fs builtin (highly experimental and potentially dangerous)

2022-07-06 12:17:42 +02:00
parent 0388b6a2a4
commit f1a7cc1fb7
3 changed files with 121 additions and 0 deletions
@@ -0,0 +1,87 @@
+import { readdir, readFile, stat, writeFile, unlink } from "fs/promises";
+import path from "path";
+import type { SysCallMapping } from "../system";
+
+export type FileMeta = {
+  name: string;
+  lastModified: number;
+};
+
+export default function fileSystemSyscalls(root: string = "/"): SysCallMapping {
+  function resolvedPath(p: string): string {
+    p = path.resolve(root, p);
+    if (!p.startsWith(root)) {
+      throw Error("Path outside root, not allowed");
+    }
+    return p;
+  }
+
+  return {
+    "fs.readFile": async (
+      ctx,
+      filePath: string
+    ): Promise<{ text: string; meta: FileMeta }> => {
+      let p = resolvedPath(filePath);
+      let text = await readFile(p, "utf8");
+      let s = await stat(p);
+      return {
+        text,
+        meta: {
+          name: filePath,
+          lastModified: s.mtime.getTime(),
+        },
+      };
+    },
+    "fs.getFileMeta": async (ctx, filePath: string): Promise<FileMeta> => {
+      let p = resolvedPath(filePath);
+      let s = await stat(p);
+      return {
+        name: filePath,
+        lastModified: s.mtime.getTime(),
+      };
+    },
+    "fs.writeFile": async (
+      ctx,
+      filePath: string,
+      text: string
+    ): Promise<FileMeta> => {
+      let p = resolvedPath(filePath);
+      await writeFile(p, text);
+      let s = await stat(p);
+      return {
+        name: filePath,
+        lastModified: s.mtime.getTime(),
+      };
+    },
+    "fs.deleteFile": async (ctx, filePath: string): Promise<void> => {
+      let p = resolvedPath(filePath);
+      await unlink(p);
+    },
+    "fs.listFiles": async (
+      ctx,
+      dirPath: string,
+      recursive: boolean
+    ): Promise<FileMeta[]> => {
+      dirPath = resolvedPath(dirPath);
+      let allFiles: FileMeta[] = [];
+
+      async function walkPath(dir: string) {
+        let files = await readdir(dir);
+        for (let file of files) {
+          const fullPath = path.join(dir, file);
+          let s = await stat(fullPath);
+          if (s.isDirectory() && recursive) {
+            await walkPath(fullPath);
+          } else {
+            allFiles.push({
+              name: fullPath.substring(dirPath.length + 1),
+              lastModified: s.mtime.getTime(),
+            });
+          }
+        }
+      }
+      await walkPath(dirPath);
+      return allFiles;
+    },
+  };
+}