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class Cell {
var x: int;
var i: int;
var y: Cell;
var f: int;
var g: int;
invariant rd(x);
predicate valid { rd(x) }
method a1(n: int) // test various arithmetic operations on permissions
requires acc(x,1+1) && acc(x,1) && acc(x,3) && acc(x,1-rd(5-7)+rd(3)) && rd(x) && rd(this.y);
ensures acc(x,100-97);
{
}
method a2(n: int)
requires acc(x,1-rd(1)-2);
{
assert false; // this should verify, as the precondition contains an invalid permission
}
method a3(n: int)
{
assert acc(x,1-rd(1)-2); // ERROR: invalid (negative) permission
}
method a4(n: int)
requires acc(x,rd(n));
{
}
method a5(n: int)
requires acc(x,rd(n)-rd(2));
{
}
method a6()
requires acc(x);
{
call a5(1); // ERROR: n=1 makes the permission in the precondition negative
}
method a7(c: Cell)
requires acc(c.x,100-rd(c));
requires c != null && acc(c.mu) && waitlevel << c;
ensures acc(c.x);
{
acquire(c);
unshare(c);
}
method a8()
requires acc(x,100-rd(valid)) && valid;
ensures acc(x);
{
unfold valid;
}
method a9()
requires acc(x,rd(valid));
ensures valid;
{
fold valid;
}
method a10()
requires valid;
ensures acc(x,rd(valid));
{
unfold valid;
}
method a11() // ERROR: postcondition does not hold (not enough permission)
requires valid;
ensures acc(x);
{
unfold valid;
}
method a12()
requires rd(this.i) && this.i > 0 && acc(x,rd(this.i));
ensures rd(this.i) && this.i > 0 && acc(x,rd(i));
{
}
method a13(i: int) // ERROR: postcondition does not hold
requires rd(this.i) && this.i > 0 && i > 0 && acc(x,rd(this.i));
ensures i > 0 && acc(x,rd(i));
{
}
method a14()
requires acc(y) && this.y == this; // test aliasing
requires acc(x,100-rd(y));
requires y != null && acc(this.mu) && waitlevel << this;
ensures acc(x);
lockchange this;
{
acquire this;
}
method a15()
requires acc(x,rd(this.i)); // ERROR: this.i is not readable
ensures acc(x,rd(this.i));
{
}
method a16()
requires acc(x,rd(this.y)); // ERROR: this.y is not readable
ensures acc(x,rd(this.y));
{
}
method a17(tk: token<Cell.void>)
requires acc(x,100-rd(tk)) && acc(tk.joinable) && tk.joinable;
requires eval(tk.fork this.void(),true);
ensures acc(x);
{
join tk;
}
method a18()
requires acc(x,rd+rd-rd+10*rd-rd*(5+5))
ensures rd(x)
{
call void();
}
method a19()
requires acc(x)
requires acc(this.mu) && lockbottom == this.mu
ensures acc(x)
lockchange this;
{
share this;
acquire this;
unshare this;
}
method a20()
requires rd(x)
requires acc(this.mu) && lockbottom == this.mu
lockchange this;
{
share this; // ERROR: not enough permission
}
method a21()
requires acc(x,rd*2)
ensures rd(x) && rd(x)
{
assert acc(x,rd+rd)
assert acc(x,(1+1)*rd)
}
method a22()
requires acc(x,1*2*5)
ensures acc(x,10)
{
}
method a23(c: Cell) // ERROR: permission in postcondition not positive
requires acc(x,rd-rd(c))
ensures acc(x,rd(c)-rd)
{
}
method a24()
requires rd*(x)
requires rd*(x)
{
}
method a25() // ERROR: postcondition does not hold, possibly not enough permission
requires rd*(x)
ensures acc(x,rd)
{
}
// interaction of monitors and predicates
method a26()
requires acc(x,rd(this))
requires acc(mu) && lockbottom == this.mu
ensures valid
lockchange this
{
share this
acquire this
fold valid
}
method a27()
requires acc(f,100-rd) && acc(f,rd)
{
assert acc(f) // ok, we have full access
}
method a28()
requires acc(f)
{
call a27();
var x: int
x := f // ERROR: no permission left
}
method a27b()
requires acc(f,100-rd)
requires acc(f,rd)
{
assert acc(f) // ok, we have full access
}
method a28b()
requires acc(f)
{
call a27b();
var x: int
x := f // ERROR: no permission left
}
method a29()
requires acc(f, 100-rd) && acc(g, rd)
{ }
method a30()
requires acc(f, 100) && acc(g, rd)
{
call a29();
var tmp: int := this.g;
}
method a31(c: Cell)
requires acc(f, 100-rd) && acc(c.f, rd)
{ }
method a32(c: Cell)
requires acc(f, 100) && acc(c.f, rd)
{
call a31(c);
var tmp: int := this.f;
}
method void() requires rd(x); ensures rd(x); {}
}
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