7 files changed, 99 insertions, 15 deletions

diff --git a/erts/doc/src/erl_nif.xml b/erts/doc/src/erl_nif.xml
index 27b0945c10..cabc07d020 100644
--- a/erts/doc/src/erl_nif.xml
+++ b/erts/doc/src/erl_nif.xml
@@ -2185,6 +2185,20 @@ enif_inspect_iovec(env, max_elements, term, &tail, &iovec);
     </func>
 
     <func>
+      <name><ret>int</ret>
+        <nametext>enif_make_map_from_arrays(ErlNifEnv* env, ERL_NIF_TERM keys[],
+        ERL_NIF_TERM values[], size_t cnt, ERL_NIF_TERM *map_out)</nametext></name>
+      <fsummary>Make map term from the given keys and values.</fsummary>
+      <desc>
+        <p>Makes a map term from the given keys and values.</p>
+        <p>If successful, this function sets <c>*map_out</c> to the new map and
+          returns <c>true</c>. Returns <c>false</c> there are any duplicate
+          keys.</p>
+        <p>All keys and values must belong to <c>env</c>.</p>
+      </desc>
+    </func>
+
+    <func>
       <name><ret>unsigned char *</ret><nametext>enif_make_new_binary(ErlNifEnv*
         env, size_t size, ERL_NIF_TERM* termp)</nametext></name>
       <fsummary>Allocate and create a new binary term.</fsummary>
diff --git a/erts/emulator/beam/erl_map.c b/erts/emulator/beam/erl_map.c
index 8047a9567f..4ec6960997 100644
--- a/erts/emulator/beam/erl_map.c
+++ b/erts/emulator/beam/erl_map.c
@@ -490,7 +490,9 @@ Eterm erts_map_from_ks_and_vs(ErtsHeapFactory *factory, Eterm *ks0, Eterm *vs0,
         sys_memcpy(ks, ks0, n * sizeof(Eterm));
         sys_memcpy(vs, vs0, n * sizeof(Eterm));
 
-        erts_validate_and_sort_flatmap(mp);
+        if (!erts_validate_and_sort_flatmap(mp)) {
+            return THE_NON_VALUE;
+        }
 
         return make_flatmap(mp);
     } else {
diff --git a/erts/emulator/beam/erl_nif.c b/erts/emulator/beam/erl_nif.c
index 1d337d9792..f883b3f1e3 100644
--- a/erts/emulator/beam/erl_nif.c
+++ b/erts/emulator/beam/erl_nif.c
@@ -2934,6 +2934,44 @@ ERL_NIF_TERM enif_make_new_map(ErlNifEnv* env)
     return make_flatmap(mp);
 }
 
+int enif_make_map_from_arrays(ErlNifEnv *env,
+                              ERL_NIF_TERM keys[],
+                              ERL_NIF_TERM values[],
+                              size_t cnt,
+                              ERL_NIF_TERM *map_out)
+{
+    ErtsHeapFactory factory;
+    int succeeded;
+
+#ifdef ERTS_NIF_ASSERT_IN_ENV
+    size_t index = 0;
+
+    while (index < cnt) {
+        ASSERT_IN_ENV(env, keys[index], index, "key");
+        ASSERT_IN_ENV(env, values[index], index, "value");
+        index++;
+    }
+#endif
+
+    flush_env(env);
+
+    erts_factory_proc_prealloc_init(&factory, env->proc,
+        cnt * 2 + MAP_HEADER_FLATMAP_SZ + 1);
+
+    (*map_out) = erts_map_from_ks_and_vs(&factory, keys, values, cnt);
+    succeeded = (*map_out) != THE_NON_VALUE;
+
+    if (!succeeded) {
+        erts_factory_undo(&factory);
+    }
+
+    erts_factory_close(&factory);
+
+    cache_env(env);
+
+    return succeeded;
+}
+
 int enif_make_map_put(ErlNifEnv* env,
 	              Eterm map_in,
 		      Eterm key,
diff --git a/erts/emulator/beam/erl_nif.h b/erts/emulator/beam/erl_nif.h
index e051ecb26e..1906da732b 100644
--- a/erts/emulator/beam/erl_nif.h
+++ b/erts/emulator/beam/erl_nif.h
@@ -53,7 +53,7 @@
 ** 2.12: 20.0 add enif_select, enif_open_resource_type_x
 ** 2.13: 20.1 add enif_ioq
 ** 2.14: 21.0 add enif_ioq_peek_head, enif_(mutex|cond|rwlock|thread)_name
-**                enif_vfprintf, enif_vsnprintf
+**                enif_vfprintf, enif_vsnprintf, enif_make_map_from_arrays
 */
 #define ERL_NIF_MAJOR_VERSION 2
 #define ERL_NIF_MINOR_VERSION 14
diff --git a/erts/emulator/beam/erl_nif_api_funcs.h b/erts/emulator/beam/erl_nif_api_funcs.h
index 744f7c9f69..61f8fcf6ed 100644
--- a/erts/emulator/beam/erl_nif_api_funcs.h
+++ b/erts/emulator/beam/erl_nif_api_funcs.h
@@ -208,6 +208,8 @@ ERL_NIF_API_FUNC_DECL(char*,enif_thread_name,(ErlNifTid));
 ERL_NIF_API_FUNC_DECL(int,enif_vfprintf,(FILE*, const char *fmt, va_list));
 ERL_NIF_API_FUNC_DECL(int,enif_vsnprintf,(char*, size_t, const char *fmt, va_list));
 
+ERL_NIF_API_FUNC_DECL(int,enif_make_map_from_arrays,(ErlNifEnv *env, ERL_NIF_TERM keys[], ERL_NIF_TERM values[], size_t cnt, ERL_NIF_TERM *map_out));
+
 /*
 ** ADD NEW ENTRIES HERE (before this comment) !!!
 */
@@ -389,6 +391,7 @@ ERL_NIF_API_FUNC_DECL(int,enif_vsnprintf,(char*, size_t, const char *fmt, va_lis
 #  define enif_thread_name ERL_NIF_API_FUNC_MACRO(enif_thread_name)
 #  define enif_vfprintf ERL_NIF_API_FUNC_MACRO(enif_vfprintf)
 #  define enif_vsnprintf ERL_NIF_API_FUNC_MACRO(enif_vsnprintf)
+#  define enif_make_map_from_arrays ERL_NIF_API_FUNC_MACRO(enif_make_map_from_arrays)
 
 /*
 ** ADD NEW ENTRIES HERE (before this comment)
diff --git a/erts/emulator/test/nif_SUITE.erl b/erts/emulator/test/nif_SUITE.erl
index b6e15ababb..a9eb4b2768 100644
--- a/erts/emulator/test/nif_SUITE.erl
+++ b/erts/emulator/test/nif_SUITE.erl
@@ -1170,6 +1170,12 @@ maps(Config) when is_list(Config) ->
     {1, M2} = make_map_remove_nif(M2, "key3"),
     {0, undefined} = make_map_remove_nif(self(), key),
 
+    M1 = maps_from_list_nif(maps:to_list(M1)),
+    M2 = maps_from_list_nif(maps:to_list(M2)),
+    M3 = maps_from_list_nif(maps:to_list(M3)),
+
+    has_duplicate_keys = maps_from_list_nif([{1,1},{1,1}]),
+
     verify_tmpmem(TmpMem),
     ok.
  
diff --git a/erts/emulator/test/nif_SUITE_data/nif_SUITE.c b/erts/emulator/test/nif_SUITE_data/nif_SUITE.c
index fa9ae1015c..e8d9302505 100644
--- a/erts/emulator/test/nif_SUITE_data/nif_SUITE.c
+++ b/erts/emulator/test/nif_SUITE_data/nif_SUITE.c
@@ -2140,24 +2140,45 @@ static ERL_NIF_TERM make_map_remove_nif(ErlNifEnv* env, int argc, const ERL_NIF_
 /* maps */
 static ERL_NIF_TERM maps_from_list_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
 {
-    ERL_NIF_TERM cell = argv[0];
-    ERL_NIF_TERM map  = enif_make_new_map(env);
-    ERL_NIF_TERM tuple;
-    const ERL_NIF_TERM *pair;
-    int arity = -1;
+    ERL_NIF_TERM *keys, *values;
+    ERL_NIF_TERM result, cell;
+    unsigned count;
 
-    if (argc != 1 && !enif_is_list(env, cell)) return enif_make_badarg(env);
+    if (argc != 1 || !enif_get_list_length(env, argv[0], &count)) {
+        return enif_make_badarg(env);
+    }
 
-    /* assume sorted keys */
+    keys = enif_alloc(sizeof(ERL_NIF_TERM) * count * 2);
+    values = keys + count;
 
-    while (!enif_is_empty_list(env,cell)) {
-	if (!enif_get_list_cell(env, cell, &tuple, &cell)) return enif_make_badarg(env);
-	if (enif_get_tuple(env,tuple,&arity,&pair)) {
-	    enif_make_map_put(env, map, pair[0], pair[1], &map);
-	}
+    cell = argv[0];
+    count = 0;
+
+    while (!enif_is_empty_list(env, cell)) {
+        const ERL_NIF_TERM *pair;
+        ERL_NIF_TERM tuple;
+        int arity;
+
+        if (!enif_get_list_cell(env, cell, &tuple, &cell)
+            || !enif_get_tuple(env, tuple, &arity, &pair)
+            || arity != 2) {
+            enif_free(keys);
+            return enif_make_badarg(env);
+        }
+
+        keys[count] = pair[0];
+        values[count] = pair[1];
+
+        count++;
     }
 
-    return map;
+    if (!enif_make_map_from_arrays(env, keys, values, count, &result)) {
+        result = enif_make_atom(env, "has_duplicate_keys");
+    }
+
+    enif_free(keys);
+
+    return result;
 }
 
 static ERL_NIF_TERM sorted_list_from_maps_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[]) {