fix: fix tar padding (#943)

ethersphere · Sep 10, 2024 · a40d5ec · a40d5ec
1 parent e6487b2
commit a40d5ec
Show file tree

Hide file tree

Showing 4 changed files with 98 additions and 40 deletions.
diff --git a/src/utils/tar-writer.browser.ts b/src/utils/tar-writer.browser.ts
@@ -5,7 +5,7 @@ import { TarStream } from './tar'
 export async function writeTar(collection: Collection, tarStream: TarStream) {
   for (const item of collection) {
     if (item.file) {
-      await tarStream.beginFile(item.path, item.file.size)
+      tarStream.beginFile(item.path, item.file.size)
       await tarStream.appendFile(new Uint8Array(await fileArrayBuffer(item.file)))
       await tarStream.endFile()
     } else {

diff --git a/src/utils/tar-writer.ts b/src/utils/tar-writer.ts
@@ -4,7 +4,7 @@ import { TarStream } from './tar'
 
 export async function writeTar(collection: Collection, tarStream: TarStream) {
   for (const item of collection) {
-    await tarStream.beginFile(item.path, item.size)
+    tarStream.beginFile(item.path, item.size)
 
     if (item.fsPath) {
       const stream = createReadStream(item.fsPath)

diff --git a/src/utils/tar.browser.ts b/src/utils/tar.browser.ts
@@ -1,6 +1,7 @@
 export class TarStream {
   pieces = [] as Uint8Array[]
   currentFileSize = 0
+
   get output() {
     return this.pieces.reduce((acc, piece) => {
       const newAcc = new Uint8Array(acc.length + piece.length)
@@ -10,54 +11,74 @@ export class TarStream {
       return newAcc
     })
   }
-  async beginFile(path: string, size: number) {
+
+  beginFile(path: string, size: number) {
     const header = createHeader(path, size)
     this.pieces.push(header)
     this.currentFileSize = 0
   }
+
   async appendFile(data: Uint8Array) {
     this.pieces.push(data)
     this.currentFileSize += data.length
   }
+
   async endFile() {
-    const padding = 512 - (this.currentFileSize % 512)
-    this.pieces.push(new Uint8Array(padding))
+    const padding = this.currentFileSize % 512 === 0 ? 0 : 512 - (this.currentFileSize % 512)
+    if (padding > 0) {
+      this.pieces.push(new Uint8Array(padding))
+    }
   }
+
   async end() {
     this.pieces.push(createEndOfArchive())
   }
 }
 
 function createHeader(path: string, size: number): Uint8Array {
-  const header = new Uint8Array(512) // Initialize header with zeros
   const encoder = new TextEncoder()
 
   function writeToBuffer(str: string, offset: number, length: number) {
     const bytes = encoder.encode(str)
     header.set(bytes.slice(0, length), offset)
   }
 
-  writeToBuffer(path, 0, 100) // File name
-  writeToBuffer('0000777', 100, 8) // File mode
-  writeToBuffer('0001750', 108, 8) // UID
-  writeToBuffer('0001750', 116, 8) // GID
-  writeToBuffer(size.toString(8).padStart(11, '0') + ' ', 124, 12) // File size
-  writeToBuffer(Math.floor(Date.now() / 1000).toString(8) + ' ', 136, 12) // Mod time
-  writeToBuffer('        ', 148, 8) // Checksum placeholder
-  writeToBuffer('0', 156, 1) // Typeflag
-  writeToBuffer('ustar  ', 257, 8) // Magic and version
-
-  for (let i = 345; i < 512; i++) {
-    header[i] = 0 // Fill remaining with zeros
-  }
+  // Initialize header with zeros
+  const header = new Uint8Array()
+  header.fill(0, 0, 512)
+
+  // File name, truncated to 100 characters if necessary
+  writeToBuffer(path.slice(0, 100).padEnd(100, '\0'), 0, 100)
+
+  // File mode (octal) and null-terminated
+  writeToBuffer('0000777\0', 100, 8)
+
+  // UID and GID (octal) and null-terminated
+  writeToBuffer('0001750\0', 108, 8) // UID
+  writeToBuffer('0001750\0', 116, 8) // GID
+
+  // File size in octal (11 chars) and null-terminated
+  writeToBuffer(size.toString(8).padStart(11, '0') + '\0', 124, 12)
+
+  // Modification time in octal and null-terminated
+  const modTime = Math.floor(new Date().getTime() / 1000)
+  writeToBuffer(modTime.toString(8).padStart(11, '0') + '\0', 136, 12)
+
+  // Checksum placeholder (8 spaces)
+  writeToBuffer('        ', 148, 8)
+
+  // Typeflag (normal file)
+  writeToBuffer('0', 156, 1)
+
+  // USTAR magic and version
+  writeToBuffer('ustar\0\0', 257, 8)
 
   // Calculate checksum
   let checksum = 0
   for (let i = 0; i < 512; i++) {
     checksum += header[i]
   }
 
-  // Write checksum
   writeToBuffer(checksum.toString(8).padStart(6, '0') + '\0 ', 148, 8)
 
   return header

diff --git a/src/utils/tar.ts b/src/utils/tar.ts
@@ -3,43 +3,80 @@ import { PassThrough } from 'stream'
 export class TarStream {
   output = new PassThrough()
   currentFileSize = 0
-  async beginFile(path: string, size: number) {
+
+  beginFile(path: string, size: number) {
     const header = createHeader(path, size)
     this.output.write(header)
     this.currentFileSize = 0
   }
+
   async appendFile(data: Uint8Array) {
     return new Promise<void>(resolve => {
-      this.output.write(data, () => {
+      if (!this.output.write(data)) {
+        this.output.once('drain', () => {
+          resolve()
+        })
+      } else {
         resolve()
-      })
+      }
       this.currentFileSize += data.length
     })
   }
+
   async endFile() {
-    const padding = 512 - (this.currentFileSize % 512)
-    this.output.write(Buffer.alloc(padding, 0))
+    const padding = this.currentFileSize % 512 === 0 ? 0 : 512 - (this.currentFileSize % 512)
+    if (padding > 0) {
+      this.output.write(Buffer.alloc(padding, 0))
+    }
   }
+
   async end() {
-    this.output.write(createEndOfArchive())
-    this.output.end()
+    return new Promise<void>(resolve => {
+      this.output.write(createEndOfArchive())
+      this.output.end(() => {
+        resolve()
+      })
+    })
   }
 }
 
 function createHeader(path: string, size: number): Uint8Array {
-  const header = Buffer.alloc(512, 0) // Initialize header with zeros
-  header.write(path, 0, 100) // File name
-  header.write('0000777', 100, 8) // File mode
-  header.write('0001750', 108, 8) // UID
-  header.write('0001750', 116, 8) // GID
-  header.write(size.toString(8).padStart(11, '0') + ' ', 124, 12) // File size
-  header.write(Math.floor(new Date().getTime() / 1000).toString(8) + ' ', 136, 12) // Mod time
-  header.write('        ', 148, 8) // Checksum placeholder
-  header.write('0', 156, 1) // Typeflag
-  header.write('ustar  ', 257, 8) // Magic and version
-  header.write('0'.repeat(8 * 12), 345, 8 * 12) // Fill remaining with zeros
-  const checksum = header.reduce((sum, elem) => sum + elem, 0)
-  header.write(checksum.toString(8).padStart(6, '0') + '\0 ', 148, 8) // Write checksum
+  // Initialize header with zeros
+  const header = Buffer.alloc(512, 0)
+
+  // File name, truncated to 100 characters if necessary
+  header.write(path.slice(0, 100).padEnd(100, '\0'), 0, 100)
+
+  // File mode (octal) and null-terminated
+  header.write('0000777\0', 100, 8)
+
+  // UID and GID (octal) and null-terminated
+  header.write('0001750\0', 108, 8) // UID
+  header.write('0001750\0', 116, 8) // GID
+
+  // File size in octal (11 chars) and null-terminated
+  header.write(size.toString(8).padStart(11, '0') + '\0', 124, 12)
+
+  // Modification time in octal and null-terminated
+  const modTime = Math.floor(new Date().getTime() / 1000)
+  header.write(modTime.toString(8).padStart(11, '0') + '\0', 136, 12)
+
+  // Checksum placeholder (8 spaces)
+  header.write('        ', 148, 8)
+
+  // Typeflag (normal file)
+  header.write('0', 156, 1)
+
+  // USTAR magic and version
+  header.write('ustar\0\0', 257, 8)
+
+  // Calculate checksum
+  let checksum = 0
+  for (let i = 0; i < 512; i++) {
+    checksum += header[i]
+  }
+
+  header.write(checksum.toString(8).padStart(6, '0') + '\0 ', 148, 8)
 
   return header
 }