Compress Observatory assets

runtime/bin/main.cc

Index: runtime/bin/main.cc
diff --git a/runtime/bin/main.cc b/runtime/bin/main.cc
index f8ef12f0fc5fb1b1bcb469e9aa8ce66bc4119806..3c42d8b2828fe43af330bbeae488536b7eb51317 100644
--- a/runtime/bin/main.cc
+++ b/runtime/bin/main.cc
@@ -26,6 +26,7 @@
 #include "platform/globals.h"
 #include "platform/hashmap.h"
 #include "platform/text_buffer.h"
+#include "zlib/zlib.h"
 
 namespace dart {
 namespace bin {
@@ -1282,10 +1283,83 @@ bool RunMainIsolate(const char* script_name,
 extern unsigned int observatory_assets_archive_len;
 extern const uint8_t* observatory_assets_archive;
 
+
+// |input| is assumed to be a gzipped stream.
+// This function allocates the output buffer in the C heap and the caller
+// is responsible for freeing it.
+void Decompress(const uint8_t* input, unsigned int input_len,
+                uint8_t** output, unsigned int* output_length) {
+  ASSERT(input != NULL);
+  ASSERT(input_len > 0);
+  ASSERT(output != NULL);
+  ASSERT(output_length != NULL);
+
+  // Initialize output.
+  *output = NULL;
+  *output_length = 0;
+
+  const intptr_t kChunkSize = 256 * 1024;
+  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);
+
+  unsigned int input_cursor = 0;
+  unsigned int output_cursor = 0;
+  do {
+    // Setup input.
+    unsigned int 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.
+      unsigned int size_out = kChunkSize - strm.avail_out;
+      *output_length += size_out;
+      *output = reinterpret_cast<uint8_t*>(realloc(*output, *output_length));
+      // 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);
+}
+
+
 Dart_Handle GetVMServiceAssetsArchiveCallback() {
-  return DartUtils::MakeUint8Array(
-      observatory_assets_archive,
-      observatory_assets_archive_len);
+  uint8_t* decompressed = NULL;
+  unsigned int decompressed_len = 0;
+  Decompress(observatory_assets_archive,
+             observatory_assets_archive_len,
+             &decompressed,
+             &decompressed_len);
+  Dart_Handle tar_file = DartUtils::MakeUint8Array(decompressed,
+                                                   decompressed_len);
+  // Free decompressed memory as it has been copied into a Dart array.
+  free(decompressed);
+  return tar_file;
 }