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Implement runtime errors, divide-by-zero checking, nil pointer

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checking, bounds checking, and map key checking.

R=rsc
APPROVED=rsc
DELTA=202  (108 added, 72 deleted, 22 changed)
OCL=33981
CL=34031
This commit is contained in:
Austin Clements 2009-08-28 10:39:57 -07:00
parent 636cdc7622
commit 9d517ba3fd
4 changed files with 134 additions and 94 deletions
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2
usr/austin/eval/Makefile
View File

@ -6,6 +6,8 @@ include $(GOROOT)/src/Make.$(GOARCH)
TARG=eval
GOFILES=\
abort.go\
bridge.go\
compiler.go\
decls.go\
expr.go\

71
usr/austin/eval/abort.go Normal file
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@ -0,0 +1,71 @@
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package eval
import (
"fmt";
"os";
"runtime";
)
// TODO(austin) This is not thread-safe. We could include the abort
// channel in the Frame structure, but then the Value methods need to
// take the Frame. However, passing something to the Value methods
// might be necessary to generate back traces.
var abortChan = make(chan os.Error)
// Abort aborts the current computation. If this is called within the
// extent of a Try call, this immediately returns to the Try with the
// given error. If not, then this panic's.
func Abort(e os.Error) {
if abortChan == nil {
panic("Abort: " + e.String());
}
abortChan <- e;
runtime.Goexit();
}
// Try executes a computation with the ability to Abort.
func Try(f func()) os.Error {
abortChan = make(chan os.Error);
go func() {
f();
abortChan <- nil;
}();
res := <-abortChan;
abortChan = nil;
return res;
}
type DivByZero struct {}
func (DivByZero) String() string {
return "divide by zero";
}
type NilPointer struct {}
func (NilPointer) String() string {
return "nil pointer dereference";
}
type IndexOutOfBounds struct {
Idx, Len int64;
}
func (e IndexOutOfBounds) String() string {
if e.Idx < 0 {
return fmt.Sprintf("negative index: %d", e.Idx);
}
return fmt.Sprintf("index %d exceeds length %d", e.Idx, e.Len);
}
type KeyNotFound struct {
Key interface {};
}
func (e KeyNotFound) String() string {
return fmt.Sprintf("key %s not found in map", e.Key);
}

151
usr/austin/eval/expr.go
View File

@ -990,8 +990,12 @@ func (a *exprInfo) compileIndexExpr(l, r *expr) *expr {
switch _ := r.t.lit().(type) {
case *idealIntType:
val := r.asIdealInt()();
if val.IsNeg() || (maxIndex != -1 && val.Cmp(bignum.Int(maxIndex)) >= 0) {
a.diag("array index out of bounds");
if val.IsNeg() {
a.diag("negative index: %s", val);
return nil;
}
if maxIndex != -1 && val.Cmp(bignum.Int(maxIndex)) >= 0 {
a.diag("index %s exceeds length %d", val, maxIndex);
return nil;
}
r = r.convertTo(IntType);
@ -1022,36 +1026,45 @@ func (a *exprInfo) compileIndexExpr(l, r *expr) *expr {
// Compile
switch lt := l.t.lit().(type) {
case *ArrayType:
// TODO(austin) Bounds check
expr.genIndexArray(l, r);
lf := l.asArray();
rf := r.asInt();
expr.evalAddr = func(f *Frame) Value {
return lf(f).Elem(rf(f));
};
bound := lt.Len;
expr.genValue(func(f *Frame) Value {
l, r := lf(f), rf(f);
if r < 0 || r >= bound {
Abort(IndexOutOfBounds{r, bound});
}
return l.Elem(r);
});
case *SliceType:
// TODO(austin) Bounds check
// TODO(austin) Can this be done with genValue?
expr.genIndexSlice(l, r);
lf := l.asSlice();
rf := r.asInt();
expr.evalAddr = func(f *Frame) Value {
return lf(f).Base.Elem(rf(f));
};
expr.genValue(func(f *Frame) Value {
l, r := lf(f), rf(f);
if l.Base == nil {
Abort(NilPointer{});
}
if r < 0 || r >= l.Len {
Abort(IndexOutOfBounds{r, l.Len});
}
return l.Base.Elem(r);
});
case *stringType:
// TODO(austin) Bounds check
lf := l.asString();
rf := r.asInt();
// TODO(austin) This pulls over the whole string in a
// remote setting, instead of just the one character.
expr.evalUint = func(f *Frame) uint64 {
return uint64(lf(f)[rf(f)]);
l, r := lf(f), rf(f);
if r < 0 || r >= int64(len(l)) {
Abort(IndexOutOfBounds{r, int64(len(l))});
}
return uint64(l[r]);
}
case *MapType:
// TODO(austin) Bounds check
lf := l.asMap();
rf := r.asInterface();
expr.genValue(func(f *Frame) Value {
@ -1059,8 +1072,7 @@ func (a *exprInfo) compileIndexExpr(l, r *expr) *expr {
k := rf(f);
e := m.Elem(k);
if e == nil {
// TODO(austin) Use an exception
panic("key ", k, " not found in map");
Abort(KeyNotFound{k});
}
return e;
});
@ -1068,6 +1080,7 @@ func (a *exprInfo) compileIndexExpr(l, r *expr) *expr {
// aren't addressable.
expr.evalAddr = nil;
expr.evalMapValue = func(f *Frame) (Map, interface{}) {
// TODO(austin) Key check?
return lf(f), rf(f);
};
@ -1153,8 +1166,14 @@ func (a *exprInfo) compileStarExpr(v *expr) *expr {
switch vt := v.t.lit().(type) {
case *PtrType:
expr := a.newExpr(vt.Elem, "indirect expression");
// TODO(austin) Deal with nil pointers
expr.genValue(v.asPtr());
vf := v.asPtr();
expr.genValue(func(f *Frame) Value {
v := vf(f);
if v == nil {
Abort(NilPointer{});
}
return v;
});
return expr;
}
@ -1496,6 +1515,18 @@ func (a *exprInfo) compileBinaryExpr(op token.Token, l, r *expr) *expr {
binOpDescs[op] = desc;
}
// Check for ideal divide by zero
switch op {
case token.QUO, token.REM:
if r.t.isIdeal() {
if (r.t.isInteger() && r.asIdealInt()().IsZero()) ||
(r.t.isFloat() && r.asIdealFloat()().IsZero()) {
a.diag("divide by zero");
return nil;
}
}
}
// Compile
expr := a.newExpr(t, desc);
switch op {
@ -1509,13 +1540,11 @@ func (a *exprInfo) compileBinaryExpr(op token.Token, l, r *expr) *expr {
expr.genBinOpMul(l, r);
case token.QUO:
// TODO(austin) What if divisor is zero?
// TODO(austin) Clear higher bits that may have
// accumulated in our temporary.
expr.genBinOpQuo(l, r);
case token.REM:
// TODO(austin) What if divisor is zero?
// TODO(austin) Clear higher bits that may have
// accumulated in our temporary.
expr.genBinOpRem(l, r);
@ -1697,10 +1726,10 @@ type Expr struct {
f func(f *Frame, out Value);
}
func (expr *Expr) Eval(f *Frame) Value {
func (expr *Expr) Eval(f *Frame) (Value, os.Error) {
v := expr.t.Zero();
expr.f(f, v);
return v;
err := Try(func() {expr.f(f, v)});
return v, err;
}
func CompileExpr(scope *Scope, expr ast.Expr) (*Expr, os.Error) {
@ -1820,68 +1849,6 @@ func (a *expr) genIdentOp(level int, index int) {
}
}
func (a *expr) genIndexArray(l, r *expr) {
lf := l.asArray();
rf := r.asInt();
switch _ := a.t.lit().(type) {
case *boolType:
a.evalBool = func(f *Frame) bool { return lf(f).Elem(rf(f)).(BoolValue).Get() };
case *uintType:
a.evalUint = func(f *Frame) uint64 { return lf(f).Elem(rf(f)).(UintValue).Get() };
case *intType:
a.evalInt = func(f *Frame) int64 { return lf(f).Elem(rf(f)).(IntValue).Get() };
case *floatType:
a.evalFloat = func(f *Frame) float64 { return lf(f).Elem(rf(f)).(FloatValue).Get() };
case *stringType:
a.evalString = func(f *Frame) string { return lf(f).Elem(rf(f)).(StringValue).Get() };
case *ArrayType:
a.evalArray = func(f *Frame) ArrayValue { return lf(f).Elem(rf(f)).(ArrayValue).Get() };
case *StructType:
a.evalStruct = func(f *Frame) StructValue { return lf(f).Elem(rf(f)).(StructValue).Get() };
case *PtrType:
a.evalPtr = func(f *Frame) Value { return lf(f).Elem(rf(f)).(PtrValue).Get() };
case *FuncType:
a.evalFunc = func(f *Frame) Func { return lf(f).Elem(rf(f)).(FuncValue).Get() };
case *SliceType:
a.evalSlice = func(f *Frame) Slice { return lf(f).Elem(rf(f)).(SliceValue).Get() };
case *MapType:
a.evalMap = func(f *Frame) Map { return lf(f).Elem(rf(f)).(MapValue).Get() };
default:
log.Crashf("unexpected result type %v at %v", a.t, a.pos);
}
}
func (a *expr) genIndexSlice(l, r *expr) {
lf := l.asSlice();
rf := r.asInt();
switch _ := a.t.lit().(type) {
case *boolType:
a.evalBool = func(f *Frame) bool { return lf(f).Base.Elem(rf(f)).(BoolValue).Get() };
case *uintType:
a.evalUint = func(f *Frame) uint64 { return lf(f).Base.Elem(rf(f)).(UintValue).Get() };
case *intType:
a.evalInt = func(f *Frame) int64 { return lf(f).Base.Elem(rf(f)).(IntValue).Get() };
case *floatType:
a.evalFloat = func(f *Frame) float64 { return lf(f).Base.Elem(rf(f)).(FloatValue).Get() };
case *stringType:
a.evalString = func(f *Frame) string { return lf(f).Base.Elem(rf(f)).(StringValue).Get() };
case *ArrayType:
a.evalArray = func(f *Frame) ArrayValue { return lf(f).Base.Elem(rf(f)).(ArrayValue).Get() };
case *StructType:
a.evalStruct = func(f *Frame) StructValue { return lf(f).Base.Elem(rf(f)).(StructValue).Get() };
case *PtrType:
a.evalPtr = func(f *Frame) Value { return lf(f).Base.Elem(rf(f)).(PtrValue).Get() };
case *FuncType:
a.evalFunc = func(f *Frame) Func { return lf(f).Base.Elem(rf(f)).(FuncValue).Get() };
case *SliceType:
a.evalSlice = func(f *Frame) Slice { return lf(f).Base.Elem(rf(f)).(SliceValue).Get() };
case *MapType:
a.evalMap = func(f *Frame) Map { return lf(f).Base.Elem(rf(f)).(MapValue).Get() };
default:
log.Crashf("unexpected result type %v at %v", a.t, a.pos);
}
}
func (a *expr) genFuncCall(call func(f *Frame) []Value) {
a.exec = func(f *Frame) { call(f) };
switch _ := a.t.lit().(type) {
@ -2091,11 +2058,11 @@ func (a *expr) genBinOpQuo(l, r *expr) {
case *uintType:
lf := l.asUint();
rf := r.asUint();
a.evalUint = func(f *Frame) uint64 { return lf(f) / rf(f) };
a.evalUint = func(f *Frame) uint64 { l, r := lf(f), rf(f); if r == 0 { Abort(DivByZero{}) }; return l / r };
case *intType:
lf := l.asInt();
rf := r.asInt();
a.evalInt = func(f *Frame) int64 { return lf(f) / rf(f) };
a.evalInt = func(f *Frame) int64 { l, r := lf(f), rf(f); if r == 0 { Abort(DivByZero{}) }; return l / r };
case *idealIntType:
lf := l.asIdealInt();
rf := r.asIdealInt();
@ -2104,7 +2071,7 @@ func (a *expr) genBinOpQuo(l, r *expr) {
case *floatType:
lf := l.asFloat();
rf := r.asFloat();
a.evalFloat = func(f *Frame) float64 { return lf(f) / rf(f) };
a.evalFloat = func(f *Frame) float64 { l, r := lf(f), rf(f); if r == 0 { Abort(DivByZero{}) }; return l / r };
case *idealFloatType:
lf := l.asIdealFloat();
rf := r.asIdealFloat();
@ -2120,11 +2087,11 @@ func (a *expr) genBinOpRem(l, r *expr) {
case *uintType:
lf := l.asUint();
rf := r.asUint();
a.evalUint = func(f *Frame) uint64 { return lf(f) % rf(f) };
a.evalUint = func(f *Frame) uint64 { l, r := lf(f), rf(f); if r == 0 { Abort(DivByZero{}) }; return l % r };
case *intType:
lf := l.asInt();
rf := r.asInt();
a.evalInt = func(f *Frame) int64 { return lf(f) % rf(f) };
a.evalInt = func(f *Frame) int64 { l, r := lf(f), rf(f); if r == 0 { Abort(DivByZero{}) }; return l % r };
case *idealIntType:
lf := l.asIdealInt();
rf := r.asIdealInt();

4
usr/austin/eval/stmt.go
View File

@ -1281,8 +1281,8 @@ type Stmt struct {
f func (f *Frame);
}
func (s *Stmt) Exec(f *Frame) {
s.f(f);
func (s *Stmt) Exec(f *Frame) os.Error {
return Try(func() {s.f(f)});
}
func CompileStmts(scope *Scope, stmts []ast.Stmt) (*Stmt, os.Error) {