kernel: validate {CHANGED_,SET_,}METHODS_OPERATION args

This ensures we don't return garbage resp. don't trigger an
assertion (in debug builds) when e.g. passing an argument list
with 7 or more entries to ApplicableMethod.

src/opers.c

@@ -3446,8 +3446,9 @@ Obj FuncMETHODS_OPERATION (
     Obj                 meth;
 
     RequireOperation(oper);
-    RequireNonnegativeSmallInt("METHODS_OPERATION", narg);
-    n = INT_INTOBJ( narg );
+    n = IS_INTOBJ(narg) ? INT_INTOBJ(narg) : -1;
+    if (n < 0 || n >= 7)
+        RequireArgument("METHODS_OPERATION", narg, "narg", "must be an integer between 0 and 6");
     meth = MethsOper( oper, (UInt)n );
 #ifdef HPCGAP
     MEMBAR_READ();
@@ -3471,13 +3472,14 @@ Obj FuncCHANGED_METHODS_OPERATION (
     Int                 i;
 
     RequireOperation(oper);
-    RequireNonnegativeSmallInt("CHANGED_METHODS_OPERATION", narg);
+    n = IS_INTOBJ(narg) ? INT_INTOBJ(narg) : -1;
+    if (n < 0 || n >= 7)
+        RequireArgument("CHANGED_METHODS_OPERATION", narg, "narg", "must be an integer between 0 and 6");
 #ifdef HPCGAP
     if (!PreThreadCreation) {
         ErrorQuit("Methods may only be changed before thread creation",0L,0L);
     }
 #endif
-    n = INT_INTOBJ( narg );
     cacheBag = CacheOper( oper, (UInt) n );
     cache = ADDR_OBJ( cacheBag );
     for ( i = 1;  i < SIZE_OBJ(cacheBag) / sizeof(Obj);  i++ ) {
@@ -3500,8 +3502,9 @@ Obj FuncSET_METHODS_OPERATION (
     Int                 n;
 
     RequireOperation(oper);
-    RequireNonnegativeSmallInt("SET_METHODS_OPERATION", narg);
-    n = INT_INTOBJ( narg );
+    n = IS_INTOBJ(narg) ? INT_INTOBJ(narg) : -1;
+    if (n < 0 || n >= 7)
+        RequireArgument("SET_METHODS_OPERATION", narg, "narg", "must be an integer between 0 and 6");
 #ifdef HPCGAP
     MEMBAR_WRITE();
 #endif

src/opers.h

@@ -42,10 +42,10 @@ typedef struct {
     Obj tester;
 
     // method list of an operation
-    Obj methods[8];
+    Obj methods[7];
 
     // cache of an operation
-    Obj cache[8];
+    Obj cache[7];
 
     // small integer encoding a set of bit flags with information about the
     // operation, see OperExtras below
@@ -177,13 +177,13 @@ static inline void SET_TESTR_FILT(Obj oper, Obj x)
 */
 static inline Obj METHS_OPER(Obj oper, Int i)
 {
-    GAP_ASSERT(0 <= i && i < 8);
+    GAP_ASSERT(0 <= i && i < 7);
     return CONST_OPER(oper)->methods[i];
 }
 
 static inline void SET_METHS_OPER(Obj oper, Int i, Obj x)
 {
-    GAP_ASSERT(0 <= i && i < 8);
+    GAP_ASSERT(0 <= i && i < 7);
     OPER(oper)->methods[i] = x;
 }
 
@@ -194,13 +194,13 @@ static inline void SET_METHS_OPER(Obj oper, Int i, Obj x)
 */
 static inline Obj CACHE_OPER(Obj oper, Int i)
 {
-    GAP_ASSERT(0 <= i && i < 8);
+    GAP_ASSERT(0 <= i && i < 7);
     return CONST_OPER(oper)->cache[i];
 }
 
 static inline void SET_CACHE_OPER(Obj oper, Int i, Obj x)
 {
-    GAP_ASSERT(0 <= i && i < 8);
+    GAP_ASSERT(0 <= i && i < 7);
     OPER(oper)->cache[i] = x;
 }
 

tst/testinstall/kernel/opers.tst

@@ -214,28 +214,41 @@ Error, operation already installed
 gap> METHODS_OPERATION(fail,1);
 Error, METHODS_OPERATION: <oper> must be an operation (not the value 'fail')
 gap> METHODS_OPERATION(Size,-1);
-Error, METHODS_OPERATION: <narg> must be a non-negative small integer (not the\
- integer -1)
+Error, METHODS_OPERATION: <narg> must be an integer between 0 and 6 (not the i\
+nteger -1)
 gap> METHODS_OPERATION(Size,0);
 [  ]
+gap> METHODS_OPERATION(Size,6);
+[  ]
+gap> METHODS_OPERATION(Size,7);
+Error, METHODS_OPERATION: <narg> must be an integer between 0 and 6 (not the i\
+nteger 7)
 
 # note: CHANGED_METHODS_OPERATION is not usable on HPC-GAP
 gap> CHANGED_METHODS_OPERATION(fail,1);
 Error, CHANGED_METHODS_OPERATION: <oper> must be an operation (not the value '\
 fail')
 gap> CHANGED_METHODS_OPERATION(Size,-1);
-Error, CHANGED_METHODS_OPERATION: <narg> must be a non-negative small integer \
-(not the integer -1)
+Error, CHANGED_METHODS_OPERATION: <narg> must be an integer between 0 and 6 (n\
+ot the integer -1)
 gap> if not IsHPCGAP then CHANGED_METHODS_OPERATION(Size,0); fi;
+gap> if not IsHPCGAP then CHANGED_METHODS_OPERATION(Size,6); fi;
+gap> CHANGED_METHODS_OPERATION(Size,7);
+Error, CHANGED_METHODS_OPERATION: <narg> must be an integer between 0 and 6 (n\
+ot the integer 7)
 
 #
 gap> SET_METHODS_OPERATION (fail,1,[]);
 Error, SET_METHODS_OPERATION: <oper> must be an operation (not the value 'fail\
 ')
 gap> SET_METHODS_OPERATION (Size,-1,[]);
-Error, SET_METHODS_OPERATION: <narg> must be a non-negative small integer (not\
- the integer -1)
+Error, SET_METHODS_OPERATION: <narg> must be an integer between 0 and 6 (not t\
+he integer -1)
 gap> SET_METHODS_OPERATION (Size,0,[]);
+gap> SET_METHODS_OPERATION (Size,6,[]);
+gap> SET_METHODS_OPERATION (Size,7,[]);
+Error, SET_METHODS_OPERATION: <narg> must be an integer between 0 and 6 (not t\
+he integer 7)
 
 #
 gap> f:=SETTER_FUNCTION("foobar", IsPGroup);;