Fix off-by-one error in CopyListEntries

The length of the list may be changed if we add new members to the list to the end of list, or unbind the final element.
gap-system · Jul 7, 2022 · a40ffa3 · a40ffa3
1 parent bdf94cb
commit a40ffa3
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Showing 2 changed files with 10 additions and 1 deletion.
diff --git a/src/listfunc.c b/src/listfunc.c
@@ -1388,7 +1388,7 @@ static Obj FuncCOPY_LIST_ENTRIES(Obj self, Obj args)
         }
     }
 
-  if (dstmax > LEN_PLIST(dstlist))
+  if (dstmax >= LEN_PLIST(dstlist))
     {
       sptr = CONST_ADDR_OBJ(dstlist)+dstmax;
       ct = dstmax;

diff --git a/tst/testinstall/listindex.tst b/tst/testinstall/listindex.tst
@@ -265,6 +265,15 @@ gap> CopyListEntries(l,2,2,l,3,2,2); l;
 gap> l := [1,2,3,4,5];;
 gap> CopyListEntries(l,1,1,l,3,2,2); l;
 [ 1, 2, 1, 4, 2 ]
+gap> l := [1,2,3,4,5];;
+gap> CopyListEntries([],1,1,l,1,1,5); l;
+[  ]
+gap> l := [1,2,3,4,5];;
+gap> CopyListEntries([],1,1,l,1,1,6); l;
+[  ]
+gap> l := [1,2,3,4,5];;
+gap> CopyListEntries([1,,,,,,7],1,1,l,1,1,6); l;
+[ 1 ]
 
 #
 gap> CopyListEntries();