add support for chunked reading in fs/promises

Author: mertcanaltin

lib/internal/fs/promises.js

@@ -45,7 +45,7 @@ const {
   },
 } = require('internal/errors');
 const { isArrayBufferView } = require('internal/util/types');
-
+const console = require('internal/console/global');
 const {
   constants: {
     kMaxUserId,
@@ -519,8 +519,17 @@ async function readFileHandle(filehandle, options) {
 
   let size = 0;
   let length = 0;
-  if ((statFields[1/* mode */] & S_IFMT) === S_IFREG) {
-    size = statFields[8/* size */];
+  const maxFileSize = 2 ** 31 - 1; // 2 GiB limit for file size
+
+  if ((statFields[1 /* mode */] & S_IFMT) === S_IFREG) {
+    size = statFields[8 /* size */];
+
+    if (size > maxFileSize) {
+      console.warn(
+        `Warning: File size (${size} bytes) exceeds the supported limit of ${maxFileSize} bytes. Consider using chunked reading.`,
+      );
+    }
+
     length = encoding ? MathMin(size, kReadFileBufferLength) : size;
   }
   if (length === 0) {
@@ -549,9 +558,11 @@ async function readFileHandle(filehandle, options) {
     )) ?? 0;
     totalRead += bytesRead;
 
-    if (bytesRead === 0 ||
-        totalRead === size ||
-        (bytesRead !== buffer.length && !chunkedRead && !noSize)) {
+    if (
+      bytesRead === 0 ||
+      totalRead === size ||
+      (bytesRead !== buffer.length && !chunkedRead && !noSize)
+    ) {
       const singleRead = bytesRead === totalRead;
 
       const bytesToCheck = chunkedRead ? totalRead : bytesRead;
@@ -574,9 +585,10 @@ async function readFileHandle(filehandle, options) {
       result += decoder.end(buffer);
       return result;
     }
-    const readBuffer = bytesRead !== buffer.length ?
-      buffer.subarray(0, bytesRead) :
-      buffer;
+    const readBuffer =
+      bytesRead !== buffer.length ?
+        buffer.subarray(0, bytesRead) :
+        buffer;
     if (encoding) {
       result += decoder.write(readBuffer);
     } else if (size !== 0) {
@@ -590,6 +602,7 @@ async function readFileHandle(filehandle, options) {
   }
 }
 
+
 // All of the functions are defined as async in order to ensure that errors
 // thrown cause promise rejections rather than being thrown synchronously.
 async function access(path, mode = F_OK) {

test/parallel/test-fs-promises-file-handle-readFile.js

@@ -9,6 +9,7 @@ const fs = require('node:fs');
 const {
   open,
   readFile,
+  truncate,
   writeFile,
 } = fs.promises;
 const path = require('node:path');
@@ -123,6 +124,25 @@ async function doReadAndCancel() {
 
     await fileHandle.close();
   }
+
+  // For validates the ability of the filesystem module to handle large files
+  {
+    const largeFileSize = 5 * 1024 * 1024 * 1024; // 5 GiB
+    const newFile = path.resolve(tmpDir, 'dogs-running3.txt');
+
+    if (!tmpdir.hasEnoughSpace(largeFileSize)) {
+      common.printSkipMessage(`Not enough space in ${tmpDir}`);
+    } else {
+      await writeFile(newFile, Buffer.from('0'));
+      await truncate(newFile, largeFileSize);
+
+      const fileHandle = await open(newFile, 'r');
+
+      const data = await fileHandle.readFile();
+      console.log(`File read successfully, size: ${data.length} bytes`);
+      await fileHandle.close();
+    }
+  }
 }
 
 validateReadFile()

test/parallel/test-fs-readfile.js

@@ -57,19 +57,23 @@ for (const e of fileInfo) {
 {
   const kLargeFileSize = 3 * 1024 * 1024 * 1024; // 3 GiB
 
-  const file = path.join(tmpdir.path, 'temp-large-file.txt');
-  fs.writeFileSync(file, Buffer.alloc(1024));
-  fs.truncateSync(file, kLargeFileSize);
+  if (!tmpdir.hasEnoughSpace(kLargeFileSize)) {
+    // truncateSync() will fail with ENOSPC if there is not enough space.
+    common.printSkipMessage(`Not enough space in ${tmpdir.path}`);
+  } else {
+    const file = path.join(tmpdir.path, 'temp-large-file.txt');
+    fs.writeFileSync(file, Buffer.alloc(1024));
+    fs.truncateSync(file, kLargeFileSize);
 
-  fs.readFile(file, (err, data) => {
-    if (err) {
-      console.error('Error reading file:', err);
-    } else {
-      console.log('File read successfully:', data.length);
-    }
-  });
+    fs.readFile(file, (err, data) => {
+      if (err) {
+        console.error('Error reading file:', err);
+      } else {
+        console.log('File read successfully:', data.length);
+      }
+    });
+  }
 }
-
 {
   // Test cancellation, before
   const signal = AbortSignal.abort();