all: basic support for the os package

The resulting binary is pretty big due to lacking optimizations
(probably because of interfaces), so that should be fixed.

interpreter.go

@@ -22,6 +22,7 @@ var ignoreInitCalls = map[string]struct{}{
 	"(syscall/js.Value).Get": struct{}{},
 	"(syscall/js.Value).New": struct{}{},
 	"(syscall/js.Value).Int": struct{}{},
+	"os.init$1":              struct{}{},
 }
 
 // Interpret instructions as far as possible, and drop those instructions from
@@ -91,14 +92,67 @@ func (p *Program) interpret(instrs []ssa.Instruction, paramKeys []*ssa.Parameter
 			if callee == nil {
 				return i, nil // don't understand dynamic dispatch
 			}
-			if _, ok := ignoreInitCalls[callee.String()]; ok && callee.Signature.Results().Len() == 1 {
+			if _, ok := ignoreInitCalls[callee.String()]; ok {
 				// These calls are not needed and can be ignored, for the time
 				// being.
-				var err error
-				locals[instr], err = p.getZeroValue(callee.Signature.Results().At(0).Type())
+				results := make([]Value, callee.Signature.Results().Len())
+				for i := range results {
+					var err error
+					results[i], err = p.getZeroValue(callee.Signature.Results().At(i).Type())
+					if err != nil {
+						return i, err
+					}
+				}
+				if len(results) == 1 {
+					locals[instr] = results[0]
+				} else if len(results) > 1 {
+					locals[instr] = &StructValue{Fields: results}
+				}
+				continue
+			}
+			if callee.String() == "os.NewFile" {
+				// Emulate the creation of os.Stdin, os.Stdout and os.Stderr.
+				resultPtrType := callee.Signature.Results().At(0).Type().(*types.Pointer)
+				resultStructOuterType := resultPtrType.Elem().Underlying().(*types.Struct)
+				if resultStructOuterType.NumFields() != 1 {
+					panic("expected 1 field in os.File struct")
+				}
+				fileInnerPtrType := resultStructOuterType.Field(0).Type().(*types.Pointer)
+				fileInnerType := fileInnerPtrType.Elem().(*types.Named)
+				fileInnerStructType := fileInnerType.Underlying().(*types.Struct)
+				fileInner, err := p.getZeroValue(fileInnerType) // os.file
 				if err != nil {
 					return i, err
 				}
+				for fieldIndex := 0; fieldIndex < fileInnerStructType.NumFields(); fieldIndex++ {
+					field := fileInnerStructType.Field(fieldIndex)
+					if field.Name() == "name" {
+						// Set the 'name' field.
+						name, err := p.getValue(common.Args[1], locals)
+						if err != nil {
+							return i, err
+						}
+						fileInner.(*StructValue).Fields[fieldIndex] = name
+					} else if field.Type().String() == "internal/poll.FD" {
+						// Set the file descriptor field.
+						field := field.Type().Underlying().(*types.Struct)
+						for subfieldIndex := 0; subfieldIndex < field.NumFields(); subfieldIndex++ {
+							subfield := field.Field(subfieldIndex)
+							if subfield.Name() == "Sysfd" {
+								sysfd, err := p.getValue(common.Args[0], locals)
+								if err != nil {
+									return i, err
+								}
+								sysfd = &ConstValue{Expr: ssa.NewConst(sysfd.(*ConstValue).Expr.Value, subfield.Type())}
+								fileInner.(*StructValue).Fields[fieldIndex].(*StructValue).Fields[subfieldIndex] = sysfd
+							}
+						}
+					}
+				}
+				fileInnerPtr := &PointerValue{fileInnerPtrType, &fileInner}                                   // *os.file
+				var fileOuter Value = &StructValue{Type: resultPtrType.Elem(), Fields: []Value{fileInnerPtr}} // os.File
+				result := &PointerValue{resultPtrType.Elem(), &fileOuter}                                     // *os.File
+				locals[instr] = result
 				continue
 			}
 			if canInterpret(callee) {
@@ -165,6 +219,12 @@ func (p *Program) interpret(instrs []ssa.Instruction, paramKeys []*ssa.Parameter
 			}
 		case *ssa.DebugRef:
 			// ignore
+		case *ssa.Extract:
+			tuple, err := p.getValue(instr.Tuple, locals)
+			if err != nil {
+				return i, err
+			}
+			locals[instr] = tuple.(*StructValue).Fields[instr.Index]
 		case *ssa.FieldAddr:
 			x, err := p.getValue(instr.X, locals)
 			if err != nil {
@@ -311,6 +371,7 @@ func canInterpret(callee *ssa.Function) bool {
 		case *ssa.Alloc:
 		case *ssa.Convert:
 		case *ssa.DebugRef:
+		case *ssa.Extract:
 		case *ssa.FieldAddr:
 		case *ssa.IndexAddr:
 		case *ssa.MakeInterface:

src/runtime/atomic.go

@@ -0,0 +1,24 @@
+package runtime
+
+// This file contains implementations for the sync/atomic package.
+
+// All implementations assume there are no goroutines, threads or interrupts.
+
+//go:linkname loadUint64 sync/atomic.LoadUint64
+func loadUint64(addr *uint64) uint64 {
+	return *addr
+}
+
+//go:linkname storeUint32 sync/atomic.StoreUint32
+func storeUint32(addr *uint32, val uint32) {
+	*addr = val
+}
+
+//go:linkname compareAndSwapUint64 sync/atomic.CompareAndSwapUint64
+func compareAndSwapUint64(addr *uint64, old, new uint64) bool {
+	if *addr == old {
+		*addr = new
+		return true
+	}
+	return false
+}

src/runtime/poll.go

@@ -0,0 +1,23 @@
+package runtime
+
+// This file implements stub functions for internal/poll.
+
+//go:linkname poll_runtime_pollServerInit internal/poll.runtime_pollServerInit
+func poll_runtime_pollServerInit(ctx *uint8) {
+	panic("todo: runtime_pollServerInit")
+}
+
+//go:linkname poll_runtime_pollOpen internal/poll.runtime_pollOpen
+func poll_runtime_pollOpen(fd uintptr) (uintptr, int) {
+	panic("todo: runtime_pollOpen")
+}
+
+//go:linkname poll_runtime_pollClose internal/poll.runtime_pollClose
+func poll_runtime_pollClose(ctx uintptr) {
+	panic("todo: runtime_pollClose")
+}
+
+//go:linkname poll_runtime_pollUnblock internal/poll.runtime_pollUnblock
+func poll_runtime_pollUnblock(ctx uintptr) {
+	panic("todo: runtime_pollUnblock")
+}

src/runtime/runtime.go

@@ -49,6 +49,11 @@ func GOROOT() string {
 	return "/usr/local/go"
 }
 
+//go:linkname os_runtime_args os.runtime_args
+func os_runtime_args() []string {
+	return nil
+}
+
 // Copy size bytes from src to dst. The memory areas must not overlap.
 func memcpy(dst, src unsafe.Pointer, size uintptr) {
 	for i := uintptr(0); i < size; i++ {

src/runtime/sync.go

@@ -1 +1,13 @@
 package runtime
+
+// This file contains stub implementations for internal/poll.
+
+//go:linkname semacquire internal/poll.runtime_Semacquire
+func semacquire(sema *uint32) {
+	panic("todo: semacquire")
+}
+
+//go:linkname semrelease internal/poll.runtime_Semrelease
+func semrelease(sema *uint32) {
+	panic("todo: semrelease")
+}

src/runtime/syscall.go

@@ -0,0 +1,13 @@
+package runtime
+
+// This file implements syscall.Syscall and the like.
+
+//go:linkname syscall_Syscall syscall.Syscall
+func syscall_Syscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err uintptr) {
+	panic("syscall")
+}
+
+//go:linkname syscall_Syscall6 syscall.Syscall6
+func syscall_Syscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err uintptr) {
+	panic("syscall6")
+}