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License: zlib License
Ultra fast native zlib implementation for golang using cgo and the original zlib library written in C by Jean-loup Gailly and Mark Adler.
License: zlib License
Hi,
I noticed that Read() does not adhere to the io.Reader specifications;.
The specification says Read reads up to len(p) bytes into p
(source)
Meanwhile, the library's Read() does the following (source)
min := len(p)
if len(p) < r.outBuffer.Len() {
min = r.outBuffer.Len()
}
copy(p, r.outBuffer.Bytes()[:min])
Consequently, the read could be larger than len(p)
.
I'm wondering whether this deviation is deliberate?
Thanks!
Running the below code on AMD64 platform, MBP 2019
func main() {
var a = "i love you"
writter := zlib2.NewWriter(nil)
result := OldCompress([]byte(a))
result2, _ := writter.WriteBuffer([]byte(a), nil)
fmt.Println(result)
fmt.Println(result2)
reader, _ := zlib2.NewReader(nil)
readResult := DeCompress(result2)
_, readReuslt2, _ := reader.ReadBuffer(result2, nil)
fmt.Println(string(readResult))
fmt.Println(string(readReuslt2))
}
func OldCompress(src []byte) []byte {
var in bytes.Buffer
w := zlib.NewWriter(&in)
_, error := w.Write(src)
if error != nil {
return nil
}
error = w.Close()
if error != nil {
return nil
}
return in.Bytes()
}
func DeCompress(compressSrc []byte) []byte {
b := bytes.NewReader(compressSrc)
var out bytes.Buffer
r, error := zlib.NewReader(b)
if error != nil {
return nil
}
_, error = io.Copy(&out, r)
if error != nil {
return nil
}
return out.Bytes()
}
output:
[120 156 202 84 200 201 47 75 85 168 204 47 5 4 0 0 255 255 19 168 3 189]
[120 156 203 84 200 201 47 75 85 168 204 47 5 0 19 168 3 189]
i love you
i love you
The compressed bytes are a bit different so I would love to know why
I have the following compressor / decompressor combo:
zlibCompressorFactory := func(compressionLevel int) func(rawBytes []byte) ([]byte, error) {
return func(rawBytes []byte) ([]byte, error) {
compressedBytesBufferWriter := &bytes.Buffer{}
zlibCompressor, err := zlib.NewWriterLevel(compressedBytesBufferWriter, compressionLevel)
if err != nil {
return nil, err
}
_, err = zlibCompressor.Write(rawBytes)
zlibCompressor.Close() //dont use defer it wont work
if err != nil {
return nil, err
}
return compressedBytesBufferWriter.Bytes(), err
}
}
zlibDecompressorFactory := func() func(compressedBytes []byte) ([]byte, error) {
return func(compressedBytes []byte) ([]byte, error) {
compressedInputBuffer := bytes.NewReader(compressedBytes)
zlibDecompressor, err := zlib.NewReader(compressedInputBuffer)
if err != nil {
return nil, err
}
decompressedBytes, err := ioutil.ReadAll(zlibDecompressor)
zlibDecompressor.Close()
if err != nil {
return nil, err
}
return decompressedBytes, nil
}
}
But when trying to decompress I get the following error - this doesn't happen with "common/zlib" it only happens with "go-zlib" (tested with both golang 1.17 and 1.18):
Running tool: /usr/local/go/bin/go test -benchmem -run=^$ -bench ^Benchmark___DecompressionAndDeserializationPerformance___Json$ github.com/klauspost/compress/arena/bb-decompression-deserialization-performance
goos: linux
panic: runtime error: slice bounds out of range [:1034] with capacity 896
goroutine 21 [running]:
io.ReadAll({0xbae4e0, 0xc0002208d0})
/usr/local/go/src/io/io.go:646 +0x197
io/ioutil.ReadAll(...)
/usr/local/go/src/io/ioutil/ioutil.go:27
github.com/klauspost/compress/arena.InitCompressionTestCases.func2.1({0xc000382000, 0x2d3, 0x351})
/mnt/c/VS/laerdal/magellan-serialization-and-compression-benchmarks-testbed/arena/initialize-alternative-datasources-from-main-datasource.go:210 +0x9f
github.com/klauspost/compress/arena/bb-decompression-deserialization-performance.Benchmark___DecompressionAndDeserializationPerformance___Json.func1(0xc0001f6240)
/mnt/c/VS/laerdal/magellan-serialization-and-compression-benchmarks-testbed/arena/bb-decompression-deserialization-performance/xaa_json_test.go:40 +0x3c3
testing.(*B).runN(0xc0001f6240, 0x1)
/usr/local/go/src/testing/benchmark.go:193 +0x102
testing.(*B).run1.func1()
/usr/local/go/src/testing/benchmark.go:233 +0x59
created by testing.(*B).run1
/usr/local/go/src/testing/benchmark.go:226 +0x9c
exit status 2
FAIL github.com/klauspost/compress/arena/bb-decompression-deserialization-performance 0.018s
FAIL
What gives?
README.md shows an alternative method for decompressing data using ReadBytes()
method. Was this method removed?
good libs and wonder if some function equal to zlib.h 's uncompress function
When I tried to build my go project on arm64 Ubuntu 18.04, it failed to build and the error message is:
# github.com/4kills/go-zlib/native
/usr/bin/ld: ../../../go/pkg/mod/github.com/4kills/[email protected]/native/libs/linuxlibz.a(deflate.o): Relocations in generic ELF (EM: 62)
/usr/bin/ld: ../../../go/pkg/mod/github.com/4kills/[email protected]/native/libs/linuxlibz.a(deflate.o): Relocations in generic ELF (EM: 62)
/usr/bin/ld: ../../../go/pkg/mod/github.com/4kills/[email protected]/native/libs/linuxlibz.a(deflate.o): Relocations in generic ELF (EM: 62)
/usr/bin/ld: ../../../go/pkg/mod/github.com/4kills/[email protected]/native/libs/linuxlibz.a: error adding symbols: file in wrong format
collect2: error: ld returned 1 exit status
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