[standalone] Automatically decompress gzip'd resources, including sources and script snapshots.

runtime/bin/gzip.cc

Index: runtime/bin/gzip.cc
diff --git a/runtime/bin/gzip.cc b/runtime/bin/gzip.cc
new file mode 100644
index 0000000000000000000000000000000000000000..ebeb408261076a50dd1a73dc274be0ad92cec45a
--- /dev/null
+++ b/runtime/bin/gzip.cc
@@ -0,0 +1,86 @@
+// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#include "bin/gzip.h"
+
+#include "platform/assert.h"
+#include "platform/globals.h"
+#include "zlib/zlib.h"
+
+namespace dart {
+namespace bin {
+
+void Decompress(const uint8_t* input,
+                intptr_t input_len,
+                uint8_t** output,
+                intptr_t* output_length) {
+  ASSERT(input != NULL);
+  ASSERT(input_len > 0);
+  ASSERT(output != NULL);
+  ASSERT(output_length != NULL);
+
+  const intptr_t kChunkSize = 256 * 1024;
+
+  // Initialize output.
+  intptr_t output_capacity = input_len * 2;
+  if (output_capacity < kChunkSize) {
+    output_capacity = kChunkSize;
+  }
+  *output = reinterpret_cast<uint8_t*>(malloc(output_capacity));
+
+  uint8_t chunk_out[kChunkSize];
+  z_stream strm;
+  strm.zalloc = Z_NULL;
+  strm.zfree = Z_NULL;
+  strm.opaque = Z_NULL;
+  strm.avail_in = 0;
+  strm.next_in = 0;
+  int ret = inflateInit2(&strm, 32 + MAX_WBITS);
+  ASSERT(ret == Z_OK);
+
+  intptr_t input_cursor = 0;
+  intptr_t output_cursor = 0;
+  do {
+    // Setup input.
+    intptr_t size_in = input_len - input_cursor;
+    if (size_in > kChunkSize) {
+      size_in = kChunkSize;
+    }
+    strm.avail_in = size_in;
+    strm.next_in = const_cast<uint8_t*>(&input[input_cursor]);
+
+    // Inflate until we've exhausted the current input chunk.
+    do {
+      // Setup output.
+      strm.avail_out = kChunkSize;
+      strm.next_out = &chunk_out[0];
+      // Inflate.
+      ret = inflate(&strm, Z_SYNC_FLUSH);
+      // We either hit the end of the stream or made forward progress.
+      ASSERT((ret == Z_STREAM_END) || (ret == Z_OK));
+      // Grow output buffer size.
+      intptr_t size_out = kChunkSize - strm.avail_out;
+      if (size_out > (output_capacity - output_cursor)) {
+        output_capacity *= 2;
+        ASSERT(size_out <= (output_capacity - output_cursor));
+        *output = reinterpret_cast<uint8_t*>(realloc(*output, output_capacity));
+      }
+      // Copy output.
+      memmove(&((*output)[output_cursor]), &chunk_out[0], size_out);
+      output_cursor += size_out;
+    } while (strm.avail_out == 0);
+
+    // We've processed size_in bytes.
+    input_cursor += size_in;
+
+    // We're finished decompressing when zlib tells us.
+  } while (ret != Z_STREAM_END);
+
+  inflateEnd(&strm);
+
+  *output_length = output_cursor;
+}
+
+}  // namespace bin
+}  // namespace dart