From d4dc5a733908d2af7416718d3baea2d05417cd9e Mon Sep 17 00:00:00 2001
From: Andrea Mazzoleni <amadvance@gmail.com>
Date: Wed, 26 Aug 2026 13:02:55 +0200
Subject: [PATCH] Reject standalone absolute directory filter pattern /**/
 during parsing

---
 cmdline/elem.c     |  4 ++--
 cmdline/selftest.c | 41 +++++++++++++++++++++++++++++++++++++++++
 doc/snapraid.1     |  1 +
 doc/snapraid.d     |  1 +
 doc/snapraid.txt   |  1 +
 5 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/cmdline/elem.c b/cmdline/elem.c
index 380eb648..9f650efc 100644
--- a/cmdline/elem.c
+++ b/cmdline/elem.c
@@ -45,8 +45,8 @@ struct snapraid_filter* filter_alloc_file(int direction, const char* root, const
 	pathimport(filter->root, sizeof(filter->root), root);
 	filter->direction = direction;
 
-	/* reject the root directory as an invalid pattern */
-	if (pathcmp(filter->pattern, "/") == 0) {
+	/* reject the root directory and standalone absolute directory wildcard as invalid patterns */
+	if (pathcmp(filter->pattern, "/") == 0 || pathcmp(filter->pattern, "/**/") == 0) {
 		free(filter);
 		return 0;
 	}
diff --git a/cmdline/selftest.c b/cmdline/selftest.c
index 28d2c0bc..e402d154 100644
--- a/cmdline/selftest.c
+++ b/cmdline/selftest.c
@@ -896,6 +896,44 @@ static void test_wnmatch(void)
 	}
 }
 
+struct {
+	const char* pattern;
+	int valid;
+} FILTER_TEST[] = {
+	/* invalid standalone root and standalone double-star patterns */
+	{ "/", 0 },
+	{ "/**/", 0 },
+
+	/* valid single and multi-level patterns */
+	{ "/foo/", 1 },
+	{ "/foo/**/", 1 },
+	{ "/**/foo/", 1 },
+	{ "/foo/**/bar", 1 },
+	{ "/foo/**/bar/", 1 },
+	{ "foo/**/bar", 1 },
+	{ "foo/**/", 1 },
+	{ "**", 1 },
+	{ "**/", 1 },
+
+	{ 0, 0 }
+};
+
+static void test_filter(void)
+{
+	for (int i = 0; FILTER_TEST[i].pattern; ++i) {
+		struct snapraid_filter* f = filter_alloc_file(1, "", FILTER_TEST[i].pattern);
+		if ((f != 0) != FILTER_TEST[i].valid) {
+			/* LCOV_EXCL_START */
+			log_fatal(EINTERNAL, "Failed filter test '%s', expected %s\n",
+				FILTER_TEST[i].pattern, FILTER_TEST[i].valid ? "valid" : "invalid");
+			exit(EXIT_FAILURE);
+			/* LCOV_EXCL_STOP */
+		}
+		if (f != 0)
+			filter_free(f);
+	}
+}
+
 static void test_parse_smartctl(void)
 {
 	char smartctl[SMART_MAX];
@@ -1169,6 +1207,9 @@ void selftest(void)
 	/* wildcard and path pattern matching */
 	test_wnmatch();
 
+	/* filter pattern parsing */
+	test_filter();
+
 	/* smartctl output parsing */
 	test_parse_smartctl();
 
diff --git a/doc/snapraid.1 b/doc/snapraid.1
index 7ad62a93..4cf2293a 100644
--- a/doc/snapraid.1
+++ b/doc/snapraid.1
@@ -1988,6 +1988,7 @@ at any depth in a directory tree without knowing the exact path structure.
 For example, the pattern \`src/**/main.js\` matches \`src/main.js\` (skipping
 zero directories), \`src/ui/main.js\` (skipping one directory), and
 \`src/ui/components/main.js\` (skipping two directories).
+The standalone form \`/**/\` is not accepted as a complete pattern.
 .PP
 Character classes using square brackets match a single character from a
 specified set or range. Like the other single character patterns, they do
diff --git a/doc/snapraid.d b/doc/snapraid.d
index 6d5692ab..42a7af60 100644
--- a/doc/snapraid.d
+++ b/doc/snapraid.d
@@ -1593,6 +1593,7 @@ Pattern
 	For example, the pattern `src/**/main.js` matches `src/main.js` (skipping
 	zero directories), `src/ui/main.js` (skipping one directory), and
 	`src/ui/components/main.js` (skipping two directories).
+	The standalone form `/**/` is not accepted as a complete pattern.
 
 	Character classes using square brackets match a single character from a
 	specified set or range. Like the other single character patterns, they do
diff --git a/doc/snapraid.txt b/doc/snapraid.txt
index f01f78c9..2073128a 100644
--- a/doc/snapraid.txt
+++ b/doc/snapraid.txt
@@ -1706,6 +1706,7 @@ at any depth in a directory tree without knowing the exact path structure.
 For example, the pattern `src/**/main.js` matches `src/main.js` (skipping
 zero directories), `src/ui/main.js` (skipping one directory), and
 `src/ui/components/main.js` (skipping two directories).
+The standalone form `/**/` is not accepted as a complete pattern.
 
 Character classes using square brackets match a single character from a
 specified set or range. Like the other single character patterns, they do