Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

internal/exec: Fix stdio pipe problems #2021

Merged
merged 1 commit into from
Feb 12, 2024
Merged
Changes from all commits
Commits
File filter

Filter by extension

Filter by extension

Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
53 changes: 19 additions & 34 deletions internal/exec/exec.go
Original file line number Diff line number Diff line change
Expand Up @@ -15,8 +15,7 @@ import (
)

var (
errProcNotStarted = errors.New("process has not started yet")
errProcNotFinished = errors.New("process has not finished yet")
errProcNotStarted = errors.New("process has not started yet")
)

// Exec is an object that represents an external process. A user should NOT initialize one manually and instead should
Expand Down Expand Up @@ -44,7 +43,6 @@ type Exec struct {
// stdioPipesProcSide are the stdio pipes that will be passed into the process. These should not be interacted with at all
// and aren't exposed in any way to a user of Exec.
stdioPipesProcSide [3]*os.File
attrList *windows.ProcThreadAttributeListContainer
*execConfig
}

Expand Down Expand Up @@ -122,10 +120,11 @@ func (e *Exec) Start() error {
// 2. Pseudo console setup if one was requested.
// 3. Inherit only stdio handles if ones were requested.
// Therefore we need a list of size 3.
e.attrList, err = windows.NewProcThreadAttributeList(3)
attrList, err := windows.NewProcThreadAttributeList(3)
if err != nil {
return fmt.Errorf("failed to initialize process thread attribute list: %w", err)
}
defer attrList.Delete()

// Need to know whether the process needs to inherit stdio handles. The below setup is so that we only inherit the
// stdio pipes and nothing else into the new process.
Expand All @@ -139,7 +138,7 @@ func (e *Exec) Start() error {
}

// Set up the process to only inherit stdio handles and nothing else.
err := e.attrList.Update(
err := attrList.Update(
windows.PROC_THREAD_ATTRIBUTE_HANDLE_LIST,
unsafe.Pointer(&handles[0]),
uintptr(len(handles))*unsafe.Sizeof(handles[0]),
Expand All @@ -161,13 +160,13 @@ func (e *Exec) Start() error {
}

if e.job != nil {
if err := e.job.UpdateProcThreadAttribute(e.attrList); err != nil {
if err := e.job.UpdateProcThreadAttribute(attrList); err != nil {
return err
}
}

if e.cpty != nil {
if err := e.cpty.UpdateProcThreadAttribute(e.attrList); err != nil {
if err := e.cpty.UpdateProcThreadAttribute(attrList); err != nil {
return err
}
}
Expand All @@ -176,7 +175,7 @@ func (e *Exec) Start() error {
pSec := &windows.SecurityAttributes{Length: uint32(unsafe.Sizeof(zeroSec)), InheritHandle: 1}
tSec := &windows.SecurityAttributes{Length: uint32(unsafe.Sizeof(zeroSec)), InheritHandle: 1}

siEx.ProcThreadAttributeList = e.attrList.List() //nolint:govet // unusedwrite: ProcThreadAttributeList will be read in syscall
siEx.ProcThreadAttributeList = attrList.List() //nolint:govet // unusedwrite: ProcThreadAttributeList will be read in syscall
siEx.Cb = uint32(unsafe.Sizeof(*siEx))
if e.execConfig.token != 0 {
err = windows.CreateProcessAsUser(
Expand Down Expand Up @@ -214,6 +213,17 @@ func (e *Exec) Start() error {
_ = windows.CloseHandle(windows.Handle(pi.Thread))
}()

// Now that the process has started, we need to close our copies of its stdio handles.
// If we keep these around, then our ends of the pipes won't ever reach "EOF" after the process exits.
for i := range e.stdioPipesProcSide {
if e.stdioPipesProcSide[i] != nil {
if err := e.stdioPipesProcSide[i].Close(); err != nil {
return fmt.Errorf("close process's stdio handle %d: %w", i, err)
}
e.stdioPipesProcSide[i] = nil
}
}

// Grab an *os.Process to avoid reinventing the wheel here. The stdlib has great logic around waiting, exit code status/cleanup after a
// process has been launched.
e.process, err = os.FindProcess(int(pi.ProcessId))
Expand All @@ -236,16 +246,6 @@ func (e *Exec) Run() error {
return e.Wait()
}

// Close will release resources tied to the process (stdio etc.)
func (e *Exec) close() error {
if e.procState == nil {
return errProcNotFinished
}
e.attrList.Delete()
e.closeStdio()
return nil
}

// Pid returns the pid of the running process. If the process isn't running, this will return -1.
func (e *Exec) Pid() int {
if e.process == nil {
Expand Down Expand Up @@ -284,7 +284,7 @@ func (e *Exec) Wait() (err error) {
if err != nil {
return err
}
return e.close()
return nil
}

// Kill will forcefully kill the process.
Expand Down Expand Up @@ -386,21 +386,6 @@ func (e *Exec) setupStdio() error {
return nil
}

func (e *Exec) closeStdio() {
for i, file := range e.stdioPipesOurSide {
if file != nil {
file.Close()
}
e.stdioPipesOurSide[i] = nil
}
for i, file := range e.stdioPipesProcSide {
if file != nil {
file.Close()
}
e.stdioPipesProcSide[i] = nil
}
}

//
// Below are a bunch of helpers for working with Windows' CreateProcess family of functions. These are mostly exact copies of the same utilities
// found in the go stdlib.
Expand Down
Loading