From 3fe6f3c0caecec522c7e14353eda6bbb86c9e8d6 Mon Sep 17 00:00:00 2001
From: Sverker Eriksson <sverker@erlang.org>
Date: Fri, 3 Feb 2017 15:22:48 +0100
Subject: erts: Add deallocation veto for magic destructors

A magic destructor can return 0 and thereby take control
and prolong the lifetime of a magic binary.
---
 erts/emulator/beam/beam_load.c      |  5 +++--
 erts/emulator/beam/binary.c         |  6 ++++--
 erts/emulator/beam/dist.c           |  4 +++-
 erts/emulator/beam/dist.h           |  2 +-
 erts/emulator/beam/erl_bif_binary.c | 15 ++++++++-------
 erts/emulator/beam/erl_bif_re.c     |  3 ++-
 erts/emulator/beam/erl_binary.h     | 16 ++++++++++------
 erts/emulator/beam/erl_db_util.c    |  5 +++--
 erts/emulator/beam/erl_db_util.h    |  2 +-
 erts/emulator/beam/erl_map.c        |  3 ++-
 erts/emulator/beam/erl_nif.c        |  3 ++-
 erts/emulator/beam/erl_ptab.c       |  6 ++++--
 erts/emulator/beam/erl_unicode.c    |  3 ++-
 erts/emulator/beam/external.c       |  6 ++++--
 erts/emulator/beam/global.h         |  2 +-
 erts/emulator/hipe/hipe_load.c      |  3 ++-
 16 files changed, 52 insertions(+), 32 deletions(-)

diff --git a/erts/emulator/beam/beam_load.c b/erts/emulator/beam/beam_load.c
index 309465bcd3..119c004f1f 100644
--- a/erts/emulator/beam/beam_load.c
+++ b/erts/emulator/beam/beam_load.c
@@ -481,7 +481,7 @@ typedef struct LoaderState {
 static void free_loader_state(Binary* magic);
 static ErlHeapFragment* new_literal_fragment(Uint size);
 static void free_literal_fragment(ErlHeapFragment*);
-static void loader_state_dtor(Binary* magic);
+static int loader_state_dtor(Binary* magic);
 #ifdef HIPE
 static Eterm stub_insert_new_code(Process *c_p, ErtsProcLocks c_p_locks,
 				  Eterm group_leader, Eterm module,
@@ -1012,7 +1012,7 @@ static void free_literal_fragment(ErlHeapFragment* bp)
 /*
  * This destructor function can safely be called multiple times.
  */
-static void
+static int
 loader_state_dtor(Binary* magic)
 {
     LoaderState* stp = ERTS_MAGIC_BIN_DATA(magic);
@@ -1097,6 +1097,7 @@ loader_state_dtor(Binary* magic)
      */
 
     ASSERT(stp->genop_blocks == 0);
+    return 1;
 }
 
 #ifdef HIPE
diff --git a/erts/emulator/beam/binary.c b/erts/emulator/beam/binary.c
index 071a356260..9894992b70 100644
--- a/erts/emulator/beam/binary.c
+++ b/erts/emulator/beam/binary.c
@@ -355,9 +355,10 @@ typedef struct {
     Uint bitoffs;
 } ErtsB2LState;
 
-static void b2l_state_destructor(Binary *mbp)
+static int b2l_state_destructor(Binary *mbp)
 {
     ASSERT(ERTS_MAGIC_BIN_DESTRUCTOR(mbp) == b2l_state_destructor);
+    return 1;
 }
 
 static BIF_RETTYPE
@@ -729,12 +730,13 @@ list_to_binary_engine(ErtsL2BState *sp)
     }
 }
 
-static void
+static int
 l2b_state_destructor(Binary *mbp)
 {
     ErtsL2BState *sp = ERTS_MAGIC_BIN_DATA(mbp); 
     ASSERT(ERTS_MAGIC_BIN_DESTRUCTOR(mbp) == l2b_state_destructor);
     DESTROY_SAVED_ESTACK(&sp->buf.iolist.estack);
+    return 1;
 }
 
 static ERTS_INLINE Eterm
diff --git a/erts/emulator/beam/dist.c b/erts/emulator/beam/dist.c
index 990edb274e..9e8f853279 100644
--- a/erts/emulator/beam/dist.c
+++ b/erts/emulator/beam/dist.c
@@ -713,7 +713,7 @@ static void clear_dist_entry(DistEntry *dep)
     }
 }
 
-void erts_dsend_context_dtor(Binary* ctx_bin)
+int erts_dsend_context_dtor(Binary* ctx_bin)
 {
     ErtsSendContext* ctx = ERTS_MAGIC_BIN_DATA(ctx_bin);
     switch (ctx->dss.phase) {
@@ -730,6 +730,8 @@ void erts_dsend_context_dtor(Binary* ctx_bin)
     }
     if (ctx->dep_to_deref)
 	erts_deref_dist_entry(ctx->dep_to_deref);
+
+    return 1;
 }
 
 Eterm erts_dsend_export_trap_context(Process* p, ErtsSendContext* ctx)
diff --git a/erts/emulator/beam/dist.h b/erts/emulator/beam/dist.h
index e82b416286..8799e54057 100644
--- a/erts/emulator/beam/dist.h
+++ b/erts/emulator/beam/dist.h
@@ -375,7 +375,7 @@ extern int erts_dsig_send_monitor(ErtsDSigData *, Eterm, Eterm, Eterm);
 extern int erts_dsig_send_m_exit(ErtsDSigData *, Eterm, Eterm, Eterm, Eterm);
 
 extern int erts_dsig_send(ErtsDSigData *dsdp, struct erts_dsig_send_context* ctx);
-extern void erts_dsend_context_dtor(Binary*);
+extern int erts_dsend_context_dtor(Binary*);
 extern Eterm erts_dsend_export_trap_context(Process* p, ErtsSendContext* ctx);
 
 extern int erts_dist_command(Port *prt, int reds);
diff --git a/erts/emulator/beam/erl_bif_binary.c b/erts/emulator/beam/erl_bif_binary.c
index 6e10980b6b..24debedce2 100644
--- a/erts/emulator/beam/erl_bif_binary.c
+++ b/erts/emulator/beam/erl_bif_binary.c
@@ -239,13 +239,13 @@ static void dump_ac_node(ACNode *node, int indent, int ch);
 /*
  * Callback for the magic binary
  */
-static void cleanup_my_data_ac(Binary *bp)
+static int cleanup_my_data_ac(Binary *bp)
 {
-    return;
+    return 1;
 }
-static void cleanup_my_data_bm(Binary *bp)
+static int cleanup_my_data_bm(Binary *bp)
 {
-    return;
+    return 1;
 }
 
 /*
@@ -2066,7 +2066,7 @@ static int do_search_backward(CommonData *cd, Uint *posp, Uint *redsp)
     }
 }
 
-static void cleanup_common_data(Binary *bp)
+static int cleanup_common_data(Binary *bp)
 {
     int i;
     CommonData *cd;
@@ -2083,7 +2083,7 @@ static void cleanup_common_data(Binary *bp)
 	    break;
 	}
     }
-    return;
+    return 1;
 }
 
 static BIF_RETTYPE do_longest_common(Process *p, Eterm list, int direction)
@@ -2563,7 +2563,7 @@ typedef struct {
 
 #define BINARY_COPY_LOOP_FACTOR 100
 
-static void cleanup_copy_bin_state(Binary *bp)
+static int cleanup_copy_bin_state(Binary *bp)
 {
     CopyBinState *cbs = (CopyBinState *) ERTS_MAGIC_BIN_DATA(bp);
     if (cbs->result != NULL) {
@@ -2583,6 +2583,7 @@ static void cleanup_copy_bin_state(Binary *bp)
 	break;
     }
     cbs->source_type =  BC_TYPE_EMPTY;
+    return 1;
 }
 
 /*
diff --git a/erts/emulator/beam/erl_bif_re.c b/erts/emulator/beam/erl_bif_re.c
index ff7746ce1d..391fee5753 100644
--- a/erts/emulator/beam/erl_bif_re.c
+++ b/erts/emulator/beam/erl_bif_re.c
@@ -600,10 +600,11 @@ static void cleanup_restart_context(RestartContext *rc)
     }
 }
 
-static void cleanup_restart_context_bin(Binary *bp)
+static int cleanup_restart_context_bin(Binary *bp)
 {
     RestartContext *rc = ERTS_MAGIC_BIN_DATA(bp);
     cleanup_restart_context(rc);
+    return 1;
 }
 
 /*
diff --git a/erts/emulator/beam/erl_binary.h b/erts/emulator/beam/erl_binary.h
index fdc5efea98..52efa06816 100644
--- a/erts/emulator/beam/erl_binary.h
+++ b/erts/emulator/beam/erl_binary.h
@@ -189,10 +189,10 @@ ERTS_GLB_INLINE Binary *erts_bin_realloc_fnf(Binary *bp, Uint size);
 ERTS_GLB_INLINE Binary *erts_bin_realloc(Binary *bp, Uint size);
 ERTS_GLB_INLINE void erts_bin_free(Binary *bp);
 ERTS_GLB_INLINE Binary *erts_create_magic_binary_x(Uint size,
-                                                  void (*destructor)(Binary *),
+                                                  int (*destructor)(Binary *),
                                                   int unaligned);
 ERTS_GLB_INLINE Binary *erts_create_magic_binary(Uint size,
-						 void (*destructor)(Binary *));
+						 int (*destructor)(Binary *));
 
 #if ERTS_GLB_INLINE_INCL_FUNC_DEF
 
@@ -320,8 +320,12 @@ erts_bin_realloc(Binary *bp, Uint size)
 ERTS_GLB_INLINE void
 erts_bin_free(Binary *bp)
 {
-    if (bp->flags & BIN_FLAG_MAGIC)
-	ERTS_MAGIC_BIN_DESTRUCTOR(bp)(bp);
+    if (bp->flags & BIN_FLAG_MAGIC) {
+	if (!ERTS_MAGIC_BIN_DESTRUCTOR(bp)(bp)) {
+            /* Destructor took control of the deallocation */
+            return;
+        }
+    }
     if (bp->flags & BIN_FLAG_DRV)
 	erts_free(ERTS_ALC_T_DRV_BINARY, (void *) bp);
     else
@@ -329,7 +333,7 @@ erts_bin_free(Binary *bp)
 }
 
 ERTS_GLB_INLINE Binary *
-erts_create_magic_binary_x(Uint size, void (*destructor)(Binary *),
+erts_create_magic_binary_x(Uint size, int (*destructor)(Binary *),
                            int unaligned)
 {
     Uint bsize = unaligned ? ERTS_MAGIC_BIN_UNALIGNED_SIZE(size)
@@ -348,7 +352,7 @@ erts_create_magic_binary_x(Uint size, void (*destructor)(Binary *),
 }
 
 ERTS_GLB_INLINE Binary *
-erts_create_magic_binary(Uint size, void (*destructor)(Binary *))
+erts_create_magic_binary(Uint size, int (*destructor)(Binary *))
 {
     return erts_create_magic_binary_x(size, destructor, 0);
 }
diff --git a/erts/emulator/beam/erl_db_util.c b/erts/emulator/beam/erl_db_util.c
index 4e987d5bee..991d63a18b 100644
--- a/erts/emulator/beam/erl_db_util.c
+++ b/erts/emulator/beam/erl_db_util.c
@@ -1702,17 +1702,18 @@ error: /* Here is were we land when compilation failed. */
 /*
 ** Free a match program (in a binary)
 */
-void erts_db_match_prog_destructor(Binary *bprog)
+int erts_db_match_prog_destructor(Binary *bprog)
 {
     MatchProg *prog;
     if (bprog == NULL)
-	return;
+	return 1;
     prog = Binary2MatchProg(bprog);
     if (prog->term_save != NULL) {
 	free_message_buffer(prog->term_save); 
     }
     if (prog->saved_program_buf != NULL)
 	free_message_buffer(prog->saved_program_buf);
+    return 1;
 }
 
 void
diff --git a/erts/emulator/beam/erl_db_util.h b/erts/emulator/beam/erl_db_util.h
index 49e5f6b4cf..3e29fdcbcf 100644
--- a/erts/emulator/beam/erl_db_util.h
+++ b/erts/emulator/beam/erl_db_util.h
@@ -355,7 +355,7 @@ Eterm db_add_counter(Eterm** hpp, Wterm counter, Eterm incr);
 Eterm db_match_set_lint(Process *p, Eterm matchexpr, Uint flags);
 Binary *db_match_set_compile(Process *p, Eterm matchexpr, 
 			     Uint flags);
-void erts_db_match_prog_destructor(Binary *);
+int erts_db_match_prog_destructor(Binary *);
 
 typedef struct match_prog {
     ErlHeapFragment *term_save; /* Only if needed, a list of message 
diff --git a/erts/emulator/beam/erl_map.c b/erts/emulator/beam/erl_map.c
index 979a0040b0..3015158b24 100644
--- a/erts/emulator/beam/erl_map.c
+++ b/erts/emulator/beam/erl_map.c
@@ -1188,12 +1188,13 @@ typedef struct HashmapMergeContext_ {
 #endif
 } HashmapMergeContext;
 
-static void hashmap_merge_ctx_destructor(Binary* ctx_bin)
+static int hashmap_merge_ctx_destructor(Binary* ctx_bin)
 {
     HashmapMergeContext* ctx = (HashmapMergeContext*) ERTS_MAGIC_BIN_DATA(ctx_bin);
     ASSERT(ERTS_MAGIC_BIN_DESTRUCTOR(ctx_bin) == hashmap_merge_ctx_destructor);
 
     PSTACK_DESTROY_SAVED(&ctx->pstack);
+    return 1;
 }
 
 BIF_RETTYPE maps_merge_trap_1(BIF_ALIST_1) {
diff --git a/erts/emulator/beam/erl_nif.c b/erts/emulator/beam/erl_nif.c
index 85fa53a886..fbe94708a5 100644
--- a/erts/emulator/beam/erl_nif.c
+++ b/erts/emulator/beam/erl_nif.c
@@ -2109,7 +2109,7 @@ static void rollback_opened_resource_types(void)
 }
 
 
-static void nif_resource_dtor(Binary* bin)
+static int nif_resource_dtor(Binary* bin)
 {
     ErlNifResource* resource = (ErlNifResource*) ERTS_MAGIC_BIN_UNALIGNED_DATA(bin);
     ErlNifResourceType* type = resource->type;
@@ -2128,6 +2128,7 @@ static void nif_resource_dtor(Binary* bin)
 	steal_resource_type(type);
 	erts_free(ERTS_ALC_T_NIF, type);
     }
+    return 1;
 }
 
 void erts_resource_stop(ErlNifResource* resource, ErlNifEvent e,
diff --git a/erts/emulator/beam/erl_ptab.c b/erts/emulator/beam/erl_ptab.c
index 22830a19c4..578ae14b9f 100644
--- a/erts/emulator/beam/erl_ptab.c
+++ b/erts/emulator/beam/erl_ptab.c
@@ -733,7 +733,7 @@ erts_ptab_delete_element(ErtsPTab *ptab,
  * erts_ptab_list() implements BIFs listing the content of the table,
  * e.g. erlang:processes/0.
  */
-static void cleanup_ptab_list_bif_data(Binary *bp);
+static int cleanup_ptab_list_bif_data(Binary *bp);
 static int ptab_list_bif_engine(Process *c_p, Eterm *res_accp, Binary *mbp);
 
 
@@ -787,7 +787,7 @@ erts_ptab_list(Process *c_p, ErtsPTab *ptab)
     return ret_val;
 }
 
-static void
+static int
 cleanup_ptab_list_bif_data(Binary *bp)
 {
     ErtsPTabListBifData *ptlbdp = ERTS_MAGIC_BIN_DATA(bp);
@@ -875,6 +875,8 @@ cleanup_ptab_list_bif_data(Binary *bp)
 
     ERTS_PTAB_LIST_DBG_TRACE(ptlbdp->debug.caller, return);
     ERTS_PTAB_LIST_DBG_CLEANUP(ptlbdp);
+
+    return 1;
 }
 
 static int
diff --git a/erts/emulator/beam/erl_unicode.c b/erts/emulator/beam/erl_unicode.c
index bd5e1482fb..3167ca5eef 100644
--- a/erts/emulator/beam/erl_unicode.c
+++ b/erts/emulator/beam/erl_unicode.c
@@ -123,10 +123,11 @@ static void cleanup_restart_context(RestartContext *rc)
     }
 }
 
-static void cleanup_restart_context_bin(Binary *bp)
+static int cleanup_restart_context_bin(Binary *bp)
 {
     RestartContext *rc = ERTS_MAGIC_BIN_DATA(bp);
     cleanup_restart_context(rc);
+    return 1;
 }
 
 static RestartContext *get_rc_from_bin(Eterm bin)
diff --git a/erts/emulator/beam/external.c b/erts/emulator/beam/external.c
index 10e452fa25..cb3486fde2 100644
--- a/erts/emulator/beam/external.c
+++ b/erts/emulator/beam/external.c
@@ -1387,12 +1387,13 @@ static void b2t_destroy_context(B2TContext* context)
     }
 }
 
-static void b2t_context_destructor(Binary *context_bin)
+static int b2t_context_destructor(Binary *context_bin)
 {
     B2TContext* ctx = (B2TContext*) ERTS_MAGIC_BIN_DATA(context_bin);
     ASSERT(ERTS_MAGIC_BIN_DESTRUCTOR(context_bin) == b2t_context_destructor);
 
     b2t_destroy_context(ctx);
+    return 1;
 }
 
 static BIF_RETTYPE binary_to_term_trap_1(BIF_ALIST_1)
@@ -1797,7 +1798,7 @@ erts_term_to_binary(Process* p, Eterm Term, int level, Uint flags) {
 #endif
 #define TERM_TO_BINARY_MEMCPY_FACTOR 8
 
-static void ttb_context_destructor(Binary *context_bin)
+static int ttb_context_destructor(Binary *context_bin)
 {
     TTBContext *context = ERTS_MAGIC_BIN_DATA(context_bin);
     if (context->alive) {
@@ -1831,6 +1832,7 @@ static void ttb_context_destructor(Binary *context_bin)
 	    break;
 	}
     }
+    return 1;
 }
 
 static Eterm erts_term_to_binary_int(Process* p, Eterm Term, int level, Uint flags, 
diff --git a/erts/emulator/beam/global.h b/erts/emulator/beam/global.h
index 2158f54a49..91e5bbbd98 100644
--- a/erts/emulator/beam/global.h
+++ b/erts/emulator/beam/global.h
@@ -274,7 +274,7 @@ typedef struct binary {
 typedef struct {
     ERTS_INTERNAL_BINARY_FIELDS
     SWord orig_size;
-    void (*destructor)(Binary *);
+    int (*destructor)(Binary *);
     union {
         struct {
             ERTS_BINARY_STRUCT_ALIGNMENT
diff --git a/erts/emulator/hipe/hipe_load.c b/erts/emulator/hipe/hipe_load.c
index 2998ed87a2..87c5004d2b 100644
--- a/erts/emulator/hipe/hipe_load.c
+++ b/erts/emulator/hipe/hipe_load.c
@@ -61,7 +61,7 @@ void hipe_free_loader_state(HipeLoaderState *stp)
     stp->module = NIL;
 }
 
-static void
+static int
 hipe_loader_state_dtor(Binary* magic)
 {
     HipeLoaderState* stp = ERTS_MAGIC_BIN_DATA(magic);
@@ -69,6 +69,7 @@ hipe_loader_state_dtor(Binary* magic)
     ASSERT(ERTS_MAGIC_BIN_DESTRUCTOR(magic) == hipe_loader_state_dtor);
 
     hipe_free_loader_state(stp);
+    return 1;
 }
 
 Binary *hipe_alloc_loader_state(Eterm module)
-- 
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