Handle raw gzip deflate stream

Author: platypii

src/gzip.js

@@ -57,10 +57,12 @@ function shft(p) {
  * @returns {number}
  */
 function gzipStart(input, i) {
-  if (input[i++] !== 31 || input[i++] !== 139 || input[i++] !== 8) throw new Error('invalid gzip data')
+  // if missing gzip header, assume raw deflate stream
+  if (input[i++] !== 31 || input[i++] !== 139 || input[i++] !== 8) return 0
   const flag = input[i++]
-  i += 6
-  if (flag & 4) i += (input[i + 10] | input[i + 11] << 8) + 2
+  i += 6 // skip header
+  if (flag & 4) i += (input[i + 10] | input[i + 11] << 8) + 2 // skip extra
+  // skip name and comment
   for (let zs = (flag >> 3 & 1) + (flag >> 4 & 1); zs > 0; zs -= Number(!input[i++]));
   return i + (flag & 2)
 }

test/gzip.test.js

@@ -60,4 +60,45 @@ describe('gzip compressor', () => {
     const resized = gunzip(input)
     expect(resized).toEqual(new Uint8Array([11, 11, 22, 33]))
   })
+
+  it('gzip raw deflate stream (from avro)', () => {
+    const input = new Uint8Array([
+      13, 200, 193, 13, 130, 48, 20, 0,
+      208, 210, 113, 76, 190, 191, 41, 173,
+      5, 183, 249, 45, 63, 194, 161, 208,
+      180, 128, 113, 19, 227, 213, 33, 188,
+      58, 5, 94, 117, 3, 71, 208, 119, 124,
+      207, 170, 212, 116, 68, 236, 47, 137,
+      115, 162, 76, 17, 134, 192, 158, 243,
+      9, 207, 148, 185, 159, 150, 194, 232,
+      151, 113, 28, 184, 96, 228, 153, 58,
+      154, 9, 169, 177, 173, 171, 217, 128,
+      81, 170, 5, 19, 60, 65, 227, 44,
+      131, 213, 174, 33, 29, 14, 74, 187,
+      14, 162, 218, 211, 154, 167, 45, 9,
+      33, 229, 245, 241, 250, 188, 111, 219,
+      253, 91, 73, 33, 118, 255, 17, 63,
+    ])
+    const expected = new Uint8Array([
+      192, 1, 115, 51, 97, 58, 47, 47,
+      104, 121, 112, 101, 114, 112, 97, 114,
+      97, 109, 45, 105, 99, 101, 98, 101,
+      114, 103, 47, 119, 97, 114, 101, 104,
+      111, 117, 115, 101, 47, 98, 117, 110,
+      110, 105, 101, 115, 47, 109, 101, 116,
+      97, 100, 97, 116, 97, 47, 97, 56,
+      53, 57, 55, 51, 101, 52, 45, 52,
+      48, 48, 57, 45, 52, 99, 98, 97,
+      45, 56, 55, 53, 101, 45, 53, 50,
+      55, 56, 97, 50, 99, 54, 48, 50,
+      55, 100, 45, 109, 48, 46, 97, 118,
+      114, 111, 214, 112, 0, 0, 2, 2,
+      152, 183, 215, 225, 224, 154, 214, 163,
+      240, 1, 2, 0, 0, 42, 0, 0,
+      2, 0,
+    ])
+
+    const output = gunzip(input)
+    expect(output).toEqual(expected)
+  })
 })