♻ Read local file header separately

src/ssn/getManifest.ts

@@ -36,7 +36,7 @@ export default async function getManifest(product: Product): Promise<IManifest>
   const stream = arrayBufferToStream(ssnFile, firstFile.offset);
 
   //Extract manifest.xml file
-  await readLocalFileHeader(stream);
+  await readLocalFileHeader(stream, true);
   const patchmanifestStream = extractFileStream(firstFile, stream);
 
   //Convert ArrayBuffer to string

src/ssn/getSolidpkg.ts

@@ -41,7 +41,7 @@ export default async function getSolidpkg(product: Product, from: number, to: nu
   const stream = arrayBufferToStream(ssnFile, firstFile.offset);
 
   //Extract metafile.solid file
-  await readLocalFileHeader(stream);
+  await readLocalFileHeader(stream, skipAdditionalLength);
   const solidFileStream = extractFileStream(firstFile, stream);
   const solidFileArrayBuffer = await streamToArrayBuffer(solidFileStream);
   const solidContents = parseBencode(new DataView(solidFileArrayBuffer)) as ISolid;

src/ssn/streams/getFileFromDisks.ts

@@ -11,15 +11,14 @@ interface IGetFileFromDisksOptions {
   storedSize: number;
 }
 
-function getStream(disks: string[], index: number, offset: number, length: number = Infinity) {
+function createFileStream(disks: string[], index: number, offset: number, length: number = Infinity): fs.ReadStream {
   return fs.createReadStream(disks[index], { start: offset, end: offset + length - 1 });
 }
 
 /** Takes a list of ReadableStreams (the disks), as well as the offset and length, and returns a stream for just one file. */
-export default async function getFileFromDisks(disks: string[], { diskStart, offset, storedSize }: IGetFileFromDisksOptions): Promise<stream.Readable> {
+async function getFullStream(disks: string[], { diskStart, offset, storedSize }: IGetFileFromDisksOptions): Promise<stream.Readable> {
   let curDiskIndex = diskStart;
-  let curDisk = getStream(disks, diskStart, offset);
-  let localFileHeaderLength = 0;
+  let curDisk: fs.ReadStream = createFileStream(disks, diskStart, offset);
   let totalRead = 0;
 
   //Create new stream that concatenates disks until storedSize is reached, then ends the stream.
@@ -28,8 +27,8 @@ export default async function getFileFromDisks(disks: string[], { diskStart, off
   const onData = (chunk: Buffer) => {
     totalRead += chunk.length;
     //If we've reached the end, we can stop reading after this chunk
-    const readTooManyBytes = totalRead - (localFileHeaderLength + storedSize);
-    if (localFileHeaderLength !== 0 && readTooManyBytes >= 0) {
+    const readTooManyBytes = totalRead - storedSize;
+    if (readTooManyBytes >= 0) {
       //We can still write the whole chunk before ending the stream
       if (readTooManyBytes === 0) {
         outputStream.end(chunk);
@@ -40,6 +39,7 @@ export default async function getFileFromDisks(disks: string[], { diskStart, off
         const shortenedChunk = Buffer.alloc(shortenedLength, chunk);
         outputStream.end(shortenedChunk);
         curDisk.close();
+        curDisk.off('data', onData);
       }
     } else {
       //Nowhere near the end, so just write normally
@@ -52,10 +52,10 @@ export default async function getFileFromDisks(disks: string[], { diskStart, off
   const onEnd = () => {
     curDiskIndex += 1;
     //End if we are at end of file or end of disks
-    if (curDiskIndex >= disks.length || (localFileHeaderLength !== 0 && totalRead >= localFileHeaderLength + storedSize)) {
+    if (curDiskIndex >= disks.length || totalRead >= storedSize) {
       outputStream.end();
     } else {
-      curDisk = getStream(disks, curDiskIndex, 0, (localFileHeaderLength === 0) ? Infinity : localFileHeaderLength + storedSize - totalRead);
+      curDisk = createFileStream(disks, curDiskIndex, 0, storedSize - totalRead);
       //set up new listeners for data and end
       curDisk.on('data', onData);
       curDisk.on('end', onEnd);
@@ -67,9 +67,15 @@ export default async function getFileFromDisks(disks: string[], { diskStart, off
   curDisk.on('end', onEnd);
   curDisk.on('error', onError);
 
-  //Read local file header
-  localFileHeaderLength = await readLocalFileHeader(outputStream);
-  //now that local file header has been read, we will restrict length of stream to storedSize
-
   return outputStream;
 }
+
+export default async function getFileFromDisks(disks: string[], { diskStart, offset, storedSize }: IGetFileFromDisksOptions): Promise<stream.Readable> {
+  //read local file header
+  const headerStream = await getFullStream(disks, { diskStart, offset, storedSize: 30 });
+  const localFileHeaderLength = await readLocalFileHeader(headerStream);
+  headerStream.destroy(); //TODO
+
+  //read actual file
+  return getFullStream(disks, { diskStart, offset: offset + localFileHeaderLength, storedSize });
+}

src/ssn/streams/readLocalFileHeader.ts

@@ -16,7 +16,7 @@ function waitReadableLength(inputStream: stream.Readable, minLength: number): Pr
  * each stored file, and advances the stream accordingly.
  * Returns length of the local file header.
  */
-export default async function readLocalFileHeader(inputStream: stream.Readable): Promise<number> {
+export default async function readLocalFileHeader(inputStream: stream.Readable, skipAdditionalLength = false): Promise<number> {
   let localFileHeader: Buffer = inputStream.read(30);
   if (localFileHeader === null) {
     //need to wait until data is ready for reading
@@ -37,7 +37,7 @@ export default async function readLocalFileHeader(inputStream: stream.Readable):
 
   //skip local file name and extra field
   const additionalLength = localFilenameSize + localExtraSize;
-  if (additionalLength > 0) {
+  if (skipAdditionalLength && additionalLength > 0) {
     await waitReadableLength(inputStream, additionalLength);
     const tmpChunk = inputStream.read(additionalLength);
     if (tmpChunk === null) {