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//go:build freebsd || openbsd || netbsd || dragonfly || darwin || linux || solaris
// +build freebsd openbsd netbsd dragonfly darwin linux solaris
package internal
import (
"os"
"golang.org/x/sys/unix"
)
func NewOutputInterceptor() OutputInterceptor {
return &genericOutputInterceptor{
interceptedContent: make(chan string),
pipeChannel: make(chan pipePair),
shutdown: make(chan interface{}),
implementation: &dupSyscallOutputInterceptorImpl{},
}
}
type dupSyscallOutputInterceptorImpl struct{}
func (impl *dupSyscallOutputInterceptorImpl) CreateStdoutStderrClones() (*os.File, *os.File) {
// To clone stdout and stderr we:
// First, create two clone file descriptors that point to the stdout and stderr file descriptions
stdoutCloneFD, _ := unix.Dup(1)
stderrCloneFD, _ := unix.Dup(2)
// Important, set the fds to FD_CLOEXEC to prevent them leaking into childs
// https://github.com/onsi/ginkgo/issues/1191
flags, err := unix.FcntlInt(uintptr(stdoutCloneFD), unix.F_GETFD, 0)
if err == nil {
unix.FcntlInt(uintptr(stdoutCloneFD), unix.F_SETFD, flags|unix.FD_CLOEXEC)
}
flags, err = unix.FcntlInt(uintptr(stderrCloneFD), unix.F_GETFD, 0)
if err == nil {
unix.FcntlInt(uintptr(stderrCloneFD), unix.F_SETFD, flags|unix.FD_CLOEXEC)
}
// And then wrap the clone file descriptors in files.
// One benefit of this (that we don't use yet) is that we can actually write
// to these files to emit output to the console even though we're intercepting output
stdoutClone := os.NewFile(uintptr(stdoutCloneFD), "stdout-clone")
stderrClone := os.NewFile(uintptr(stderrCloneFD), "stderr-clone")
//these clones remain alive throughout the lifecycle of the suite and don't need to be recreated
//this speeds things up a bit, actually.
return stdoutClone, stderrClone
}
func (impl *dupSyscallOutputInterceptorImpl) ConnectPipeToStdoutStderr(pipeWriter *os.File) {
// To redirect output to our pipe we need to point the 1 and 2 file descriptors (which is how the world tries to log things)
// to the write end of the pipe.
// We do this with Dup2 (possibly Dup3 on some architectures) to have file descriptors 1 and 2 point to the same file description as the pipeWriter
// This effectively shunts data written to stdout and stderr to the write end of our pipe
unix.Dup2(int(pipeWriter.Fd()), 1)
unix.Dup2(int(pipeWriter.Fd()), 2)
}
func (impl *dupSyscallOutputInterceptorImpl) RestoreStdoutStderrFromClones(stdoutClone *os.File, stderrClone *os.File) {
// To restore stdour/stderr from the clones we have the 1 and 2 file descriptors
// point to the original file descriptions that we saved off in the clones.
// This has the added benefit of closing the connection between these descriptors and the write end of the pipe
// which is important to cause the io.Copy on the pipe.Reader to end.
unix.Dup2(int(stdoutClone.Fd()), 1)
unix.Dup2(int(stderrClone.Fd()), 2)
}
func (impl *dupSyscallOutputInterceptorImpl) ShutdownClones(stdoutClone *os.File, stderrClone *os.File) {
// We're done with the clones so we can close them to clean up after ourselves
stdoutClone.Close()
stderrClone.Close()
}
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