Merge pull request #1400 from tburghart/trb/erts/enif_whereis

Add enif_whereis_pid() and enif_whereis_port() functions

OTP-14453

9 files changed, 923 insertions, 7 deletions

diff --git a/erts/doc/src/erl_nif.xml b/erts/doc/src/erl_nif.xml
index 3eb3e04f33..5a69bed34c 100644
--- a/erts/doc/src/erl_nif.xml
+++ b/erts/doc/src/erl_nif.xml
@@ -3002,6 +3002,63 @@ if (retval & ERL_NIF_SELECT_STOP_CALLED) {
           <c>erl_drv_tsd_set</c></seealso>.</p>
       </desc>
     </func>
+
+    <func>
+      <name><ret>int</ret>
+        <nametext>enif_whereis_pid(ErlNifEnv *env,
+          ERL_NIF_TERM name, ErlNifPid *pid)</nametext></name>
+      <fsummary>Looks up a process by its registered name.</fsummary>
+      <desc>
+        <p>Looks up a process by its registered name.</p>
+        <taglist>
+          <tag><c>env</c></tag>
+          <item>The environment of the calling process. Must be <c>NULL</c>
+            only if calling from a created thread.</item>
+          <tag><c>name</c></tag>
+          <item>The name of a registered process, as an atom.</item>
+          <tag><c>*pid</c></tag>
+          <item>The <seealso marker="#ErlNifPid"><c>ErlNifPid</c></seealso>
+            in which the resolved process id is stored.</item>
+        </taglist>
+        <p>On success, sets <c>*pid</c> to the local process registered with
+          <c>name</c> and returns <c>true</c>. If <c>name</c> is not a
+          registered process, or is not an atom, <c>false</c> is returned and
+          <c>*pid</c> is unchanged.</p>
+        <p>Works as <seealso marker="erlang#whereis-1">
+          <c>erlang:whereis/1</c></seealso>, but restricted to processes. See
+          <seealso marker="#enif_whereis_port"><c>enif_whereis_port</c></seealso>
+          to resolve registered ports.</p>
+      </desc>
+    </func>
+
+    <func>
+      <name><ret>int</ret>
+        <nametext>enif_whereis_port(ErlNifEnv *env,
+          ERL_NIF_TERM name, ErlNifPort *port)</nametext></name>
+      <fsummary>Looks up a port by its registered name.</fsummary>
+      <desc>
+        <p>Looks up a port by its registered name.</p>
+        <taglist>
+          <tag><c>env</c></tag>
+          <item>The environment of the calling process. Must be <c>NULL</c>
+            only if calling from a created thread.</item>
+          <tag><c>name</c></tag>
+          <item>The name of a registered port, as an atom.</item>
+          <tag><c>*port</c></tag>
+          <item>The <seealso marker="#ErlNifPort"><c>ErlNifPort</c></seealso>
+            in which the resolved port id is stored.</item>
+        </taglist>
+        <p>On success, sets <c>*port</c> to the port registered with
+          <c>name</c> and returns <c>true</c>. If <c>name</c> is not a
+          registered port, or is not an atom, <c>false</c> is returned and
+          <c>*port</c> is unchanged.</p>
+        <p>Works as <seealso marker="erlang#whereis-1">
+          <c>erlang:whereis/1</c></seealso>, but restricted to ports. See
+          <seealso marker="#enif_whereis_pid"><c>enif_whereis_pid</c></seealso>
+          to resolve registered processes.</p>
+      </desc>
+    </func>
+
   </funcs>
 
   <section>
diff --git a/erts/emulator/beam/erl_nif.c b/erts/emulator/beam/erl_nif.c
index ea835d1b64..4815e5e7bb 100644
--- a/erts/emulator/beam/erl_nif.c
+++ b/erts/emulator/beam/erl_nif.c
@@ -879,6 +879,64 @@ enif_port_command(ErlNifEnv *env, const ErlNifPort* to_port,
     return res;
 }
 
+/*
+ *  env must be the caller's environment in a scheduler or NULL in a
+ *      non-scheduler thread.
+ *  name must be an atom - anything else will just waste time.
+ */
+static Eterm call_whereis(ErlNifEnv *env, Eterm name)
+{
+    Process *c_p;
+    Eterm res;
+    int scheduler;
+    int unlock;
+
+    execution_state(env, &c_p, &scheduler);
+    ASSERT((c_p && scheduler) || (!c_p && !scheduler));
+
+    unlock = 0;
+    if (scheduler < 0) {
+        /* dirty scheduler */
+        if (ERTS_PROC_IS_EXITING(c_p))
+            return 0;
+
+        if (env->proc->static_flags & ERTS_STC_FLG_SHADOW_PROC) {
+            erts_smp_proc_lock(c_p, ERTS_PROC_LOCK_MAIN);
+            unlock = 1;
+        }
+    }
+    res = erts_whereis_name_to_id(c_p, name);
+
+    if (unlock)
+        erts_smp_proc_unlock(c_p, ERTS_PROC_LOCK_MAIN);
+
+    return res;
+}
+
+int enif_whereis_pid(ErlNifEnv *env, ERL_NIF_TERM name, ErlNifPid *pid)
+{
+    Eterm res;
+
+    if (is_not_atom(name))
+        return 0;
+
+    res = call_whereis(env, name);
+    /* enif_get_local_ functions check the type */
+    return enif_get_local_pid(env, res, pid);
+}
+
+int enif_whereis_port(ErlNifEnv *env, ERL_NIF_TERM name, ErlNifPort *port)
+{
+    Eterm res;
+
+    if (is_not_atom(name))
+        return 0;
+
+    res = call_whereis(env, name);
+    /* enif_get_local_ functions check the type */
+    return enif_get_local_port(env, res, port);
+}
+
 ERL_NIF_TERM enif_make_copy(ErlNifEnv* dst_env, ERL_NIF_TERM src_term)
 {
     Uint sz;
diff --git a/erts/emulator/beam/erl_nif_api_funcs.h b/erts/emulator/beam/erl_nif_api_funcs.h
index c305732d63..94c04cd126 100644
--- a/erts/emulator/beam/erl_nif_api_funcs.h
+++ b/erts/emulator/beam/erl_nif_api_funcs.h
@@ -181,6 +181,8 @@ ERL_NIF_API_FUNC_DECL(int, enif_monitor_process,(ErlNifEnv*,void* obj,const ErlN
 ERL_NIF_API_FUNC_DECL(int, enif_demonitor_process,(ErlNifEnv*,void* obj,const ErlNifMonitor *monitor));
 ERL_NIF_API_FUNC_DECL(int, enif_compare_monitors,(const ErlNifMonitor*,const ErlNifMonitor*));
 ERL_NIF_API_FUNC_DECL(ErlNifUInt64,enif_hash,(ErlNifHash type, ERL_NIF_TERM term, ErlNifUInt64 salt));
+ERL_NIF_API_FUNC_DECL(int, enif_whereis_pid, (ErlNifEnv *env, ERL_NIF_TERM name, ErlNifPid *pid));
+ERL_NIF_API_FUNC_DECL(int, enif_whereis_port, (ErlNifEnv *env, ERL_NIF_TERM name, ErlNifPort *port));
 
 /*
 ** ADD NEW ENTRIES HERE (before this comment) !!!
@@ -344,6 +346,8 @@ ERL_NIF_API_FUNC_DECL(ErlNifUInt64,enif_hash,(ErlNifHash type, ERL_NIF_TERM term
 #  define enif_demonitor_process ERL_NIF_API_FUNC_MACRO(enif_demonitor_process)
 #  define enif_compare_monitors ERL_NIF_API_FUNC_MACRO(enif_compare_monitors)
 #  define enif_hash ERL_NIF_API_FUNC_MACRO(enif_hash)
+#  define enif_whereis_pid ERL_NIF_API_FUNC_MACRO(enif_whereis_pid)
+#  define enif_whereis_port ERL_NIF_API_FUNC_MACRO(enif_whereis_port)
 
 /*
 ** ADD NEW ENTRIES HERE (before this comment)
diff --git a/erts/emulator/test/dirty_nif_SUITE.erl b/erts/emulator/test/dirty_nif_SUITE.erl
index f62f1e9dce..13806fd5c4 100644
--- a/erts/emulator/test/dirty_nif_SUITE.erl
+++ b/erts/emulator/test/dirty_nif_SUITE.erl
@@ -34,7 +34,8 @@
 	 dirty_scheduler_exit/1, dirty_call_while_terminated/1,
 	 dirty_heap_access/1, dirty_process_info/1,
 	 dirty_process_register/1, dirty_process_trace/1,
-	 code_purge/1, dirty_nif_send_traced/1]).
+	 code_purge/1, dirty_nif_send_traced/1,
+	 nif_whereis/1, nif_whereis_parallel/1, nif_whereis_proxy/1]).
 
 -define(nif_stub,nif_stub_error(?LINE)).
 
@@ -51,7 +52,9 @@ all() ->
      dirty_process_register,
      dirty_process_trace,
      code_purge,
-     dirty_nif_send_traced].
+     dirty_nif_send_traced,
+     nif_whereis,
+     nif_whereis_parallel].
 
 init_per_suite(Config) ->
     case erlang:system_info(dirty_cpu_schedulers) of
@@ -531,6 +534,137 @@ mcall(Node, Funs) ->
                       end
               end, Refs).
 
+%% Test enif_whereis_...
+%% These tests are mostly identical to their counterparts in nif_SUITE.erl,
+%% with just name and count changes in the first few lines.
+
+nif_whereis(Config) when is_list(Config) ->
+    erl_ddll:try_load(?config(data_dir, Config), echo_drv, []),
+
+    RegName = dirty_nif_whereis_test_thing,
+    undefined = erlang:whereis(RegName),
+    false = whereis_term(pid, RegName),
+
+    Mgr = self(),
+    Ref = make_ref(),
+    ProcMsg = {Ref, ?LINE},
+    PortMsg = ?MODULE_STRING " whereis hello\n",
+
+    {Pid, Mon} = spawn_monitor(?MODULE, nif_whereis_proxy, [Ref]),
+    true = register(RegName, Pid),
+    Pid = erlang:whereis(RegName),
+    Pid = whereis_term(pid, RegName),
+    false = whereis_term(port, RegName),
+    false = whereis_term(pid, [RegName]),
+
+    ok = whereis_send(pid, RegName, {forward, Mgr, ProcMsg}),
+    ok = receive ProcMsg -> ok end,
+
+    Pid ! {Ref, quit},
+    ok = receive {'DOWN', Mon, process, Pid, normal} -> ok end,
+    undefined = erlang:whereis(RegName),
+    false = whereis_term(pid, RegName),
+
+    Port = open_port({spawn, echo_drv}, [eof]),
+    true = register(RegName, Port),
+    Port = erlang:whereis(RegName),
+    Port = whereis_term(port, RegName),
+    false = whereis_term(pid, RegName),
+    false = whereis_term(port, [RegName]),
+
+    ok = whereis_send(port, RegName, PortMsg),
+    ok = receive {Port, {data, PortMsg}} -> ok end,
+
+    port_close(Port),
+    undefined = erlang:whereis(RegName),
+    false = whereis_term(port, RegName),
+    ok.
+
+nif_whereis_parallel(Config) when is_list(Config) ->
+
+    %% try to be at least a little asymetric
+    NProcs = trunc(3.5 * erlang:system_info(schedulers)),
+    NSeq = lists:seq(1, NProcs),
+    Names = [list_to_atom("dirty_nif_whereis_proc_" ++ integer_to_list(N))
+            || N <- NSeq],
+    Mgr = self(),
+    Ref = make_ref(),
+
+    NotReg = fun(Name) ->
+        erlang:whereis(Name) == undefined
+    end,
+    PidReg = fun({Name, Pid, _Mon}) ->
+        erlang:whereis(Name) == Pid andalso whereis_term(pid, Name) == Pid
+    end,
+    RecvDown = fun({_Name, Pid, Mon}) ->
+        receive {'DOWN', Mon, process, Pid, normal} -> true
+        after   1500 -> false end
+    end,
+    RecvNum = fun(N) ->
+        receive {N, Ref} -> true
+        after   1500 -> false end
+    end,
+
+    true = lists:all(NotReg, Names),
+
+    %% {Name, Pid, Mon}
+    Procs = lists:map(
+        fun(N) ->
+            Name = lists:nth(N, Names),
+            Prev = lists:nth((if N == 1 -> NProcs; true -> (N - 1) end), Names),
+            Next = lists:nth((if N == NProcs -> 1; true -> (N + 1) end), Names),
+            {Pid, Mon} = spawn_monitor(
+                ?MODULE, nif_whereis_proxy, [{N, Ref, Mgr, [Prev, Next]}]),
+            true = register(Name, Pid),
+            {Name, Pid, Mon}
+        end, NSeq),
+
+    true = lists:all(PidReg, Procs),
+
+    %% tell them all to 'fire' as fast as we can
+    [P ! {Ref, send_proc} || {_, P, _} <- Procs],
+
+    %% each gets forwarded through two processes
+    true = lists:all(RecvNum, NSeq),
+    true = lists:all(RecvNum, NSeq),
+
+    %% tell them all to 'quit' by name
+    [N ! {Ref, quit} || {N, _, _} <- Procs],
+    true = lists:all(RecvDown, Procs),
+    true = lists:all(NotReg, Names),
+    ok.
+
+%% exported to be spawned by MFA by whereis tests
+nif_whereis_proxy({N, Ref, Mgr, Targets} = Args) ->
+    receive
+        {forward, To, Data} ->
+            To ! Data,
+            nif_whereis_proxy(Args);
+        {Ref, quit} ->
+            ok;
+        {Ref, send_port} ->
+            Msg = ?MODULE_STRING " whereis " ++ integer_to_list(N) ++ "\n",
+            lists:foreach(
+                fun(T) ->
+                    ok = whereis_send(port, T, Msg)
+                end, Targets),
+            nif_whereis_proxy(Args);
+        {Ref, send_proc} ->
+            lists:foreach(
+                fun(T) ->
+                    ok = whereis_send(pid, T, {forward, Mgr, {N, Ref}})
+                end, Targets),
+            nif_whereis_proxy(Args)
+    end;
+nif_whereis_proxy(Ref) ->
+    receive
+        {forward, To, Data} ->
+            To ! Data,
+            nif_whereis_proxy(Ref);
+        {Ref, quit} ->
+            ok
+    end.
+
 %% The NIFs:
 lib_loaded() -> false.
 call_dirty_nif(_,_,_) -> ?nif_stub.
@@ -542,6 +676,8 @@ dirty_call_while_terminated_nif(_) -> ?nif_stub.
 dirty_sleeper() -> ?nif_stub.
 dirty_sleeper(_) -> ?nif_stub.
 dirty_heap_access_nif(_) -> ?nif_stub.
+whereis_term(_Type,_Name) -> ?nif_stub.
+whereis_send(_Type,_Name,_Msg) -> ?nif_stub.
 
 nif_stub_error(Line) ->
     exit({nif_not_loaded,module,?MODULE,line,Line}).
diff --git a/erts/emulator/test/dirty_nif_SUITE_data/Makefile.src b/erts/emulator/test/dirty_nif_SUITE_data/Makefile.src
index e9301753b0..4462afd815 100644
--- a/erts/emulator/test/dirty_nif_SUITE_data/Makefile.src
+++ b/erts/emulator/test/dirty_nif_SUITE_data/Makefile.src
@@ -1,6 +1,6 @@
 
 NIF_LIBS = dirty_nif_SUITE@dll@
 
-all: $(NIF_LIBS)
+all: $(NIF_LIBS) echo_drv@dll@
 
 @SHLIB_RULES@
diff --git a/erts/emulator/test/dirty_nif_SUITE_data/dirty_nif_SUITE.c b/erts/emulator/test/dirty_nif_SUITE_data/dirty_nif_SUITE.c
index caf99c952f..1ab39466db 100644
--- a/erts/emulator/test/dirty_nif_SUITE_data/dirty_nif_SUITE.c
+++ b/erts/emulator/test/dirty_nif_SUITE_data/dirty_nif_SUITE.c
@@ -25,8 +25,35 @@
 #include <unistd.h>
 #endif
 
+/*
+ * Hack to get around this function missing from the NIF API.
+ * TODO: Add this function/macro in the appropriate place, probably with
+ *       enif_make_pid() in erl_nif_api_funcs.h
+ */
+#ifndef enif_make_port
+#define enif_make_port(ENV, PORT) ((void)(ENV),(const ERL_NIF_TERM)((PORT)->port_id))
+#endif
+
+static ERL_NIF_TERM atom_badarg;
+static ERL_NIF_TERM atom_error;
+static ERL_NIF_TERM atom_false;
+static ERL_NIF_TERM atom_lookup;
+static ERL_NIF_TERM atom_ok;
+static ERL_NIF_TERM atom_pid;
+static ERL_NIF_TERM atom_port;
+static ERL_NIF_TERM atom_send;
+
 static int load(ErlNifEnv* env, void** priv_data, ERL_NIF_TERM load_info)
 {
+    atom_badarg = enif_make_atom(env, "badarg");
+    atom_error = enif_make_atom(env, "error");
+    atom_false = enif_make_atom(env,"false");
+    atom_lookup = enif_make_atom(env, "lookup");
+    atom_ok = enif_make_atom(env,"ok");
+    atom_pid = enif_make_atom(env, "pid");
+    atom_port = enif_make_atom(env, "port");
+    atom_send = enif_make_atom(env, "send");
+
     return 0;
 }
 
@@ -257,6 +284,147 @@ static ERL_NIF_TERM dirty_heap_access_nif(ErlNifEnv* env, int argc, const ERL_NI
     return res;
 }
 
+/*
+ * enif_whereis_... tests
+ * subset of the functions in nif_SUITE.c
+ */
+
+enum {
+    /* results */
+    WHEREIS_SUCCESS,
+    WHEREIS_ERROR_TYPE,
+    WHEREIS_ERROR_LOOKUP,
+    WHEREIS_ERROR_SEND,
+    /* types */
+    WHEREIS_LOOKUP_PID,     /* enif_whereis_pid() */
+    WHEREIS_LOOKUP_PORT     /* enif_whereis_port() */
+};
+
+typedef union {
+    ErlNifPid   pid;
+    ErlNifPort  port;
+} whereis_term_data_t;
+
+static int whereis_type(ERL_NIF_TERM type)
+{
+    if (enif_is_identical(type, atom_pid))
+        return WHEREIS_LOOKUP_PID;
+
+    if (enif_is_identical(type, atom_port))
+        return WHEREIS_LOOKUP_PORT;
+
+    return WHEREIS_ERROR_TYPE;
+}
+
+static int whereis_lookup_internal(
+    ErlNifEnv* env, int type, ERL_NIF_TERM name, whereis_term_data_t* out)
+{
+    if (type == WHEREIS_LOOKUP_PID)
+        return enif_whereis_pid(env, name, & out->pid)
+            ? WHEREIS_SUCCESS : WHEREIS_ERROR_LOOKUP;
+
+    if (type == WHEREIS_LOOKUP_PORT)
+        return enif_whereis_port(env, name, & out->port)
+            ? WHEREIS_SUCCESS : WHEREIS_ERROR_LOOKUP;
+
+    return WHEREIS_ERROR_TYPE;
+}
+
+static int whereis_send_internal(
+    ErlNifEnv* env, int type, whereis_term_data_t* to, ERL_NIF_TERM msg)
+{
+    if (type == WHEREIS_LOOKUP_PID)
+        return enif_send(env, & to->pid, NULL, msg)
+            ? WHEREIS_SUCCESS : WHEREIS_ERROR_SEND;
+
+    if (type == WHEREIS_LOOKUP_PORT)
+        return enif_port_command(env, & to->port, NULL, msg)
+            ? WHEREIS_SUCCESS : WHEREIS_ERROR_SEND;
+
+    return WHEREIS_ERROR_TYPE;
+}
+
+static int whereis_lookup_term(
+    ErlNifEnv* env, int type, ERL_NIF_TERM name, ERL_NIF_TERM* out)
+{
+    whereis_term_data_t res;
+    int rc = whereis_lookup_internal(env, type, name, &res);
+    if (rc == WHEREIS_SUCCESS) {
+        switch (type) {
+            case WHEREIS_LOOKUP_PID:
+                *out = enif_make_pid(env, & res.pid);
+                break;
+            case WHEREIS_LOOKUP_PORT:
+                *out = enif_make_port(env, & res.port);
+                break;
+            default:
+                rc = WHEREIS_ERROR_TYPE;
+                break;
+        }
+    }
+    return rc;
+}
+
+static ERL_NIF_TERM whereis_result_term(ErlNifEnv* env, int result)
+{
+    ERL_NIF_TERM err;
+    switch (result)
+    {
+        case WHEREIS_SUCCESS:
+            return atom_ok;
+        case WHEREIS_ERROR_LOOKUP:
+            err = atom_lookup;
+            break;
+        case WHEREIS_ERROR_SEND:
+            err = atom_send;
+            break;
+        case WHEREIS_ERROR_TYPE:
+            err = atom_badarg;
+            break;
+        default:
+            err = enif_make_int(env, -result);
+            break;
+    }
+    return enif_make_tuple2(env, atom_error, err);
+}
+
+/* whereis_term(Type, Name) -> pid() | port() | false */
+static ERL_NIF_TERM
+whereis_term(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
+{
+    ERL_NIF_TERM ret;
+    int type, rc;
+
+    if (argc != 2)  /* allow non-atom name for testing */
+        return enif_make_badarg(env);
+
+    if ((type = whereis_type(argv[0])) == WHEREIS_ERROR_TYPE)
+        return enif_make_badarg(env);
+
+    rc = whereis_lookup_term(env, type, argv[1], &ret);
+    return (rc == WHEREIS_SUCCESS) ? ret : atom_false;
+}
+
+/* whereis_send(Type, Name, Message) -> ok | {error, Reason} */
+static ERL_NIF_TERM
+whereis_send(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
+{
+    whereis_term_data_t to;
+    int type, rc;
+
+    if (argc != 3 || !enif_is_atom(env, argv[1]))
+        return enif_make_badarg(env);
+
+    if ((type = whereis_type(argv[0])) == WHEREIS_ERROR_TYPE)
+        return enif_make_badarg(env);
+
+    rc = whereis_lookup_internal(env, type, argv[1], & to);
+    if (rc == WHEREIS_SUCCESS)
+        rc = whereis_send_internal(env, type, & to, argv[2]);
+
+    return whereis_result_term(env, rc);
+}
+
 
 static ErlNifFunc nif_funcs[] =
 {
@@ -269,7 +437,9 @@ static ErlNifFunc nif_funcs[] =
     {"dirty_sleeper", 0, dirty_sleeper, ERL_NIF_DIRTY_JOB_IO_BOUND},
     {"dirty_sleeper", 1, dirty_sleeper, ERL_NIF_DIRTY_JOB_CPU_BOUND},
     {"dirty_call_while_terminated_nif", 1, dirty_call_while_terminated_nif, ERL_NIF_DIRTY_JOB_CPU_BOUND},
-    {"dirty_heap_access_nif", 1, dirty_heap_access_nif, ERL_NIF_DIRTY_JOB_CPU_BOUND}
+    {"dirty_heap_access_nif", 1, dirty_heap_access_nif, ERL_NIF_DIRTY_JOB_CPU_BOUND},
+    {"whereis_send", 3, whereis_send, ERL_NIF_DIRTY_JOB_IO_BOUND},
+    {"whereis_term", 2, whereis_term, ERL_NIF_DIRTY_JOB_CPU_BOUND}
 };
 
 ERL_NIF_INIT(dirty_nif_SUITE,nif_funcs,load,NULL,NULL,NULL)
diff --git a/erts/emulator/test/dirty_nif_SUITE_data/echo_drv.c b/erts/emulator/test/dirty_nif_SUITE_data/echo_drv.c
new file mode 100644
index 0000000000..2b3510c641
--- /dev/null
+++ b/erts/emulator/test/dirty_nif_SUITE_data/echo_drv.c
@@ -0,0 +1,62 @@
+#include <stdio.h>
+#include "erl_driver.h"
+
+static ErlDrvPort erlang_port;
+static ErlDrvData echo_start(ErlDrvPort, char *);
+static void from_erlang(ErlDrvData, char*, ErlDrvSizeT);
+static ErlDrvSSizeT echo_call(ErlDrvData drv_data, unsigned int command,
+			      char *buf, ErlDrvSizeT len,
+			      char **rbuf, ErlDrvSizeT rlen, unsigned *ret_flags);
+static ErlDrvEntry echo_driver_entry = { 
+    NULL,			/* Init */
+    echo_start,
+    NULL,			/* Stop */
+    from_erlang,
+    NULL,			/* Ready input */
+    NULL,			/* Ready output */
+    "echo_drv",
+    NULL,
+    NULL,
+    NULL,
+    NULL,
+    NULL,
+    NULL,
+    NULL,
+    echo_call,
+    NULL,
+    ERL_DRV_EXTENDED_MARKER,
+    ERL_DRV_EXTENDED_MAJOR_VERSION,
+    ERL_DRV_EXTENDED_MINOR_VERSION,
+    0,
+    NULL,
+    NULL,
+    NULL
+};
+
+DRIVER_INIT(echo_drv)
+{
+    return &echo_driver_entry;
+}
+
+static ErlDrvData
+echo_start(ErlDrvPort port, char *buf)
+{
+    return (ErlDrvData) port;
+}
+
+static void
+from_erlang(ErlDrvData data, char *buf, ErlDrvSizeT count)
+{
+    driver_output((ErlDrvPort) data, buf, count);
+}
+
+static ErlDrvSSizeT
+echo_call(ErlDrvData drv_data, unsigned int command,
+	  char *buf, ErlDrvSizeT len, char **rbuf, ErlDrvSizeT rlen,
+	  unsigned *ret_flags)
+{
+    *rbuf = buf;
+    *ret_flags |= DRIVER_CALL_KEEP_BUFFER;
+    return len;
+}
+
diff --git a/erts/emulator/test/nif_SUITE.erl b/erts/emulator/test/nif_SUITE.erl
index bcea9e3539..05c250125d 100644
--- a/erts/emulator/test/nif_SUITE.erl
+++ b/erts/emulator/test/nif_SUITE.erl
@@ -59,7 +59,9 @@
          nif_snprintf/1,
          nif_internal_hash/1,
          nif_internal_hash_salted/1,
-         nif_phash2/1
+         nif_phash2/1,
+         nif_whereis/1, nif_whereis_parallel/1,
+         nif_whereis_threaded/1, nif_whereis_proxy/1
 	]).
 
 -export([many_args_100/100]).
@@ -96,7 +98,8 @@ all() ->
      nif_snprintf,
      nif_internal_hash,
      nif_internal_hash_salted,
-     nif_phash2].
+     nif_phash2,
+     nif_whereis, nif_whereis_parallel, nif_whereis_threaded].
 
 groups() ->
     [{G, [], api_repeaters()} || G <- api_groups()]
@@ -134,6 +137,11 @@ init_per_testcase(hipe, Config) ->
 	undefined -> {skip, "HiPE is disabled"};
 	_ -> Config
     end;
+init_per_testcase(nif_whereis_threaded, Config) ->
+    case erlang:system_info(threads) of
+        true -> Config;
+        false -> {skip, "No thread support"}
+    end;
 init_per_testcase(select, Config) ->
     case os:type() of
         {win32,_} ->
@@ -2791,6 +2799,161 @@ random_pid() ->
     Processes = erlang:processes(),
     lists:nth(rand:uniform(length(Processes)), Processes).
 
+%% Test enif_whereis_...
+
+nif_whereis(Config) when is_list(Config) ->
+    ensure_lib_loaded(Config),
+
+    RegName = nif_whereis_test_thing,
+    undefined = erlang:whereis(RegName),
+    false = whereis_term(pid, RegName),
+
+    Mgr = self(),
+    Ref = make_ref(),
+    ProcMsg = {Ref, ?LINE},
+    PortMsg = ?MODULE_STRING " whereis hello\n",
+
+    {Pid, Mon} = spawn_monitor(?MODULE, nif_whereis_proxy, [Ref]),
+    true = register(RegName, Pid),
+    Pid = erlang:whereis(RegName),
+    Pid = whereis_term(pid, RegName),
+    false = whereis_term(port, RegName),
+    false = whereis_term(pid, [RegName]),
+
+    ok = whereis_send(pid, RegName, {forward, Mgr, ProcMsg}),
+    ok = receive ProcMsg -> ok end,
+
+    Pid ! {Ref, quit},
+    ok = receive {'DOWN', Mon, process, Pid, normal} -> ok end,
+    undefined = erlang:whereis(RegName),
+    false = whereis_term(pid, RegName),
+
+    Port = open_port({spawn, echo_drv}, [eof]),
+    true = register(RegName, Port),
+    Port = erlang:whereis(RegName),
+    Port = whereis_term(port, RegName),
+    false = whereis_term(pid, RegName),
+    false = whereis_term(port, [RegName]),
+
+    ok = whereis_send(port, RegName, PortMsg),
+    ok = receive {Port, {data, PortMsg}} -> ok end,
+
+    port_close(Port),
+    undefined = erlang:whereis(RegName),
+    false = whereis_term(port, RegName),
+    ok.
+
+nif_whereis_parallel(Config) when is_list(Config) ->
+    ensure_lib_loaded(Config),
+
+    %% try to be at least a little asymetric
+    NProcs = trunc(3.7 * erlang:system_info(schedulers)),
+    NSeq = lists:seq(1, NProcs),
+    Names = [list_to_atom("nif_whereis_proc_" ++ integer_to_list(N))
+            || N <- NSeq],
+    Mgr = self(),
+    Ref = make_ref(),
+
+    NotReg = fun(Name) ->
+        erlang:whereis(Name) == undefined
+    end,
+    PidReg = fun({Name, Pid, _Mon}) ->
+        erlang:whereis(Name) == Pid andalso whereis_term(pid, Name) == Pid
+    end,
+    RecvDown = fun({_Name, Pid, Mon}) ->
+        receive {'DOWN', Mon, process, Pid, normal} -> true
+        after   1500 -> false end
+    end,
+    RecvNum = fun(N) ->
+        receive {N, Ref} -> true
+        after   1500 -> false end
+    end,
+
+    true = lists:all(NotReg, Names),
+
+    %% {Name, Pid, Mon}
+    Procs = lists:map(
+        fun(N) ->
+            Name = lists:nth(N, Names),
+            Prev = lists:nth((if N == 1 -> NProcs; true -> (N - 1) end), Names),
+            Next = lists:nth((if N == NProcs -> 1; true -> (N + 1) end), Names),
+            {Pid, Mon} = spawn_monitor(
+                ?MODULE, nif_whereis_proxy, [{N, Ref, Mgr, [Prev, Next]}]),
+            true = register(Name, Pid),
+            {Name, Pid, Mon}
+        end, NSeq),
+
+    true = lists:all(PidReg, Procs),
+
+    %% tell them all to 'fire' as fast as we can
+    [P ! {Ref, send_proc} || {_, P, _} <- Procs],
+
+    %% each gets forwarded through two processes
+    true = lists:all(RecvNum, NSeq),
+    true = lists:all(RecvNum, NSeq),
+
+    %% tell them all to 'quit' by name
+    [N ! {Ref, quit} || {N, _, _} <- Procs],
+    true = lists:all(RecvDown, Procs),
+    true = lists:all(NotReg, Names),
+    ok.
+
+nif_whereis_threaded(Config) when is_list(Config) ->
+    ensure_lib_loaded(Config),
+
+    RegName = nif_whereis_test_threaded,
+    undefined = erlang:whereis(RegName),
+
+    Ref = make_ref(),
+    {Pid, Mon} = spawn_monitor(?MODULE, nif_whereis_proxy, [Ref]),
+    true = register(RegName, Pid),
+
+    {ok, ProcThr} = whereis_thd_lookup(pid, RegName),
+    {ok, Pid} = whereis_thd_result(ProcThr),
+
+    Pid ! {Ref, quit},
+    ok = receive {'DOWN', Mon, process, Pid, normal} -> ok end,
+
+    Port = open_port({spawn, echo_drv}, [eof]),
+    true = register(RegName, Port),
+
+    {ok, PortThr} = whereis_thd_lookup(port, RegName),
+    {ok, Port} = whereis_thd_result(PortThr),
+
+    port_close(Port),
+    ok.
+
+%% exported to be spawned by MFA by whereis tests
+nif_whereis_proxy({N, Ref, Mgr, Targets} = Args) ->
+    receive
+        {forward, To, Data} ->
+            To ! Data,
+            nif_whereis_proxy(Args);
+        {Ref, quit} ->
+            ok;
+        {Ref, send_port} ->
+            Msg = ?MODULE_STRING " whereis " ++ integer_to_list(N) ++ "\n",
+            lists:foreach(
+                fun(T) ->
+                    ok = whereis_send(port, T, Msg)
+                end, Targets),
+            nif_whereis_proxy(Args);
+        {Ref, send_proc} ->
+            lists:foreach(
+                fun(T) ->
+                    ok = whereis_send(pid, T, {forward, Mgr, {N, Ref}})
+                end, Targets),
+            nif_whereis_proxy(Args)
+    end;
+nif_whereis_proxy(Ref) ->
+    receive
+        {forward, To, Data} ->
+            To ! Data,
+            nif_whereis_proxy(Ref);
+        {Ref, quit} ->
+            ok
+    end.
+
 %% The NIFs:
 lib_version() -> undefined.
 call_history() -> ?nif_stub.
@@ -2866,6 +3029,12 @@ demonitor_process_nif(_,_) -> ?nif_stub.
 compare_monitors_nif(_,_) -> ?nif_stub.
 monitor_frenzy_nif(_,_,_,_) -> ?nif_stub.
 
+%% whereis
+whereis_send(_Type,_Name,_Msg) -> ?nif_stub.
+whereis_term(_Type,_Name) -> ?nif_stub.
+whereis_thd_lookup(_Type,_Name) -> ?nif_stub.
+whereis_thd_result(_Thd) -> ?nif_stub.
+
 %% maps
 is_map_nif(_) -> ?nif_stub.
 get_map_size_nif(_) -> ?nif_stub.
diff --git a/erts/emulator/test/nif_SUITE_data/nif_SUITE.c b/erts/emulator/test/nif_SUITE_data/nif_SUITE.c
index 15d31162ed..307d1c390f 100644
--- a/erts/emulator/test/nif_SUITE_data/nif_SUITE.c
+++ b/erts/emulator/test/nif_SUITE_data/nif_SUITE.c
@@ -52,6 +52,15 @@ static ErlNifMutex* dbg_trace_lock;
 #define DBG_TRACE4(FMT, A, B, C, D)
 #endif
 
+/*
+ * Hack to get around this function missing from the NIF API.
+ * TODO: Add this function/macro in the appropriate place, probably with
+ *       enif_make_pid() in erl_nif_api_funcs.h
+ */
+#ifndef enif_make_port
+#define enif_make_port(ENV, PORT) ((void)(ENV),(const ERL_NIF_TERM)((PORT)->port_id))
+#endif
+
 static int static_cntA; /* zero by default */
 static int static_cntB = NIF_SUITE_LIB_VER * 100;
 
@@ -76,6 +85,11 @@ static ERL_NIF_TERM atom_stats;
 static ERL_NIF_TERM atom_done;
 static ERL_NIF_TERM atom_stop;
 static ERL_NIF_TERM atom_null;
+static ERL_NIF_TERM atom_pid;
+static ERL_NIF_TERM atom_port;
+static ERL_NIF_TERM atom_send;
+static ERL_NIF_TERM atom_lookup;
+static ERL_NIF_TERM atom_badarg;
 
 typedef struct
 {
@@ -170,6 +184,9 @@ static ErlNifResourceTypeInit frenzy_rt_init = {
     frenzy_resource_down
 };
 
+static ErlNifResourceType* whereis_resource_type;
+static void whereis_thread_resource_dtor(ErlNifEnv* env, void* obj);
+
 static int get_pointer(ErlNifEnv* env, ERL_NIF_TERM term, void** pp)
 {
     ErlNifBinary bin;
@@ -223,6 +240,9 @@ static int load(ErlNifEnv* env, void** priv_data, ERL_NIF_TERM load_info)
 						      &frenzy_rt_init,
 						      ERL_NIF_RT_CREATE, NULL);
 
+    whereis_resource_type = enif_open_resource_type(env, NULL, "nif_SUITE.whereis",
+                            whereis_thread_resource_dtor, ERL_NIF_RT_CREATE, NULL);
+
     atom_false = enif_make_atom(env,"false");
     atom_true = enif_make_atom(env,"true");
     atom_self = enif_make_atom(env,"self");
@@ -244,6 +264,11 @@ static int load(ErlNifEnv* env, void** priv_data, ERL_NIF_TERM load_info)
     atom_done = enif_make_atom(env,"done");
     atom_stop = enif_make_atom(env,"stop");
     atom_null = enif_make_atom(env,"null");
+    atom_pid = enif_make_atom(env, "pid");
+    atom_port = enif_make_atom(env, "port");
+    atom_send = enif_make_atom(env, "send");
+    atom_lookup = enif_make_atom(env, "lookup");
+    atom_badarg = enif_make_atom(env, "badarg");
 
     *priv_data = data;
     return 0;
@@ -1161,6 +1186,237 @@ static void fill(void* dst, unsigned bytes, int seed)
     }
 }
 
+/* enif_whereis_... tests */
+
+enum {
+    /* results */
+    WHEREIS_SUCCESS,
+    WHEREIS_ERROR_TYPE,
+    WHEREIS_ERROR_LOOKUP,
+    WHEREIS_ERROR_SEND,
+    /* types */
+    WHEREIS_LOOKUP_PID,     /* enif_whereis_pid() */
+    WHEREIS_LOOKUP_PORT     /* enif_whereis_port() */
+};
+
+typedef union {
+    ErlNifPid   pid;
+    ErlNifPort  port;
+} whereis_term_data_t;
+
+/* single use, no cross-thread access/serialization */
+typedef struct {
+    ErlNifEnv* env;
+    ERL_NIF_TERM name;
+    whereis_term_data_t res;
+    ErlNifTid tid;
+    int type;
+} whereis_thread_resource_t;
+
+static whereis_thread_resource_t* whereis_thread_resource_create(void)
+{
+    whereis_thread_resource_t* rp = (whereis_thread_resource_t*)
+        enif_alloc_resource(whereis_resource_type, sizeof(*rp));
+    memset(rp, 0, sizeof(*rp));
+    rp->env = enif_alloc_env();
+
+    return rp;
+}
+
+static void whereis_thread_resource_dtor(ErlNifEnv* env, void* obj)
+{
+    whereis_thread_resource_t* rp = (whereis_thread_resource_t*) obj;
+    enif_free_env(rp->env);
+}
+
+static int whereis_type(ERL_NIF_TERM type)
+{
+    if (enif_is_identical(type, atom_pid))
+        return WHEREIS_LOOKUP_PID;
+
+    if (enif_is_identical(type, atom_port))
+        return WHEREIS_LOOKUP_PORT;
+
+    return WHEREIS_ERROR_TYPE;
+}
+
+static int whereis_lookup_internal(
+    ErlNifEnv* env, int type, ERL_NIF_TERM name, whereis_term_data_t* out)
+{
+    if (type == WHEREIS_LOOKUP_PID)
+        return enif_whereis_pid(env, name, & out->pid)
+            ? WHEREIS_SUCCESS : WHEREIS_ERROR_LOOKUP;
+
+    if (type == WHEREIS_LOOKUP_PORT)
+        return enif_whereis_port(env, name, & out->port)
+            ? WHEREIS_SUCCESS : WHEREIS_ERROR_LOOKUP;
+
+    return WHEREIS_ERROR_TYPE;
+}
+
+static int whereis_send_internal(
+    ErlNifEnv* env, int type, whereis_term_data_t* to, ERL_NIF_TERM msg)
+{
+    if (type == WHEREIS_LOOKUP_PID)
+        return enif_send(env, & to->pid, NULL, msg)
+            ? WHEREIS_SUCCESS : WHEREIS_ERROR_SEND;
+
+    if (type == WHEREIS_LOOKUP_PORT)
+        return enif_port_command(env, & to->port, NULL, msg)
+            ? WHEREIS_SUCCESS : WHEREIS_ERROR_SEND;
+
+    return WHEREIS_ERROR_TYPE;
+}
+
+static int whereis_resolved_term(
+    ErlNifEnv* env, int type, whereis_term_data_t* res, ERL_NIF_TERM* out)
+{
+    switch (type) {
+        case WHEREIS_LOOKUP_PID:
+            *out = enif_make_pid(env, & res->pid);
+            break;
+        case WHEREIS_LOOKUP_PORT:
+            *out = enif_make_port(env, & res->port);
+            break;
+        default:
+            return WHEREIS_ERROR_TYPE;
+    }
+    return WHEREIS_SUCCESS;
+}
+
+static ERL_NIF_TERM whereis_result_term(ErlNifEnv* env, int result)
+{
+    ERL_NIF_TERM err;
+    switch (result)
+    {
+        case WHEREIS_SUCCESS:
+            return atom_ok;
+        case WHEREIS_ERROR_LOOKUP:
+            err = atom_lookup;
+            break;
+        case WHEREIS_ERROR_SEND:
+            err = atom_send;
+            break;
+        case WHEREIS_ERROR_TYPE:
+            err = atom_badarg;
+            break;
+        default:
+            err = enif_make_int(env, -result);
+            break;
+    }
+    return enif_make_tuple2(env, atom_error, err);
+}
+
+static void* whereis_lookup_thread(void* arg)
+{
+    whereis_thread_resource_t* rp = (whereis_thread_resource_t*) arg;
+    int rc;
+
+    /* enif_whereis_xxx should work with allocated or null env */
+    rc = whereis_lookup_internal(
+        ((rp->type == WHEREIS_LOOKUP_PID) ? NULL : rp->env),
+        rp->type, rp->name, & rp->res);
+
+    return (((char*) NULL) + rc);
+}
+
+/* whereis_term(Type, Name) -> pid() | port() | false */
+static ERL_NIF_TERM
+whereis_term(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
+{
+    whereis_term_data_t res;
+    ERL_NIF_TERM ret;
+    int type, rc;
+
+    if (argc != 2)  /* allow non-atom name for testing */
+        return enif_make_badarg(env);
+
+    if ((type = whereis_type(argv[0])) == WHEREIS_ERROR_TYPE)
+        return enif_make_badarg(env);
+
+    rc = whereis_lookup_internal(env, type, argv[1], & res);
+    if (rc == WHEREIS_SUCCESS) {
+        rc = whereis_resolved_term(env, type, & res, & ret);
+    }
+    return (rc == WHEREIS_SUCCESS) ? ret : atom_false;
+}
+
+/* whereis_send(Type, Name, Message) -> ok | {error, Reason} */
+static ERL_NIF_TERM
+whereis_send(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
+{
+    whereis_term_data_t to;
+    int type, rc;
+
+    if (argc != 3 || !enif_is_atom(env, argv[1]))
+        return enif_make_badarg(env);
+
+    if ((type = whereis_type(argv[0])) == WHEREIS_ERROR_TYPE)
+        return enif_make_badarg(env);
+
+    rc = whereis_lookup_internal(env, type, argv[1], & to);
+    if (rc == WHEREIS_SUCCESS)
+        rc = whereis_send_internal(env, type, & to, argv[2]);
+
+    return whereis_result_term(env, rc);
+}
+
+/* whereis_thd_lookup(Type, Name) -> {ok, Resource} | {error, SysErrno} */
+static ERL_NIF_TERM
+whereis_thd_lookup(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
+{
+    whereis_thread_resource_t* rp;
+    int type, rc;
+
+    if (argc != 2 || !enif_is_atom(env, argv[1]))
+        return enif_make_badarg(env);
+
+    if ((type = whereis_type(argv[0])) == WHEREIS_ERROR_TYPE)
+        return enif_make_badarg(env);
+
+    rp = whereis_thread_resource_create();
+    rp->type = type;
+    rp->name = enif_make_copy(rp->env, argv[1]);
+
+    rc = enif_thread_create(
+        "nif_SUITE:whereis_thd", & rp->tid, whereis_lookup_thread, rp, NULL);
+
+    if (rc == 0) {
+        return enif_make_tuple2(env, atom_ok, enif_make_resource(env, rp));
+    }
+    else {
+        enif_release_resource(rp);
+        return enif_make_tuple2(env, atom_error, enif_make_int(env, rc));
+    }
+}
+
+/* whereis_thd_result(Resource) -> {ok, pid() | port()} | {error, ErrNum} */
+static ERL_NIF_TERM
+whereis_thd_result(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
+{
+    whereis_thread_resource_t* rp;
+    ERL_NIF_TERM ret;
+    char* thdret; /* so we can keep compilers happy converting to int */
+    int rc;
+
+    if (argc != 1
+    || !enif_get_resource(env, argv[0], whereis_resource_type, (void**) & rp))
+        return enif_make_badarg(env);
+
+    if ((rc = enif_thread_join(rp->tid, (void**) & thdret)) != 0)
+        return enif_make_tuple2(env, atom_error, enif_make_int(env, rc));
+    
+    rc = (int)(thdret - ((char*) NULL));
+    if (rc == WHEREIS_SUCCESS) {
+        rc = whereis_resolved_term(env, rp->type, & rp->res, & ret);
+    }
+    ret = (rc == WHEREIS_SUCCESS)
+        ? enif_make_tuple2(env, atom_ok, ret) : whereis_result_term(env, rc);
+    
+    enif_release_resource(rp);
+    return ret;
+}
+
 #define MAKE_TERM_REUSE_LEN 16
 struct make_term_info
 {
@@ -2995,7 +3251,11 @@ static ErlNifFunc nif_funcs[] =
     {"monitor_process_nif", 4, monitor_process_nif},
     {"demonitor_process_nif", 2, demonitor_process_nif},
     {"compare_monitors_nif", 2, compare_monitors_nif},
-    {"monitor_frenzy_nif", 4, monitor_frenzy_nif}
+    {"monitor_frenzy_nif", 4, monitor_frenzy_nif},
+    {"whereis_send", 3, whereis_send},
+    {"whereis_term", 2, whereis_term},
+    {"whereis_thd_lookup", 2, whereis_thd_lookup},
+    {"whereis_thd_result", 1, whereis_thd_result}
 };
 
 ERL_NIF_INIT(nif_SUITE,nif_funcs,load,NULL,upgrade,unload)