chore: make webfs usable

src/program/Echo.ts

@@ -7,17 +7,24 @@ export class Echo extends Program {
         super()
     }
 
-    async Exec(_: SimpleStream<string>, stdout: SimpleStream<string>, ___: Item, args: string[]): Promise<number> {
-        let item: Item = await Item.open(args[1])
+    async Exec(_: SimpleStream<string>, stdout: SimpleStream<string>, workdir: Item, args: string[]): Promise<number> {
+        if (args.length < 2) {
+            stdout.emit("echo: error: missing path argument\n")
+            return 1
+        }
+
+        const item = await Item.open(args[1].startsWith('/')
+                ? args[1]
+                : `${workdir.GetPath()}${workdir.GetPath().endsWith('/') ? '' : '/'}${args[1]}`)
 
         if (!(await item.Exists())) {
             stdout.emit(`echo: error: item ${item.GetPath()} doesn't exist.\n`)
-            return 1
+            return 2
         }
 
         if (item.IsDirectory()) {
             stdout.emit(`echo: error: can't write data to a directory; item ${item.GetPath()} is a directory.\n`)
-            return 2
+            return 3
         }
 
         await item.Write(args.slice(2).join(' '))