gzip_test.go

Documentation: github.com/containerd/stargz-snapshotter/estargz

     1  /*
     2     Copyright The containerd Authors.
     3  
     4     Licensed under the Apache License, Version 2.0 (the "License");
     5     you may not use this file except in compliance with the License.
     6     You may obtain a copy of the License at
     7  
     8         http://www.apache.org/licenses/LICENSE-2.0
     9  
    10     Unless required by applicable law or agreed to in writing, software
    11     distributed under the License is distributed on an "AS IS" BASIS,
    12     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13     See the License for the specific language governing permissions and
    14     limitations under the License.
    15  */
    16  
    17  /*
    18     Copyright 2019 The Go Authors. All rights reserved.
    19     Use of this source code is governed by a BSD-style
    20     license that can be found in the LICENSE file.
    21  */
    22  
    23  package estargz
    24  
    25  import (
    26  	"bytes"
    27  	"compress/gzip"
    28  	"fmt"
    29  	"testing"
    30  )
    31  
    32  // TestGzipEStargz tests gzip-based eStargz
    33  func TestGzipEStargz(t *testing.T) {
    34  	CompressionTestSuite(t,
    35  		gzipControllerWithLevel(gzip.NoCompression),
    36  		gzipControllerWithLevel(gzip.BestSpeed),
    37  		gzipControllerWithLevel(gzip.BestCompression),
    38  		gzipControllerWithLevel(gzip.DefaultCompression),
    39  		gzipControllerWithLevel(gzip.HuffmanOnly),
    40  	)
    41  }
    42  
    43  func gzipControllerWithLevel(compressionLevel int) TestingControllerFactory {
    44  	return func() TestingController {
    45  		return &gzipController{&GzipCompressor{compressionLevel}, &GzipDecompressor{}}
    46  	}
    47  }
    48  
    49  type gzipController struct {
    50  	*GzipCompressor
    51  	*GzipDecompressor
    52  }
    53  
    54  func (gc *gzipController) String() string {
    55  	return fmt.Sprintf("gzip_compression_level=%v", gc.GzipCompressor.compressionLevel)
    56  }
    57  
    58  // TestStream tests the passed estargz blob contains the specified list of streams.
    59  func (gc *gzipController) TestStreams(t *testing.T, b []byte, streams []int64) {
    60  	CheckGzipHasStreams(t, b, streams)
    61  }
    62  
    63  func (gc *gzipController) DiffIDOf(t *testing.T, b []byte) string {
    64  	return GzipDiffIDOf(t, b)
    65  }
    66  
    67  // Tests footer encoding, size, and parsing of gzip-based eStargz.
    68  func TestGzipFooter(t *testing.T) {
    69  	for off := int64(0); off <= 200000; off += 1023 {
    70  		checkFooter(t, off)
    71  		checkLegacyFooter(t, off)
    72  	}
    73  }
    74  
    75  // TODO: check fallback
    76  func checkFooter(t *testing.T, off int64) {
    77  	footer := gzipFooterBytes(off)
    78  	if len(footer) != FooterSize {
    79  		t.Fatalf("for offset %v, footer length was %d, not expected %d. got bytes: %q", off, len(footer), FooterSize, footer)
    80  	}
    81  	_, got, _, err := (&GzipDecompressor{}).ParseFooter(footer)
    82  	if err != nil {
    83  		t.Fatalf("failed to parse footer for offset %d, footer: %x: err: %v",
    84  			off, footer, err)
    85  	}
    86  	if got != off {
    87  		t.Fatalf("ParseFooter(footerBytes(offset %d)) = %d; want %d", off, got, off)
    88  	}
    89  }
    90  
    91  func checkLegacyFooter(t *testing.T, off int64) {
    92  	footer := legacyFooterBytes(off)
    93  	if len(footer) != legacyFooterSize {
    94  		t.Fatalf("for offset %v, footer length was %d, not expected %d. got bytes: %q", off, len(footer), legacyFooterSize, footer)
    95  	}
    96  	_, got, _, err := (&LegacyGzipDecompressor{}).ParseFooter(footer)
    97  	if err != nil {
    98  		t.Fatalf("failed to parse legacy footer for offset %d, footer: %x: err: %v",
    99  			off, footer, err)
   100  	}
   101  	if got != off {
   102  		t.Fatalf("ParseFooter(legacyFooterBytes(offset %d)) = %d; want %d", off, got, off)
   103  	}
   104  }
   105  
   106  func legacyFooterBytes(tocOff int64) []byte {
   107  	buf := bytes.NewBuffer(make([]byte, 0, legacyFooterSize))
   108  	gz, _ := gzip.NewWriterLevel(buf, gzip.NoCompression)
   109  	gz.Header.Extra = []byte(fmt.Sprintf("%016xSTARGZ", tocOff))
   110  	gz.Close()
   111  	if buf.Len() != legacyFooterSize {
   112  		panic(fmt.Sprintf("footer buffer = %d, not %d", buf.Len(), legacyFooterSize))
   113  	}
   114  	return buf.Bytes()
   115  }
   116
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