add file writing/reading

build.sh

@@ -1,11 +0,0 @@
-#! /bin/sh -e
-cd "cmd/land"
-vgo build -o ../../bin/land
-cd "../../userland/src/lib"
-node ../../compile.js counter.walt counter.wasm
-node ../../compile.js memory.walt memory.wasm
-wat2wasm -o add.wasm add.wast
-wat2wasm -o env.wasm env.wast
-wat2wasm -o hello.wasm hello.wast
-cd "../../.."
-go test -v ./cmd/land | tee bin/test.log

cmd/land/process.go

@@ -6,6 +6,7 @@ import (
 	"io"
 	"os"
 	"reflect"
+	"strings"
 
 	"github.com/Xe/ln"
 	"github.com/go-interpreter/wagon/exec"
@@ -17,10 +18,10 @@ import (
 // Process is a larger level wrapper around a webassembly VM that gives it
 // system call access.
 type Process struct {
-	id  int32
-	vm  *exec.VM
-	mod *wasm.Module
-	fs  afero.Fs
+	id    int32
+	vm    *exec.VM
+	mod   *wasm.Module
+	fs    afero.Fs
 	files []afero.File
 }
 
@@ -44,6 +45,7 @@ func NewProcess(fin io.Reader) (*Process, error) {
 
 	p.mod = mod
 	p.vm = vm
+	p.fs = afero.NewMemMapFs()
 
 	return p, nil
 }
@@ -59,6 +61,11 @@ func (p *Process) importer(name string) (*wasm.Module, error) {
 					ParamTypes:  []wasm.ValueType{wasm.ValueTypeI32, wasm.ValueTypeI32},
 					ReturnTypes: []wasm.ValueType{wasm.ValueTypeI32},
 				},
+				{
+					Form:        0,
+					ParamTypes:  []wasm.ValueType{wasm.ValueTypeI32, wasm.ValueTypeI32, wasm.ValueTypeI32},
+					ReturnTypes: []wasm.ValueType{wasm.ValueTypeI32},
+				},
 			},
 		}
 		m.FunctionIndexSpace = []wasm.Function{
@@ -67,6 +74,16 @@ func (p *Process) importer(name string) (*wasm.Module, error) {
 				Host: reflect.ValueOf(p.log),
 				Body: &wasm.FunctionBody{},
 			},
+			{
+				Sig:  &m.Types.Entries[0],
+				Host: reflect.ValueOf(p.open),
+				Body: &wasm.FunctionBody{},
+			},
+			{
+				Sig:  &m.Types.Entries[1],
+				Host: reflect.ValueOf(p.write),
+				Body: &wasm.FunctionBody{},
+			},
 		}
 		m.Export = &wasm.SectionExports{
 			Entries: map[string]wasm.ExportEntry{
@@ -75,6 +92,16 @@ func (p *Process) importer(name string) (*wasm.Module, error) {
 					Kind:     wasm.ExternalFunction,
 					Index:    0,
 				},
+				"open": {
+					FieldStr: "open",
+					Kind:     wasm.ExternalFunction,
+					Index:    1,
+				},
+				"write": {
+					FieldStr: "write",
+					Kind:     wasm.ExternalFunction,
+					Index:    2,
+				},
 			},
 		}
 		return m, nil
@@ -146,6 +173,44 @@ func (p *Process) readMem(ptr int32) []byte {
 	return result
 }
 
+func (p *Process) open(fnamesP int32, flags int32) int32 {
+	str := string(p.readMem(fnamesP))
+
+	var fi afero.File
+	var err error
+	switch str {
+	case "magic://stdout":
+		fi, err = afero.OsFs{}.Create("/dev/stdout")
+
+	default:
+		fi, err = p.fs.OpenFile(string(str), int(flags), 0666)
+		if err != nil {
+			if strings.Contains(err.Error(), afero.ErrFileNotFound.Error()) {
+				fi, err = p.fs.Create(str)
+			}
+		}
+	}
+
+	if err != nil {
+		panic(err)
+	}
+
+	fd := len(p.files)
+	p.files = append(p.files, fi)
+
+	return int32(fd)
+}
+
+func (p *Process) write(fd int32, ptr int32, len int32) int32 {
+	data := p.vm.Memory()[ptr : ptr+len]
+	n, err := p.files[fd].Write(data)
+	if err != nil {
+		panic(err)
+	}
+
+	return int32(n)
+}
+
 func (p *Process) Main() (uint32, error) {
 	foundMain := false
 	mainID := uint32(0)

cmd/land/process_test.go

@@ -5,6 +5,28 @@ import (
 	"testing"
 )
 
+func testWasmFile(t *testing.T, fname string) {
+	fin, err := os.Open(fname)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer fin.Close()
+
+	p, err := NewProcess(fin)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	ret, err := p.Main()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if ret != 0 {
+		t.Fatalf("expected return code to be 0, got: %d", ret)
+	}
+}
+
 func TestHelloWorld(t *testing.T) {
 	fin, err := os.Open("./testdata/hello.wasm")
 	if err != nil {
@@ -41,3 +63,7 @@ func TestHelloWorld(t *testing.T) {
 		t.Fatalf("wanted \"goodbye\", got: %q", string(data))
 	}
 }
+
+func TestWriteFile(t *testing.T) {
+	testWasmFile(t, "./testdata/writefile.wasm")
+}

go.mod

@@ -3,6 +3,7 @@ module git.xeserv.us/xena/land
 require (
 	github.com/Xe/ln v0.0.0-20180508032019-ae4f7456500d
 	github.com/go-interpreter/wagon v0.0.0-20180520092357-d4bc452fd57e
+	github.com/kr/pretty v0.1.0
 	github.com/pkg/errors v0.8.0
 	github.com/spf13/afero v1.1.1
 	golang.org/x/text v0.3.0

go.modverify

@@ -1,5 +1,7 @@
 github.com/Xe/ln v0.0.0-20180508032019-ae4f7456500d h1:dQgIfnQayXRfcxefFjA7rfL2hIouSrIEiOyB2hypQTw=
 github.com/go-interpreter/wagon v0.0.0-20180520092357-d4bc452fd57e h1:l4e38KpmR/OxRvJrZtqQ0yFwuGH8ta8ZZkOA+h5ovPg=
+github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=
+github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
 github.com/pkg/errors v0.8.0 h1:WdK/asTD0HN+q6hsWO3/vpuAkAr+tw6aNJNDFFf0+qw=
 github.com/spf13/afero v1.1.1 h1:Lt3ihYMlE+lreX1GS4Qw4ZsNpYQLxIXKBTEOXm3nt6I=
 golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg=

userland/src/lib/writefile.wast

@@ -0,0 +1,16 @@
+(module
+ (func $open (import "env" "open") (param i32 i32) (result i32))
+ (func $write (import "env" "write") (param i32 i32 i32) (result i32))
+ (memory $mem 1)
+ (data (i32.const 200) "stdout")
+ (data (i32.const 230) "Hello, world!\n")
+ (func $main (result i32)
+    (i32.const 200)
+    (i32.const 42)
+    (call $open)
+    (i32.const 230)
+    (i32.const 14)
+    (call $write)
+    (drop)
+    (i32.const 0))
+ (export "main" (func $main)))