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

Add enif_whereis_pid() and enif_whereis_port() functions

OTP-14453

2 files changed, 62 insertions, 0 deletions

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)