sparse-checkout: write escaped patterns in cone mode

If a user somehow creates a directory with an asterisk (*) or backslash
(\), then the "git sparse-checkout set" command will struggle to provide
the correct pattern in the sparse-checkout file. When not in cone mode,
the provided pattern is written directly into the sparse-checkout file.
However, in cone mode we expect a list of paths to directories and then
we convert those into patterns.

Even more specifically, the goal is to always allow the following from
the root of a repo:

  git ls-tree --name-only -d HEAD | git sparse-checkout set --stdin

The ls-tree command provides directory names with an unescaped asterisk.
It also quotes the directories that contain an escaped backslash. We
must remove these quotes, then keep the escaped backslashes.

However, there is some care needed for the timing of these escapes. The
in-memory pattern list is used to update the working directory before
writing the patterns to disk. Thus, we need the command to have the
unescaped names in the hashsets for the cone comparisons, then escape
the patterns later.

Signed-off-by: Derrick Stolee <[email protected]>

Author: derrickstolee

builtin/sparse-checkout.c

@@ -140,6 +140,22 @@ static int update_working_directory(struct pattern_list *pl)
 	return result;
 }
 
+static char *escaped_pattern(char *pattern)
+{
+	char *p = pattern;
+	struct strbuf final = STRBUF_INIT;
+
+	while (*p) {
+		if (*p == '*' || *p == '\\')
+			strbuf_addch(&final, '\\');
+
+		strbuf_addch(&final, *p);
+		p++;
+	}
+
+	return strbuf_detach(&final, NULL);
+}
+
 static void write_cone_to_file(FILE *fp, struct pattern_list *pl)
 {
 	int i;
@@ -164,10 +180,11 @@ static void write_cone_to_file(FILE *fp, struct pattern_list *pl)
 	fprintf(fp, "/*\n!/*/\n");
 
 	for (i = 0; i < sl.nr; i++) {
-		char *pattern = sl.items[i].string;
+		char *pattern = escaped_pattern(sl.items[i].string);
 
 		if (strlen(pattern))
 			fprintf(fp, "%s/\n!%s/*/\n", pattern, pattern);
+		free(pattern);
 	}
 
 	string_list_clear(&sl, 0);
@@ -185,8 +202,9 @@ static void write_cone_to_file(FILE *fp, struct pattern_list *pl)
 	string_list_remove_duplicates(&sl, 0);
 
 	for (i = 0; i < sl.nr; i++) {
-		char *pattern = sl.items[i].string;
+		char *pattern = escaped_pattern(sl.items[i].string);
 		fprintf(fp, "%s/\n", pattern);
+		free(pattern);
 	}
 }
 
@@ -337,7 +355,9 @@ static void insert_recursive_pattern(struct pattern_list *pl, struct strbuf *pat
 {
 	struct pattern_entry *e = xmalloc(sizeof(*e));
 	e->patternlen = path->len;
-	e->pattern = strbuf_detach(path, NULL);
+	e->pattern = dup_and_filter_pattern(path->buf);
+	strbuf_release(path);
+
 	hashmap_entry_init(&e->ent,
 			   ignore_case ?
 			   strihash(e->pattern) :
@@ -369,13 +389,35 @@ static void insert_recursive_pattern(struct pattern_list *pl, struct strbuf *pat
 
 static void strbuf_to_cone_pattern(struct strbuf *line, struct pattern_list *pl)
 {
+	int i;
 	strbuf_trim(line);
 
 	strbuf_trim_trailing_dir_sep(line);
 
 	if (!line->len)
 		return;
 
+	for (i = 0; i < line->len; i++) {
+		if (line->buf[i] == '*') {
+			strbuf_insert(line, i, "\\", 1);
+			i++;
+		}
+
+		if (line->buf[i] == '\\') {
+			if (i < line->len - 1 && line->buf[i + 1] == '\\')
+				i++;
+			else
+				strbuf_insert(line, i, "\\", 1);
+
+			i++;
+		}
+	}
+
+	if (line->buf[0] == '"' && line->buf[line->len - 1] == '"') {
+		strbuf_remove(line, 0, 1);
+		strbuf_remove(line, line->len - 1, 1);
+	}
+
 	if (line->buf[0] != '/')
 		strbuf_insert(line, 0, "/", 1);
 

t/t1091-sparse-checkout-builtin.sh

@@ -309,6 +309,9 @@ check_read_tree_errors () {
 	REPO=$1
 	FILES=$2
 	ERRORS=$3
+	git -C $REPO -c core.sparseCheckoutCone=false read-tree -mu HEAD 2>err &&
+	test_must_be_empty err &&
+	check_files $REPO "$FILES" &&
 	git -C $REPO read-tree -mu HEAD 2>err &&
 	if test -z "$ERRORS"
 	then
@@ -379,14 +382,28 @@ test_expect_success BSLASHPSPEC 'pattern-checks: escaped "*"' '
 	git -C escaped reset --hard $COMMIT &&
 	check_files escaped "a deep folder1 folder2 zbad\\dir zdoes*exist" &&
 	git -C escaped sparse-checkout init --cone &&
-	cat >escaped/.git/info/sparse-checkout <<-\EOF &&
+	git -C escaped sparse-checkout set zbad\\dir zdoes\*not\*exist zdoes\*exist &&
+	cat >expect <<-\EOF &&
 	/*
 	!/*/
 	/zbad\\dir/
+	/zdoes\*exist/
 	/zdoes\*not\*exist/
+	EOF
+	test_cmp expect escaped/.git/info/sparse-checkout &&
+	check_read_tree_errors escaped "a zbad\\dir zdoes*exist" &&
+	git -C escaped ls-tree -d --name-only HEAD | git -C escaped sparse-checkout set --stdin &&
+	cat >expect <<-\EOF &&
+	/*
+	!/*/
+	/deep/
+	/folder1/
+	/folder2/
+	/zbad\\dir/
 	/zdoes\*exist/
 	EOF
-	check_read_tree_errors escaped "a zbad\\dir zdoes*exist"
+	test_cmp expect escaped/.git/info/sparse-checkout &&
+	check_files escaped "a deep folder1 folder2 zbad\\dir zdoes*exist"
 '
 
 test_done