string: add a test for memcmp

src/main.c

@@ -44,6 +44,7 @@ ft_list headers_libc[] = {
         &ft_string_memset,
         &ft_string_memcpy,
         &ft_string_memmove,
+        &ft_string_memcmp,
         NULL,
     }},
     { "<time.h>", NULL },

src/string/core.c

@@ -166,3 +166,47 @@ ft_test ft_string_memmove = {
     .function = _string_memmove,
     .widget = _string_memmove_widget,
 };
+
+//---
+// memcmp
+//---
+
+static int _string_memcmp_func(memarray_args_t const *args)
+{
+    /* Create data that matches in the given regions */
+    fill(args->full_left1,  args->full_size, args->left1  - args->full_left1);
+    fill(args->full_right1, args->full_size, args->right1 - args->full_right1);
+
+    /* Check equality */
+    if(memcmp(args->left1, args->right1, args->size) !=
+        naive_memcmp(args->left1, args->right1, args->size)) return 1;
+
+    /* Check that changing single bytes changes the result */
+    for(size_t i = 0; i < args->size / 4; i++) {
+        ((uint8_t *)args->right1)[i] ^= 0xff;
+        if(memcmp(args->left1, args->right1, args->size) !=
+            naive_memcmp(args->left1, args->right1, args->size)) return 1;
+        ((uint8_t *)args->right1)[i] ^= 0xff;
+    }
+
+    return 0;
+}
+
+uint8_t _string_memcmp_rc[MEMARRAY_RC_DOUBLE];
+
+static void _string_memcmp(ft_test *t)
+{
+    memarray_double(_string_memcmp_rc, false, _string_memcmp_func);
+    memarray_assert(_string_memcmp_rc, t);
+}
+
+static jwidget *_string_memcmp_widget(GUNUSED ft_test *t)
+{
+    return memarray_widget(_string_memcmp_rc);
+}
+
+ft_test ft_string_memcmp=  {
+    .name = "Configurations of memcmp",
+    .function = _string_memcmp,
+    .widget = _string_memcmp_widget,
+};