encoding/binary: Read fails with slice of fixed-size values #64384

3052 · 2023-11-25T22:23:25Z

Go version

go version go1.21.0 windows/amd64

Reproducibility

Does this issue reproduce with the latest release?

What operating system and processor architecture are you using (`go env`)?

set GO111MODULE=
set GOARCH=amd64
set GOBIN=
set GOCACHE=C:\Users\Steven\AppData\Local\go-build
set GOENV=C:\Users\Steven\AppData\Roaming\go\env
set GOEXE=.exe
set GOEXPERIMENT=
set GOFLAGS=
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GOINSECURE=
set GOMODCACHE=C:\Users\Steven\go\pkg\mod
set GONOPROXY=
set GONOSUMDB=
set GOOS=windows
set GOPATH=C:\Users\Steven\go
set GOPRIVATE=
set GOPROXY=https://proxy.golang.org,direct
set GOROOT=D:\go
set GOSUMDB=sum.golang.org
set GOTMPDIR=
set GOTOOLCHAIN=auto
set GOTOOLDIR=D:\go\pkg\tool\windows_amd64
set GOVCS=
set GOVERSION=go1.21.0
set GCCGO=gccgo
set GOAMD64=v1
set AR=ar
set CC=gcc
set CXX=g++
set CGO_ENABLED=1
set GOMOD=NUL
set GOWORK=
set CGO_CFLAGS=-O2 -g
set CGO_CPPFLAGS=
set CGO_CXXFLAGS=-O2 -g
set CGO_FFLAGS=-O2 -g
set CGO_LDFLAGS=-O2 -g
set PKG_CONFIG=pkg-config
set GOGCCFLAGS=-m64 -mthreads -fno-caret-diagnostics -Qunused-arguments -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=C:\Windows\TEMP\go-build154863652=/tmp/go-build -gno-record-gcc-switches

What did you do?

this code gives expected result:

package main

import (
   "bytes"
   "encoding/binary"
   "fmt"
)

func main() {
   r := bytes.NewReader([]byte{1,2})
   var i [2]int8
   err := binary.Read(r, binary.BigEndian, &i)
   if err != nil {
      panic(err)
   }
   fmt.Println(i) // [1 2]
}

but if I use a slice instead, I get no error and nil output:

[]int8(nil)

What did you expect to see?

this behavior seems to disagree with the docs:

What did you see instead?

Data must be a pointer to a fixed-size value or a slice of fixed-size values.

https://godocs.io/encoding/binary#Read

The text was updated successfully, but these errors were encountered:

3052 · 2023-11-25T22:27:00Z

my mistake, you have to allocate:

package main

import (
   "bytes"
   "encoding/binary"
   "fmt"
)

func main() {
   r := bytes.NewReader([]byte{1,2})
   i := make([]int8, 2)
   err := binary.Read(r, binary.BigEndian, i)
   if err != nil {
      panic(err)
   }
   fmt.Println(i) // [1 2]
}

3052 closed this as completed Nov 25, 2023

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encoding/binary: Read fails with slice of fixed-size values #64384

encoding/binary: Read fails with slice of fixed-size values #64384

3052 commented Nov 25, 2023 •

edited

3052 commented Nov 25, 2023

encoding/binary: Read fails with slice of fixed-size values #64384

encoding/binary: Read fails with slice of fixed-size values #64384

Comments

3052 commented Nov 25, 2023 • edited

Go version

Reproducibility

What operating system and processor architecture are you using (go env)?

What did you do?

What did you expect to see?

What did you see instead?

3052 commented Nov 25, 2023

3052 commented Nov 25, 2023 •

edited

What operating system and processor architecture are you using (`go env`)?