zlib: support concatenated archives

src/node_zlib.cc

@@ -41,6 +41,9 @@ enum node_zlib_mode {
   UNZIP
 };
 
+#define GZIP_HEADER_ID1 0x1f
+#define GZIP_HEADER_ID2 0x8b
+#define GZIP_MIN_HEADER_SIZE 10
 
 void InitZlib(v8::Local<v8::Object> target);
 
@@ -254,6 +257,19 @@ class ZCtx : public AsyncWrap {
             ctx->err_ = Z_NEED_DICT;
           }
         }
+        while (ctx->strm_.avail_in >= GZIP_MIN_HEADER_SIZE &&
+               ctx->mode_ == GUNZIP) {
+          // Bytes remain in input buffer. Perhaps this is another compressed
+          // member in the same archive, or just trailing garbage.
+          // Check the header to find out.
+          if (ctx->strm_.next_in[0] != GZIP_HEADER_ID1 ||
+              ctx->strm_.next_in[1] != GZIP_HEADER_ID2) {
+            // Not a valid gzip member
+            break;
+          }
+          Reset(ctx);
+          ctx->err_ = inflate(&ctx->strm_, ctx->flush_);
+        }
         break;
       default:
         CHECK(0 && "wtf?");
@@ -524,10 +540,12 @@ class ZCtx : public AsyncWrap {
     switch (ctx->mode_) {
       case DEFLATE:
       case DEFLATERAW:
+      case GZIP:
         ctx->err_ = deflateReset(&ctx->strm_);
         break;
       case INFLATE:
       case INFLATERAW:
+      case GUNZIP:
         ctx->err_ = inflateReset(&ctx->strm_);
         break;
       default:

test/parallel/test-zlib-from-concatenated-gzip.js

@@ -0,0 +1,18 @@
+'use strict';
+// Test unzipping a gzip file that contains multiple concatenated "members"
+
+const common = require('../common');
+const assert = require('assert');
+const zlib = require('zlib');
+
+const data = Buffer.concat([
+  zlib.gzipSync('abc'),
+  zlib.gzipSync('def')
+]);
+
+assert.equal(zlib.gunzipSync(data).toString(), 'abcdef');
+
+zlib.gunzip(data, common.mustCall((err, result) => {
+  assert.ifError(err);
+  assert.equal(result, 'abcdef', 'result should match original string');
+}));

test/parallel/test-zlib-from-gzip-with-trailing-garbage.js

@@ -0,0 +1,50 @@
+'use strict';
+// test unzipping a gzip file that has trailing garbage
+
+const common = require('../common');
+const assert = require('assert');
+const zlib = require('zlib');
+
+// should ignore trailing null-bytes
+let data = Buffer.concat([
+  zlib.gzipSync('abc'),
+  zlib.gzipSync('def'),
+  Buffer(10).fill(0)
+]);
+
+assert.equal(zlib.gunzipSync(data).toString(), 'abcdef');
+
+zlib.gunzip(data, common.mustCall((err, result) => {
+  assert.ifError(err);
+  assert.equal(result, 'abcdef', 'result should match original string');
+}));
+
+// if the trailing garbage happens to look like a gzip header, it should
+// throw an error.
+data = Buffer.concat([
+  zlib.gzipSync('abc'),
+  zlib.gzipSync('def'),
+  Buffer([0x1f, 0x8b, 0xff, 0xff]),
+  Buffer(10).fill(0)
+]);
+
+assert.throws(() => zlib.gunzipSync(data));
+
+zlib.gunzip(data, common.mustCall((err, result) => {
+  assert(err);
+}));
+
+// In this case the trailing junk is too short to be a gzip segment
+// So we ignore it and decompression succeeds.
+data = Buffer.concat([
+  zlib.gzipSync('abc'),
+  zlib.gzipSync('def'),
+  Buffer([0x1f, 0x8b, 0xff, 0xff])
+]);
+
+assert.equal(zlib.gunzipSync(data).toString(), 'abcdef');
+
+zlib.gunzip(data, common.mustCall((err, result) => {
+  assert.ifError(err);
+  assert.equal(result, 'abcdef', 'result should match original string');
+}));