Subject: [PATCH 2/2] ls-files: add --sparse option

From: "Derrick Stolee via GitGitGadget" <[email-masked]>
Date: Tue, 16 Nov 2021 15:38:02 +0000

From: Derrick Stolee <[email-masked]>

Existing callers to 'git ls-files' are expecting file names, not
directories. It is best to expand a sparse index to show all of the
contained files in this case.

However, expert users may want to inspect the contents of the index
itself including which directories are sparse. Add a --sparse option to
allow users to request this information.

During testing, I noticed that options such as --modified did not affect
the output when the files in question were outside the sparse-checkout
definition. Tests are added to document this preexisting behavior and
how it remains unchanged with the sparse index and the --sparse option.

Signed-off-by: Derrick Stolee <[email-masked]>
---
 Documentation/git-ls-files.txt           |  4 ++
 builtin/ls-files.c                       | 12 +++++-
 t/t1092-sparse-checkout-compatibility.sh | 47 ++++++++++++++++++++++++
 3 files changed, 61 insertions(+), 2 deletions(-)

diff --git a/Documentation/git-ls-files.txt b/Documentation/git-ls-files.txt
index 6d11ab506b7..1c5d5f85ec5 100644
--- a/Documentation/git-ls-files.txt
+++ b/Documentation/git-ls-files.txt
@@ -187,6 +187,10 @@ Both the <eolinfo> in the index ("i/<eolinfo>")
 and in the working tree ("w/<eolinfo>") are shown for regular files,
 followed by the  ("attr/<eolattr>").
 
+--sparse::
+	If the index is sparse, show the sparse directories without expanding
+	to the contained files.
+
 \--::
 	Do not interpret any more arguments as options.
 
diff --git a/builtin/ls-files.c b/builtin/ls-files.c
index 031fef1bcaa..c151eb1fb77 100644
--- a/builtin/ls-files.c
+++ b/builtin/ls-files.c
@@ -37,6 +37,7 @@ static int debug_mode;
 static int show_eol;
 static int recurse_submodules;
 static int skipping_duplicates;
+static int show_sparse_dirs;
 
 static const char *prefix;
 static int max_prefix_len;
@@ -315,8 +316,10 @@ static void show_files(struct repository *repo, struct dir_struct *dir)
 
 	if (!(show_cached || show_stage || show_deleted || show_modified))
 		return;
-	/* TODO: audit for interaction with sparse-index. */
-	ensure_full_index(repo->index);
+
+	if (!show_sparse_dirs)
+		ensure_full_index(repo->index);
+
 	for (i = 0; i < repo->index->cache_nr; i++) {
 		const struct cache_entry *ce = repo->index->cache[i];
 		struct stat st;
@@ -670,6 +673,8 @@ int cmd_ls_files(int argc, const char **argv, const char *cmd_prefix)
 		OPT_BOOL(0, "debug", &debug_mode, N_("show debugging data")),
 		OPT_BOOL(0, "deduplicate", &skipping_duplicates,
 			 N_("suppress duplicate entries")),
+		OPT_BOOL(0, "sparse", &show_sparse_dirs,
+			 N_("show sparse directories in the presence of a sparse index")),
 		OPT_END()
 	};
 	int ret = 0;
@@ -677,6 +682,9 @@ int cmd_ls_files(int argc, const char **argv, const char *cmd_prefix)
 	if (argc == 2 && !strcmp(argv[1], "-h"))
 		usage_with_options(ls_files_usage, builtin_ls_files_options);
 
+	prepare_repo_settings(the_repository);
+	the_repository->settings.command_requires_full_index = 0;
+
 	prefix = cmd_prefix;
 	if (prefix)
 		prefix_len = strlen(prefix);
diff --git a/t/t1092-sparse-checkout-compatibility.sh b/t/t1092-sparse-checkout-compatibility.sh
index f8a8dde60af..ffb6052ff60 100755
--- a/t/t1092-sparse-checkout-compatibility.sh
+++ b/t/t1092-sparse-checkout-compatibility.sh
@@ -814,6 +814,12 @@ test_expect_success 'sparse-index is expanded and converted back' '
 	GIT_TRACE2_EVENT="$(pwd)/trace2.txt" GIT_TRACE2_EVENT_NESTING=10 \
 		git -C sparse-index reset -- folder1/a &&
 	test_region index convert_to_sparse trace2.txt &&
+	test_region index ensure_full_index trace2.txt &&
+
+	# ls-files expands on read, but does not write.
+	rm trace2.txt &&
+	GIT_TRACE2_EVENT="$(pwd)/trace2.txt" GIT_TRACE2_EVENT_NESTING=10 \
+		git -C sparse-index ls-files &&
 	test_region index ensure_full_index trace2.txt
 '
 
@@ -838,6 +844,7 @@ test_expect_success 'sparse-index is not expanded' '
 	init_repos &&
 
 	ensure_not_expanded status &&
+	ensure_not_expanded ls-files --sparse &&
 	ensure_not_expanded commit --allow-empty -m empty &&
 	echo >>sparse-index/a &&
 	ensure_not_expanded commit -a -m a &&
@@ -942,6 +949,46 @@ test_expect_success 'sparse index is not expanded: fetch/pull' '
 	ensure_not_expanded pull full base
 '
 
+test_expect_success 'ls-files' '
+	init_repos &&
+
+	# Behavior agrees by default. Sparse index is expanded.
+	test_all_match git ls-files &&
+
+	# With --sparse, the sparse index data changes behavior.
+	git -C sparse-index ls-files --sparse >sparse-index-out &&
+	grep "^folder1/\$" sparse-index-out &&
+	grep "^folder2/\$" sparse-index-out &&
+
+	# With --sparse and no sparse index, nothing changes.
+	git -C sparse-checkout ls-files --sparse >sparse-checkout-out &&
+	grep "^folder1/0/0/0\$" sparse-checkout-out &&
+	! grep "/\$" sparse-checkout-out &&
+
+	write_script edit-content <<-\EOF &&
+	mkdir folder1 &&
+	echo content >>folder1/a
+	EOF
+	run_on_sparse ../edit-content &&
+
+	# ls-files does not notice modified files whose
+	# cache entries are marked SKIP_WORKTREE.
+	test_sparse_match git ls-files --modified &&
+	test_must_be_empty sparse-checkout-out &&
+	test_must_be_empty sparse-index-out &&
+
+	git -C sparse-index ls-files --sparse --modified >sparse-index-out &&
+	test_must_be_empty sparse-index-out &&
+
+	run_on_sparse git sparse-checkout add folder1 &&
+	test_sparse_match git ls-files --modified &&
+	grep "^folder1/a\$" sparse-checkout-out &&
+	grep "^folder1/a\$" sparse-index-out &&
+
+	# Double-check index expansion
+	ensure_not_expanded ls-files --sparse
+'
+
 # NEEDSWORK: a sparse-checkout behaves differently from a full checkout
 # in this scenario, but it shouldn't.
 test_expect_success 'reset mixed and checkout orphan' '
-- 
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