From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

Implement a function for checking if a string ends with a different
string and add its kunit test cases.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
 include/linux/string.h   | 18 ++++++++++++++++++
 lib/tests/string_kunit.c | 13 +++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/include/linux/string.h b/include/linux/string.h
index fdd3442c6bcbd786e177b6e87358e1065a0ffafc..929d05d1247c76eb9011fe34250b487834b2d3c9 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -562,4 +562,22 @@ static inline bool strstarts(const char *str, const char *prefix)
 	return strncmp(str, prefix, strlen(prefix)) == 0;
 }
 
+/**
+ * strends - Check if a string ends with another string.
+ * @str - NULL-terminated string to check against @suffix
+ * @suffix - NULL-terminated string defining the suffix to look for in @str
+ *
+ * Returns:
+ * True if @str ends with @suffix. False in all other cases.
+ */
+static inline bool strends(const char *str, const char *suffix)
+{
+	unsigned int str_len = strlen(str), suffix_len = strlen(suffix);
+
+	if (str_len < suffix_len)
+		return false;
+
+	return !(strcmp(str + str_len - suffix_len, suffix));
+}
+
 #endif /* _LINUX_STRING_H_ */
diff --git a/lib/tests/string_kunit.c b/lib/tests/string_kunit.c
index 0ed7448a26d3aa0fe9e2a6a894d4c49c2c0b86e0..f9a8e557ba7734c9848d58ff986407d8000f52ee 100644
--- a/lib/tests/string_kunit.c
+++ b/lib/tests/string_kunit.c
@@ -602,6 +602,18 @@ static void string_test_memtostr(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, dest[7], '\0');
 }
 
+static void string_test_strends(struct kunit *test)
+{
+	KUNIT_EXPECT_TRUE(test, strends("foo-bar", "bar"));
+	KUNIT_EXPECT_TRUE(test, strends("foo-bar", "-bar"));
+	KUNIT_EXPECT_TRUE(test, strends("foobar", "foobar"));
+	KUNIT_EXPECT_TRUE(test, strends("foobar", ""));
+	KUNIT_EXPECT_FALSE(test, strends("bar", "foobar"));
+	KUNIT_EXPECT_FALSE(test, strends("", "foo"));
+	KUNIT_EXPECT_FALSE(test, strends("foobar", "ba"));
+	KUNIT_EXPECT_TRUE(test, strends("", ""));
+}
+
 static struct kunit_case string_test_cases[] = {
 	KUNIT_CASE(string_test_memset16),
 	KUNIT_CASE(string_test_memset32),
@@ -623,6 +635,7 @@ static struct kunit_case string_test_cases[] = {
 	KUNIT_CASE(string_test_strlcat),
 	KUNIT_CASE(string_test_strtomem),
 	KUNIT_CASE(string_test_memtostr),
+	KUNIT_CASE(string_test_strends),
 	{}
 };
 

-- 
2.48.1

On Wed, Oct 29, 2025 at 12:20:37PM +0100, Bartosz Golaszewski wrote:
> 
> Implement a function for checking if a string ends with a different
> string and add its kunit test cases.

...

> +/**
> + * strends - Check if a string ends with another string.
> + * @str - NULL-terminated string to check against @suffix
> + * @suffix - NULL-terminated string defining the suffix to look for in @str
> + *
> + * Returns:
> + * True if @str ends with @suffix. False in all other cases.
> + */
> +static inline bool strends(const char *str, const char *suffix)
> +{
> +	unsigned int str_len = strlen(str), suffix_len = strlen(suffix);
> +
> +	if (str_len < suffix_len)
> +		return false;
> +
> +	return !(strcmp(str + str_len - suffix_len, suffix));
> +}

Can you rather re-use strcmp_suffix() from drivers/of/property.c?

-- 
With Best Regards,
Andy Shevchenko

On Wed, Oct 29, 2025 at 12:42 PM Andy Shevchenko
<andriy.shevchenko@intel.com> wrote:
>
> On Wed, Oct 29, 2025 at 12:20:37PM +0100, Bartosz Golaszewski wrote:
> >
> > Implement a function for checking if a string ends with a different
> > string and add its kunit test cases.
>
> ...
>
> > +/**
> > + * strends - Check if a string ends with another string.
> > + * @str - NULL-terminated string to check against @suffix
> > + * @suffix - NULL-terminated string defining the suffix to look for in @str
> > + *
> > + * Returns:
> > + * True if @str ends with @suffix. False in all other cases.
> > + */
> > +static inline bool strends(const char *str, const char *suffix)
> > +{
> > +     unsigned int str_len = strlen(str), suffix_len = strlen(suffix);
> > +
> > +     if (str_len < suffix_len)
> > +             return false;
> > +
> > +     return !(strcmp(str + str_len - suffix_len, suffix));
> > +}
>
> Can you rather re-use strcmp_suffix() from drivers/of/property.c?
>

I think that strends() and its boolean return value are a bit more
intuitive to use than strcmp_suffix() and its integer return value,
the meaning of which you typically have to look-up to figure out. If
there are no objections, I'd like to keep it and - when it's upstream
- convert property.c to using it instead. Also: the name
strcmp_suffix() could use some improvement, seeing how I wasn't able
to find it, even though I looked hard across the kernel source, while
I easily stumbled upon a similar implementation of strends() already
existing in dtc sources.

Bart

On Wed, Oct 29, 2025 at 01:36:55PM +0100, Bartosz Golaszewski wrote:
> On Wed, Oct 29, 2025 at 12:42 PM Andy Shevchenko
> <andriy.shevchenko@intel.com> wrote:
> > On Wed, Oct 29, 2025 at 12:20:37PM +0100, Bartosz Golaszewski wrote:

...

> > Can you rather re-use strcmp_suffix() from drivers/of/property.c?
> 
> I think that strends() and its boolean return value are a bit more
> intuitive to use than strcmp_suffix() and its integer return value,
> the meaning of which you typically have to look-up to figure out. If
> there are no objections, I'd like to keep it and - when it's upstream
> - convert property.c to using it instead. Also: the name
> strcmp_suffix() could use some improvement, seeing how I wasn't able
> to find it, even though I looked hard across the kernel source, while
> I easily stumbled upon a similar implementation of strends() already
> existing in dtc sources.

I fine as long as the replacement (deduplication) change is provided.

-- 
With Best Regards,
Andy Shevchenko