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[PATCH 32/32] object-file-convert: Implement repo_submodule_oid_to_algop

From
Eric W. Biederman <ebiederm@xmission.com>
Date
Sep 8, 2023, 23:10 UTC
Message-ID
<20230908231049.2035003-32-ebiederm@xmission.com>
In-Reply-To
<87sf7ol0z3.fsf@email.froward.int.ebiederm.org>

From time to time git tree objects contain gitlinks. These gitlinks contain the oid of an object in another git repository. To succesfully translate these oids it is necessary to look at the mapping tables in the submodules where the mapping tables live.

Limiting myself to submodule interfaces I can see in the code repo_submodule_oid_to_algop is the best I can figure out how to do, for a gitlink agnostic implementation.

The big downsides are that the code as implemented is not thread safe, it depends upon a worktree, and it always walks through all of the submodules.

There are interfaces in the code to lookup the submodule for an individual gitlink. As such iterating all of the submodules could be avoided if care was taken to compute the path to the gitlink and to recognizes the code is translating a gitlink.

The dependency on a worktree, and the thread safety issues I do not see a solution to short of reworking how git deals with submodules.

For now repo_oid_to_algop does not call repo_submodule_oid_to_algop to allow avoiding the thread safety issues.

Update callers of repo_oid_to_algop that can benefit from a submodule translation to also call repo_sumodule_oid_to_algop.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 builtin/fast-import.c |  5 ++++-
 builtin/index-pack.c  |  4 +++-
 object-file-convert.c | 45 +++++++++++++++++++++++++++++++++++++++++++
 object-file-convert.h |  5 +++++
 4 files changed, 57 insertions(+), 2 deletions(-)
diff --git a/builtin/fast-import.c b/builtin/fast-import.c
index f1c250dd3c8f..66c471bc730e 100644
--- a/builtin/fast-import.c
+++ b/builtin/fast-import.c
@@ -1070,7 +1070,10 @@ static int store_object(
 			else if (pobj)
 				break;
 			else if (repo_oid_to_algop(repo, &state.oid, compat,
-						   &state.mapped_oid))
+						   &state.mapped_oid) &&
+				 repo_submodule_oid_to_algop(repo, &state.oid,
+							     compat,
+							     &state.mapped_oid))
 				break;
 		}
 		convert_object_file_end(&state, ret);
diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index 6827d14b91ce..4100fd56a845 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -2093,7 +2093,9 @@ static void compute_compat_oid(struct object_entry *obj)
 		else if (pobj)
 			cco = cco_push(cco, pobj);
 		else if (repo_oid_to_algop(repo, &cco->state.oid, compat,
-					   &cco->state.mapped_oid))
+					   &cco->state.mapped_oid) &&
+			 repo_submodule_oid_to_algop(repo, &cco->state.oid, compat,
+						     &cco->state.mapped_oid))
 			die(_("When converting %s no mapping for oid %s to %s\n"),
 			    oid_to_hex(&cco->obj->idx.oid),
 			    oid_to_hex(&cco->state.oid),
diff --git a/object-file-convert.c b/object-file-convert.c
index 3fd080ebc112..2306e17dd57e 100644
--- a/object-file-convert.c
+++ b/object-file-convert.c
@@ -11,6 +11,45 @@
 #include "gpg-interface.h"
 #include "pack-compat-map.h"
 #include "object-file-convert.h"
+#include "read-cache.h"
+#include "submodule-config.h"
+
+int repo_submodule_oid_to_algop(struct repository *repo,
+				const struct object_id *src,
+				const struct git_hash_algo *to,
+				struct object_id *dest)
+{
+	int i;
+
+	if (repo_read_index(repo) < 0)
+		die(_("index file corrupt"));
+
+	for (i = 0; i < repo->index->cache_nr; i++) {
+		const struct cache_entry *ce = repo->index->cache[i];
+		struct repository subrepo = {};
+		int ret;
+
+		if (!S_ISGITLINK(ce->ce_mode))
+			continue;
+
+		while (i + 1 < repo->index->cache_nr &&
+		       !strcmp(ce->name, repo->index->cache[i + 1]->name))
+			/*
+			 * Skip entries with the same name in different stages
+			 * to make sure an entry is returned only once.
+			 */
+			i++;
+
+		if (repo_submodule_init(&subrepo, repo, ce->name, null_oid()))
+			continue;
+
+		ret = repo_oid_to_algop(&subrepo, src, to, dest);
+		repo_clear(&subrepo);
+		if (ret == 0)
+			return 0;
+	}
+	return -1;
+}
 
 int repo_oid_to_algop(struct repository *repo, const struct object_id *src,
 		      const struct git_hash_algo *to, struct object_id *dest)
@@ -34,6 +73,7 @@ int repo_oid_to_algop(struct repository *repo, const struct object_id *src,
 		 */
 		if (!repo_packed_oid_to_algop(repo, src, to, dest))
 			return 0;
+
 		/*
 		 * We may have loaded the object map at repo initialization but
 		 * another process (perhaps upstream of a pipe from us) may have
@@ -306,6 +346,11 @@ int convert_object_file(struct strbuf *outbuf,
 			break;
 		ret = repo_oid_to_algop(the_repository, &state.oid, state.to,
 					&state.mapped_oid);
+		if (ret)
+			ret = repo_submodule_oid_to_algop(the_repository,
+							  &state.oid,
+							  state.to,
+							  &state.mapped_oid);
 		if (ret) {
 			error(_("failed to map %s entry for %s"),
 			      type_name(type), oid_to_hex(&state.oid));
diff --git a/object-file-convert.h b/object-file-convert.h
index da032d7a91ef..7a19feda5f0c 100644
--- a/object-file-convert.h
+++ b/object-file-convert.h
@@ -10,6 +10,11 @@ struct strbuf;
 int repo_oid_to_algop(struct repository *repo, const struct object_id *src,
 		      const struct git_hash_algo *to, struct object_id *dest);
 
+int repo_submodule_oid_to_algop(struct repository *repo,
+				const struct object_id *src,
+				const struct git_hash_algo *to,
+				struct object_id *dest);
+
 struct object_file_convert_state {
 	struct strbuf *outbuf;
 	const struct git_hash_algo *from;
-- 
2.41.0
Previous: Eric W. BiedermanNext: Eric W. Biederman
Message 37 of 59 in “SHA256 and SHA1 interoperability”
  1. Eric W. BiedermanSep 8, 2023
  2. 02/32 doc hash-function-transition: Replace compatObjectFormat with compatMapEric W. Biederman, Sep 8, 2023
  3. brian m. carlsonSep 10, 2023
  4. Eric W. BiedermanSep 10, 2023
  5. Junio C HamanoSep 11, 2023
  6. 02/32 doc hash-function-transition: Replace compatObjectFormat with mapObjectFormatEric W. Biederman, Sep 11, 2023
  7. 02/32 doc hash-function-transition: Augment compatObjectFormat with readCompatMapEric W. Biederman, Sep 11, 2023
  8. Oswald BuddenhagenSep 12, 2023
  9. Eric W. BiedermanSep 12, 2023
  10. Oswald BuddenhagenSep 13, 2023
  11. 04/32 object-name: Initial support for ^{sha1} and ^{sha256}Eric W. Biederman, Sep 8, 2023
  12. 06/32 repository: Implement core.compatMapEric W. Biederman, Sep 8, 2023
  13. 07/32 loose: add a mapping between SHA-1 and SHA-256 for loose objectsEric W. Biederman, Sep 8, 2023
  14. 19/32 object-file-convert: convert tag commits when writingEric W. Biederman, Sep 8, 2023
  15. 20/32 builtin/cat-file: Let the oid determine the output algorithmEric W. Biederman, Sep 8, 2023
  16. 22/32 object-file: Handle compat objects in check_object_signatureEric W. Biederman, Sep 8, 2023
  17. 26/32 object-file-convert: Implement convert_object_file_{begin,step,end}Eric W. Biederman, Sep 8, 2023
  18. Junio C HamanoSep 11, 2023
  19. 27/32 builtin/fast-import: compute compatibility hashs for imported objectsEric W. Biederman, Sep 8, 2023
  20. 29/32 builtin/index-pack: Compute the compatibility hashEric W. Biederman, Sep 8, 2023
  21. 31/32 unpack-objects: Update to compute and write the compatibility hashesEric W. Biederman, Sep 8, 2023
  22. 16/32 object: Factor out parse_mode out of fast-import and tree-walk into in object.hEric W. Biederman, Sep 8, 2023
  23. 10/32 bulk-checkin: Only accept blobsEric W. Biederman, Sep 8, 2023
  24. 23/32 builtin/ls-tree: Let the oid determine the output algorithmEric W. Biederman, Sep 8, 2023
  25. 12/32 bulk-checkin: hash object with compatibility algorithmEric W. Biederman, Sep 8, 2023
  26. Junio C HamanoSep 11, 2023
  27. 14/32 commit: write commits for both hashesEric W. Biederman, Sep 8, 2023
  28. Junio C HamanoSep 11, 2023
  29. 03/32 object-file-convert: Stubs for converting from one object format to anotherEric W. Biederman, Sep 8, 2023
  30. 08/32 loose: Compatibilty short name supportEric W. Biederman, Sep 8, 2023
  31. 01/32 doc hash-file-transition: A map file for mapping between sha1 and sha256Eric W. Biederman, Sep 8, 2023
  32. brian m. carlsonSep 10, 2023
  33. Eric W. BiedermanSep 10, 2023
  34. brian m. carlsonSep 12, 2023
  35. Eric W. BiedermanSep 12, 2023
  36. 15/32 cache: add a function to read an OID of a specific algorithmEric W. Biederman, Sep 8, 2023
  37. 32/32 object-file-convert: Implement repo_submodule_oid_to_algopEric W. Biederman, Sep 8, 2023
  38. 30/32 builtin/index-pack: Make the stack in compute_compat_oid explicitEric W. Biederman, Sep 8, 2023
  39. 28/32 builtin/index-pack: Add a simple oid indexEric W. Biederman, Sep 8, 2023
  40. 25/32 pack-compat-map: Add support for .compat files of a packfileEric W. Biederman, Sep 8, 2023
  41. Junio C HamanoSep 11, 2023
  42. Taylor BlauOct 5, 2023
  43. 21/32 tree-walk: init_tree_desc take an oid to get the hash algorithmEric W. Biederman, Sep 8, 2023
  44. 24/32 builtin/pack-objects: Communicate the compatibility hash through struct pack_idx_entryEric W. Biederman, Sep 8, 2023
  45. 18/32 object-file-convert: convert commit objects when writingEric W. Biederman, Sep 8, 2023
  46. 17/32 object-file-convert: add a function to convert trees between algorithmsEric W. Biederman, Sep 8, 2023
  47. 09/32 object-file: Update the loose object map when writing loose objectsEric W. Biederman, Sep 8, 2023
  48. 11/32 pack: Communicate the compat_oid through struct pack_idx_entryEric W. Biederman, Sep 8, 2023
  49. 05/32 repository: add a compatibility hash algorithmEric W. Biederman, Sep 8, 2023
  50. 13/32 object-file: Add a compat_oid_in parameter to write_object_file_flagsEric W. Biederman, Sep 8, 2023
  51. Eric W. BiedermanSep 9, 2023
  52. brian m. carlsonSep 10, 2023
  53. Eric W. BiedermanSep 10, 2023
  54. Junio C HamanoSep 11, 2023
  55. Eric W. BiedermanSep 11, 2023
  56. brian m. carlsonSep 11, 2023
  57. Eric W. BiedermanSep 12, 2023
  58. Junio C HamanoSep 12, 2023
  59. Eric W. BiedermanSep 14, 2023

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