strbuf_reset(&t->path);
+	strbuf_addstr(&t->path, path);
+	free(path);
+}
+
 int tmp_objdir_destroy(struct tmp_objdir *t)
 {
 	int err;
@@ -51,6 +66,7 @@ int tmp_objdir_destroy(struct tmp_objdir *t)
 
 	err = remove_dir_recursively(&t->path, 0);
 
+	chdir_notify_unregister(NULL, tmp_objdir_reparent, t);
 	tmp_objdir_free(t);
 
 	return err;
@@ -137,6 +153,9 @@ struct tmp_objdir *tmp_objdir_create(struct repository *r,
 	strbuf_addf(&t->path, "%s/tmp_objdir-%s-XXXXXX",
 		    repo_get_object_directory(r), prefix);
 
+	if (!is_absolute_path(t->path.buf))
+		chdir_notify_register(NULL, tmp_objdir_reparent, t);
+
 	if (!mkdtemp(t->path.buf)) {
 		/* free, not destroy, as we never touched the filesystem */
 		tmp_objdir_free(t);
@@ -315,26 +334,3 @@ void tmp_objdir_replace_primary_odb(struct tmp_objdir *t, int will_destroy)
 							  t->path.buf, will_destroy);
 	t->will_destroy = will_destroy;
 }
-
-struct tmp_objdir *tmp_objdir_unapply_primary_odb(void)
-{
-	if (!the_tmp_objdir || !the_tmp_objdir->prev_source)
-		return NULL;
-
-	odb_restore_primary_source(the_tmp_objdir->repo->objects,
-				   the_tmp_objdir->prev_source, the_tmp_objdir->path.buf);
-	the_tmp_objdir->prev_source = NULL;
-	return the_tmp_objdir;
-}
-
-void tmp_objdir_reapply_primary_odb(struct tmp_objdir *t, const char *old_cwd,
-		const char *new_cwd)
-{
-	char *path;
-
-	path = reparent_relative_path(old_cwd, new_cwd, t->path.buf);
-	strbuf_reset(&t->path);
-	strbuf_addstr(&t->path, path);
-	free(path);
-	tmp_objdir_replace_primary_odb(t, t->will_destroy);
-}
diff --git a/tmp-objdir.h b/tmp-objdir.h
index fceda14979..ccf800faa7 100644
--- a/tmp-objdir.h
+++ b/tmp-objdir.h
@@ -68,19 +68,4 @@ void tmp_objdir_add_as_alternate(const struct tmp_objdir *);
  */
 void tmp_objdir_replace_primary_odb(struct tmp_objdir *, int will_destroy);
 
-/*
- * If the primary object database was replaced by a temporary object directory,
- * restore it to its original value while keeping the directory contents around.
- * Returns NULL if the primary object database was not replaced.
- */
-struct tmp_objdir *tmp_objdir_unapply_primary_odb(void);
-
-/*
- * Reapplies the former primary temporary object database, after potentially
- * changing its relative path.
- */
-void tmp_objdir_reapply_primary_odb(struct tmp_objdir *, const char *old_cwd,
-		const char *new_cwd);
-
-
 #endif /* TMP_OBJDIR_H */
-- 
2.53.0.797.g7842e34a66.dirty
Previous: Patrick SteinhardtNext: Patrick Steinhardt
Message 58 of 77 in “odb: make object database sources pluggable”
  1. 00/17 odb: make object database sources pluggablePatrick Steinhardt, Feb 23, 2026
  2. 01/17 odb: split `struct odb_source` into separate headerPatrick Steinhardt, Feb 23, 2026
  3. 02/17 odb: introduce "files" sourcePatrick Steinhardt, Feb 23, 2026
  4. 03/17 odb: embed base source in the "files" backendPatrick Steinhardt, Feb 23, 2026
  5. 04/17 odb: move reparenting logic into respective subsystemsPatrick Steinhardt, Feb 23, 2026
  6. 05/17 odb/source: introduce source type for robustnessPatrick Steinhardt, Feb 23, 2026
  7. 06/17 odb/source: make `free()` function pluggablePatrick Steinhardt, Feb 23, 2026
  8. 07/17 odb/source: make `reprepare()` function pluggablePatrick Steinhardt, Feb 23, 2026
  9. 08/17 odb/source: make `close()` function pluggablePatrick Steinhardt, Feb 23, 2026
  10. 09/17 odb/source: make `read_object_info()` function pluggablePatrick Steinhardt, Feb 23, 2026
  11. 10/17 odb/source: make `read_object_stream()` function pluggablePatrick Steinhardt, Feb 23, 2026
  12. 11/17 odb/source: make `for_each_object()` function pluggablePatrick Steinhardt, Feb 23, 2026
  13. 12/17 odb/source: make `freshen_object()` function pluggablePatrick Steinhardt, Feb 23, 2026
  14. 13/17 odb/source: make `write_object()` function pluggablePatrick Steinhardt, Feb 23, 2026
  15. 14/17 odb/source: make `write_object_stream()` function pluggablePatrick Steinhardt, Feb 23, 2026
  16. 15/17 odb/source: make `read_alternates()` function pluggablePatrick Steinhardt, Feb 23, 2026
  17. 16/17 odb/source: make `write_alternate()` function pluggablePatrick Steinhardt, Feb 23, 2026
  18. 17/17 odb/source: make `begin_transaction()` function pluggablePatrick Steinhardt, Feb 23, 2026
  19. Patrick SteinhardtFeb 23, 2026
  20. Junio C HamanoFeb 23, 2026
  21. Patrick SteinhardtFeb 24, 2026
  22. Justin ToblerMar 4, 2026
  23. Justin ToblerMar 4, 2026
  24. Justin ToblerMar 4, 2026
  25. Justin ToblerMar 4, 2026
  26. Justin ToblerMar 4, 2026
  27. Justin ToblerMar 4, 2026
  28. Justin ToblerMar 4, 2026
  29. Justin ToblerMar 4, 2026
  30. Justin ToblerMar 4, 2026
  31. Justin ToblerMar 4, 2026
  32. Justin ToblerMar 4, 2026
  33. Karthik NayakMar 5, 2026
  34. Karthik NayakMar 5, 2026
  35. Karthik NayakMar 5, 2026
  36. Karthik NayakMar 5, 2026
  37. Karthik NayakMar 5, 2026
  38. Karthik NayakMar 5, 2026
  39. Karthik NayakMar 5, 2026
  40. Patrick SteinhardtMar 5, 2026
  41. Karthik NayakMar 5, 2026
  42. Patrick SteinhardtMar 5, 2026
  43. Patrick SteinhardtMar 5, 2026
  44. Patrick SteinhardtMar 5, 2026
  45. Patrick SteinhardtMar 5, 2026
  46. Patrick SteinhardtMar 5, 2026
  47. Patrick SteinhardtMar 5, 2026
  48. Patrick SteinhardtMar 5, 2026
  49. Patrick SteinhardtMar 5, 2026
  50. Patrick SteinhardtMar 5, 2026
  51. Patrick SteinhardtMar 5, 2026
  52. Patrick SteinhardtMar 5, 2026
  53. Patrick SteinhardtMar 5, 2026
  54. 00/17 odb: make object database sources pluggablePatrick Steinhardt, Mar 5, 2026
  55. 01/17 odb: split `struct odb_source` into separate headerPatrick Steinhardt, Mar 5, 2026
  56. 02/17 odb: introduce "files" sourcePatrick Steinhardt, Mar 5, 2026
  57. 03/17 odb: embed base source in the "files" backendPatrick Steinhardt, Mar 5, 2026
  58. 04/17 odb: move reparenting logic into respective subsystemsPatrick Steinhardt, Mar 5, 2026
  59. 05/17 odb/source: introduce source type for robustnessPatrick Steinhardt, Mar 5, 2026
  60. 06/17 odb/source: make `free()` function pluggablePatrick Steinhardt, Mar 5, 2026
  61. 07/17 odb/source: make `reprepare()` function pluggablePatrick Steinhardt, Mar 5, 2026
  62. 08/17 odb/source: make `close()` function pluggablePatrick Steinhardt, Mar 5, 2026
  63. 09/17 odb/source: make `read_object_info()` function pluggablePatrick Steinhardt, Mar 5, 2026
  64. 10/17 odb/source: make `read_object_stream()` function pluggablePatrick Steinhardt, Mar 5, 2026
  65. 11/17 odb/source: make `for_each_object()` function pluggablePatrick Steinhardt, Mar 5, 2026
  66. 12/17 odb/source: make `freshen_object()` function pluggablePatrick Steinhardt, Mar 5, 2026
  67. 13/17 odb/source: make `write_object()` function pluggablePatrick Steinhardt, Mar 5, 2026
  68. 14/17 odb/source: make `write_object_stream()` function pluggablePatrick Steinhardt, Mar 5, 2026
  69. 15/17 odb/source: make `read_alternates()` function pluggablePatrick Steinhardt, Mar 5, 2026
  70. 16/17 odb/source: make `write_alternate()` function pluggablePatrick Steinhardt, Mar 5, 2026
  71. 17/17 odb/source: make `begin_transaction()` function pluggablePatrick Steinhardt, Mar 5, 2026
  72. Justin ToblerMar 5, 2026
  73. Justin ToblerMar 5, 2026
  74. Justin ToblerMar 5, 2026
  75. Justin ToblerMar 5, 2026
  76. Junio C HamanoMar 5, 2026
  77. Patrick SteinhardtMar 10, 2026

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