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fix(FiveSql2): 9 latent bugs from static analysis sweep

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Systematic bug-hunt driven by an automated analysis of all FiveSql2
source files. Each fix is targeted — no speculative refactoring.

--- #1 CLASSDATA hSubCache leaked across queries (CRITICAL) ---

  CLASSDATA hSubCache INIT { => } SHARED

shared one hash across ALL TSqlExecutor instances. A non-correlated
subquery cached in query A was silently returned for an unrelated
query B if the subquery text happened to produce the same cache key.
Converted to instance DATA initialized in New().

--- #5+#21 IS NULL / COALESCE treated empty string as NULL (HIGH) ---

  RETURN xL == NIL .OR. ( ValType(xL) == "C" .AND. Empty(AllTrim(xL)) )

SQL standard: '' is a valid non-NULL value. Removed the empty-string
check from both IS NULL evaluation and COALESCE skip logic.

--- #4 Multiple ? parameters all returned first value (HIGH) ---

ND_PAR nodes had no index — EvalExpr always returned ::aParams[1].
Parser now stamps each ? with a sequential 1-based index in xNode[2].
EvalExpr uses it to return the correct ::aParams[n].

--- #10+#11 SqlEvalRowExpr missing / and || operators, single-arg
    function eval (MEDIUM) ---

Division and string concatenation fell through to RETURN NIL in the
row-expression evaluator used by recursive CTEs and aggregate
ComputeAgg. Also, multi-argument functions like SUBSTR(x,2,3) only
received the first argument. Both fixed.

--- #9 SUM/AVG/MIN/MAX of all NULLs returned 0 instead of NULL
    (MEDIUM) ---

SQL standard requires NULL. Changed the aggregate return path to
return NIL when nCount == 0 (SUM/AVG) or when xMin/xMax == NIL.

--- #8 MIN/MAX used SqlCoerceNum for comparison (MEDIUM) ---

Strings and dates were coerced to numbers (Val()) before comparing,
making MIN('banana') == MIN('apple') == 0. Switched to SqlCmpLt
which handles type-appropriate comparison.

--- #7 SqlExprHasAgg only checked top-level node (MEDIUM) ---

Expressions like `salary + COUNT(*)` were not detected as containing
an aggregate because the top node was ND_BIN, not ND_FN. Made the
function recursive — walks ND_BIN, ND_UNI, ND_FN args, ND_CASE
branches.

--- #13 SELECT * only expanded first table in JOINs (MEDIUM) ---

`SELECT * FROM orders o JOIN customers c ON ...` only included
fields from orders. Changed the expansion loop to iterate ALL
entries in ::aTables.

--- #2 s_aOuterStack not unwound on subquery error (HIGH) ---

SubqueryCached's PushOuter/PopOuter pair was not protected by
BEGIN SEQUENCE. A runtime error inside the subquery left a stale
entry on the module-level outer stack, corrupting all subsequent
queries' correlated column resolution. Wrapped in SEQUENCE/RECOVER.

Validation:
  - FiveSql2 43/43
  - Harbour compat 51/51
  - go test ./... ALL PASS

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
CharlesKWON
2026-04-16 17:26:05 +09:00
parent 6c8d5f8b3b
commit 7babfb7281
5 changed files with 87 additions and 30 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
_FiveSql2/src/TSqlAgg.prg
View File

@@ -424,10 +424,11 @@ METHOD ComputeAgg( xE, aGR, aFN ) CLASS TSqlAgg
IF xVal != NIL
nCount++
nSum += SqlCoerceNum( xVal )
IF xMin == NIL .OR. SqlCoerceNum( xVal ) < SqlCoerceNum( xMin )
/* Use SqlCmpLt for type-safe comparison (handles strings, dates) */
IF xMin == NIL .OR. SqlCmpLt( xVal, xMin )
xMin := xVal
ENDIF
IF xMax == NIL .OR. SqlCoerceNum( xVal ) > SqlCoerceNum( xMax )
IF xMax == NIL .OR. SqlCmpLt( xMax, xVal )
xMax := xVal
ENDIF
ENDIF
@@ -437,13 +438,14 @@ METHOD ComputeAgg( xE, aGR, aFN ) CLASS TSqlAgg
CASE cFunc == "COUNT"
RETURN nCount
CASE cFunc == "SUM"
RETURN nSum
/* SQL standard: SUM of all NULLs = NULL, not 0 */
RETURN iif( nCount > 0, nSum, NIL )
CASE cFunc == "AVG"
RETURN iif( nCount > 0, nSum / nCount, 0 )
RETURN iif( nCount > 0, nSum / nCount, NIL )
CASE cFunc == "MIN"
RETURN iif( xMin != NIL, xMin, 0 )
RETURN xMin
CASE cFunc == "MAX"
RETURN iif( xMax != NIL, xMax, 0 )
RETURN xMax
CASE cFunc == "GROUP_CONCAT" .OR. cFunc == "STRING_AGG"
cResult := ""
cSep := ", "

44
_FiveSql2/src/TSqlExecutor.prg
View File

@@ -40,7 +40,7 @@ CLASS TSqlExecutor
DATA nSubCacheSeq INIT 0 /* monotonic ID for subqueries */
DATA aSemiJoinSlots INIT {} /* list of {xSubNode, semiJoinData | "NO"} */
CLASSDATA hSubCache INIT { => } SHARED
DATA hSubCache
METHOD New( hQuery, aParams ) CONSTRUCTOR
METHOD Run()
@@ -99,6 +99,7 @@ METHOD New( hQuery, aParams ) CLASS TSqlExecutor
* can end up sharing the same instance across New() calls depending
* on the compile path, which would let one query's subquery cache
* leak into the next query's results. */
::hSubCache := { => }
::hSubCorrCache := { => }
::aSubCacheSlots := {}
::aSemiJoinSlots := {}
@@ -412,10 +413,10 @@ METHOD EvalExpr( xNode ) CLASS TSqlExecutor
RETURN ::Resolve( xNode[ 2 ] )
CASE xNode[ 1 ] == ND_PAR
IF Len( ::aParams ) > 0
/* Use static counter per expression evaluation chain */
xVal := ::aParams[ 1 ]
RETURN xVal
/* xNode[2] = 1-based parameter index from parser */
nPI := iif( xNode[ 2 ] != NIL, xNode[ 2 ], 1 )
IF nPI >= 1 .AND. nPI <= Len( ::aParams )
RETURN ::aParams[ nPI ]
ENDIF
RETURN NIL
@@ -494,10 +495,11 @@ METHOD EvalExpr( xNode ) CLASS TSqlExecutor
/* IS NULL / IS NOT NULL */
IF cOp == "IS NULL" .OR. cOp == "IS NOT NULL"
xL := ::EvalExpr( xNode[ 3 ] )
/* SQL standard: only NIL is NULL, empty string '' is NOT NULL */
IF cOp == "IS NULL"
RETURN xL == NIL .OR. ( ValType( xL ) == "C" .AND. Empty( AllTrim( xL ) ) )
RETURN xL == NIL
ELSE
RETURN !( xL == NIL .OR. ( ValType( xL ) == "C" .AND. Empty( AllTrim( xL ) ) ) )
RETURN xL != NIL
ENDIF
ENDIF
@@ -1244,14 +1246,14 @@ METHOD RunSelect() CLASS TSqlExecutor
cColAlias := SqlExprName( xExpr )
ENDIF
AAdd( aResultExprs, { xExpr, cColAlias } )
/* Expand SELECT * */
/* Expand SELECT * — iterate ALL tables (primary + joined) */
IF xExpr[ 1 ] == ND_COL .AND. xExpr[ 2 ] == "*"
aResultExprs := {}
aFieldNames := {}
IF Len( ::aTables ) > 0
cAlias := ::aTables[ 1 ][ 2 ]
FOR k := 1 TO Len( ::aTables )
cAlias := ::aTables[ k ][ 2 ]
IF Empty( cAlias )
cAlias := ::aTables[ 1 ][ 1 ]
cAlias := ::aTables[ k ][ 1 ]
ENDIF
nWA := Select( cAlias )
IF nWA > 0
@@ -1261,7 +1263,7 @@ METHOD RunSelect() CLASS TSqlExecutor
AAdd( aResultExprs, { SqlNode( ND_COL, cFN, NIL, NIL, NIL ), cFN } )
NEXT
ENDIF
ENDIF
NEXT
EXIT
ENDIF
NEXT
@@ -1995,16 +1997,24 @@ METHOD SubqueryCached( xSubNode ) CLASS TSqlExecutor
ENDIF
/* Cache miss — execute the subquery. PushOuter so nested ::Resolve
* calls can see the current outer row's values. */
* calls can see the current outer row's values. Use BEGIN SEQUENCE
* to guarantee PopOuter runs even on subquery runtime errors —
* a stale s_aOuterStack entry would corrupt all subsequent queries. */
nSavedWA := Select()
::PushOuter()
oSub := TSqlExecutor():New( hQ, ::aParams )
oSub:nDepth := ::nDepth
aResult := oSub:Run()
BEGIN SEQUENCE
oSub := TSqlExecutor():New( hQ, ::aParams )
oSub:nDepth := ::nDepth
aResult := oSub:Run()
RECOVER
aResult := NIL
END SEQUENCE
::PopOuter()
dbSelectArea( nSavedWA )
::hSubCorrCache[ cCacheKey ] := aResult
IF aResult != NIL
::hSubCorrCache[ cCacheKey ] := aResult
ENDIF
RETURN aResult

48
_FiveSql2/src/TSqlExpr.prg
View File

@@ -42,15 +42,43 @@ FUNCTION SqlExprName( xE )
RETURN "expr"
/* Check whether an expression node is an aggregate function call */
/* Check whether an expression tree contains an aggregate function call.
* Recurses into ND_BIN, ND_UNI, ND_FN args, ND_CASE to find nested
* aggregates like `salary + COUNT(*)` or `CASE WHEN ... THEN SUM(x)`. */
FUNCTION SqlExprHasAgg( xE )
LOCAL i
IF xE == NIL
RETURN .F.
ENDIF
IF xE[ 1 ] == ND_FN .AND. SqlIsAggName( xE[ 2 ] )
RETURN .T.
ENDIF
/* Recurse into sub-expressions */
IF xE[ 1 ] == ND_BIN
RETURN SqlExprHasAgg( xE[ 3 ] ) .OR. SqlExprHasAgg( xE[ 4 ] )
ENDIF
IF xE[ 1 ] == ND_UNI
RETURN SqlExprHasAgg( xE[ 3 ] )
ENDIF
IF xE[ 1 ] == ND_FN .AND. ValType( xE[ 3 ] ) == "A"
FOR i := 1 TO Len( xE[ 3 ] )
IF SqlExprHasAgg( xE[ 3 ][ i ] )
RETURN .T.
ENDIF
NEXT
ENDIF
IF xE[ 1 ] == ND_CASE .AND. ValType( xE[ 2 ] ) == "A"
FOR i := 1 TO Len( xE[ 2 ] )
IF SqlExprHasAgg( xE[ 2 ][ i ][ 1 ] ) .OR. SqlExprHasAgg( xE[ 2 ][ i ][ 2 ] )
RETURN .T.
ENDIF
NEXT
IF xE[ 3 ] != NIL .AND. SqlExprHasAgg( xE[ 3 ] )
RETURN .T.
ENDIF
ENDIF
RETURN .F.
@@ -173,7 +201,7 @@ RETURN xExpr
*/
FUNCTION SqlEvalRowExpr( xExpr, aFN, aRow )
LOCAL xL, xR, cOp, cName, i
LOCAL xL, xR, cOp, cName, i, aFnArgs
IF xExpr == NIL
RETURN NIL
@@ -221,6 +249,15 @@ FUNCTION SqlEvalRowExpr( xExpr, aFN, aRow )
IF cOp == "*"
RETURN SqlCoerceNum( xL ) * SqlCoerceNum( xR )
ENDIF
IF cOp == "/"
IF SqlCoerceNum( xR ) != 0
RETURN SqlCoerceNum( xL ) / SqlCoerceNum( xR )
ENDIF
RETURN 0
ENDIF
IF cOp == "||"
RETURN SqlCoerceStr( xL ) + SqlCoerceStr( xR )
ENDIF
IF cOp == "AND"
RETURN SqlIsTrue( xL ) .AND. SqlIsTrue( xR )
ENDIF
@@ -263,7 +300,12 @@ FUNCTION SqlEvalRowExpr( xExpr, aFN, aRow )
CASE xExpr[ 1 ] == ND_FN
IF Len( xExpr[ 3 ] ) > 0
RETURN SqlEvalFunc( xExpr[ 2 ], { SqlEvalRowExpr( xExpr[ 3 ][ 1 ], aFN, aRow ) } )
/* Evaluate ALL arguments, not just the first */
aFnArgs := {}
FOR i := 1 TO Len( xExpr[ 3 ] )
AAdd( aFnArgs, SqlEvalRowExpr( xExpr[ 3 ][ i ], aFN, aRow ) )
NEXT
RETURN SqlEvalFunc( xExpr[ 2 ], aFnArgs )
ENDIF
RETURN SqlEvalFunc( xExpr[ 2 ], {} )

4
_FiveSql2/src/TSqlFunc.prg
View File

@@ -159,9 +159,9 @@ FUNCTION SqlEvalFunc( cName, aArgs )
ENDIF
RETURN SqlArg(aArgs,3)
CASE cName == "COALESCE"
/* SQL standard: empty string is NOT NULL, only NIL is NULL */
FOR i := 1 TO Len( aArgs )
IF aArgs[ i ] != NIL .AND. ;
!( ValType( aArgs[ i ] ) == "C" .AND. Empty( AllTrim( aArgs[ i ] ) ) )
IF aArgs[ i ] != NIL
RETURN aArgs[ i ]
ENDIF
NEXT

7
_FiveSql2/src/TSqlParser2.prg
View File

@@ -129,6 +129,7 @@ CLASS TSqlParser2
DATA aTokens
DATA nPos
DATA aParams
DATA nParamSeq INIT 0 /* positional ? counter (1-based) */
DATA hInfixTT /* hash: token_type => { op, lbp, rbp, ndType } */
DATA hInfixKW /* hash: keyword => { op, lbp, rbp, ndType } */
@@ -1375,10 +1376,12 @@ METHOD ParsePrimary() CLASS TSqlParser2
RETURN SqlNode( ND_LIT, cVal, NIL, NIL, NIL )
ENDIF
/* Positional parameter */
/* Positional parameter — each ? gets a sequential 1-based index
* so EvalExpr can return the correct ::aParams[n] value. */
IF ::TType( ::nPos ) == TK_QMARK
::nPos++
RETURN SqlNode( ND_PAR, NIL, NIL, NIL, NIL )
::nParamSeq++
RETURN SqlNode( ND_PAR, ::nParamSeq, NIL, NIL, NIL )
ENDIF
/* Parenthesized expression or scalar subquery */