feat: add support for O_SYMLINK (#944)

uhyo · web-flow · commit 96cbce414589 · 2023-09-16T10:48:25.000+12:00
diff --git a/src/__tests__/volume.test.ts b/src/__tests__/volume.test.ts
@@ -6,6 +6,9 @@ import { Volume, filenameToSteps, StatWatcher } from '../volume';
 import hasBigInt from './hasBigInt';
 import { tryGetChild, tryGetChildNode } from './util';
 import { genRndStr6 } from '../node/util';
+import { constants } from '../constants';
+
+const { O_RDWR, O_SYMLINK } = constants;
 
 describe('volume', () => {
   describe('filenameToSteps(filename): string[]', () => {
@@ -484,13 +487,26 @@ describe('volume', () => {
       });
     });
     describe('.read(fd, buffer, offset, length, position, callback)', () => {
-      xit('...', () => {});
+      const vol = new Volume();
+      const data = 'trololo';
+      const fileNode = (vol as any).createLink(vol.root, 'text.txt').getNode();
+      fileNode.setString(data);
+      vol.symlinkSync('/text.txt', '/link.txt');
+
+      it('Attempt to read from a symlink should throw EPERM', () => {
+        const fd = vol.openSync('/link.txt', O_SYMLINK);
+        expect(vol.fstatSync(fd).isSymbolicLink()).toBe(true);
+        const buf = Buffer.alloc(10);
+        const fn = () => vol.readSync(fd, buf, 0, 10, 0);
+        expect(fn).toThrowError('EPERM');
+      });
     });
     describe('.readFileSync(path[, options])', () => {
       const vol = new Volume();
       const data = 'trololo';
       const fileNode = (vol as any).createLink(vol.root, 'text.txt').getNode();
       fileNode.setString(data);
+
       it('Read file at root (/text.txt)', () => {
         const buf = vol.readFileSync('/text.txt');
         const str = buf.toString();
@@ -584,6 +600,16 @@ describe('volume', () => {
         vol.closeSync(fd);
         expect(vol.readFileSync('/overwrite.txt', 'utf8')).toBe('mArmagedon');
       });
+      it('Attempt to write to a symlink should throw EBADF', () => {
+        const data = 'asdfasdf asdfasdf asdf';
+        vol.writeFileSync('/file.txt', data);
+        vol.symlinkSync('/file.txt', '/link.txt');
+
+        const fd = vol.openSync('/link.txt', O_SYMLINK | O_RDWR);
+        expect(vol.fstatSync(fd).isSymbolicLink()).toBe(true);
+        const fn = () => vol.writeSync(fd, 'hello');
+        expect(fn).toThrowError('EBADF');
+      });
     });
     describe('.write(fd, buffer, offset, length, position, callback)', () => {
       it('Simple write to a file descriptor', done => {
@@ -834,6 +860,8 @@ describe('volume', () => {
       const data = '(function(){})();';
       dojo.getNode().setString(data);
 
+      vol.symlinkSync('/dojo.js', '/link.js');
+
       it('Returns basic file stats', () => {
         const fd = vol.openSync('/dojo.js', 'r');
         const stats = vol.fstatSync(fd);
@@ -855,6 +883,21 @@ describe('volume', () => {
           expect(() => vol.fstatSync(fd, { bigint: true })).toThrowError();
         }
       });
+      it('Returns stats about regular file for fd opened without O_SYMLINK', () => {
+        const fd = vol.openSync('/link.js', 0);
+        const stats = vol.fstatSync(fd);
+        expect(stats).toBeInstanceOf(Stats);
+        expect(stats.size).toBe(data.length);
+        expect(stats.isFile()).toBe(true);
+        expect(stats.isDirectory()).toBe(false);
+      });
+      it('Returns stats about symlink itself for fd opened with O_SYMLINK', () => {
+        const fd = vol.openSync('/link.js', O_SYMLINK);
+        const stats = vol.fstatSync(fd);
+        expect(stats.isSymbolicLink()).toBe(true);
+        expect(stats.isFile()).toBe(false);
+        expect(stats.size).toBe(0);
+      });
     });
     describe('.fstat(fd, callback)', () => {
       xit('...', () => {});
diff --git a/src/constants.ts b/src/constants.ts
@@ -19,6 +19,7 @@ export const constants = {
   O_NOATIME: 262144,
   O_NOFOLLOW: 131072,
   O_SYNC: 1052672,
+  O_SYMLINK: 2097152,
   O_DIRECT: 16384,
   O_NONBLOCK: 2048,
   S_IRWXU: 448,
diff --git a/src/volume.ts b/src/volume.ts
@@ -68,6 +68,7 @@ const {
   O_TRUNC,
   O_APPEND,
   O_DIRECTORY,
+  O_SYMLINK,
   F_OK,
   COPYFILE_EXCL,
   COPYFILE_FICLONE_FORCE,
@@ -95,6 +96,7 @@ const kMinPoolSpace = 128;
 
 // ---------------------------------------- Error messages
 
+const EPERM = 'EPERM';
 const ENOENT = 'ENOENT';
 const EBADF = 'EBADF';
 const EINVAL = 'EINVAL';
@@ -703,7 +705,7 @@ export class Volume implements FsCallbackApi {
     const modeNum = modeToNumber(mode);
     const fileName = pathToFilename(path);
     const flagsNum = flagsToNumber(flags);
-    return this.openBase(fileName, flagsNum, modeNum);
+    return this.openBase(fileName, flagsNum, modeNum, !(flagsNum & O_SYMLINK));
   }
 
   open(path: PathLike, flags: TFlags, /* ... */ callback: TCallback<number>);
@@ -722,7 +724,7 @@ export class Volume implements FsCallbackApi {
     const fileName = pathToFilename(path);
     const flagsNum = flagsToNumber(flags);
 
-    this.wrapAsync(this.openBase, [fileName, flagsNum, modeNum], callback);
+    this.wrapAsync(this.openBase, [fileName, flagsNum, modeNum, !(flagsNum & O_SYMLINK)], callback);
   }
 
   private closeFile(file: File) {
@@ -762,6 +764,9 @@ export class Volume implements FsCallbackApi {
     position: number,
   ): number {
     const file = this.getFileByFdOrThrow(fd);
+    if (file.node.isSymlink()) {
+      throw createError(EPERM, 'read', file.link.getPath());
+    }
     return file.read(buffer, Number(offset), Number(length), position);
   }
 
@@ -851,6 +856,9 @@ export class Volume implements FsCallbackApi {
 
   private writeBase(fd: number, buf: Buffer, offset?: number, length?: number, position?: number | null): number {
     const file = this.getFileByFdOrThrow(fd, 'write');
+    if (file.node.isSymlink()) {
+      throw createError(EBADF, 'write', file.link.getPath());
+    }
     return file.write(buf, offset, length, position);
   }
 
