Added enif_get_reverse_list to nif API

6 files changed, 54 insertions, 4 deletions

diff --git a/erts/doc/src/erl_nif.xml b/erts/doc/src/erl_nif.xml
index cdce4ec0b8..6b9a405647 100644
--- a/erts/doc/src/erl_nif.xml
+++ b/erts/doc/src/erl_nif.xml
@@ -604,6 +604,13 @@ typedef enum {
       <desc><p>Set <c>*len</c> to the length of list <c>term</c> and return true,
       or return false if <c>term</c> is not a list.</p></desc>
     </func>
+    <func><name><ret>int</ret><nametext>enif_get_reverse_list(ErlNifEnv* env, ERL_NIF_TERM term, ERL_NIF_TERM *list)</nametext></name>
+      <fsummary>Get the reverse list of the list <c>term</c>.</fsummary>
+      <desc><p>Set <c>*list</c> to the reverse list of the list <c>term</c> and return true,
+      or return false if <c>term</c> is not a list. This function should only be used on
+      short lists as a copy will be created of the list which will not be released until after the
+      nif returns.</p></desc>
+    </func>
     <func><name><ret>int</ret><nametext>enif_get_long(ErlNifEnv* env, ERL_NIF_TERM term, long int* ip)</nametext></name>
       <fsummary>Read an long integer term.</fsummary>
       <desc><p>Set <c>*ip</c> to the long integer value of <c>term</c> and
diff --git a/erts/emulator/beam/erl_nif.c b/erts/emulator/beam/erl_nif.c
index 68421b4387..d1afeb4f03 100644
--- a/erts/emulator/beam/erl_nif.c
+++ b/erts/emulator/beam/erl_nif.c
@@ -1007,6 +1007,30 @@ void enif_system_info(ErlNifSysInfo *sip, size_t si_size)
     driver_system_info(sip, si_size);
 }
 
+int enif_get_reverse_list(ErlNifEnv* env, ERL_NIF_TERM term, ERL_NIF_TERM *list) {
+    Eterm *listptr, *ret, *hp;
+
+    if (is_nil(term)) {
+	*list = term;
+        return 1;
+    }
+
+    ret = alloc_heap(env, 2);
+    *ret = NIL;
+
+    while (is_not_nil(term)) {
+	if (is_not_list(term)) {
+	    return 0;
+	}
+	hp = alloc_heap(env, 2);
+	listptr = list_val(term);
+	*ret = CONS(hp, CAR(listptr), *ret);
+	term = CDR(listptr);
+    }
+    *list = *ret;
+    return 1;
+}
+
 
 ErlNifMutex* enif_mutex_create(char *name) { return erl_drv_mutex_create(name); }
 void enif_mutex_destroy(ErlNifMutex *mtx) {  erl_drv_mutex_destroy(mtx); }
diff --git a/erts/emulator/beam/erl_nif.h b/erts/emulator/beam/erl_nif.h
index d028567faf..bb557e39e9 100644
--- a/erts/emulator/beam/erl_nif.h
+++ b/erts/emulator/beam/erl_nif.h
@@ -34,7 +34,7 @@
 ** 2.2: R14B03 enif_is_exception
 */
 #define ERL_NIF_MAJOR_VERSION 2
-#define ERL_NIF_MINOR_VERSION 2
+#define ERL_NIF_MINOR_VERSION 3
 
 #include <stdlib.h>
 
diff --git a/erts/emulator/beam/erl_nif_api_funcs.h b/erts/emulator/beam/erl_nif_api_funcs.h
index c991b61abe..465d52227d 100644
--- a/erts/emulator/beam/erl_nif_api_funcs.h
+++ b/erts/emulator/beam/erl_nif_api_funcs.h
@@ -136,6 +136,7 @@ ERL_NIF_API_FUNC_DECL(ERL_NIF_TERM,enif_make_int64,(ErlNifEnv*, ErlNifSInt64));
 ERL_NIF_API_FUNC_DECL(ERL_NIF_TERM,enif_make_uint64,(ErlNifEnv*, ErlNifUInt64));
 #endif
 ERL_NIF_API_FUNC_DECL(int,enif_is_exception,(ErlNifEnv*, ERL_NIF_TERM term));
+ERL_NIF_API_FUNC_DECL(int,enif_get_reverse_list,(ErlNifEnv*, ERL_NIF_TERM term, ERL_NIF_TERM *list));
 
 /*
 ** Add new entries here to keep compatibility on Windows!!!
@@ -256,6 +257,7 @@ ERL_NIF_API_FUNC_DECL(int,enif_is_exception,(ErlNifEnv*, ERL_NIF_TERM term));
 #endif
 
 #  define enif_is_exception ERL_NIF_API_FUNC_MACRO(enif_is_exception)
+#  define enif_get_reverse_list ERL_NIF_API_FUNC_MACRO(enif_get_reverse_list)
 
 /*
 ** Add new entries here
diff --git a/erts/emulator/test/nif_SUITE.erl b/erts/emulator/test/nif_SUITE.erl
index 91d695d979..813ed65f4b 100644
--- a/erts/emulator/test/nif_SUITE.erl
+++ b/erts/emulator/test/nif_SUITE.erl
@@ -35,7 +35,7 @@
 	 resource_takeover/1,
 	 threading/1, send/1, send2/1, send3/1, send_threaded/1, neg/1, 
 	 is_checks/1,
-	 get_length/1, make_atom/1, make_string/1]).
+	 get_length/1, make_atom/1, make_string/1, reverse_list_test/1]).
 
 -export([many_args_100/100]).
 
@@ -60,7 +60,7 @@ all() ->
      iolist_as_binary, resource, resource_binary,
      resource_takeover, threading, send, send2, send3,
      send_threaded, neg, is_checks, get_length, make_atom,
-     make_string].
+     make_string,reverse_list_test].
 
 groups() -> 
     [].
@@ -1164,6 +1164,13 @@ make_string(Config) when is_list(Config) ->
     AStringWithAccents = [$E,$r,$l,$a,$n,$g,$ ,16#e4,$r,$ ,$e,$t,$t,$ ,$g,$e,$n,$e,$r,$e,$l,$l,$t,$ ,$p,$r,$o,$g,$r,$a,$m,$s,$p,$r,16#e5,$k],
     ?line Strings = {A0String,A0String,A0String,A0String0, AStringWithAccents}.
 
+reverse_list_test(Config) ->
+    ?line ensure_lib_loaded(Config, 1),
+    List = lists:seq(1,100),
+    RevList = lists:reverse(List),
+    ?line RevList = reverse_list(List),
+    badarg = reverse_list(foo).
+
 tmpmem() ->
     case erlang:system_info({allocator,temp_alloc}) of
 	false -> undefined;
@@ -1269,6 +1276,7 @@ send_blob_thread(_,_,_) -> ?nif_stub.
 join_send_thread(_) -> ?nif_stub.
 copy_blob(_) -> ?nif_stub.
 send_term(_,_) -> ?nif_stub.
+reverse_list(_) -> ?nif_stub.
 
 nif_stub_error(Line) ->
     exit({nif_not_loaded,module,?MODULE,line,Line}).
diff --git a/erts/emulator/test/nif_SUITE_data/nif_SUITE.c b/erts/emulator/test/nif_SUITE_data/nif_SUITE.c
index 0bb93daa33..87b4d4c4ed 100644
--- a/erts/emulator/test/nif_SUITE_data/nif_SUITE.c
+++ b/erts/emulator/test/nif_SUITE_data/nif_SUITE.c
@@ -1373,6 +1373,14 @@ static ERL_NIF_TERM send_term(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[
     return enif_make_int(env, ret);
 }
 
+static ERL_NIF_TERM reverse_list(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[]) {
+    ERL_NIF_TERM rev_list;
+
+    if(!enif_get_reverse_list(env, argv[0], &rev_list))
+	return enif_make_atom(env, "badarg");
+    return rev_list;
+}
+
 static ErlNifFunc nif_funcs[] =
 {
     {"lib_version", 0, lib_version},
@@ -1417,7 +1425,8 @@ static ErlNifFunc nif_funcs[] =
     {"send_blob_thread", 3, send_blob_thread},
     {"join_send_thread", 1, join_send_thread},
     {"copy_blob", 1, copy_blob},
-    {"send_term", 2, send_term}
+    {"send_term", 2, send_term},
+    {"reverse_list",1, reverse_list}
 };
 
 ERL_NIF_INIT(nif_SUITE,nif_funcs,load,reload,upgrade,unload)