// Copyright 2008, Google Inc.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
//  1. Redistributions of source code must retain the above copyright notice,
//     this list of conditions and the following disclaimer.
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//     this list of conditions and the following disclaimer in the documentation
//     and/or other materials provided with the distribution.
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//     used to endorse or promote products derived from this software without
//     specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
// WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
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// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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#ifdef OFFICIAL_BUILD
// The blob API has not been finalized for official builds
#else

#include <assert.h>

#include "gears/blob/slice_blob.h"

SliceBlob::SliceBlob(BlobInterface *source, int64 offset, int64 length)
    : blob_(source), offset_(offset), length_(length) {
  // We explicitly allow offset and length to indicate a slice that extends
  // beyond the end of the source blob, although Read will return no data for
  // that portion.
  assert(offset_ >= 0);
  assert(length_ >= 0);
}

int64 SliceBlob::Read(uint8 *destination, int64 offset, int64 max_bytes) const {
  if (offset < 0 || max_bytes < 0) {
    return -1;
  }
  if (offset >= length_) {
    return 0;
  }
  int64 available = length_ - offset;
  if (available > max_bytes) {
    available = max_bytes;
  }
  return blob_->Read(destination, offset_ + offset, available);
}

int64 SliceBlob::Length() const {
  return length_;
}

#endif  // not OFFICIAL_BUILD