[PATCH 1/2] lib/test_string.c: add strspn and strcspn tests

[PATCH 1/2] lib/test_string.c: add strspn and strcspn tests

[Rasmus Villemoes]

Before refactoring strspn() and strcspn(), add some simple test cases.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 lib/test_string.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/lib/test_string.c b/lib/test_string.c
index 9dfd6f52de92..c5cb92fb710e 100644
--- a/lib/test_string.c
+++ b/lib/test_string.c
@@ -179,6 +179,34 @@ static __init int strnchr_selftest(void)
 	return 0;
 }
 
+static __init int strspn_selftest(void)
+{
+	static const struct strspn_test {
+		const char str[16];
+		const char accept[16];
+		const char reject[16];
+		unsigned a;
+		unsigned r;
+	} tests[] __initconst = {
+		{ "foobar", "", "", 0, 6 },
+		{ "abba", "abc", "ABBA", 4, 4 },
+		{ "abba", "a", "b", 1, 1 },
+		{ "", "abc", "abc", 0, 0},
+	};
+	const struct strspn_test *s = tests;
+	size_t i, res;
+
+	for (i = 0; i < ARRAY_SIZE(tests); ++i, ++s) {
+		res = strspn(s->str, s->accept);
+		if (res != s->a)
+			return 0x100 + 2*i;
+		res = strcspn(s->str, s->reject);
+		if (res != s->r)
+			return 0x100 + 2*i + 1;
+	}
+	return 0;
+}
+
 static __exit void string_selftest_remove(void)
 {
 }
@@ -212,6 +240,11 @@ static __init int string_selftest_init(void)
 	if (subtest)
 		goto fail;
 
+	test = 6;
+	subtest = strspn_selftest();
+	if (subtest)
+		goto fail;
+
 	pr_info("String selftests succeeded\n");
 	return 0;
 fail:
-- 
2.31.1

[PATCH 2/2] lib/string.c: simplify str[c]spn

[Rasmus Villemoes]

Use strchr(), which makes them a lot shorter, and more obviously
symmetric in their treatment of accept/reject. It also saves a little
bit of .text; bloat-o-meter for an arm build says

Function                                     old     new   delta
strcspn                                       92      76     -16
strspn                                       108      76     -32

While here, also remove a stray empty line before EXPORT_SYMBOL().

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 lib/string.c | 25 ++++++-------------------
 1 file changed, 6 insertions(+), 19 deletions(-)

diff --git a/lib/string.c b/lib/string.c
index 485777c9da83..6f334420f687 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -517,21 +517,13 @@ EXPORT_SYMBOL(strnlen);
 size_t strspn(const char *s, const char *accept)
 {
 	const char *p;
-	const char *a;
-	size_t count = 0;
 
 	for (p = s; *p != '\0'; ++p) {
-		for (a = accept; *a != '\0'; ++a) {
-			if (*p == *a)
-				break;
-		}
-		if (*a == '\0')
-			return count;
-		++count;
+		if (!strchr(accept, *p))
+			break;
 	}
-	return count;
+	return p - s;
 }
-
 EXPORT_SYMBOL(strspn);
 #endif
 
@@ -544,17 +536,12 @@ EXPORT_SYMBOL(strspn);
 size_t strcspn(const char *s, const char *reject)
 {
 	const char *p;
-	const char *r;
-	size_t count = 0;
 
 	for (p = s; *p != '\0'; ++p) {
-		for (r = reject; *r != '\0'; ++r) {
-			if (*p == *r)
-				return count;
-		}
-		++count;
+		if (strchr(reject, *p))
+			break;
 	}
-	return count;
+	return p - s;
 }
 EXPORT_SYMBOL(strcspn);
 #endif
-- 
2.31.1