From 79efde2d8503e5055ef9e8afa5d8d63208710b1f Mon Sep 17 00:00:00 2001
From: Sverker Eriksson <sverker@erlang.org>
Date: Wed, 16 Dec 2015 20:03:32 +0100
Subject: erts: Make copy_literals more fail safe

* Same process must do enable-disable.
* System process will force it and never get 'aborted'
---
 erts/emulator/beam/beam_bif_load.c        |  28 +++++++++++++++++-----------
 erts/emulator/beam/global.h               |   1 +
 erts/preloaded/ebin/erts_code_purger.beam | Bin 8996 -> 8832 bytes
 erts/preloaded/src/erts_code_purger.erl   |  12 +++++-------
 4 files changed, 23 insertions(+), 18 deletions(-)

(limited to 'erts')

diff --git a/erts/emulator/beam/beam_bif_load.c b/erts/emulator/beam/beam_bif_load.c
index 39a5bff04c..892b2d16c2 100644
--- a/erts/emulator/beam/beam_bif_load.c
+++ b/erts/emulator/beam/beam_bif_load.c
@@ -1013,7 +1013,7 @@ any_heap_refs(Eterm* start, Eterm* end, char* mod_start, Uint mod_size)
 static void copy_literals_commit(void*);
 #endif
 
-copy_literals_t erts_clrange = {NULL, 0};
+copy_literals_t erts_clrange = {NULL, 0, THE_NON_VALUE};
 
 /* copy literals
  *
@@ -1033,7 +1033,6 @@ copy_literals_t erts_clrange = {NULL, 0};
 
 BIF_RETTYPE erts_internal_copy_literals_2(BIF_ALIST_2)
 {
-    Module* modp;
     ErtsCodeIndex code_ix;
     Eterm res = am_true;
 
@@ -1048,21 +1047,28 @@ BIF_RETTYPE erts_internal_copy_literals_2(BIF_ALIST_2)
 
     code_ix = erts_active_code_ix();
 
-    if ((modp = erts_get_module(BIF_ARG_1, code_ix)) == NULL || !modp->old.code_hdr) {
-        res = am_false;
-        goto done;
-    }
-
     if (BIF_ARG_2 == am_true) {
-        if (erts_clrange.ptr != NULL) {
+        Module* modp = erts_get_module(BIF_ARG_1, code_ix);
+        if (!modp || !modp->old.code_hdr) {
+            res = am_false;
+            goto done;
+        }
+        if (erts_clrange.ptr != NULL
+            && !(BIF_P->static_flags & ERTS_STC_FLG_SYSTEM_PROC)) {
             res = am_aborted;
             goto done;
-       }
-        erts_clrange.ptr = (Eterm*) modp->old.code_hdr->literals_start;
-        erts_clrange.sz  = (Eterm*) modp->old.code_hdr->literals_end - erts_clrange.ptr;
+        }
+        erts_clrange.ptr = modp->old.code_hdr->literals_start;
+        erts_clrange.sz  = modp->old.code_hdr->literals_end - erts_clrange.ptr;
+        erts_clrange.pid = BIF_P->common.id;
     } else if (BIF_ARG_2 == am_false) {
+        if (erts_clrange.pid != BIF_P->common.id) {
+            res = am_false;
+            goto done;
+        }
         erts_clrange.ptr = NULL;
         erts_clrange.sz  = 0;
+        erts_clrange.pid = THE_NON_VALUE;
     }
 
 #ifdef ERTS_SMP
diff --git a/erts/emulator/beam/global.h b/erts/emulator/beam/global.h
index 0bf5988244..bbf684d49d 100644
--- a/erts/emulator/beam/global.h
+++ b/erts/emulator/beam/global.h
@@ -990,6 +990,7 @@ Eterm erts_check_process_code(Process *c_p, Eterm module, int allow_gc, int *red
 typedef struct {
     Eterm *ptr;
     Uint   sz;
+    Eterm pid;
 } copy_literals_t;
 
 extern copy_literals_t erts_clrange;
diff --git a/erts/preloaded/ebin/erts_code_purger.beam b/erts/preloaded/ebin/erts_code_purger.beam
index 74001fc799..c5aec6bb25 100644
Binary files a/erts/preloaded/ebin/erts_code_purger.beam and b/erts/preloaded/ebin/erts_code_purger.beam differ
diff --git a/erts/preloaded/src/erts_code_purger.erl b/erts/preloaded/src/erts_code_purger.erl
index c7fe3ce22f..791ef72f13 100644
--- a/erts/preloaded/src/erts_code_purger.erl
+++ b/erts/preloaded/src/erts_code_purger.erl
@@ -63,11 +63,10 @@ purge(Mod) when is_atom(Mod) ->
 
 
 do_purge(Mod) ->
-    case erlang:check_old_code(Mod) of
+    case erts_internal:copy_literals(Mod, true) of
         false ->
             {false, false};
         true ->
-            true = erts_internal:copy_literals(Mod, true),
             DidKill = check_proc_code(erlang:processes(), Mod, true),
             true = erts_internal:copy_literals(Mod, false),
 	    WasPurged = erts_internal:purge_module(Mod),
@@ -89,17 +88,16 @@ soft_purge(Mod) ->
 
 
 do_soft_purge(Mod) ->
-    case erlang:check_old_code(Mod) of
+    case erts_internal:copy_literals(Mod, true) of
 	false ->
 	    true;
 	true ->
-            true = erts_internal:copy_literals(Mod, true),
-	    case check_proc_code(erlang:processes(), Mod, false) of
+	    DoPurge = check_proc_code(erlang:processes(), Mod, false),
+	    true = erts_internal:copy_literals(Mod, false),
+	    case DoPurge of
 		false ->
-                    true = erts_internal:copy_literals(Mod, false),
 		    false;
 		true ->
-                    true = erts_internal:copy_literals(Mod, false),
 		    erts_internal:purge_module(Mod),
 		    true
 	    end
-- 
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