feat: new gps remover

package.json

@@ -57,7 +57,6 @@
     "cross-env": "^7.0.3",
     "dayjs": "^1.11.13",
     "dotenv": "^16.5.0",
-    "exif-be-gone": "^1.5.1",
     "fast-glob": "^3.3.3",
     "fastify": "^5.3.3",
     "fastify-plugin": "^5.0.1",

pnpm-lock.yaml

@@ -101,9 +101,6 @@ importers:
       dotenv:
         specifier: ^16.5.0
         version: 16.5.0
-      exif-be-gone:
-        specifier: ^1.5.1
-        version: 1.5.1
       fast-glob:
         specifier: ^3.3.3
         version: 3.3.3
@@ -2818,10 +2815,6 @@ packages:
     resolution: {integrity: sha512-mQw+2fkQbALzQ7V0MY0IqdnXNOeTtP4r0lN9z7AAawCXgqea7bDii20AYrIBrFd/Hx0M2Ocz6S111CaFkUcb0Q==}
     engines: {node: '>=0.8.x'}
 
-  exif-be-gone@1.5.1:
-    resolution: {integrity: sha512-+fV9PoomNVR5Hmp0n1c0ZVl78/GaFrpnC0t7q4F9Aey8NcL+7Lutcez8KY2Ni30NWpvgLXawqiRFFwtdo4QgFg==}
-    hasBin: true
-
   extend@3.0.2:
     resolution: {integrity: sha512-fjquC59cD7CyW6urNXK0FBufkZcoiGG80wTuPujX590cB5Ttln20E2UB4S/WARVqhXffZl2LNgS+gQdPIIim/g==}
 
@@ -7871,8 +7864,6 @@ snapshots:
 
   events@3.3.0: {}
 
-  exif-be-gone@1.5.1: {}
-
   extend@3.0.2: {}
 
   fast-decode-uri-component@1.0.1: {}

src/lib/api/upload/upload.ts

@@ -112,9 +112,9 @@ export async function handleFile({
   let removedGps = false;
 
   if (mimetype.startsWith('image/') && config.files.removeGpsMetadata) {
-    file.buffer = await removeGps(file.buffer);
+    const removed = removeGps(file.buffer);
 
-    if (file.buffer.length < file.file.bytesRead) {
+    if (removed) {
       logger.c('gps').debug(`removed gps metadata from ${file.filename}`, {
         nsize: bytes(file.buffer.length),
         osize: bytes(file.file.bytesRead),

src/lib/gps.ts

@@ -1,27 +0,0 @@
-import ExifTransformer from 'exif-be-gone';
-import { PassThrough } from 'stream';
-
-export async function removeGps(buffer: Buffer): Promise<Buffer> {
-  return new Promise<Buffer>((resolve, reject) => {
-    const input = new PassThrough();
-    input.end(buffer);
-
-    const transformer = new ExifTransformer();
-
-    const chunks: Buffer[] = [];
-    transformer.on('data', (chunk: Buffer) => {
-      chunks.push(chunk);
-    });
-
-    transformer.once('error', (err: Error) => {
-      reject(err);
-    });
-
-    transformer.once('end', () => {
-      const stripped = Buffer.concat(chunks);
-      resolve(stripped);
-    });
-
-    input.pipe(transformer);
-  });
-}

src/lib/gps/constants.ts

@@ -0,0 +1,14 @@
+export const EXIF_JPEG_TAG = 0x45786966;
+export const EXIF_PNG_TAG = 0x65584966;
+
+export const GPS_IFD_TAG = 0x8825;
+
+export const JPEG_EXIF_TAG = 0xffd8ffe1;
+export const JPEG_APP1_TAG = 0xffe1;
+export const JPEG_JFIF_TAG = 0xffd8ffe0;
+
+export const TIFF_LE = 0x49492a00;
+export const TIFF_BE = 0x4d4d002a;
+
+export const PNG_TAG = 0x89504e47;
+export const PNG_IEND = 0x49454e44;

src/lib/gps/index.ts

@@ -0,0 +1,131 @@
+// heavily modified from @xoi/gps-metadata-remover to fit the needs of zipline
+
+import {
+  PNG_TAG,
+  PNG_IEND,
+  EXIF_PNG_TAG,
+  JPEG_EXIF_TAG,
+  JPEG_JFIF_TAG,
+  JPEG_APP1_TAG,
+  EXIF_JPEG_TAG,
+  TIFF_LE,
+  TIFF_BE,
+  GPS_IFD_TAG,
+} from './constants';
+
+function isLE(buffer: Buffer): boolean {
+  return buffer.readUInt32BE(0) === TIFF_LE;
+}
+
+function removeGpsEntries(buffer: Buffer, offset: number, le: boolean): void {
+  const numEntries = le ? buffer.readUInt16LE(offset) : buffer.readUInt16BE(offset);
+
+  const fieldsStart = offset + 2;
+  const toClear = numEntries * 12;
+  const zeroBuffer = Buffer.alloc(toClear);
+
+  zeroBuffer.copy(buffer, fieldsStart);
+}
+
+function parseExifTag(buffer: Buffer, offset: number, le: boolean) {
+  const tag = le ? buffer.readUInt16LE(offset) : buffer.readUInt16BE(offset);
+  const field = le ? buffer.readUInt16LE(offset + 2) : buffer.readUInt16BE(offset + 2);
+  const count = le ? buffer.readUInt32LE(offset + 4) : buffer.readUInt32BE(offset + 4);
+  const valueOffset = le ? buffer.readUInt32LE(offset + 8) : buffer.readUInt32BE(offset + 8);
+
+  return { tag, field, count, valueOffset };
+}
+
+function locateGpsTagOffset(buffer: Buffer, offset: number, le: boolean): number {
+  const numEntries = le ? buffer.readUInt16LE(offset) : buffer.readUInt16BE(offset);
+  const fieldsStart = offset + 2;
+
+  for (let i = 0; i < numEntries; i++) {
+    const entryOffset = fieldsStart + i * 12;
+    const { tag, field, count, valueOffset } = parseExifTag(buffer, entryOffset, le);
+
+    if (tag === GPS_IFD_TAG && field === 4 && count === 1) {
+      return valueOffset;
+    }
+  }
+
+  return -1;
+}
+
+function stripGpsFromTiff(buffer: Buffer, offset: number, le: boolean): boolean {
+  const gpsDirectoryOffset = locateGpsTagOffset(buffer, offset, le);
+
+  if (gpsDirectoryOffset >= 0) {
+    removeGpsEntries(buffer, gpsDirectoryOffset, le);
+    return true;
+  }
+
+  return false;
+}
+
+function stripGpsFromExif(buffer: Buffer, offset: number): boolean {
+  const headerSlice = buffer.subarray(offset, offset + 8);
+  const littleEndian = isLE(headerSlice);
+  const gpsDirectoryOffset = locateGpsTagOffset(buffer, offset + 8, littleEndian);
+
+  if (gpsDirectoryOffset >= 0) {
+    removeGpsEntries(buffer, gpsDirectoryOffset + offset, littleEndian);
+    return true;
+  }
+
+  return false;
+}
+
+export function removeGps(buffer: Buffer): boolean {
+  const signature = buffer.readUInt32BE(0);
+  let offset = 0;
+  let removed = false;
+
+  if (signature === PNG_TAG) {
+    offset += 8;
+
+    let chunkLength = 0;
+    let chunkType = 0;
+    while (chunkType !== PNG_IEND) {
+      chunkLength = buffer.readUInt32BE(offset);
+      chunkType = buffer.readUInt32BE(offset + 4);
+
+      if (chunkType === EXIF_PNG_TAG) {
+        const exifDataOffset = offset + 8;
+        removed = stripGpsFromExif(buffer, exifDataOffset);
+      }
+
+      if (chunkType !== PNG_IEND) {
+        offset += 12 + chunkLength;
+      }
+    }
+  } else if (signature === JPEG_EXIF_TAG || signature === JPEG_JFIF_TAG) {
+    offset += 4;
+
+    if (signature === JPEG_JFIF_TAG) {
+      const jfifSegmentSize = buffer.readUInt16BE(offset);
+      offset += jfifSegmentSize;
+      const nextMarker = buffer.readUInt16BE(offset);
+
+      if (nextMarker === JPEG_APP1_TAG) {
+        offset += 2;
+      } else {
+        return removed;
+      }
+    }
+
+    const exifSignature = buffer.readUInt32BE(offset + 2);
+
+    if (exifSignature === EXIF_JPEG_TAG) {
+      offset += 8;
+      removed = stripGpsFromExif(buffer, offset);
+    }
+  } else if (signature === TIFF_LE || signature === TIFF_BE) {
+    const littleEndian = isLE(buffer);
+    offset += 4;
+    const tiffIfdOffset = littleEndian ? buffer.readUInt32LE(offset) : buffer.readUInt32BE(offset);
+    removed = stripGpsFromTiff(buffer, tiffIfdOffset, littleEndian);
+  }
+
+  return removed;
+}