Go version
go version go1.24.6 linux/amd64
Output of go env in your module/workspace:
AR='ar'
CC='gcc'
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_ENABLED='1'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
CXX='g++'
GCCGO='gccgo'
GO111MODULE=''
GOAMD64='v1'
GOARCH='amd64'
GOAUTH='netrc'
GOBIN=''
GOCACHE='/home/vboxuser/.cache/go-build'
GOCACHEPROG=''
GODEBUG=''
GOENV='/home/vboxuser/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFIPS140='off'
GOFLAGS=''
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build4029059829=/tmp/go-build -gno-record-gcc-switches'
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMOD='/dev/null'
GOMODCACHE='/home/vboxuser/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/home/vboxuser/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/usr/local/go'
GOSUMDB='sum.golang.org'
GOTELEMETRY='local'
GOTELEMETRYDIR='/home/vboxuser/.config/go/telemetry'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/usr/local/go/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.24.6'
GOWORK=''
PKG_CONFIG='pkg-config'
What did you do?
I'm trying to start again Cmd if the first try was unsuccessful. However, Cmd.Wait() returns an error if it is OK with command.
The cause is that the goroutines are saved from the first try but the pipes are closed. The process is not started that's why parentsIOPipes will be closed. And if this function try to read from pipe then the we will get the error.
Example:
package main
import (
"bytes"
"fmt"
"os/exec"
)
func main() {
var stdout2 bytes.Buffer
cmd := exec.Command("bash", "-c", "sleep 10")
cmd.Stdout = &stdout2
var str string
// Set 0 to env to return err in cmd.Start()
str = string([]byte{0})
cmd.Env = []string{str}
err := cmd.Start()
fmt.Println(err)
cmd.Env = nil
err = cmd.Start()
fmt.Println(err)
err = cmd.Wait()
fmt.Println(err)
}Example where cmd.Start is called twice - https://github.com/opencontainers/runc/blob/v1.4.0/libcontainer/process_linux.go#L370
What did you see happen?
vboxuser@vboxuser:~/golang-bug$ go run main.go
exec: environment variable contains NUL
<nil>
read |0: file already closed
What did you expect to see?
Cmd.Wait() do not return an error. If c.goroutine = nil is set in defer function then the error is not returned.
vboxuser@vboxuser:~/golang-bug$ go run main.go
exec: environment variable contains NUL
<nil>
<nil>
Go version
go version go1.24.6 linux/amd64
Output of
go envin your module/workspace:What did you do?
I'm trying to start again Cmd if the first try was unsuccessful. However, Cmd.Wait() returns an error if it is OK with command.
The cause is that the goroutines are saved from the first try but the pipes are closed. The process is not started that's why parentsIOPipes will be closed. And if this function try to read from pipe then the we will get the error.
Example:
Example where cmd.Start is called twice - https://github.com/opencontainers/runc/blob/v1.4.0/libcontainer/process_linux.go#L370
What did you see happen?
What did you expect to see?
Cmd.Wait() do not return an error. If c.goroutine = nil is set in defer function then the error is not returned.