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[PATCH] diff: introduce --restrict option

From
ZheNing Hu via GitGitGadget <gitgitgadget@gmail.com>
Date
Sep 24, 2022, 16:14 UTC
Message-ID
<pull.1368.git.1664036052741.gitgitgadget@gmail.com>
From: ZheNing Hu <adlternative@gmail.com>

When we use sparse-checkout, we often want the set of files that some commands operate on to be restricted to the sparse-checkout cone(s).

So introduce the `--restrict` option to git diff, which can restrict diff filespec to the sparse-checkout cone(s).

Signed-off-by: ZheNing Hu <adlternative@gmail.com>
---
    diff: introduce --restrict option
    
    In [1], we discovered that users working on different sparse-checkout
    cone(s) may download unnecessary blobs from each other's cone(s) in
    collaboration. And in [2] Junio suggested that maybe we can restrict
    some git command's filespec in sparse-checkout cone(s) to elegantly
    solve this problem above.
    
    So this patch is attempt to do this thing on git diff:
    
    v1:
    
     1. add --restrict option to git diff, which restrict diff filespec in
        sparse-checkout cone(s).
    
    [1]:
    https://lore.kernel.org/git/CAOLTT8SHo66kGbvWr=+LQ9UVd1NHgqGGEYK2qq6==QgRCgLZqQ@mail.gmail.com/
    [2]: https://lore.kernel.org/git/xmqqzgeqw0sy.fsf@gitster.g/
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1368%2Fadlternative%2Fzh%2Fdiff-restrict-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1368/adlternative/zh/diff-restrict-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/1368
 Documentation/diff-options.txt           |  4 ++
 diff.c                                   | 57 ++++++++++++++++++++++++
 diff.h                                   |  1 +
 t/t1092-sparse-checkout-compatibility.sh | 30 +++++++++++++
 4 files changed, 92 insertions(+)
diff --git a/Documentation/diff-options.txt b/Documentation/diff-options.txt
index 3674ac48e92..8ee5b6b4603 100644
--- a/Documentation/diff-options.txt
+++ b/Documentation/diff-options.txt
@@ -631,6 +631,10 @@ Also, these upper-case letters can be downcased to exclude.  E.g.
 Note that not all diffs can feature all types. For instance, copied and
 renamed entries cannot appear if detection for those types is disabled.
 
+--restrict::
+	Restrict the diff filespec in the sparse-checkout cone(s).
+	See linkgit:git-sparse-checkout[1] for more details.
+
 -S<string>::
 	Look for differences that change the number of occurrences of
 	the specified string (i.e. addition/deletion) in a file.
diff --git a/diff.c b/diff.c
index 648f6717a55..95e13607041 100644
--- a/diff.c
+++ b/diff.c
@@ -4923,6 +4923,19 @@ static int diff_opt_diff_filter(const struct option *option,
 	return 0;
 }
 
+static int diff_opt_diff_restrict(const struct option *option,
+				const char *optarg, int unset)
+{
+	struct diff_options *opt = option->value;
+
+	BUG_ON_OPT_NEG(unset);
+	CALLOC_ARRAY(opt->sparse_checkout_patterns, 1);
+
+	if (get_sparse_checkout_patterns(opt->sparse_checkout_patterns) < 0)
+		FREE_AND_NULL(opt->sparse_checkout_patterns);
+	return 0;
+}
+
 static void enable_patch_output(int *fmt)
 {
 	*fmt &= ~DIFF_FORMAT_NO_OUTPUT;
@@ -5660,6 +5673,9 @@ static void prep_parse_options(struct diff_options *options)
 		OPT_CALLBACK_F(0, "diff-filter", options, N_("[(A|C|D|M|R|T|U|X|B)...[*]]"),
 			       N_("select files by diff type"),
 			       PARSE_OPT_NONEG, diff_opt_diff_filter),
+		OPT_CALLBACK_F(0, "restrict", options, NULL,
+			       N_("restrict files in sparse-checkout patterns"),
+			       PARSE_OPT_NONEG | PARSE_OPT_OPTARG, diff_opt_diff_restrict),
 		{ OPTION_CALLBACK, 0, "output", options, N_("<file>"),
 		  N_("output to a specific file"),
 		  PARSE_OPT_NONEG, NULL, 0, diff_opt_output },
@@ -6601,6 +6617,24 @@ free_queue:
 	}
 }
 
+
+static int match_sparse_checkout_patterns_by_spec(const struct diff_options *options, struct diff_filespec *spec) {
+	int dtype = DT_REG;
+
+	if (!spec)
+		return 0;
+
+	return path_matches_pattern_list(spec->path, strlen(spec->path),
+					 "", &dtype, options->sparse_checkout_patterns,
+					 the_repository->index) > 0;
+}
+
+static int match_sparse_checkout_patterns(const struct diff_options *options, const struct diff_filepair *p)
+{
+	return match_sparse_checkout_patterns_by_spec(options, p->one) ||
+	       match_sparse_checkout_patterns_by_spec(options, p->two);
+}
+
 static int match_filter(const struct diff_options *options, const struct diff_filepair *p)
 {
 	return (((p->status == DIFF_STATUS_MODIFIED) &&
@@ -6612,6 +6646,28 @@ static int match_filter(const struct diff_options *options, const struct diff_fi
 		 filter_bit_tst(p->status, options)));
 }
 
+static void diffcore_apply_restrict(struct diff_options *options)
+{
+	int i;
+	struct diff_queue_struct *q = &diff_queued_diff;
+	struct diff_queue_struct outq;
+
+	DIFF_QUEUE_CLEAR(&outq);
+
+	if (!options->sparse_checkout_patterns)
+		return;
+
+	for (i = 0; i < q->nr; i++) {
+		struct diff_filepair *p = q->queue[i];
+		if (match_sparse_checkout_patterns(options, p))
+			diff_q(&outq, p);
+		else
+			diff_free_filepair(p);
+	}
+	free(q->queue);
+	*q = outq;
+}
+
 static void diffcore_apply_filter(struct diff_options *options)
 {
 	int i;
@@ -6827,6 +6883,7 @@ void diffcore_std(struct diff_options *options)
 		/* See try_to_follow_renames() in tree-diff.c */
 		diff_resolve_rename_copy();
 	diffcore_apply_filter(options);
+	diffcore_apply_restrict(options);
 
 	if (diff_queued_diff.nr && !options->flags.diff_from_contents)
 		options->flags.has_changes = 1;
diff --git a/diff.h b/diff.h
index 8ae18e5ab1e..f651216da13 100644
--- a/diff.h
+++ b/diff.h
@@ -396,6 +396,7 @@ struct diff_options {
 	struct repository *repo;
 	struct option *parseopts;
 	struct strmap *additional_path_headers;
+	struct pattern_list *sparse_checkout_patterns;
 
 	int no_free;
 };
diff --git a/t/t1092-sparse-checkout-compatibility.sh b/t/t1092-sparse-checkout-compatibility.sh
index b9350c075c2..4c416ef8e82 100755
--- a/t/t1092-sparse-checkout-compatibility.sh
+++ b/t/t1092-sparse-checkout-compatibility.sh
@@ -504,6 +504,36 @@ test_expect_success 'diff --cached' '
 	test_all_match git diff --cached
 '
 
+test_expect_success 'diff --restrict' '
+	init_repos &&
+
+	test_all_match mkdir modules &&
+	test_all_match touch modules/a &&
+	test_all_match touch deep/b &&
+	test_all_match git rm deep/a &&
+	test_all_match git add --sparse modules deep &&
+	run_on_all git diff --restrict --staged --stat &&
+	cat >expect <<-EOF &&
+	 deep/a | 1 -
+	 deep/b | 0
+	 2 files changed, 1 deletion(-)
+	EOF
+	test_cmp expect sparse-checkout-out &&
+	cat >expect <<-EOF &&
+	 deep/a | 1 -
+	 deep/b | 0
+	 2 files changed, 1 deletion(-)
+	EOF
+	test_cmp expect sparse-index-out &&
+	cat >expect <<-EOF &&
+	 deep/a    | 1 -
+	 deep/b    | 0
+	 modules/a | 0
+	 3 files changed, 1 deletion(-)
+	EOF
+	test_cmp expect full-checkout-out
+'
+
 # NEEDSWORK: sparse-checkout behaves differently from full-checkout when
 # running this test with 'df-conflict-2' after 'df-conflict-1'.
 test_expect_success 'diff with renames and conflicts' '

base-commit: dda7228a83e2e9ff584bf6adbf55910565b41e14

-- 
gitgitgadget
Next: Elijah Newren
Message 1 of 3 in “diff: introduce --restrict option”
  1. diff: introduce --restrict optionZheNing Hu via GitGitGadget, Sep 24, 2022
  2. Elijah NewrenSep 24, 2022
  3. ZheNing HuSep 27, 2022

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