basic: add ascii_strcasecmp_nn() call

In contrast to ascii_strcasecmp_nn() it takes two character buffers with their individual length. It will then compare
the buffers up the smaller size of the two buffers, and finally the length themselves.

3 files changed, 34 insertions, 0 deletions

diff --git a/src/basic/string-util.c b/src/basic/string-util.c
index b7b8c97bc0..1f95a9abba 100644
--- a/src/basic/string-util.c
+++ b/src/basic/string-util.c
@@ -363,6 +363,21 @@ int ascii_strcasecmp_n(const char *a, const char *b, size_t n) {
         return 0;
 }
 
+int ascii_strcasecmp_nn(const char *a, size_t n, const char *b, size_t m) {
+        int r;
+
+        r = ascii_strcasecmp_n(a, b, MIN(n, m));
+        if (r != 0)
+                return r;
+
+        if (n < m)
+                return -1;
+        else if (n > m)
+                return 1;
+        else
+                return 0;
+}
+
 bool chars_intersect(const char *a, const char *b) {
         const char *p;
 
diff --git a/src/basic/string-util.h b/src/basic/string-util.h
index 6374e11119..8ea18f45aa 100644
--- a/src/basic/string-util.h
+++ b/src/basic/string-util.h
@@ -135,6 +135,7 @@ char *ascii_strlower(char *s);
 char *ascii_strlower_n(char *s, size_t n);
 
 int ascii_strcasecmp_n(const char *a, const char *b, size_t n);
+int ascii_strcasecmp_nn(const char *a, size_t n, const char *b, size_t m);
 
 bool chars_intersect(const char *a, const char *b) _pure_;
 
diff --git a/src/test/test-string-util.c b/src/test/test-string-util.c
index 4758108706..12889ce873 100644
--- a/src/test/test-string-util.c
+++ b/src/test/test-string-util.c
@@ -82,8 +82,26 @@ static void test_ascii_strcasecmp_n(void) {
         assert_se(ascii_strcasecmp_n("xxxxYxxxx", "xxxxXxxxx", 9) > 0);
 }
 
+static void test_ascii_strcasecmp_nn(void) {
+        assert_se(ascii_strcasecmp_nn("", 0, "", 0) == 0);
+        assert_se(ascii_strcasecmp_nn("", 0, "", 1) < 0);
+        assert_se(ascii_strcasecmp_nn("", 1, "", 0) > 0);
+        assert_se(ascii_strcasecmp_nn("", 1, "", 1) == 0);
+
+        assert_se(ascii_strcasecmp_nn("aaaa", 4, "aaAa", 4) == 0);
+        assert_se(ascii_strcasecmp_nn("aaa", 3, "aaAa", 4) < 0);
+        assert_se(ascii_strcasecmp_nn("aaa", 4, "aaAa", 4) < 0);
+        assert_se(ascii_strcasecmp_nn("aaaa", 4, "aaA", 3) > 0);
+        assert_se(ascii_strcasecmp_nn("aaaa", 4, "AAA", 4) > 0);
+
+        assert_se(ascii_strcasecmp_nn("aaaa", 4, "bbbb", 4) < 0);
+        assert_se(ascii_strcasecmp_nn("aaAA", 4, "BBbb", 4) < 0);
+        assert_se(ascii_strcasecmp_nn("BBbb", 4, "aaaa", 4) > 0);
+}
+
 int main(int argc, char *argv[]) {
         test_string_erase();
         test_ascii_strcasecmp_n();
+        test_ascii_strcasecmp_nn();
         return 0;
 }