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[PATCH v5 3/3] fetch-pack: accept "pack" output for packfile URIs

From
Ted Nyman <tnyman@openai.com>
Date
Jul 26, 2026, 06:44 UTC
Message-ID
<fee6f292cba09a8190cc78595d0aa80e31243a8d.1785047139.git.tnyman@openai.com>
In-Reply-To
<cover.1785047139.git.tnyman@openai.com>

When index-pack finds an existing keep file it reports pack rather than keep. Accept either result from http-fetch, and only register a keep lockfile when this fetch created it.

Read the pack/keep prefix and hash without consuming any following fsck output, validate the reported pack hash against the advertised hash, and exercise a packfile URI fetch with a pre-existing keep file.

Signed-off-by: Ted Nyman <tnyman@openai.com>
---
 fetch-pack.c           | 33 ++++++++++++++++++---------------
 t/t5702-protocol-v2.sh | 31 +++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+), 15 deletions(-)
diff --git a/fetch-pack.c b/fetch-pack.c
index 29c41132ee..e9f24fbd63 100644
--- a/fetch-pack.c
+++ b/fetch-pack.c
@@ -1887,9 +1887,10 @@ static struct ref *do_fetch_pack_v2(struct fetch_pack_args *args,
 	}
 
 	for (i = 0; i < packfile_uris.nr; i++) {
+		bool created_keep;
 		int j;
 		struct child_process cmd = CHILD_PROCESS_INIT;
-		char packname[GIT_MAX_HEXSZ + 1];
+		char packhash[GIT_MAX_HEXSZ + 1];
 		const char *uri = packfile_uris.items[i].string +
 			the_hash_algo->hexsz + 1;
 
@@ -1907,16 +1908,17 @@ static struct ref *do_fetch_pack_v2(struct fetch_pack_args *args,
 		if (start_command(&cmd))
 			die("fetch-pack: unable to spawn http-fetch");
 
-		if (read_in_full(cmd.out, packname, 5) < 0 ||
-		    memcmp(packname, "keep\t", 5))
-			die("fetch-pack: expected keep then TAB at start of http-fetch output");
+		if (read_in_full(cmd.out, packhash, 5) != 5 ||
+		    (memcmp(packhash, "keep\t", 5) &&
+		     memcmp(packhash, "pack\t", 5)))
+			die("fetch-pack: expected pack or keep then TAB at start of http-fetch output");
+		created_keep = !memcmp(packhash, "keep\t", 5);
 
-		if (read_in_full(cmd.out, packname,
-				 the_hash_algo->hexsz + 1) < 0 ||
-		    packname[the_hash_algo->hexsz] != '\n')
-			die("fetch-pack: expected hash then LF at end of http-fetch output");
-
-		packname[the_hash_algo->hexsz] = '\0';
+		if (read_in_full(cmd.out, packhash,
+				 the_hash_algo->hexsz + 1) != the_hash_algo->hexsz + 1 ||
+		    packhash[the_hash_algo->hexsz] != '\n')
+			die("fetch-pack: expected hash then LF in http-fetch output");
+		packhash[the_hash_algo->hexsz] = '\0';
 
 		parse_gitmodules_oids(cmd.out, &fsck_options.gitmodules_found);
 
@@ -1925,16 +1927,17 @@ static struct ref *do_fetch_pack_v2(struct fetch_pack_args *args,
 		if (finish_command(&cmd))
 			die("fetch-pack: unable to finish http-fetch");
 
-		if (memcmp(packfile_uris.items[i].string, packname,
+		if (memcmp(packfile_uris.items[i].string, packhash,
 			   the_hash_algo->hexsz))
 			die("fetch-pack: pack downloaded from %s does not match expected hash %.*s",
 			    uri, (int) the_hash_algo->hexsz,
 			    packfile_uris.items[i].string);
 
-		string_list_append_nodup(pack_lockfiles,
-					 xstrfmt("%s/pack/pack-%s.keep",
-						 repo_get_object_directory(the_repository),
-						 packname));
+		if (created_keep)
+			string_list_append_nodup(pack_lockfiles,
+						 xstrfmt("%s/pack/pack-%s.keep",
+							 repo_get_object_directory(the_repository),
+							 packhash));
 	}
 	string_list_clear(&packfile_uris, 0);
 	strvec_clear(&index_pack_args);
diff --git a/t/t5702-protocol-v2.sh b/t/t5702-protocol-v2.sh
index 74a2b7730b..0f05286de8 100755
--- a/t/t5702-protocol-v2.sh
+++ b/t/t5702-protocol-v2.sh
@@ -1291,6 +1291,37 @@ test_expect_success 'packfile URIs with fetch instead of clone' '
 		fetch "$HTTPD_URL/smart/http_parent"
 '
 
+test_expect_success 'packfile URI preserves an existing keep file' '
+	P="$HTTPD_DOCUMENT_ROOT_PATH/http_parent" &&
+	rm -rf "$P" http_child keep.expect &&
+
+	git init "$P" &&
+	git -C "$P" config uploadpack.allowsidebandall true &&
+
+	echo my-blob >"$P/my-blob" &&
+	git -C "$P" add my-blob &&
+	git -C "$P" commit -m x &&
+	configure_exclusion "$P" my-blob >h &&
+
+	git init http_child &&
+	packhash=$(cat packh) &&
+	keep="http_child/.git/objects/pack/pack-$packhash.keep" &&
+	echo pre-existing >"$keep" &&
+	cp "$keep" keep.expect &&
+
+	GIT_TEST_SIDEBAND_ALL=1 \
+	git -C http_child -c protocol.version=2 \
+		-c fetch.uriprotocols=http,https \
+		fetch "$HTTPD_URL/smart/http_parent" &&
+
+	test_path_is_file \
+		"http_child/.git/objects/pack/pack-$packhash.pack" &&
+	test_path_is_file \
+		"http_child/.git/objects/pack/pack-$packhash.idx" &&
+	test_cmp keep.expect "$keep" &&
+	git -C http_child cat-file -e "$(cat h)"
+'
+
 test_expect_success 'fetching with valid packfile URI but invalid hash fails' '
 	P="$HTTPD_DOCUMENT_ROOT_PATH/http_parent" &&
 	rm -rf "$P" http_child log &&
-- 
2.55.0.openai.131.g83a728de1eb6
Previous: Jeff KingNext: Jeff King
Message 44 of 57 in “packfile URIs: support concurrent downloads”
  1. 0/2 packfile URIs: support concurrent downloadsTed Nyman, Jul 13, 2026
  2. 1/2 http: use unique tempfiles for packfile URI downloadsTed Nyman, Jul 13, 2026
  3. Junio C HamanoJul 14, 2026
  4. Ted NymanJul 14, 2026
  5. Taylor BlauJul 14, 2026
  6. Jeff KingJul 14, 2026
  7. Junio C HamanoJul 14, 2026
  8. Ted NymanJul 14, 2026
  9. Taylor BlauJul 14, 2026
  10. Jeff KingJul 14, 2026
  11. Jeff KingJul 14, 2026
  12. 2/2 fetch-pack: accept "pack" output for packfile URIsTed Nyman, Jul 13, 2026
  13. Jeff KingJul 14, 2026
  14. Jeff KingJul 14, 2026
  15. Ted NymanJul 14, 2026
  16. Jeff KingJul 14, 2026
  17. Taylor BlauJul 14, 2026
  18. 0/2 packfile URIs: support concurrent downloadsTed Nyman, Jul 20, 2026
  19. 1/2 http: avoid concurrent appends to partial packsTed Nyman, Jul 20, 2026
  20. Junio C HamanoJul 21, 2026
  21. 2/2 fetch-pack: accept "pack" output for packfile URIsTed Nyman, Jul 20, 2026
  22. 0/3 packfile URIs: support concurrent downloadsTed Nyman, Jul 21, 2026
  23. 1/3 http-fetch: correct --index-pack-arg documentationTed Nyman, Jul 21, 2026
  24. 2/3 http: avoid concurrent appends to partial packsTed Nyman, Jul 21, 2026
  25. 3/3 fetch-pack: accept "pack" output for packfile URIsTed Nyman, Jul 21, 2026
  26. Junio C HamanoJul 24, 2026
  27. Jeff KingJul 25, 2026
  28. Jeff KingJul 25, 2026
  29. Jeff KingJul 25, 2026
  30. Jeff KingJul 25, 2026
  31. Junio C HamanoJul 25, 2026
  32. 0/3 packfile URIs: support concurrent downloadsTed Nyman, Jul 24, 2026
  33. 1/3 http-fetch: correct --index-pack-arg documentationTed Nyman, Jul 24, 2026
  34. Taylor BlauJul 24, 2026
  35. 2/3 http: avoid concurrent appends to partial packsTed Nyman, Jul 24, 2026
  36. 3/3 fetch-pack: accept "pack" output for packfile URIsTed Nyman, Jul 24, 2026
  37. Taylor BlauJul 24, 2026
  38. 0/3 packfile URIs: support concurrent downloadsTed Nyman, Jul 26, 2026
  39. 1/3 http-fetch: correct --index-pack-arg documentationTed Nyman, Jul 26, 2026
  40. 2/3 http: avoid concurrent appends to partial packsTed Nyman, Jul 26, 2026
  41. Jeff KingJul 26, 2026
  42. Ted NymanJul 26, 2026
  43. Jeff KingJul 26, 2026
  44. 3/3 fetch-pack: accept "pack" output for packfile URIsTed Nyman, Jul 26, 2026
  45. Jeff KingJul 26, 2026
  46. 0/6 packfile URIs: support concurrent downloadsTed Nyman, Jul 27, 2026
  47. 1/6 http-fetch: correct --index-pack-arg documentationTed Nyman, Jul 27, 2026
  48. 2/6 http: avoid closing index-pack input twiceTed Nyman, Jul 27, 2026
  49. Jeff KingAug 1, 2026
  50. 3/6 http: accept HTTP 416 for complete partial packsTed Nyman, Jul 27, 2026
  51. Jeff KingAug 1, 2026
  52. 4/6 http: avoid concurrent appends to partial packsTed Nyman, Jul 27, 2026
  53. 5/6 http: permit unlinking partial packs on WindowsTed Nyman, Jul 27, 2026
  54. 6/6 fetch-pack: accept "pack" output for packfile URIsTed Nyman, Jul 27, 2026
  55. Junio C HamanoJul 29, 2026
  56. Jeff KingAug 1, 2026
  57. Junio C HamanoAug 8, 2026

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