[PATCH v6 19/19] sparse-checkout: check for dirty status

["Derrick Stolee via GitGitGadget" <gitgitgadget@xxxxxxxxx>]

From: Derrick Stolee <dstolee@xxxxxxxxxxxxx>

The index-merge performed by 'git sparse-checkout' will erase any staged
changes, which can lead to data loss. Prevent these attempts by requiring
a clean 'git status' output.

Helped-by: Szeder Gábor <szeder.dev@xxxxxxxxx>
Signed-off-by: Derrick Stolee <dstolee@xxxxxxxxxxxxx>
---
 builtin/sparse-checkout.c          | 13 +++++++++++++
 t/t1091-sparse-checkout-builtin.sh | 15 ++++++++++++++-
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/builtin/sparse-checkout.c b/builtin/sparse-checkout.c
index 5dbfb2a7e0..a542d617a5 100644
--- a/builtin/sparse-checkout.c
+++ b/builtin/sparse-checkout.c
@@ -12,6 +12,7 @@
 #include "lockfile.h"
 #include "resolve-undo.h"
 #include "unpack-trees.h"
+#include "wt-status.h"
 
 static const char *empty_base = "";
 
@@ -256,6 +257,10 @@ static int sparse_checkout_init(int argc, const char **argv)
 		OPT_END(),
 	};
 
+	repo_read_index(the_repository);
+	require_clean_work_tree(the_repository,
+				N_("initialize sparse-checkout"), NULL, 1, 0);
+
 	argc = parse_options(argc, argv, NULL,
 			     builtin_sparse_checkout_init_options,
 			     builtin_sparse_checkout_init_usage, 0);
@@ -368,6 +373,10 @@ static int sparse_checkout_set(int argc, const char **argv, const char *prefix)
 		OPT_END(),
 	};
 
+	repo_read_index(the_repository);
+	require_clean_work_tree(the_repository,
+				N_("set sparse-checkout patterns"), NULL, 1, 0);
+
 	memset(&pl, 0, sizeof(pl));
 
 	argc = parse_options(argc, argv, prefix,
@@ -427,6 +436,10 @@ static int sparse_checkout_disable(int argc, const char **argv)
 	struct pattern_list pl;
 	struct strbuf match_all = STRBUF_INIT;
 
+	repo_read_index(the_repository);
+	require_clean_work_tree(the_repository,
+				N_("disable sparse-checkout"), NULL, 1, 0);
+
 	memset(&pl, 0, sizeof(pl));
 	hashmap_init(&pl.recursive_hashmap, pl_hashmap_cmp, NULL, 0);
 	hashmap_init(&pl.parent_hashmap, pl_hashmap_cmp, NULL, 0);
diff --git a/t/t1091-sparse-checkout-builtin.sh b/t/t1091-sparse-checkout-builtin.sh
index e61ddb4ad5..d5e2892526 100755
--- a/t/t1091-sparse-checkout-builtin.sh
+++ b/t/t1091-sparse-checkout-builtin.sh
@@ -250,10 +250,11 @@ test_expect_success 'cone mode: set with nested folders' '
 '
 
 test_expect_success 'revert to old sparse-checkout on bad update' '
+	test_when_finished git -C repo reset --hard &&
 	echo update >repo/deep/deeper2/a &&
 	cp repo/.git/info/sparse-checkout expect &&
 	test_must_fail git -C repo sparse-checkout set deep/deeper1 2>err &&
-	test_i18ngrep "Cannot update sparse checkout" err &&
+	test_i18ngrep "cannot set sparse-checkout patterns" err &&
 	test_cmp repo/.git/info/sparse-checkout expect &&
 	ls repo/deep >dir &&
 	cat >expect <<-EOF &&
@@ -291,4 +292,16 @@ test_expect_success '.gitignore should not warn about cone mode' '
 	test_i18ngrep ! "disabling cone patterns" err
 '
 
+test_expect_success 'sparse-checkout (init|set|disable) fails with dirty status' '
+	git clone repo dirty &&
+	echo dirty >dirty/folder1/a &&
+	test_must_fail git -C dirty sparse-checkout init &&
+	test_must_fail git -C dirty sparse-checkout set /folder2/* /deep/deeper1/* &&
+	test_must_fail git -C dirty sparse-checkout disable &&
+	git -C dirty reset --hard &&
+	git -C dirty sparse-checkout init &&
+	git -C dirty sparse-checkout set /folder2/* /deep/deeper1/* &&
+	git -C dirty sparse-checkout disable
+'
+
 test_done
-- 
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