From 12996534578771ea590efb321c0d1145b13cf9f0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=9B=D0=B5=D0=BE=D0=BD=D0=B8=D0=B4=20=D0=AE=D1=80=D1=8C?=
 =?UTF-8?q?=D0=B5=D0=B2=20=28Leonid=20Yuriev=29?= <leo@yuriev.ru>
Date: Thu, 6 Mar 2025 17:00:21 +0300
Subject: [PATCH] =?UTF-8?q?mdbx:=20=D0=B4=D0=BE=D0=B1=D0=B0=D0=B2=D0=BB?=
 =?UTF-8?q?=D0=B5=D0=BD=D0=B8=D0=B5=20`cursor=5Freset()`=20=D0=B8=20`curso?=
 =?UTF-8?q?r=5Fdrown()`.?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 src/api-cursor.c | 26 +++++++++++++-------------
 src/cursor.c     |  6 +++---
 src/cursor.h     | 16 ++++++++++++++++
 3 files changed, 32 insertions(+), 16 deletions(-)

diff --git a/src/api-cursor.c b/src/api-cursor.c
index 05c98b4b..ca6c2b18 100644
--- a/src/api-cursor.c
+++ b/src/api-cursor.c
@@ -12,8 +12,7 @@ MDBX_cursor *mdbx_cursor_create(void *context) {
   couple->outer.signature = cur_signature_ready4dispose;
   couple->outer.next = &couple->outer;
   couple->userctx = context;
-  couple->outer.top_and_flags = z_poor_mark;
-  couple->inner.cursor.top_and_flags = z_poor_mark | z_inner;
+  cursor_reset(couple);
   VALGRIND_MAKE_MEM_DEFINED(&couple->outer.backup, sizeof(couple->outer.backup));
   VALGRIND_MAKE_MEM_DEFINED(&couple->outer.tree, sizeof(couple->outer.tree));
   VALGRIND_MAKE_MEM_DEFINED(&couple->outer.clc, sizeof(couple->outer.clc));
@@ -31,13 +30,15 @@ int mdbx_cursor_reset(MDBX_cursor *mc) {
   if (unlikely(!mc))
     return LOG_IFERR(MDBX_EINVAL);
 
-  if (unlikely(mc->signature != cur_signature_ready4dispose && mc->signature != cur_signature_live))
-    return LOG_IFERR(MDBX_EBADSIGN);
+  if (likely(mc->signature == cur_signature_live)) {
+    cursor_reset((cursor_couple_t *)mc);
+    return MDBX_SUCCESS;
+  }
 
-  cursor_couple_t *couple = (cursor_couple_t *)mc;
-  couple->outer.top_and_flags = z_poor_mark;
-  couple->inner.cursor.top_and_flags = z_poor_mark | z_inner;
-  return MDBX_SUCCESS;
+  if (likely(mc->signature == cur_signature_ready4dispose))
+    return MDBX_SUCCESS;
+
+  return LOG_IFERR(MDBX_EBADSIGN);
 }
 
 int mdbx_cursor_bind(MDBX_txn *txn, MDBX_cursor *mc, MDBX_dbi dbi) {
@@ -113,7 +114,7 @@ int mdbx_cursor_unbind(MDBX_cursor *mc) {
     }
     mc->next = mc;
   }
-  be_poor(mc);
+  cursor_drown((cursor_couple_t *)mc);
   mc->signature = cur_signature_ready4dispose;
   return MDBX_SUCCESS;
 }
@@ -222,10 +223,9 @@ int mdbx_txn_release_all_cursors_ex(const MDBX_txn *txn, bool unbind, size_t *co
       ENSURE(nullptr, mc->signature == cur_signature_live && (mc->next != mc) && !mc->backup);
       txn->cursors[i] = mc->next;
       mc->next = mc;
-      if (unbind) {
-        be_poor(mc);
-        mc->signature = cur_signature_ready4dispose;
-      } else {
+      mc->signature = cur_signature_ready4dispose;
+      cursor_drown((cursor_couple_t *)mc);
+      if (!unbind) {
         mc->signature = 0;
         osal_free(mc);
       }
diff --git a/src/cursor.c b/src/cursor.c
index 1fd8cbc1..d8199748 100644
--- a/src/cursor.c
+++ b/src/cursor.c
@@ -216,7 +216,6 @@ int cursor_shadow(MDBX_cursor *cursor, MDBX_txn *nested, const size_t dbi) {
 
 MDBX_cursor *cursor_eot(MDBX_cursor *cursor, MDBX_txn *txn) {
   MDBX_cursor *const next = cursor->next;
-  cursor->next = cursor;
   const unsigned stage = cursor->signature;
   MDBX_cursor *const shadow = cursor->backup;
   ENSURE(txn->env, stage == cur_signature_live || (stage == cur_signature_wait4eot && shadow));
@@ -224,7 +223,7 @@ MDBX_cursor *cursor_eot(MDBX_cursor *cursor, MDBX_txn *txn) {
   if (shadow) {
     subcur_t *subcur = cursor->subcur;
     tASSERT(txn, txn->parent != nullptr && shadow->txn == txn->parent);
-    /* Zap: Using uninitialized memory '*mc->backup'. */
+    /* Zap: Using uninitialized memory '*subcur->backup'. */
     MDBX_SUPPRESS_GOOFY_MSVC_ANALYZER(6001);
     ENSURE(txn->env, shadow->signature == cur_signature_live);
     tASSERT(txn, subcur == shadow->subcur);
@@ -250,7 +249,8 @@ MDBX_cursor *cursor_eot(MDBX_cursor *cursor, MDBX_txn *txn) {
     osal_free(shadow);
   } else {
     ENSURE(cursor->txn->env, stage == cur_signature_live);
-    be_poor(cursor);
+    cursor_drown((cursor_couple_t *)cursor);
+    cursor->next = cursor;
     cursor->signature = cur_signature_ready4dispose /* Cursor may be reused */;
   }
   return next;
diff --git a/src/cursor.h b/src/cursor.h
index e53e91db..c8854faf 100644
--- a/src/cursor.h
+++ b/src/cursor.h
@@ -355,3 +355,19 @@ MDBX_MAYBE_UNUSED static inline void cursor_inner_refresh(const MDBX_cursor *mc,
 }
 
 MDBX_MAYBE_UNUSED MDBX_INTERNAL bool cursor_is_tracked(const MDBX_cursor *mc);
+
+static inline void cursor_reset(cursor_couple_t *couple) {
+  couple->outer.top_and_flags = z_fresh_mark;
+  couple->inner.cursor.top_and_flags = z_fresh_mark | z_inner;
+}
+
+static inline void cursor_drown(cursor_couple_t *couple) {
+  couple->outer.top_and_flags = z_poor_mark;
+  couple->inner.cursor.top_and_flags = z_poor_mark | z_inner;
+  couple->outer.txn = nullptr;
+  couple->inner.cursor.txn = nullptr;
+  couple->outer.tree = nullptr;
+  /* сохраняем clc-указатель, так он используется для вычисления dbi в mdbx_cursor_renew(). */
+  couple->outer.dbi_state = nullptr;
+  couple->inner.cursor.dbi_state = nullptr;
+}