fs: support pseudofiles in promises.readFile

PR-URL: #21497 Fixes: #21331 Refs: http://pubs.opengroup.org/onlinepubs/9699919799/functions/read.html Refs: https://groups.google.com/forum/#!topic/nodejs-dev/rxZ_RoH1Gn0 Reviewed-By: Gus Caplan <me@gus.host> Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
nodejs · Jun 24, 2018 · 4fa7150962621cc4d68640c37cbbb7967780b7a9 · 4fa7150
1 parent 6f8ebc0
commit 4fa7150962621cc4d68640c37cbbb7967780b7a9
Unified Split

Showing with 57 additions and 21 deletions.

+9 −8 lib/internal/fs/promises.js

+17 −0 test/parallel/test-fs-promises-file-handle-readFile.js

+31 −13 test/parallel/test-fs-promises-readfile.js
diff --git a/lib/internal/fs/promises.js b/lib/internal/fs/promises.js
@@ -125,6 +125,10 @@ async function writeFileHandle(filehandle, data, options) {
  } while (remaining > 0);
 }
+  
+// Note: This is different from kReadFileBufferLength used for non-promisified
+  
+// fs.readFile.
+  
+const kReadFileMaxChunkSize = 16384;
+  
+
 async function readFileHandle(filehandle, options) {
  const statFields = await binding.fstat(filehandle.fd, false, kUsePromises);
@@ -135,22 +139,19 @@ async function readFileHandle(filehandle, options) {
    size = 0;
  }
-  
-  if (size === 0)
-  
-    return options.encoding ? '' : Buffer.alloc(0);
-  
-
  if (size > kMaxLength)
    throw new ERR_FS_FILE_TOO_LARGE(size);
  const chunks = [];
-  
-  const chunkSize = Math.min(size, 16384);
-  
-  let totalRead = 0;
+  
+  const chunkSize = size === 0 ?
+  
+    kReadFileMaxChunkSize :
+  
+    Math.min(size, kReadFileMaxChunkSize);
  let endOfFile = false;
  do {
    const buf = Buffer.alloc(chunkSize);
    const { bytesRead, buffer } =
-  
-      await read(filehandle, buf, 0, chunkSize, totalRead);
-  
-    totalRead += bytesRead;
-  
-    endOfFile = bytesRead !== chunkSize;
+  
+      await read(filehandle, buf, 0, chunkSize, -1);
+  
+    endOfFile = bytesRead === 0;
    if (bytesRead > 0)
      chunks.push(buffer.slice(0, bytesRead));
  } while (!endOfFile);

diff --git a/test/parallel/test-fs-promises-file-handle-readFile.js b/test/parallel/test-fs-promises-file-handle-readFile.js
@@ -28,5 +28,22 @@ async function validateReadFile() {
  assert.deepStrictEqual(buffer, readFileData);
 }
+  
+async function validateReadFileProc() {
+  
+  // Test to make sure reading a file under the /proc directory works. Adapted
+  
+  // from test-fs-read-file-sync-hostname.js.
+  
+  // Refs:
+  
+  // - https://groups.google.com/forum/#!topic/nodejs-dev/rxZ_RoH1Gn0
+  
+  // - https://github.com/nodejs/node/issues/21331
+  
+
+  
+  // Test is Linux-specific.
+  
+  if (!common.isLinux)
+  
+    return;
+  
+
+  
+  const fileHandle = await open('/proc/sys/kernel/hostname', 'r');
+  
+  const hostname = await fileHandle.readFile();
+  
+  assert.ok(hostname.length > 0);
+  
+}
+  
+
 validateReadFile()
+  
+  .then(() => validateReadFileProc())
  .then(common.mustCall());
diff --git a/test/parallel/test-fs-promises-readfile.js b/test/parallel/test-fs-promises-readfile.js
@@ -12,17 +12,35 @@ const fn = path.join(tmpdir.path, 'large-file');
 common.crashOnUnhandledRejection();
-  
-// Creating large buffer with random content
-  
-const buffer = Buffer.from(
-  
-  Array.apply(null, { length: 16834 * 2 })
-  
-    .map(Math.random)
-  
-    .map((number) => (number * (1 << 8)))
-  
-);
-  
-
-  
-// Writing buffer to a file then try to read it
-  
-writeFile(fn, buffer)
-  
-  .then(() => readFile(fn))
-  
-  .then((readBuffer) => {
-  
-    assert.strictEqual(readBuffer.equals(buffer), true);
-  
-  })
+  
+async function validateReadFile() {
+  
+  // Creating large buffer with random content
+  
+  const buffer = Buffer.from(
+  
+    Array.apply(null, { length: 16834 * 2 })
+  
+      .map(Math.random)
+  
+      .map((number) => (number * (1 << 8)))
+  
+  );
+  
+
+  
+  // Writing buffer to a file then try to read it
+  
+  await writeFile(fn, buffer);
+  
+  const readBuffer = await readFile(fn);
+  
+  assert.strictEqual(readBuffer.equals(buffer), true);
+  
+}
+  
+
+  
+async function validateReadFileProc() {
+  
+  // Test to make sure reading a file under the /proc directory works. Adapted
+  
+  // from test-fs-read-file-sync-hostname.js.
+  
+  // Refs:
+  
+  // - https://groups.google.com/forum/#!topic/nodejs-dev/rxZ_RoH1Gn0
+  
+  // - https://github.com/nodejs/node/issues/21331
+  
+
+  
+  // Test is Linux-specific.
+  
+  if (!common.isLinux)
+  
+    return;
+  
+
+  
+  const hostname = await readFile('/proc/sys/kernel/hostname');
+  
+  assert.ok(hostname.length > 0);
+  
+}
+  
+
+  
+validateReadFile()
+  
+  .then(() => validateReadFileProc())
  .then(common.mustCall());