kernel: compare mtime's when building source or copying files from …

…`initfs`

Closes #66

Enables proper live editing within Wanix! `proc.Spawn` will rebuild commands
from source if it's been modified, and `kernel.fs` will copy in `initfs` files
if they've been modified externally *(note this will overwrite local files
inside Wanix)*.

dev/bootloader.js

@@ -84,9 +84,9 @@ if (!globalThis["ServiceWorkerGlobalScope"]) {
     const load = async (name, file) => {
       // Determine if file contains a path to fetch or embedded file contents to load.
       if(file.type === "text/plain") {
-        globalThis.initfs[name] = await (await fetch(`./sys/dev/${file.data}`)).blob();
+        globalThis.initfs[name] = { mtimeMs: file.mtimeMs, blob: await (await fetch(`./sys/dev/${file.data}`)).blob() };
       } else {
-        globalThis.initfs[name] = await (await fetch(`./~init/${name}`)).blob();
+        globalThis.initfs[name] = { mtimeMs: file.mtimeMs, blob: await (await fetch(`./~init/${name}`)).blob() };
       }
     };
 
@@ -97,8 +97,8 @@ if (!globalThis["ServiceWorkerGlobalScope"]) {
     }
     await Promise.all(loads);
 
-    globalThis.duplex = await import(URL.createObjectURL(initfs["duplex.js"]));
-    globalThis.task = await import(URL.createObjectURL(initfs["task.js"]));
+    globalThis.duplex = await import(URL.createObjectURL(initfs["duplex.js"].blob));
+    globalThis.task = await import(URL.createObjectURL(initfs["task.js"].blob));
 
     globalThis.sys = new task.Task(initfs);
 
@@ -107,7 +107,7 @@ if (!globalThis["ServiceWorkerGlobalScope"]) {
     await sys.exec("kernel");
 
     // load host API
-    await import(URL.createObjectURL(initfs["host.js"]));
+    await import(URL.createObjectURL(initfs["host.js"].blob));
 
   })();
 }

dev/initdata.go

@@ -24,7 +24,7 @@ var files = []File{
 	{Name: "build", Path: "./local/bin/build"},
 	{Name: "macro", Path: "./local/bin/micro"},
 
-	// {Name: "shell", Path: "./local/bin/shell"},
+	// Shell source files
 	{Name: "shell/main.go", Path: "shell/main.go"},
 	{Name: "shell/copy.go", Path: "shell/copy.go"},
 	{Name: "shell/download.go", Path: "shell/download.go"},
@@ -54,6 +54,10 @@ func PackFilesTo(w io.Writer, mode PackMode) {
 				files[i].Type = "application/octet-stream"
 			}
 
+			fi, err := os.Stat(files[i].Path)
+			fatal(err)
+			files[i].Mtime = fi.ModTime().UnixMilli()
+
 			data, err := os.ReadFile(files[i].Path)
 			fatal(err)
 			var gzipBuffer bytes.Buffer
@@ -68,6 +72,9 @@ func PackFilesTo(w io.Writer, mode PackMode) {
 		for i := range files {
 			files[i].Type = "text/plain"
 			files[i].Data = files[i].Path
+			fi, err := os.Stat(files[i].Path)
+			fatal(err)
+			files[i].Mtime = fi.ModTime().UnixMilli()
 		}
 	}
 
@@ -78,10 +85,11 @@ func PackFilesTo(w io.Writer, mode PackMode) {
 }
 
 type File struct {
-	Name string
-	Path string
-	Type string
-	Data string
+	Name  string
+	Path  string
+	Type  string
+	Data  string
+	Mtime int64
 }
 
 func fatal(err error) {

dev/initdata.tmpl

@@ -1,5 +1,5 @@
 globalThis.initdata = {
 {{range .}}
-  "{{.Name}}": {type: "{{.Type}}", data: "{{.Data}}"},
+  "{{.Name}}": {type: "{{.Type}}", mtimeMs: {{.Mtime}}, data: "{{.Data}}"},
 {{end}}
 }

internal/indexedfs/indexedfs.go

@@ -54,7 +54,7 @@ type FS struct {
 
 func New() (*FS, error) {
 	if helper.IsUndefined() {
-		blob := js.Global().Get("initfs").Get("indexedfs.js")
+		blob := js.Global().Get("initfs").Get("indexedfs.js").Get("blob")
 		url := js.Global().Get("URL").Call("createObjectURL", blob)
 		helper = jsutil.Await(js.Global().Call("import", url))
 	}

kernel/fs/fs.go

@@ -112,6 +112,11 @@ func getPrefixedInitFiles(prefix string) []string {
 }
 
 func (s *Service) copyFileFromInitFS(dst, src string) error {
+	initFile := js.Global().Get("initfs").Get(src)
+	if initFile.IsUndefined() {
+		return nil
+	}
+
 	var exists bool
 	fi, err := fs.Stat(s.fsys, dst)
 	if err == nil {
@@ -122,15 +127,8 @@ func (s *Service) copyFileFromInitFS(dst, src string) error {
 		return err
 	}
 
-	blob := js.Global().Get("initfs").Get(src)
-	if blob.IsUndefined() {
-		return nil
-	}
-
-	// TODO: use better heuristic. Editing a file will trigger this code and
-	// overwrite any changes. This is most definitely unintended.
-	// TODO: store the mtime for initfs files and compare them with the wanix mtime.
-	if !exists || int64(blob.Get("size").Int()) != fi.Size() {
+	if !exists || time.UnixMilli(int64(initFile.Get("mtimeMs").Float())).After(fi.ModTime()) {
+		blob := initFile.Get("blob")
 		buffer, err := jsutil.AwaitErr(blob.Call("arrayBuffer"))
 		if err != nil {
 			return err

kernel/main.go

@@ -34,7 +34,7 @@ type Kernel struct {
 
 func (k *Kernel) Run(ctx context.Context) error {
 	// import syscall.js
-	blob := js.Global().Get("initfs").Get("syscall.js")
+	blob := js.Global().Get("initfs").Get("syscall.js").Get("blob")
 	url := js.Global().Get("URL").Call("createObjectURL", blob)
 	jsutil.Await(js.Global().Call("import", url))
 

kernel/proc/proc.go

@@ -135,13 +135,45 @@ func unixToFsPath(path string) string {
 func (s *Service) buildCmdSource(path, workingDir string) (wasmPath string, err error) {
 	wasmPath = filepath.Join("/sys/bin", filepath.Base(path)+".wasm")
 
-	// TODO: use mtime and ctime to determine if cmd needs rebuilding.
-	wasmExists, err := fs.Exists(os.DirFS("/"), unixToFsPath(wasmPath))
-	if err != nil {
+	dfs := os.DirFS("/")
+	var wasmExists bool
+	wasmStat, err := fs.Stat(dfs, unixToFsPath(wasmPath))
+	if err == nil {
+		wasmExists = true
+	} else if os.IsNotExist(err) {
+		wasmExists = false
+	} else {
 		return "", err
 	}
 
+	var shouldBuild bool
 	if !wasmExists {
+		shouldBuild = true
+	} else {
+		wasmMtime := wasmStat.ModTime()
+		err = fs.WalkDir(dfs, unixToFsPath(path), func(walkPath string, d fs.DirEntry, walkErr error) error {
+			if walkErr != nil {
+				return walkErr
+			}
+
+			fi, err := d.Info()
+			if err != nil {
+				return err
+			}
+
+			if fi.ModTime().After(wasmMtime) {
+				shouldBuild = true
+				return fs.SkipAll
+			}
+
+			return nil
+		})
+		if err != nil {
+			return "", err
+		}
+	}
+
+	if shouldBuild {
 		p, err := s.Spawn(
 			"/sys/cmd/build.wasm",
 			[]string{"-output", wasmPath, path},
@@ -152,6 +184,10 @@ func (s *Service) buildCmdSource(path, workingDir string) (wasmPath string, err
 			return "", err
 		}
 
+		// TODO: https://github.com/tractordev/wanix/issues/69
+		// go io.Copy(os.Stdout, p.Stdout())
+		// go io.Copy(os.Stderr, p.Stderr())
+
 		exitCode, err := p.Wait()
 		if exitCode != 0 {
 			return "", err