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[PATCH 5/6] builtin/stash: provide a way to import stashes from a ref

From
brian m. carlson <sandals@crustytoothpaste.net>
Date
Mar 10, 2022, 17:32 UTC
Message-ID
<20220310173236.4165310-6-sandals@crustytoothpaste.net>
In-Reply-To
<20220310173236.4165310-1-sandals@crustytoothpaste.net>

Now that we have a way to export stashes to a ref, let's provide a way to import them from such a ref back to the stash. This works much the way the export code does, except that we strip off the first parent chain commit and then store each resulting commit back to the stash.

We don't clear the stash first and instead add the specified stashes to the top of the stash. This is because users may want to export just a few stashes, such as to share a small amount of work in progress with a colleague, and it would be undesirable for the receiving user to lose all of their data. For users who do want to replace the stash, it's easy to do to: simply run "git stash clear" first.

We specifically rely on the fact that we'll produce identical stash commits on both sides in our tests. This provides a cheap, straightforward check for our tests and also makes it easy for users to see if they already have the same data in both repositories. Note that the exported commits don't because we don't write a predictable base commit, however.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 builtin/stash.c  | 125 +++++++++++++++++++++++++++++++++++++++++++++++
 t/t3903-stash.sh |  52 ++++++++++++++++++++
 2 files changed, 177 insertions(+)
diff --git a/builtin/stash.c b/builtin/stash.c
index 582a04dbab..626e7b8531 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -34,6 +34,7 @@ static const char * const git_stash_usage[] = {
 	N_("git stash save [-p|--patch] [-S|--staged] [-k|--[no-]keep-index] [-q|--quiet]\n"
 	   "          [-u|--include-untracked] [-a|--all] [<message>]"),
 	N_("git stash export (--print | --to-ref <ref>) [<stashes>]"),
+	N_("git stash import <commit>"),
 	NULL
 };
 
@@ -95,6 +96,10 @@ static const char * const git_stash_export_usage[] = {
 	NULL
 };
 
+static const char * const git_stash_import_usage[] = {
+	N_("git stash import <commit>"),
+	NULL
+};
 
 static const char ref_stash[] = "refs/stash";
 static struct strbuf stash_index_path = STRBUF_INIT;
@@ -104,6 +109,7 @@ static struct strbuf stash_index_path = STRBUF_INIT;
  * b_commit is set to the base commit
  * i_commit is set to the commit containing the index tree
  * u_commit is set to the commit containing the untracked files tree
+ * c_commit is set to the first parent (chain commit) when importing and is otherwise unset
  * w_tree is set to the working tree
  * b_tree is set to the base tree
  * i_tree is set to the index tree
@@ -114,6 +120,7 @@ struct stash_info {
 	struct object_id b_commit;
 	struct object_id i_commit;
 	struct object_id u_commit;
+	struct object_id c_commit;
 	struct object_id w_tree;
 	struct object_id b_tree;
 	struct object_id i_tree;
@@ -138,6 +145,32 @@ static void assert_stash_like(struct stash_info *info, const char *revision)
 		die(_("'%s' is not a stash-like commit"), revision);
 }
 
+static int get_stash_info_for_import(struct stash_info *info, const struct object_id *oid)
+{
+	int has_parents;
+	char hexoid[GIT_MAX_HEXSZ + 1];
+	oid_to_hex_r(hexoid, oid);
+
+	oidcpy(&info->w_commit, oid);
+	if (get_oidf(&info->w_tree, "%s:", hexoid))
+		return -1;
+
+	has_parents = !get_oidf(&info->c_commit, "%s^1", hexoid);
+
+	/* If this tree is the empty one and we have no parents, we've reached the end. */
+	if (oideq(&info->w_tree, the_hash_algo->empty_tree) && !has_parents)
+		return 1;
+	if (get_oidf(&info->b_commit, "%s^2", hexoid) ||
+	    get_oidf(&info->i_commit, "%s^3", hexoid) ||
+	    get_oidf(&info->b_tree, "%s^2:", hexoid) ||
+	    get_oidf(&info->i_tree, "%s^3:", hexoid))
+		return -1;
+
+	info->has_u = !get_oidf(&info->u_commit, "%s^4", hexoid) &&
+		      !get_oidf(&info->u_tree, "%s^4:", hexoid);
+	return 0;
+}
+
 static int get_stash_info_1(struct stash_info *info, const char *commit, int quiet)
 {
 	int ret;
@@ -1827,6 +1860,96 @@ static char *write_commit_with_parents(struct object_id *out, const struct stash
 	return msg;
 }
 
+static int do_import_stash(const char *rev)
+{
+	struct object_id oid;
+	size_t nitems = 0, nalloc = 0;
+	struct stash_info *items = NULL;
+	int res = 0;
+
+	if (get_oid(rev, &oid))
+		return error(_("not a valid revision: %s"), rev);
+
+	/*
+	 * Walk the commit history, finding each stash entry, and load data into
+	 * the array.
+	 */
+	for (size_t i = 0;; i++, nitems++) {
+		int ret;
+
+		if (nalloc <= i) {
+			size_t new = nalloc * 3 / 2 + 5;
+			items = xrealloc(items, new * sizeof(*items));
+			nalloc = new;
+		}
+		memset(&items[i], 0, sizeof(*items));
+		/* We want this to be quiet because it might not exist. */
+		ret = get_stash_info_for_import(&items[i], &oid);
+		if (ret < 0)
+			return error(_("%s is not a valid exported stash commit"), oid_to_hex(&oid));
+		if (ret)
+			break;
+		oidcpy(&oid, &items[i].c_commit);
+	}
+
+	/*
+	 * Now, walk each entry, adding it to the stash as a normal stash
+	 * commit.
+	 */
+	for (ssize_t i = nitems - 1; i >= 0; i--) {
+		struct commit_list *parents = NULL;
+		struct commit_list **next = &parents;
+		struct object_id out;
+		char *msg;
+
+		next = commit_list_append(lookup_commit_reference(the_repository, &items[i].b_commit), next);
+		next = commit_list_append(lookup_commit_reference(the_repository, &items[i].i_commit), next);
+		if (items[i].has_u)
+			next = commit_list_append(lookup_commit_reference(the_repository,
+								   &items[i].u_commit),
+						  next);
+
+		msg = write_commit_with_parents(&out, &items[i], parents);
+		if (!msg) {
+			res = -1;
+			goto out;
+		}
+		if (do_store_stash(&out, msg, 1)) {
+			free(msg);
+			res = -1;
+			error(_("Cannot save the current status"));
+			goto out;
+		}
+		free(msg);
+	}
+out:
+	for (size_t i = 0; i < nitems; i++) {
+		free_stash_info(&items[i]);
+	}
+	free(items);
+
+	return res;
+}
+
+static int import_stash(int argc, const char **argv, const char *prefix)
+{
+	int ret = 0;
+	struct option options[] = {
+		OPT_END()
+	};
+
+	argc = parse_options(argc, argv, prefix, options,
+			     git_stash_import_usage,
+			     PARSE_OPT_KEEP_DASHDASH);
+
+	if (argc != 1)
+		return error(_("a revision to import from is required"));
+
+
+	ret = do_import_stash(argv[0]);
+	return ret;
+}
+
 static int do_export_stash(const char *ref, size_t argc, const char **argv)
 {
 	struct object_id base;
@@ -1996,6 +2119,8 @@ int cmd_stash(int argc, const char **argv, const char *prefix)
 		return !!save_stash(argc, argv, prefix);
 	else if (!strcmp(argv[0], "export"))
 		return !!export_stash(argc, argv, prefix);
+	else if (!strcmp(argv[0], "import"))
+		return !!import_stash(argc, argv, prefix);
 	else if (*argv[0] != '-')
 		usage_msg_optf(_("unknown subcommand: %s"),
 			       git_stash_usage, options, argv[0]);
diff --git a/t/t3903-stash.sh b/t/t3903-stash.sh
index b149e2af44..d2ddede9be 100755
--- a/t/t3903-stash.sh
+++ b/t/t3903-stash.sh
@@ -1295,6 +1295,58 @@ test_expect_success 'stash --keep-index with file deleted in index does not resu
 	test_path_is_missing to-remove
 '
 
+test_expect_success 'stash export and import round-trip stashes' '
+	git reset &&
+	>untracked &&
+	>tracked1 &&
+	>tracked2 &&
+	git add tracked* &&
+	git stash -- &&
+	>subdir/untracked &&
+	>subdir/tracked1 &&
+	>subdir/tracked2 &&
+	git add subdir/tracked* &&
+	git stash -- subdir/ &&
+	stash0=$(git rev-parse --verify stash@{0}) &&
+	stash1=$(git rev-parse --verify stash@{1}) &&
+	simple=$(git stash export --print) &&
+	git stash clear &&
+	git stash import "$simple" &&
+	imported0=$(git rev-parse --verify stash@{0}) &&
+	imported1=$(git rev-parse --verify stash@{1}) &&
+	test "$imported0" = "$stash0" &&
+	test "$imported1" = "$stash1" &&
+	git stash export --to-ref refs/heads/foo &&
+	git stash clear &&
+	git stash import foo &&
+	imported0=$(git rev-parse --verify stash@{0}) &&
+	imported1=$(git rev-parse --verify stash@{1}) &&
+	test "$imported0" = "$stash0" &&
+	test "$imported1" = "$stash1"
+'
+
+test_expect_success 'stash import appends commits' '
+	git log --format=oneline -g refs/stash >actual &&
+	echo $(cat actual | wc -l) >count &&
+	git stash import refs/heads/foo &&
+	git log --format=oneline -g refs/stash >actual &&
+	test_line_count = $(($(cat count) * 2)) actual
+'
+
+test_expect_success 'stash export can accept specified stashes' '
+	git stash clear &&
+	git stash import foo &&
+	git stash export --to-ref bar stash@{1} stash@{0} &&
+	git stash clear &&
+	git stash import bar &&
+	imported0=$(git rev-parse --verify stash@{0}) &&
+	imported1=$(git rev-parse --verify stash@{1}) &&
+	test "$imported1" = "$stash0" &&
+	test "$imported0" = "$stash1" &&
+	git log --format=oneline -g refs/stash >actual &&
+	test_line_count = 2 actual
+'
+
 test_expect_success 'stash apply should succeed with unmodified file' '
 	echo base >file &&
 	git add file &&
Previous: Junio C HamanoNext: Junio C Hamano
Message 22 of 76 in “Importing and exporting stashes to refs”
  1. 0/6 Importing and exporting stashes to refsbrian m. carlson, Mar 10, 2022
  2. 2/6 builtin/stash: fill in all commit databrian m. carlson, Mar 10, 2022
  3. Junio C HamanoMar 16, 2022
  4. 1/6 builtin/stash: factor out generic function to look up stash infobrian m. carlson, Mar 10, 2022
  5. 3/6 object-name: make get_oid quietly return an errorbrian m. carlson, Mar 10, 2022
  6. Junio C HamanoMar 16, 2022
  7. Drew StoleeMar 16, 2022
  8. brian m. carlsonMar 16, 2022
  9. 4/6 builtin/stash: provide a way to export stashes to a refbrian m. carlson, Mar 10, 2022
  10. Ævar Arnfjörð BjarmasonMar 11, 2022
  11. Phillip WoodMar 14, 2022
  12. Phillip WoodMar 15, 2022
  13. brian m. carlsonMar 16, 2022
  14. C99 %zu support (on MSVC) (was: [PATCH 4/6] builtin/stash: provide a way to export stashes to a ref)Ævar Arnfjörð Bjarmason, Mar 18, 2022
  15. Phillip WoodMar 18, 2022
  16. Johannes SchindelinMar 24, 2022
  17. ssize_t portability (was: [PATCH 4/6] builtin/stash: provide a way to export stashes to a ref)Ævar Arnfjörð Bjarmason, Mar 18, 2022
  18. Junio C HamanoMar 16, 2022
  19. 6/6 doc: add stash export and import to docsbrian m. carlson, Mar 10, 2022
  20. Junio C HamanoMar 16, 2022
  21. Junio C HamanoMar 16, 2022
  22. 5/6 builtin/stash: provide a way to import stashes from a refbrian m. carlson, Mar 10, 2022
  23. Junio C HamanoMar 16, 2022
  24. brian m. carlsonMar 16, 2022
  25. Junio C HamanoMar 10, 2022
  26. brian m. carlsonMar 10, 2022
  27. Junio C HamanoMar 10, 2022
  28. brian m. carlsonMar 10, 2022
  29. 0/4 Importing and exporting stashes to refsbrian m. carlson, Mar 29, 2022
  30. 2/4 builtin/stash: factor out revision parsing into a functionbrian m. carlson, Mar 29, 2022
  31. 1/4 object-name: make get_oid quietly return an errorbrian m. carlson, Mar 29, 2022
  32. 4/4 builtin/stash: provide a way to import stashes from a refbrian m. carlson, Mar 29, 2022
  33. 3/4 builtin/stash: provide a way to export stashes to a refbrian m. carlson, Mar 29, 2022
  34. Junio C HamanoMar 30, 2022
  35. brian m. carlsonMar 30, 2022
  36. Ævar Arnfjörð BjarmasonMar 31, 2022
  37. Junio C HamanoMar 31, 2022
  38. brian m. carlsonApr 5, 2022
  39. Ævar Arnfjörð BjarmasonApr 6, 2022
  40. Junio C HamanoApr 6, 2022
  41. Ævar Arnfjörð BjarmasonMar 31, 2022
  42. brian m. carlsonApr 5, 2022
  43. Junio C HamanoMar 31, 2022
  44. Ævar Arnfjörð BjarmasonMar 31, 2022
  45. 0/4 Importing and exporting stashes to refsbrian m. carlson, Apr 3, 2022
  46. 1/4 object-name: make get_oid quietly return an errorbrian m. carlson, Apr 3, 2022
  47. 2/4 builtin/stash: factor out revision parsing into a functionbrian m. carlson, Apr 3, 2022
  48. Phillip WoodApr 4, 2022
  49. 4/4 builtin/stash: provide a way to import stashes from a refbrian m. carlson, Apr 3, 2022
  50. Ævar Arnfjörð BjarmasonApr 4, 2022
  51. brian m. carlsonApr 5, 2022
  52. Ævar Arnfjörð BjarmasonApr 6, 2022
  53. 3/4 builtin/stash: provide a way to export stashes to a refbrian m. carlson, Apr 3, 2022
  54. Ævar Arnfjörð BjarmasonApr 4, 2022
  55. Junio C HamanoApr 4, 2022
  56. Junio C HamanoApr 4, 2022
  57. Ævar Arnfjörð BjarmasonApr 4, 2022
  58. brian m. carlsonApr 5, 2022
  59. 0/4 Importing and exporting stashes to refsbrian m. carlson, Apr 7, 2022
  60. 3/4 builtin/stash: provide a way to export stashes to a refbrian m. carlson, Apr 7, 2022
  61. Ævar Arnfjörð BjarmasonApr 13, 2022
  62. Ævar Arnfjörð BjarmasonApr 13, 2022
  63. Ævar Arnfjörð BjarmasonApr 13, 2022
  64. 2/4 builtin/stash: factor out revision parsing into a functionbrian m. carlson, Apr 7, 2022
  65. 1/4 object-name: make get_oid quietly return an errorbrian m. carlson, Apr 7, 2022
  66. 4/4 builtin/stash: provide a way to import stashes from a refbrian m. carlson, Apr 7, 2022
  67. Jonathan TanApr 12, 2022
  68. brian m. carlsonApr 13, 2022
  69. Jonathan TanApr 13, 2022
  70. Ævar Arnfjörð BjarmasonApr 13, 2022
  71. Jonathan TanApr 13, 2022
  72. Junio C HamanoApr 13, 2022
  73. brian m. carlsonApr 13, 2022
  74. Junio C HamanoApr 13, 2022
  75. Ævar Arnfjörð BjarmasonApr 13, 2022
  76. Ævar Arnfjörð BjarmasonApr 13, 2022

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