fix: reading through symlinks to http-backed files (#36)

Author: fuzzyTew

src/CacheFS.js

@@ -117,10 +117,7 @@ module.exports = class CacheFS {
       if (follow || i < parts.length - 1) {
         const stat = dir.get(STAT)
         if (stat.type === 'symlink') {
-          let target = stat.target
-          if (!target.startsWith('/')) {
-            target = path.normalize(path.join(partialPath, target))
-          }
+          let target = path.resolve(partialPath, stat.target)
           dir = this._lookup(target)
         }
         if (!partialPath) {

src/PromisifiedFS.js

@@ -168,6 +168,11 @@ module.exports = class PromisifiedFS {
       if (!this._urlauto) throw e
     }
     if (!data && this._http) {
+      let lstat = this._cache.lstat(filepath)
+      while (lstat.type === 'symlink') {
+        filepath = path.resolve(path.dirname(filepath), lstat.target)
+        lstat = this._cache.lstat(filepath)
+      }
       data = await this._http.readFile(filepath)
     }
     if (data) {

src/__tests__/__fixtures__/test-folder/.superblock.txt

@@ -6,6 +6,8 @@
 	d.txt	100644	14	1545621340683.4724
 	e.txt	100644	14	1545621349775.4539
 	f.txt	100644	14	1545621356008.1582
+2	40775
+	a.txt	100664	14	1572953161955.4033
 a.txt	100644	14	1545621375109
 b.txt	100644	14	1545621255760.9512
 c.txt	100644	14	1545621290070.7742

src/__tests__/__fixtures__/test-folder/2/a.txt

@@ -0,0 +1 @@
+Hello from "a"

src/__tests__/fallback.spec.js

@@ -18,7 +18,7 @@ describe("http fallback", () => {
     it("read root dir", done => {
       fs.readdir("/", (err, data) => {
         expect(err).toBe(null);
-        expect(data).toEqual(['0', '1', 'a.txt', 'b.txt', 'c.txt'])
+        expect(data).toEqual(['0', '1', '2', 'a.txt', 'b.txt', 'c.txt'])
         done();
       });
     });
@@ -58,6 +58,16 @@ describe("http fallback", () => {
         done();
       });
     });
+    it("make a symlink and read file /2/a.txt through it", done => {
+      fs.symlink("a.txt", "/2/symlink.txt", (err) => {
+        expect(err).toBe(null);
+        fs.readFile("/2/symlink.txt", 'utf8', (err, data) => {
+          expect(err).toBe(null);
+          expect(data).toEqual('Hello from "a"');
+          done();
+        });
+      });
+    });
   });
 
   describe("writeFile", () => {

src/path.js

@@ -7,6 +7,18 @@ function normalizePath(path) {
   return joinPath(...parts);
 }
 
+function resolvePath(...paths) {
+  let result = '';
+  for (let path of paths) {
+    if (path.startsWith('/')) {
+      result = path;
+    } else {
+      result = normalizePath(joinPath(result, path));
+    }
+  }
+  return result;
+}
+
 function joinPath(...parts) {
   if (parts.length === 0) return "";
   let path = parts.join("/");
@@ -91,4 +103,5 @@ module.exports = {
   split: splitPath,
   basename,
   dirname,
+  resolve: resolvePath,
 };