[PATCH v8 17/43] lib/parser: add match_wildcard_hyphen() for agnostic matching

[Jim Cromie via B4 Relay <devnull+jim.cromie.gmail.com@kernel.org>]

From: Jim Cromie <jim.cromie@gmail.com>

This commit introduces match_wildcard_hyphen() as a variant of the
existing match_wildcard() function. It treats hyphens and underscores
as identical characters during the matching process.

This is necessary for subsystems like dynamic_debug that need to match
module names provided by users (who often use underscores) against
names stored in the kernel (which may use hyphens, especially when
using KBUILD_MODFILE for built-ins).

To avoid code duplication, the core logic is refactored into a private
__match_wildcard() function marked as __always_inline. This allows the
compiler to generate optimized versions for both the strict and agnostic
callsites with zero runtime overhead.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
v5: move ahead of array-slice patch to silence sashiko complaint about it
v4: initial version
---
 include/linux/parser.h                             |  1 +
 lib/parser.c                                       | 58 ++++++++++++++++------
 .../selftests/dynamic_debug/dyndbg_selftest.sh     |  2 +-
 3 files changed, 45 insertions(+), 16 deletions(-)

diff --git a/include/linux/parser.h b/include/linux/parser.h
index dd79f45a37b8..a3cc7bc5fb93 100644
--- a/include/linux/parser.h
+++ b/include/linux/parser.h
@@ -34,6 +34,7 @@ int match_u64(substring_t *, u64 *result);
 int match_octal(substring_t *, int *result);
 int match_hex(substring_t *, int *result);
 bool match_wildcard(const char *pattern, const char *str);
+bool match_wildcard_hyphen(const char *pattern, const char *str);
 size_t match_strlcpy(char *, const substring_t *, size_t);
 char *match_strdup(const substring_t *);
 
diff --git a/lib/parser.c b/lib/parser.c
index 62da0ac0d438..d5be01fa9adf 100644
--- a/lib/parser.c
+++ b/lib/parser.c
@@ -268,20 +268,13 @@ int match_hex(substring_t *s, int *result)
 }
 EXPORT_SYMBOL(match_hex);
 
-/**
- * match_wildcard - parse if a string matches given wildcard pattern
- * @pattern: wildcard pattern
- * @str: the string to be parsed
- *
- * Description: Parse the string @str to check if matches wildcard
- * pattern @pattern. The pattern may contain two types of wildcards:
- *
- * * '*' - matches zero or more characters
- * * '?' - matches one character
- *
- * Return: If the @str matches the @pattern, return true, else return false.
- */
-bool match_wildcard(const char *pattern, const char *str)
+static inline char dash2underscore(char c)
+{
+	return (c == '-') ? '_' : c;
+}
+
+static __always_inline bool __match_wildcard(const char *pattern, const char *str,
+					     bool hyphen_agnostic)
 {
 	const char *s = str;
 	const char *p = pattern;
@@ -301,7 +294,9 @@ bool match_wildcard(const char *pattern, const char *str)
 			pattern = p;
 			break;
 		default:
-			if (*s == *p) {
+			if (hyphen_agnostic ?
+			    (dash2underscore(*s) == dash2underscore(*p)) :
+			    (*s == *p)) {
 				s++;
 				p++;
 			} else {
@@ -319,8 +314,41 @@ bool match_wildcard(const char *pattern, const char *str)
 		++p;
 	return !*p;
 }
+
+/**
+ * match_wildcard - parse if a string matches given wildcard pattern
+ * @pattern: wildcard pattern
+ * @str: the string to be parsed
+ *
+ * Description: Parse the string @str to check if matches wildcard
+ * pattern @pattern. The pattern may contain two types of wildcards:
+ *
+ * * '*' - matches zero or more characters
+ * * '?' - matches one character
+ *
+ * Return: If the @str matches the @pattern, return true, else return false.
+ */
+bool match_wildcard(const char *pattern, const char *str)
+{
+	return __match_wildcard(pattern, str, false);
+}
 EXPORT_SYMBOL(match_wildcard);
 
+/**
+ * match_wildcard_hyphen - parse if a string matches given wildcard pattern
+ * @pattern: wildcard pattern
+ * @str: the string to be parsed
+ *
+ * Description: Same as match_wildcard, but treats '-' and '_' as identical.
+ *
+ * Return: If the @str matches the @pattern, return true, else return false.
+ */
+bool match_wildcard_hyphen(const char *pattern, const char *str)
+{
+	return __match_wildcard(pattern, str, true);
+}
+EXPORT_SYMBOL(match_wildcard_hyphen);
+
 /**
  * match_strlcpy - Copy the characters from a substring_t to a sized buffer
  * @dest: where to copy to
diff --git a/tools/testing/selftests/dynamic_debug/dyndbg_selftest.sh b/tools/testing/selftests/dynamic_debug/dyndbg_selftest.sh
index 67b568730acc..8e881b5c860c 100755
--- a/tools/testing/selftests/dynamic_debug/dyndbg_selftest.sh
+++ b/tools/testing/selftests/dynamic_debug/dyndbg_selftest.sh
@@ -593,7 +593,7 @@ builtin_tests=(
     FT_grammar_errs
     FT_basic_queries
     #FT_path_module_queries
-    #FT_hyphen_underscore
+    FT_hyphen_underscore
 )
 
 # Modular Feature Tests (Require CONFIG_MODULES=y and test_dynamic_debug*.ko available)

-- 
2.55.0