erl_nif: add enif_get_atom_length and enif_get_list_length

Add new NIF API functions
 - enif_get_atom_length
 - enif_get_list_length

Signed-off-by: Tuncer Ayaz <[email protected]>

5 files changed, 70 insertions, 3 deletions

diff --git a/erts/doc/src/erl_nif.xml b/erts/doc/src/erl_nif.xml
index dda6354c61..dc68eb5e5e 100644
--- a/erts/doc/src/erl_nif.xml
+++ b/erts/doc/src/erl_nif.xml
@@ -477,6 +477,12 @@ typedef enum {
               <c>term</c> is not an atom with maximum length of 
               <c>size-1</c>.</p></desc>
     </func>
+    <func><name><ret>int</ret><nametext>enif_get_atom_length(ErlNifEnv* env, ERL_NIF_TERM term, unsigned* len)</nametext></name>
+      <fsummary>Get the length of atom <c>term</c>.</fsummary>
+      <desc><p>Set <c>*len</c> to the length (number of bytes excluding
+      terminating null character) of <c>term</c> or return false if
+      <c>term</c> is not an atom.</p></desc>
+    </func>
     <func><name><ret>int</ret><nametext>enif_get_double(ErlNifEnv* env, ERL_NIF_TERM term, double* dp)</nametext></name>
       <fsummary>Read a floating-point number term.</fsummary>
       <desc><p>Set <c>*dp</c> to the floating point value of
@@ -494,6 +500,11 @@ typedef enum {
       <c>list</c> or return false if <c>list</c> is not a non-empty
       list.</p></desc>
     </func>
+    <func><name><ret>int</ret><nametext>enif_get_list_length(ErlNifEnv* env, ERL_NIF_TERM term, unsigned* len)</nametext></name>
+      <fsummary>Get the length of list <c>term</c>.</fsummary>
+      <desc><p>Set <c>*len</c> to the length of <c>term</c> or return
+      false if <c>term</c> is not a list.</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
diff --git a/erts/emulator/beam/erl_nif.c b/erts/emulator/beam/erl_nif.c
index a07aa2e81f..4a3b0ad8ca 100644
--- a/erts/emulator/beam/erl_nif.c
+++ b/erts/emulator/beam/erl_nif.c
@@ -601,6 +601,15 @@ int enif_get_double(ErlNifEnv* env, Eterm term, double* dp)
     return 1;
 }
 
+int enif_get_atom_length(ErlNifEnv* env, Eterm atom, unsigned* len)
+{
+    Atom* ap;
+    if (is_not_atom(atom)) return 0;
+    ap = atom_tab(atom_val(atom));
+    *len = ap->len;
+    return 1;
+}
+
 int enif_get_list_cell(ErlNifEnv* env, Eterm term, Eterm* head, Eterm* tail)
 {
     Eterm* val;
@@ -611,6 +620,13 @@ int enif_get_list_cell(ErlNifEnv* env, Eterm term, Eterm* head, Eterm* tail)
     return 1;
 }
 
+int enif_get_list_length(ErlNifEnv* env, Eterm term, unsigned* len)
+{
+    if (is_not_list(term) && is_not_nil(term)) return 0;
+    *len = list_length(term);
+    return 1;
+}
+
 ERL_NIF_TERM enif_make_int(ErlNifEnv* env, int i)
 {
 #if SIZEOF_INT == ERTS_SIZEOF_ETERM
diff --git a/erts/emulator/beam/erl_nif_api_funcs.h b/erts/emulator/beam/erl_nif_api_funcs.h
index 1ef27c3df3..4d025567ad 100644
--- a/erts/emulator/beam/erl_nif_api_funcs.h
+++ b/erts/emulator/beam/erl_nif_api_funcs.h
@@ -108,6 +108,8 @@ ERL_NIF_API_FUNC_DECL(unsigned,enif_sizeof_resource,(ErlNifEnv*, void* obj));
 ERL_NIF_API_FUNC_DECL(unsigned char*,enif_make_new_binary,(ErlNifEnv*,unsigned size,ERL_NIF_TERM* termp));
 ERL_NIF_API_FUNC_DECL(int,enif_is_list,(ErlNifEnv*, ERL_NIF_TERM term));
 ERL_NIF_API_FUNC_DECL(int,enif_is_tuple,(ErlNifEnv*, ERL_NIF_TERM term));
+ERL_NIF_API_FUNC_DECL(int,enif_get_atom_length,(ErlNifEnv*, ERL_NIF_TERM atom, unsigned* len));
+ERL_NIF_API_FUNC_DECL(int,enif_get_list_length,(ErlNifEnv* env, ERL_NIF_TERM term, unsigned* len));
 
 /*
 ** Add last to keep compatibility on Windows!!!
@@ -202,6 +204,8 @@ ERL_NIF_API_FUNC_DECL(int,enif_is_tuple,(ErlNifEnv*, ERL_NIF_TERM term));
 #  define enif_make_new_binary ERL_NIF_API_FUNC_MACRO(enif_make_new_binary)
 #  define enif_is_list ERL_NIF_API_FUNC_MACRO(enif_is_list)
 #  define enif_is_tuple ERL_NIF_API_FUNC_MACRO(enif_is_tuple)
+#  define enif_get_atom_length ERL_NIF_API_FUNC_MACRO(enif_get_atom_length)
+#  define enif_get_list_length ERL_NIF_API_FUNC_MACRO(enif_get_list_length)
 #endif
 
 #ifndef enif_make_list1
diff --git a/erts/emulator/test/nif_SUITE.erl b/erts/emulator/test/nif_SUITE.erl
index 36bcfe26cc..c2949e7bfa 100644
--- a/erts/emulator/test/nif_SUITE.erl
+++ b/erts/emulator/test/nif_SUITE.erl
@@ -28,7 +28,7 @@
 -export([all/1, fin_per_testcase/2, basic/1, reload/1, upgrade/1, heap_frag/1,
 	 types/1, many_args/1, binaries/1, get_string/1, get_atom/1, api_macros/1,
 	 from_array/1, iolist_as_binary/1, resource/1, resource_takeover/1,
-	 threading/1, neg/1, is_checks/1]).
+	 threading/1, neg/1, is_checks/1, get_length/1]).
 
 -export([many_args_100/100]).
 -define(nif_stub,nif_stub_error(?LINE)).
@@ -36,7 +36,7 @@
 all(suite) ->
     [basic, reload, upgrade, heap_frag, types, many_args, binaries, get_string,
      get_atom, api_macros, from_array, iolist_as_binary, resource,
-     resource_takeover, threading, neg, is_checks].
+     resource_takeover, threading, neg, is_checks, get_length].
 
 %%init_per_testcase(_Case, Config) ->
 %%    ?line Dog = ?t:timetrap(?t:seconds(60*60*24)),
@@ -766,6 +766,11 @@ is_checks(Config) when is_list(Config) ->
 			self(), hd(erlang:ports()), [], [1,9,9,8],
 			{hejsan, "hejsan", [$h,"ejs",<<"an">>]}).
 
+get_length(doc) -> ["Test all enif_get_length functions"];
+get_length(Config) when is_list(Config) ->
+    ?line ensure_lib_loaded(Config, 1),
+    ?line ok = length_test(hejsan, "hejsan", [], [], not_a_list).
+
 ensure_lib_loaded(Config) ->
     ensure_lib_loaded(Config, 1).
 ensure_lib_loaded(Config, Ver) ->
@@ -861,6 +866,7 @@ release_resource(_) -> ?nif_stub.
 last_resource_dtor_call() -> ?nif_stub.
 make_new_resource(_,_) -> ?nif_stub.
 check_is(_,_,_,_,_,_,_,_,_,_) -> ?nif_stub.
+length_test(_,_,_,_,_) -> ?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 22d0d5a93b..4d010c58a5 100644
--- a/erts/emulator/test/nif_SUITE_data/nif_SUITE.c
+++ b/erts/emulator/test/nif_SUITE_data/nif_SUITE.c
@@ -661,6 +661,35 @@ static ERL_NIF_TERM check_is(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[]
     return ok_atom;
 }
 
+/*
+ * argv[0] atom with length of 6
+ * argv[1] list with length of 6
+ * argv[2] empty list
+ * argv[3] not an atom
+ * argv[4] not a list
+ */
+static ERL_NIF_TERM length_test(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
+{
+    unsigned len;
+
+    if (!enif_get_atom_length(env, argv[0], &len) || len != 6)
+	return enif_make_badarg(env);
+
+    if (!enif_get_list_length(env, argv[1], &len) || len != 6)
+	return enif_make_badarg(env);
+
+    if (!enif_get_list_length(env, argv[2], &len) || len != 0)
+	return enif_make_badarg(env);
+
+    if (enif_get_atom_length(env, argv[3], &len))
+	return enif_make_badarg(env);
+
+    if (enif_get_list_length(env, argv[4], &len))
+	return enif_make_badarg(env);
+
+    return enif_make_atom(env, "ok");
+}
+
 static ErlNifFunc nif_funcs[] =
 {
     {"lib_version", 0, lib_version},
@@ -687,7 +716,8 @@ static ErlNifFunc nif_funcs[] =
     {"release_resource", 1, release_resource},
     {"last_resource_dtor_call", 0, last_resource_dtor_call},
     {"make_new_resource", 2, make_new_resource},
-    {"check_is", 10, check_is}
+    {"check_is", 10, check_is},
+    {"length_test", 5, length_test}
 
 };