[RFC/PATCH v3 6/8] libbb: add is_suffixed_with() function

[Bartosz Golaszewski]

This function checks if given key can be found at the end of the string.

Signed-off-by: Bartosz Golaszewski <bartekgola at gmail.com>
---
 include/libbb.h              |  1 +
 libbb/compare_string_array.c | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/include/libbb.h b/include/libbb.h
index abbd2c7..336fe65 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -422,6 +422,7 @@ const char *bb_basename(const char *name) FAST_FUNC;
 char *last_char_is(const char *s, int c) FAST_FUNC;
 const char* endofname(const char *name) FAST_FUNC;
 char *is_prefixed_with(const char *string, const char *key) FAST_FUNC;
+char *is_suffixed_with(const char *string, const char *key) FAST_FUNC;
 
 int ndelay_on(int fd) FAST_FUNC;
 int ndelay_off(int fd) FAST_FUNC;
diff --git a/libbb/compare_string_array.c b/libbb/compare_string_array.c
index 901e61a..55a735e 100644
--- a/libbb/compare_string_array.c
+++ b/libbb/compare_string_array.c
@@ -21,6 +21,24 @@ char* FAST_FUNC is_prefixed_with(const char *string, const char *key)
 	return (char*)string;
 }
 
+/*
+ * Return NULL if string is not suffixed with key. Return pointer to the
+ * beginning of prefix key in string. If key is an empty string return pointer
+ * to the end of string.
+ */
+char* FAST_FUNC is_suffixed_with(const char *string, const char *key)
+{
+	size_t str_len = strlen(string), key_len = strlen(key);
+
+	if (str_len >= key_len) {
+		if (strcmp(string + str_len - key_len, key) == 0) {
+			return (char*)key;
+		}
+	}
+
+	return NULL;
+}
+
 /* returns the array index of the string */
 /* (index of first match is returned, or -1) */
 int FAST_FUNC index_in_str_array(const char *const string_array[], const char *key)
@@ -126,4 +144,18 @@ BBUNIT_DEFINE_TEST(is_prefixed_with)
 	BBUNIT_ENDTEST;
 }
 
+BBUNIT_DEFINE_TEST(is_suffixed_with)
+{
+	BBUNIT_ASSERT_STREQ("bar", is_suffixed_with("foo bar", "bar"));
+	BBUNIT_ASSERT_STREQ("foo", is_suffixed_with("foo", "foo"));
+	BBUNIT_ASSERT_STREQ("", is_suffixed_with("foo", ""));
+	BBUNIT_ASSERT_STREQ("", is_suffixed_with("", ""));
+
+	BBUNIT_ASSERT_NULL(is_suffixed_with("foo", "bar foo"));
+	BBUNIT_ASSERT_NULL(is_suffixed_with("foo foo", "bar"));
+	BBUNIT_ASSERT_NULL(is_suffixed_with("", "foo"));
+
+	BBUNIT_ENDTEST;
+}
+
 #endif /* ENABLE_UNIT_TEST */
-- 
2.1.4