1/* Copyright 2015 The TensorFlow Authors. All Rights Reserved.
2
3Licensed under the Apache License, Version 2.0 (the "License");
4you may not use this file except in compliance with the License.
5You may obtain a copy of the License at
6
7 http://www.apache.org/licenses/LICENSE-2.0
8
9Unless required by applicable law or agreed to in writing, software
10distributed under the License is distributed on an "AS IS" BASIS,
11WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12See the License for the specific language governing permissions and
13limitations under the License.
14==============================================================================*/
15
16// See docs in ../ops/parse_ops.cc.
17
18#include <algorithm>
19#include "tensorflow/core/framework/op_kernel.h"
20#include "tensorflow/core/framework/tensor.h"
21#include "tensorflow/core/framework/tensor_shape.h"
22#include "tensorflow/core/framework/types.h"
23#include "tensorflow/core/lib/core/errors.h"
24#include "tensorflow/core/lib/io/zlib_compression_options.h"
25#include "tensorflow/core/lib/io/zlib_inputstream.h"
26
27namespace tensorflow {
28namespace {
29// Wrap memory buffer into InputStreamInterface
30class MemoryInputStream : public io::InputStreamInterface {
31 public:
32 explicit MemoryInputStream(const char* buffer, size_t length)
33 : buf_(buffer), len_(length), pos_(0) {}
34
35 ~MemoryInputStream() override {}
36
37 Status ReadNBytes(int64_t bytes_to_read, tstring* result) override {
38 result->clear();
39 if (bytes_to_read < 0) {
40 return errors::InvalidArgument("Can't read a negative number of bytes: ",
41 bytes_to_read);
42 }
43 int64_t bytes = bytes_to_read;
44 Status s = OkStatus();
45 if (pos_ + bytes_to_read > len_) {
46 bytes = len_ - pos_;
47 s = errors::OutOfRange("reached end of file");
48 }
49 if (bytes > 0) {
50 result->resize(bytes);
51 memcpy(&(*result)[0], &buf_[pos_], bytes);
52 pos_ += bytes;
53 }
54 return s;
55 }
56
57 int64_t Tell() const override { return pos_; }
58
59 Status Reset() override {
60 pos_ = 0;
61 return OkStatus();
62 }
63
64 private:
65 const char* buf_; // Not owned.
66 int64_t len_;
67 int64_t pos_ = 0; // Tracks where we are in the file.
68};
69} // namespace
70
71class DecodeCompressedOp : public OpKernel {
72 public:
73 explicit DecodeCompressedOp(OpKernelConstruction* context)
74 : OpKernel(context) {
75 OP_REQUIRES_OK(context,
76 context->GetAttr("compression_type", &compression_type_));
77 OP_REQUIRES(context,
78 (compression_type_.empty() || compression_type_ == "ZLIB" ||
79 compression_type_ == "GZIP"),
80 errors::InvalidArgument(
81 "Only ZLIB, GZIP or NONE are supported compressions"));
82 }
83
84 void Compute(OpKernelContext* context) override {
85 const Tensor* bytes_tensor;
86 OP_REQUIRES_OK(context, context->input("bytes", &bytes_tensor));
87 const auto& bytes_flat = bytes_tensor->flat<tstring>();
88
89 Tensor* output_tensor = nullptr;
90 OP_REQUIRES_OK(context,
91 context->allocate_output("output", bytes_tensor->shape(),
92 &output_tensor));
93 auto output_flat = output_tensor->flat<tstring>();
94 if (compression_type_.empty()) {
95 for (int64_t i = 0; i < bytes_flat.size(); i++) {
96 output_flat(i) = bytes_flat(i);
97 }
98 } else {
99 const io::ZlibCompressionOptions zlib_options =
100 compression_type_ == "ZLIB" ? io::ZlibCompressionOptions::DEFAULT()
101 : io::ZlibCompressionOptions::GZIP();
102 for (int64_t i = 0; i < bytes_flat.size(); i++) {
103 std::unique_ptr<MemoryInputStream> input_stream(
104 new MemoryInputStream(bytes_flat(i).data(), bytes_flat(i).size()));
105 std::unique_ptr<io::ZlibInputStream> zlib_stream(
106 new io::ZlibInputStream(
107 input_stream.get(), static_cast<size_t>(kBufferSize),
108 static_cast<size_t>(kBufferSize), zlib_options));
109 tstring output_string;
110 Status s = zlib_stream->ReadNBytes(INT_MAX, &output_string);
111 OP_REQUIRES(context, (s.ok() || errors::IsOutOfRange(s)), s);
112 output_flat(i) = std::move(output_string);
113 }
114 }
115 }
116
117 private:
118 enum { kBufferSize = 256 << 10 /* 256 kB */ };
119 string compression_type_;
120};
121
122REGISTER_KERNEL_BUILDER(Name("DecodeCompressed").Device(DEVICE_CPU),
123 DecodeCompressedOp)
124
125} // namespace tensorflow
126