feat(read-chunk/readChunkStrict): attach read chunk to error if small text

@vates/read-chunk/index.js

@@ -1,6 +1,7 @@
 'use strict'
 
 const assert = require('assert')
+const isUtf8 = require('isutf8')
 
 /**
  * Read a chunk of data from a stream.
@@ -81,6 +82,13 @@ exports.readChunkStrict = async function readChunkStrict(stream, size) {
 
   if (size !== undefined && chunk.length !== size) {
     const error = new Error(`stream has ended with not enough data (actual: ${chunk.length}, expected: ${size})`)
+
+    // Buffer.isUtf8 is too recent for now
+    // @todo : replace external package by Buffer.isUtf8 when the supported version of node reach 18
+
+    if (chunk.length < 1024 && isUtf8(chunk)) {
+      error.text = chunk.toString('utf8')
+    }
     Object.defineProperties(error, {
       chunk: {
         value: chunk,

@vates/read-chunk/index.test.js

@@ -102,12 +102,37 @@ describe('readChunkStrict', function () {
     assert.strictEqual(error.chunk, undefined)
   })
 
-  it('throws if stream ends with not enough data', async () => {
+  it('throws if stream ends with not enough data, utf8', async () => {
     const error = await rejectionOf(readChunkStrict(makeStream(['foo', 'bar']), 10))
     assert(error instanceof Error)
     assert.strictEqual(error.message, 'stream has ended with not enough data (actual: 6, expected: 10)')
+    assert.strictEqual(error.text, 'foobar')
     assert.deepEqual(error.chunk, Buffer.from('foobar'))
   })
+
+  it('throws if stream ends with not enough data, non utf8 ', async () => {
+    const source = [Buffer.alloc(10, 128), Buffer.alloc(10, 128)]
+    const error = await rejectionOf(readChunkStrict(makeStream(source), 30))
+    assert(error instanceof Error)
+    assert.strictEqual(error.message, 'stream has ended with not enough data (actual: 20, expected: 30)')
+    assert.strictEqual(error.text, undefined)
+    assert.deepEqual(error.chunk, Buffer.concat(source))
+  })
+
+  it('throws if stream ends with not enough data,  utf8 , long data', async () => {
+    const source = Buffer.from('a'.repeat(1500))
+    const error = await rejectionOf(readChunkStrict(makeStream([source]), 2000))
+    assert(error instanceof Error)
+    assert.strictEqual(error.message, `stream has ended with not enough data (actual: 1500, expected: 2000)`)
+    assert.strictEqual(error.text, undefined)
+    assert.deepEqual(error.chunk, source)
+  })
+
+  it('succeed', async () => {
+    const source = Buffer.from('a'.repeat(20))
+    const chunk = await readChunkStrict(makeStream([source]), 10)
+    assert.deepEqual(source.subarray(10), chunk)
+  })
 })
 
 describe('skip', function () {
@@ -134,6 +159,16 @@ describe('skip', function () {
   it('returns less size if stream ends', async () => {
     assert.deepEqual(await skip(makeStream('foo bar'), 10), 7)
   })
+
+  it('put back if it read too much', async () => {
+    let source = makeStream(['foo', 'bar'])
+    await skip(source, 1) // read part of data chunk
+    const chunk = (await readChunkStrict(source, 2)).toString('utf-8')
+    assert.strictEqual(chunk, 'oo')
+
+    source = makeStream(['foo', 'bar'])
+    assert.strictEqual(await skip(source, 3), 3) // read aligned with data chunk
+  })
 })
 
 describe('skipStrict', function () {
@@ -144,4 +179,9 @@ describe('skipStrict', function () {
     assert.strictEqual(error.message, 'stream has ended with not enough data (actual: 7, expected: 10)')
     assert.deepEqual(error.bytesSkipped, 7)
   })
+  it('succeed', async () => {
+    const source = makeStream(['foo', 'bar', 'baz'])
+    const res = await skipStrict(source, 4)
+    assert.strictEqual(res, undefined)
+  })
 })

@vates/read-chunk/package.json

@@ -33,5 +33,8 @@
   },
   "devDependencies": {
     "test": "^3.2.1"
+  },
+  "dependencies": {
+    "isutf8": "^4.0.0"
   }
 }

CHANGELOG.unreleased.md

@@ -18,6 +18,7 @@
 - [XO Config Cloud Backup] Improve wording about passphrase (PR [#6938](https://github.com/vatesfr/xen-orchestra/pull/6938))
 - [Pool] Fix IPv6 handling when adding hosts
 - [New SR] Send provided NFS version to XAPI when probing a share
+- [Backup/exports] Show more information on error ` stream has ended with not enough data (actual: xxx, expected: 512)` (PR [#6940](https://github.com/vatesfr/xen-orchestra/pull/6940))
 
 ### Packages to release
 
@@ -41,6 +42,7 @@
 - @xen-orchestra/backups minor
 - @xen-orchestra/vmware-explorer minor
 - @xen-orchestra/xapi major
+- @vates/read-chunk minor
 - complex-matcher patch
 - xen-api patch
 - xo-server patch