chore: switched out dataview to uint8arrays

Author: aryanjassal

src/Generator.ts

@@ -4,36 +4,29 @@ import * as errors from './errors';
 import * as utils from './utils';
 import * as constants from './constants';
 
-// Computes the checksum by summing up all the bytes in the header
-function computeChecksum(header: Uint8Array): number {
-  return header.reduce((sum, byte) => sum + byte, 0);
-}
-
 function generateHeader(
   filePath: string,
   type: EntryType,
   stat: FileStat,
 ): Uint8Array {
   // TODO: implement long-file-name headers
   if (filePath.length < 1 || filePath.length > 255) {
-    throw new errors.ErrorVirtualTarInvalidFileName(
+    throw new errors.ErrorTarGeneratorInvalidFileName(
       'The file name must be longer than 1 character and shorter than 255 characters',
     );
   }
 
   // As the size does not matter for directories, it can be undefined. However,
   // if the header is being generated for a file, then it needs to have a valid
-  // size. This guard checks that.
+  // size.
   if (stat.size == null && type === EntryType.FILE) {
-    throw new errors.ErrorVirtualTarInvalidStat('Size must be set for files');
+    throw new errors.ErrorTarGeneratorInvalidStat('Size must be set for files');
   }
   const size = type === EntryType.FILE ? stat.size : 0;
 
   // The time can be undefined, which would be referring to epoch 0.
   const time = utils.dateToUnixTime(stat.mtime ?? new Date());
 
-  // Make sure to initialise the header with zeros to avoid writing nullish
-  // blocks.
   const header = new Uint8Array(constants.BLOCK_SIZE);
 
   // The TAR headers follow this structure
@@ -112,13 +105,7 @@ function generateHeader(
   );
 
   // The checksum is calculated as the sum of all bytes in the header. It is
-  // padded using ASCII spaces, as we currently don't have all the data yet.
-  utils.writeBytesToArray(
-    header,
-    utils.pad('', HeaderSize.CHECKSUM, ' '),
-    HeaderOffset.CHECKSUM,
-    HeaderSize.CHECKSUM,
-  );
+  // left blank for later calculation.
 
   // The type of file is written as a single byte in the header.
   utils.writeBytesToArray(
@@ -174,7 +161,7 @@ function generateHeader(
   );
 
   // Updating with the new checksum
-  const checksum = computeChecksum(header);
+  const checksum = utils.calculateChecksum(header);
 
   // Note the extra space in the padding for the checksum value. It is
   // intentionally placed there. The padding for checksum is ASCII spaces

src/Parser.ts

@@ -5,50 +5,86 @@ import * as constants from './constants';
 import * as errors from './errors';
 import * as utils from './utils';
 
-function parseHeader(view: DataView): HeaderToken {
-  // TODO: confirm integrity by checking against checksum
-  const filePath = utils.parseFilePath(view);
+function parseHeader(array: Uint8Array): HeaderToken {
+  // Validate header by checking checksum and magic string
+  const headerChecksum = utils.extractOctal(
+    array,
+    HeaderOffset.CHECKSUM,
+    HeaderSize.CHECKSUM,
+  );
+  const calculatedChecksum = utils.calculateChecksum(array);
+
+  if (headerChecksum !== calculatedChecksum) {
+    throw new errors.ErrorTarParserInvalidHeader(
+      `Expected checksum to be ${calculatedChecksum} but received ${headerChecksum}`,
+    );
+  }
+
+  const ustarMagic = utils.extractString(
+    array,
+    HeaderOffset.USTAR_NAME,
+    HeaderSize.USTAR_NAME,
+  );
+  if (ustarMagic !== constants.USTAR_NAME) {
+    throw new errors.ErrorTarParserInvalidHeader(
+      `Expected ustar magic to be '${constants.USTAR_NAME}', got '${ustarMagic}'`,
+    );
+  }
+
+  const ustarVersion = utils.extractString(
+    array,
+    HeaderOffset.USTAR_VERSION,
+    HeaderSize.USTAR_VERSION,
+  );
+  if (ustarVersion !== constants.USTAR_VERSION) {
+    throw new errors.ErrorTarParserInvalidHeader(
+      `Expected ustar version to be '${constants.USTAR_VERSION}', got '${ustarVersion}'`,
+    );
+  }
+
+  // Extract the relevant metadata from the header
+  const filePath = utils.parseFilePath(array);
   const fileSize = utils.extractOctal(
-    view,
+    array,
     HeaderOffset.FILE_SIZE,
     HeaderSize.FILE_SIZE,
   );
   const fileMtime = new Date(
-    utils.extractOctal(view, HeaderOffset.FILE_MTIME, HeaderSize.FILE_MTIME) *
+    utils.extractOctal(array, HeaderOffset.FILE_MTIME, HeaderSize.FILE_MTIME) *
       1000,
   );
   const fileMode = utils.extractOctal(
-    view,
+    array,
     HeaderOffset.FILE_MODE,
     HeaderSize.FILE_MODE,
   );
   const ownerGid = utils.extractOctal(
-    view,
+    array,
     HeaderOffset.OWNER_GID,
     HeaderSize.OWNER_GID,
   );
   const ownerUid = utils.extractOctal(
-    view,
+    array,
     HeaderOffset.OWNER_UID,
     HeaderSize.OWNER_UID,
   );
   const ownerName = utils.extractString(
-    view,
+    array,
     HeaderOffset.OWNER_NAME,
     HeaderSize.OWNER_NAME,
   );
   const ownerGroupName = utils.extractString(
-    view,
+    array,
     HeaderOffset.OWNER_GROUPNAME,
     HeaderSize.OWNER_GROUPNAME,
   );
   const ownerUserName = utils.extractString(
-    view,
+    array,
     HeaderOffset.OWNER_USERNAME,
     HeaderSize.OWNER_USERNAME,
   );
   const fileType =
-    utils.extractString(view, HeaderOffset.TYPE_FLAG, HeaderSize.TYPE_FLAG) ===
+    utils.extractString(array, HeaderOffset.TYPE_FLAG, HeaderSize.TYPE_FLAG) ===
     EntryType.FILE
       ? 'file'
       : 'directory';
@@ -68,11 +104,11 @@ function parseHeader(view: DataView): HeaderToken {
   };
 }
 
-function parseData(view: DataView, remainingBytes: number): DataToken {
+function parseData(array: Uint8Array, remainingBytes: number): DataToken {
   if (remainingBytes > 512) {
-    return { type: 'data', data: utils.extractBytes(view) };
+    return { type: 'data', data: utils.extractBytes(array) };
   } else {
-    const data = utils.extractBytes(view, 0, remainingBytes);
+    const data = utils.extractBytes(array, 0, remainingBytes);
     return { type: 'data', data: data };
   }
 }
@@ -83,29 +119,27 @@ class Parser {
 
   write(data: Uint8Array) {
     if (data.byteLength !== constants.BLOCK_SIZE) {
-      throw new errors.ErrorVirtualTarBlockSize(
+      throw new errors.ErrorTarParserBlockSize(
         `Expected block size to be ${constants.BLOCK_SIZE} bytes but received ${data.byteLength} bytes`,
       );
     }
 
-    const view = new DataView(data.buffer, 0, constants.BLOCK_SIZE);
-
     switch (this.state) {
       case ParserState.ENDED: {
-        throw new errors.ErrorVirtualTarEndOfArchive(
+        throw new errors.ErrorTarParserEndOfArchive(
           'Archive has already ended',
         );
       }
 
       case ParserState.READY: {
         // Check if we need to parse the end-of-archive marker
-        if (utils.checkNullView(view)) {
+        if (utils.isNullBlock(data)) {
           this.state = ParserState.NULL;
           return;
         }
 
         // Set relevant state if the header corresponds to a file
-        const headerToken = parseHeader(view);
+        const headerToken = parseHeader(data);
         if (headerToken.fileType === 'file') {
           this.state = ParserState.DATA;
           this.remainingBytes = headerToken.fileSize;
@@ -114,18 +148,18 @@ class Parser {
       }
 
       case ParserState.DATA: {
-        const parsedData = parseData(view, this.remainingBytes);
+        const parsedData = parseData(data, this.remainingBytes);
         this.remainingBytes -= 512;
         if (this.remainingBytes < 0) this.state = ParserState.READY;
         return parsedData;
       }
 
       case ParserState.NULL: {
-        if (utils.checkNullView(view)) {
+        if (utils.isNullBlock(data)) {
           this.state = ParserState.ENDED;
           return { type: 'end' } as EndToken;
         } else {
-          throw new errors.ErrorVirtualTarEndOfArchive(
+          throw new errors.ErrorTarParserEndOfArchive(
             'Received garbage data after first end marker',
           );
         }

src/constants.ts

@@ -1,3 +1,3 @@
 export const BLOCK_SIZE = 512;
-export const USTAR_NAME = 'ustar\0';
+export const USTAR_NAME = 'ustar';
 export const USTAR_VERSION = '00';

src/errors.ts

@@ -1,39 +1,49 @@
 import { AbstractError } from '@matrixai/errors';
 
-class ErrorVirtualTar<T> extends AbstractError<T> {
+class ErrorTar<T> extends AbstractError<T> {
   static description = 'VirtualTar errors';
 }
 
-class ErrorVirtualTarUndefinedBehaviour<T> extends ErrorVirtualTar<T> {
+class ErrorVirtualTarUndefinedBehaviour<T> extends ErrorTar<T> {
   static description = 'You should never see this error';
 }
 
-class ErrorVirtualTarInvalidFileName<T> extends ErrorVirtualTar<T> {
-  static description = 'The provided file name is invalid';
+class ErrorTarGenerator<T> extends ErrorTar<T> {
+  static description = 'VirtualTar genereator errors';
 }
 
-class ErrorVirtualTarInvalidHeader<T> extends ErrorVirtualTar<T> {
-  static description = 'The header has invalid data';
+class ErrorTarGeneratorInvalidFileName<T> extends ErrorTarGenerator<T> {
+  static description = 'The provided file name is invalid';
 }
 
-class ErrorVirtualTarInvalidStat<T> extends ErrorVirtualTar<T> {
+class ErrorTarGeneratorInvalidStat<T> extends ErrorTarGenerator<T> {
   static description = 'The stat contains invalid data';
 }
 
-class ErrorVirtualTarBlockSize<T> extends ErrorVirtualTar<T> {
+class ErrorTarParser<T> extends ErrorTar<T> {
+  static description = 'VirtualTar parsing errors';
+}
+
+class ErrorTarParserInvalidHeader<T> extends ErrorTarParser<T> {
+  static description = 'The checksum did not match the header';
+}
+
+class ErrorTarParserBlockSize<T> extends ErrorTarParser<T> {
   static description = 'The block size is incorrect';
 }
 
-class ErrorVirtualTarEndOfArchive<T> extends ErrorVirtualTar<T> {
+class ErrorTarParserEndOfArchive<T> extends ErrorTarParser<T> {
   static description = 'No data can come after an end-of-archive marker';
 }
 
 export {
-  ErrorVirtualTar,
+  ErrorTar,
+  ErrorTarGenerator,
   ErrorVirtualTarUndefinedBehaviour,
-  ErrorVirtualTarInvalidFileName,
-  ErrorVirtualTarInvalidHeader,
-  ErrorVirtualTarInvalidStat,
-  ErrorVirtualTarBlockSize,
-  ErrorVirtualTarEndOfArchive,
+  ErrorTarGeneratorInvalidFileName,
+  ErrorTarGeneratorInvalidStat,
+  ErrorTarParser,
+  ErrorTarParserInvalidHeader,
+  ErrorTarParserBlockSize,
+  ErrorTarParserEndOfArchive,
 };