From 805dbc8ad6e0cd272b52996695607a0bd4d27a28 Mon Sep 17 00:00:00 2001
From: dimgigov <gigov@gigov.org>
Date: Wed, 6 May 2026 02:46:24 +0300
Subject: [PATCH] =?UTF-8?q?fix:=20comprehensive=20bug=20audit=20=E2=80=94?=
 =?UTF-8?q?=2015=20critical/high/medium=20fixes?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Critical fixes:
- B-Tree splitChild: fixed out-of-bounds on child.children.len (mid+1..len → mid+1..<len)
- Wire protocol: all deserializeValue cases now properly assign to result
- Wire protocol: fkBool/fkInt8 now increment pos after reading
- MVCC: write-write conflict now detected for completed transactions
- MVCC: commit only marks visible versions as deleted (not concurrent uncommitted)
- Lexer: buffer overrun on backslash escape at end of input — added bounds check
- Bulgarian/Russian stemmers: fixed UTF-8 byte offsets for Cyrillic suffixes (2 bytes per char)

High fixes:
- WebSocket: added missing std/tables import
- Raft: added randomize() call for election timeouts
- MemTable.get: binary search O(log n) instead of linear scan O(n)

Medium fixes:
- Zerocopy: string length now written as 4-byte int32 (was single byte)
- Raft appendEntries: guard against nextIdx underflow
- Columnar: null tracking with nulls seq on ColumnPtr
- Removed dead code in lexer readIdent (redundant true/false checks)
- Updated Bulgarian stemming test to match corrected byte offsets

All 214 tests pass across 48 suites with 0 failures.
---
 src/barabadb/core/columnar.nim      | 13 +++++---
 src/barabadb/core/mvcc.nim          | 17 +++++++---
 src/barabadb/core/raft.nim          |  6 ++--
 src/barabadb/fts/multilang.nim      | 48 ++++++++++++++++-------------
 src/barabadb/protocol/websocket.nim |  1 +
 src/barabadb/protocol/wire.nim      | 30 ++++++++++--------
 src/barabadb/protocol/zerocopy.nim  |  3 +-
 src/barabadb/query/lexer.nim        |  5 +--
 src/barabadb/storage/btree.nim      |  2 +-
 src/barabadb/storage/lsm.nim        | 17 ++++++++--
 tests/test_all.nim                  |  2 +-
 11 files changed, 89 insertions(+), 55 deletions(-)

diff --git a/src/barabadb/core/columnar.nim b/src/barabadb/core/columnar.nim
index 5c2e6c0..4b149e2 100644
--- a/src/barabadb/core/columnar.nim
+++ b/src/barabadb/core/columnar.nim
@@ -19,6 +19,7 @@ type
 
   ColumnPtr* = ref object
     typ*: ColumnType
+    nulls*: seq[bool]
     case kind: ColumnType
     of ctInt64: intData: seq[int64]
     of ctFloat64: floatData: seq[float64]
@@ -34,35 +35,39 @@ proc newColumnBatch*(): ColumnBatch =
   ColumnBatch(columns: initTable[string, ColumnPtr](), rowCount: 0)
 
 proc addInt64Col*(batch: var ColumnBatch, name: string): var ColumnPtr =
-  var col = ColumnPtr(typ: ctInt64, kind: ctInt64, intData: @[])
+  var col = ColumnPtr(typ: ctInt64, kind: ctInt64, nulls: @[], intData: @[])
   batch.columns[name] = col
   return batch.columns[name]
 
 proc addFloat64Col*(batch: var ColumnBatch, name: string): var ColumnPtr =
-  var col = ColumnPtr(typ: ctFloat64, kind: ctFloat64, floatData: @[])
+  var col = ColumnPtr(typ: ctFloat64, kind: ctFloat64, nulls: @[], floatData: @[])
   batch.columns[name] = col
   return batch.columns[name]
 
 proc addStringCol*(batch: var ColumnBatch, name: string): var ColumnPtr =
-  var col = ColumnPtr(typ: ctString, kind: ctString, strData: @[])
+  var col = ColumnPtr(typ: ctString, kind: ctString, nulls: @[], strData: @[])
   batch.columns[name] = col
   return batch.columns[name]
 
 proc addBoolCol*(batch: var ColumnBatch, name: string): var ColumnPtr =
-  var col = ColumnPtr(typ: ctBool, kind: ctBool, boolData: @[])
+  var col = ColumnPtr(typ: ctBool, kind: ctBool, nulls: @[], boolData: @[])
   batch.columns[name] = col
   return batch.columns[name]
 
 proc appendInt64*(col: var ColumnPtr, val: int64, isNull: bool = false) =
+  col.nulls.add(isNull)
   col.intData.add(val)
 
 proc appendFloat64*(col: var ColumnPtr, val: float64, isNull: bool = false) =
+  col.nulls.add(isNull)
   col.floatData.add(val)
 
 proc appendString*(col: var ColumnPtr, val: string, isNull: bool = false) =
+  col.nulls.add(isNull)
   col.strData.add(val)
 
 proc appendBool*(col: var ColumnPtr, val: bool, isNull: bool = false) =
+  col.nulls.add(isNull)
   col.boolData.add(val)
 
 proc rowCount*(batch: ColumnBatch): int =
diff --git a/src/barabadb/core/mvcc.nim b/src/barabadb/core/mvcc.nim
index a866eb1..feab5aa 100644
--- a/src/barabadb/core/mvcc.nim
+++ b/src/barabadb/core/mvcc.nim
@@ -170,9 +170,12 @@ proc write*(tm: TxnManager, txn: Transaction, key: string, value: seq[byte]): bo
                 if tm.activeTxns[creator].state == tsCommitted:
                   release(tm.lock)
                   return false  # write-write conflict
-              elif creator notin tm.activeTxns:
-                # Already completed and visible
-                discard
+              else:
+                # Creator already completed — check if it committed
+                # If not in activeTxns, it either committed or aborted
+                # We treat completed-but-visible as a conflict
+                release(tm.lock)
+                return false  # write-write conflict with completed txn
 
   let lsn = tm.allocLsn()
   let version = VersionedRecord(
@@ -201,9 +204,15 @@ proc commit*(tm: TxnManager, txn: Transaction): bool =
       tm.globalVersions[key] = @[]
 
     # Mark previous versions as deleted by this txn
+    # Only mark versions that were visible to this transaction
     for i in 0..<tm.globalVersions[key].len:
       if tm.globalVersions[key][i].xmax == TxnId(0):
-        tm.globalVersions[key][i].xmax = txn.id
+        let creator = tm.globalVersions[key][i].xmin
+        # Only mark as deleted if the version was visible (committed before our snapshot)
+        if creator != txn.id:
+          if uint64(creator) <= uint64(txn.snapshotMaxTxn) and
+             creator notin txn.snapshotTxns:
+            tm.globalVersions[key][i].xmax = txn.id
 
     tm.globalVersions[key].add(version)
 
diff --git a/src/barabadb/core/raft.nim b/src/barabadb/core/raft.nim
index 06a0643..4ad0a91 100644
--- a/src/barabadb/core/raft.nim
+++ b/src/barabadb/core/raft.nim
@@ -64,6 +64,7 @@ type
     messageQueue*: Deque[RaftMessage]
 
 proc newRaftNode*(id: string, peers: seq[string]): RaftNode =
+  randomize()
   RaftNode(
     id: id,
     state: rsFollower,
@@ -211,8 +212,9 @@ proc appendEntries*(node: RaftNode, peerId: string): RaftMessage =
     prevTerm = node.log[prevIdx - 1].term
 
   var entries: seq[LogEntry] = @[]
-  for i in int(nextIdx - 1)..<node.log.len:
-    entries.add(node.log[i])
+  if nextIdx > 0:
+    for i in int(nextIdx - 1)..<node.log.len:
+      entries.add(node.log[i])
 
   return RaftMessage(
     kind: rmkAppendEntries,
diff --git a/src/barabadb/fts/multilang.nim b/src/barabadb/fts/multilang.nim
index 7dfd14d..951d70a 100644
--- a/src/barabadb/fts/multilang.nim
+++ b/src/barabadb/fts/multilang.nim
@@ -81,17 +81,19 @@ proc stemEnglish*(word: string): string =
 
 proc stemBulgarian*(word: string): string =
   if word.len <= 3: return word
-  # Bulgarian suffixes
-  if word.endsWith("ища"): return word[0..^4]
-  if word.endsWith("ище"): return word[0..^4]
-  if word.endsWith("ция"): return word[0..^4]
-  if word.endsWith("ние"): return word[0..^4]
-  if word.endsWith("ост"): return word[0..^4]
-  if word.endsWith("ство"): return word[0..^5]
-  if word.endsWith("ски"): return word[0..^4]
-  if word.endsWith("ски"): return word[0..^4]
-  if word.endsWith("на"): return word[0..^3]
-  if word.endsWith("та"): return word[0..^3]
+  # Bulgarian suffixes (all Cyrillic chars are 2 bytes)
+  # 3 Cyrillic chars = 6 bytes -> ^7
+  if word.endsWith("ища"): return word[0..^7]
+  if word.endsWith("ище"): return word[0..^7]
+  if word.endsWith("ция"): return word[0..^7]
+  if word.endsWith("ние"): return word[0..^7]
+  if word.endsWith("ост"): return word[0..^7]
+  if word.endsWith("ски"): return word[0..^7]
+  # 4 Cyrillic chars = 8 bytes -> ^9
+  if word.endsWith("ство"): return word[0..^9]
+  # 2 Cyrillic chars = 4 bytes -> ^5
+  if word.endsWith("на"): return word[0..^5]
+  if word.endsWith("та"): return word[0..^5]
   return word
 
 proc stemGerman*(word: string): string =
@@ -124,17 +126,19 @@ proc stemFrench*(word: string): string =
 
 proc stemRussian*(word: string): string =
   if word.len <= 3: return word
-  # Russian suffixes
-  if word.endsWith("ость"): return word[0..^5]
-  if word.endsWith("ение"): return word[0..^5]
-  if word.endsWith("ание"): return word[0..^5]
-  if word.endsWith("тель"): return word[0..^5]
-  if word.endsWith("ский"): return word[0..^5]
-  if word.endsWith("ция"): return word[0..^4]
-  if word.endsWith("ние"): return word[0..^4]
-  if word.endsWith("ать"): return word[0..^4]
-  if word.endsWith("ить"): return word[0..^4]
-  if word.endsWith("ыть"): return word[0..^4]
+  # Russian suffixes (all Cyrillic chars are 2 bytes)
+  # 4 Cyrillic chars = 8 bytes -> ^9
+  if word.endsWith("ость"): return word[0..^9]
+  if word.endsWith("ение"): return word[0..^9]
+  if word.endsWith("ание"): return word[0..^9]
+  if word.endsWith("тель"): return word[0..^9]
+  if word.endsWith("ский"): return word[0..^9]
+  # 3 Cyrillic chars = 6 bytes -> ^7
+  if word.endsWith("ция"): return word[0..^7]
+  if word.endsWith("ние"): return word[0..^7]
+  if word.endsWith("ать"): return word[0..^7]
+  if word.endsWith("ить"): return word[0..^7]
+  if word.endsWith("ыть"): return word[0..^7]
   return word
 
 proc getLanguageConfig*(lang: Language): LanguageConfig =
diff --git a/src/barabadb/protocol/websocket.nim b/src/barabadb/protocol/websocket.nim
index 766db89..ccc6fa7 100644
--- a/src/barabadb/protocol/websocket.nim
+++ b/src/barabadb/protocol/websocket.nim
@@ -5,6 +5,7 @@ import std/strutils
 import std/base64
 import std/sha1
 import std/hashes
+import std/tables
 
 const
   WS_FIN* = 0x80'u8
diff --git a/src/barabadb/protocol/wire.nim b/src/barabadb/protocol/wire.nim
index e5fe56f..418b803 100644
--- a/src/barabadb/protocol/wire.nim
+++ b/src/barabadb/protocol/wire.nim
@@ -180,44 +180,48 @@ proc deserializeValue*(buf: openArray[byte], pos: var int): WireValue =
   let kind = FieldKind(buf[pos])
   inc pos
   case kind
-  of fkNull: WireValue(kind: fkNull)
-  of fkBool: WireValue(kind: fkBool, boolVal: buf[pos] != 0)
-  of fkInt8: WireValue(kind: fkInt8, int8Val: cast[int8](buf[pos]))
+  of fkNull: result = WireValue(kind: fkNull)
+  of fkBool:
+    result = WireValue(kind: fkBool, boolVal: buf[pos] != 0)
+    inc pos
+  of fkInt8:
+    result = WireValue(kind: fkInt8, int8Val: cast[int8](buf[pos]))
+    inc pos
   of fkInt16:
     var val: int16
     var bytes: array[2, byte]
     for i in 0..1: bytes[i] = buf[pos + i]
     bigEndian16(addr val, unsafeAddr bytes)
     pos += 2
-    WireValue(kind: fkInt16, int16Val: val)
+    result = WireValue(kind: fkInt16, int16Val: val)
   of fkInt32:
-    WireValue(kind: fkInt32, int32Val: int32(readUint32(buf, pos)))
+    result = WireValue(kind: fkInt32, int32Val: int32(readUint32(buf, pos)))
   of fkInt64:
-    WireValue(kind: fkInt64, int64Val: int64(readUint64(buf, pos)))
+    result = WireValue(kind: fkInt64, int64Val: int64(readUint64(buf, pos)))
   of fkFloat32:
     var fl: float32
     var bytes: array[4, byte]
     for i in 0..3: bytes[i] = buf[pos + i]
     copyMem(addr fl, unsafeAddr bytes, 4)
     pos += 4
-    WireValue(kind: fkFloat32, float32Val: fl)
+    result = WireValue(kind: fkFloat32, float32Val: fl)
   of fkFloat64:
     var fl: float64
     var bytes: array[8, byte]
     for i in 0..7: bytes[i] = buf[pos + i]
     copyMem(addr fl, unsafeAddr bytes, 8)
     pos += 8
-    WireValue(kind: fkFloat64, float64Val: fl)
+    result = WireValue(kind: fkFloat64, float64Val: fl)
   of fkString:
-    WireValue(kind: fkString, strVal: readString(buf, pos))
+    result = WireValue(kind: fkString, strVal: readString(buf, pos))
   of fkBytes:
-    WireValue(kind: fkBytes, bytesVal: readBytes(buf, pos))
+    result = WireValue(kind: fkBytes, bytesVal: readBytes(buf, pos))
   of fkArray:
     let count = int(readUint32(buf, pos))
     var arr: seq[WireValue] = @[]
     for i in 0..<count:
       arr.add(deserializeValue(buf, pos))
-    WireValue(kind: fkArray, arrayVal: arr)
+    result = WireValue(kind: fkArray, arrayVal: arr)
   of fkObject:
     let count = int(readUint32(buf, pos))
     var obj: seq[(string, WireValue)] = @[]
@@ -225,7 +229,7 @@ proc deserializeValue*(buf: openArray[byte], pos: var int): WireValue =
       let name = readString(buf, pos)
       let val = deserializeValue(buf, pos)
       obj.add((name, val))
-    WireValue(kind: fkObject, objVal: obj)
+    result = WireValue(kind: fkObject, objVal: obj)
   of fkVector:
     let count = int(readUint32(buf, pos))
     var vec: seq[float32] = @[]
@@ -236,7 +240,7 @@ proc deserializeValue*(buf: openArray[byte], pos: var int): WireValue =
       copyMem(addr fl, unsafeAddr bytes, 4)
       pos += 4
       vec.add(fl)
-    WireValue(kind: fkVector, vecVal: vec)
+    result = WireValue(kind: fkVector, vecVal: vec)
 
 proc serializeMessage*(msg: WireMessage): seq[byte] =
   result = @[]
diff --git a/src/barabadb/protocol/zerocopy.nim b/src/barabadb/protocol/zerocopy.nim
index 5abfaf6..269190f 100644
--- a/src/barabadb/protocol/zerocopy.nim
+++ b/src/barabadb/protocol/zerocopy.nim
@@ -176,7 +176,8 @@ proc encodeRecord*(buf: var ZeroBuf, schema: ZcSchema,
         var v: int64 = 0
         bigEndian64(addr buf.data[field.offset], unsafeAddr v)
     of ztString:
-      buf.data[field.offset] = byte(value.len)
+      var len32 = int32(value.len)
+      bigEndian32(addr buf.data[field.offset], unsafeAddr len32)
       if value.len > 0:
         copyMem(addr buf.data[field.offset + 4], unsafeAddr value[0], value.len)
     else:
diff --git a/src/barabadb/query/lexer.nim b/src/barabadb/query/lexer.nim
index e7bc68c..3d53bac 100644
--- a/src/barabadb/query/lexer.nim
+++ b/src/barabadb/query/lexer.nim
@@ -260,6 +260,7 @@ proc readString(l: var Lexer, quote: char): string =
   while l.pos < l.input.len and l.input[l.pos] != quote:
     if l.input[l.pos] == '\\':
       discard l.advance()
+      if l.pos >= l.input.len: break
       case l.input[l.pos]
       of 'n': result.add('\n')
       of 't': result.add('\t')
@@ -295,10 +296,6 @@ proc readIdent(l: var Lexer, startLine, startCol: int): Token =
   let lowerIdent = ident.toLower()
   if lowerIdent in keywords:
     Token(kind: keywords[lowerIdent], value: ident, line: startLine, col: startCol)
-  elif lowerIdent == "true":
-    Token(kind: tkBoolLit, value: "true", line: startLine, col: startCol)
-  elif lowerIdent == "false":
-    Token(kind: tkBoolLit, value: "false", line: startLine, col: startCol)
   else:
     Token(kind: tkIdent, value: ident, line: startLine, col: startCol)
 
diff --git a/src/barabadb/storage/btree.nim b/src/barabadb/storage/btree.nim
index fa7005b..c1f0530 100644
--- a/src/barabadb/storage/btree.nim
+++ b/src/barabadb/storage/btree.nim
@@ -48,7 +48,7 @@ proc splitChild[K, V](parent: BTreeNode[K, V], index: int, order: int) =
       newNode.values.add(child.values[j])
 
   if not child.isLeaf:
-    for j in mid+1..child.children.len:
+    for j in mid+1..<child.children.len:
       newNode.children.add(child.children[j])
     child.children.setLen(mid + 1)
 
diff --git a/src/barabadb/storage/lsm.nim b/src/barabadb/storage/lsm.nim
index 684b4ea..a94ec5b 100644
--- a/src/barabadb/storage/lsm.nim
+++ b/src/barabadb/storage/lsm.nim
@@ -62,9 +62,20 @@ proc put*(mt: var MemTable, key: string, value: seq[byte], timestamp: uint64, de
   return true
 
 proc get*(mt: MemTable, key: string): (bool, Entry) =
-  for entry in mt.entries:
-    if entry.key == key:
-      return (true, entry)
+  if mt.entries.len == 0:
+    return (false, Entry())
+  # Binary search since entries are kept sorted by key
+  var lo = 0
+  var hi = mt.entries.len - 1
+  while lo <= hi:
+    let mid = (lo + hi) div 2
+    let cmp = cmp(mt.entries[mid].key, key)
+    if cmp == 0:
+      return (true, mt.entries[mid])
+    elif cmp < 0:
+      lo = mid + 1
+    else:
+      hi = mid - 1
   return (false, Entry())
 
 proc scan*(mt: MemTable, startKey, endKey: string): seq[Entry] =
diff --git a/tests/test_all.nim b/tests/test_all.nim
index 86b9536..1c6ef3e 100644
--- a/tests/test_all.nim
+++ b/tests/test_all.nim
@@ -1489,7 +1489,7 @@ suite "Multi-Language FTS":
     check mlang.stemEnglish("programming") == "programm"
 
   test "Bulgarian stemming":
-    check mlang.stemBulgarian("красота") == "красот"
+    check mlang.stemBulgarian("красота") == "красо"
 
 suite "Zero-Copy Serialization":
   test "Write and read int32":