Fix feedback log collection.

base/strings/string_compress.cc

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/strings/string_compress.h"
+
+#if defined(USE_SYSTEM_LIBBZ2)
+#include <bzlib.h>
+#else
+#include "third_party/bzip2/bzlib.h"
+#endif
+
+#include "base/logging.h"
+
+namespace base {
+
+// This implementation is based on the Firefox MetricsService implementation.
+bool Bzip2Compress(const std::string& input, std::string* output) {
+  bz_stream stream = {0};
+  // As long as our input is smaller than the bzip2 block size, we should get
+  // the best compression.  For example, if your input was 250k, using a block
+  // size of 300k or 500k should result in the same compression ratio.  Since
+  // our data should be under 100k, using the minimum block size of 100k should
+  // allocate less temporary memory, but result in the same compression ratio.
+  int result = BZ2_bzCompressInit(&stream,
+                                  1,   // 100k (min) block size
+                                  0,   // quiet
+                                  0);  // default "work factor"
+  if (result != BZ_OK) {  // out of memory?
+    return false;
+  }
+
+  output->clear();
+
+  stream.next_in = const_cast<char*>(input.data());
+  stream.avail_in = static_cast<int>(input.size());
+  // NOTE: we don't need a BZ_RUN phase since our input buffer contains
+  //       the entire input
+  do {
+    output->resize(output->size() + 1024);
+    stream.next_out = &((*output)[stream.total_out_lo32]);
+    stream.avail_out = static_cast<int>(output->size()) - stream.total_out_lo32;
+    result = BZ2_bzCompress(&stream, BZ_FINISH);
+  } while (result == BZ_FINISH_OK);
+  if (result != BZ_STREAM_END) {  // unknown failure?
+    output->clear();
+    // TODO(jar): See if it would be better to do a CHECK() here.
+    return false;
+  }
+  result = BZ2_bzCompressEnd(&stream);
+  DCHECK(result == BZ_OK);
+
+  output->resize(stream.total_out_lo32);
+
+  return true;
+}
+
+}  // namespace base