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io.go
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io.go
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package containerd
import (
"context"
"fmt"
"io"
"os"
"sync"
)
// IOConfig holds the io configurations.
type IOConfig struct {
// Terminal is true if one has been allocated
Terminal bool
// Stdin path
Stdin string
// Stdout path
Stdout string
// Stderr path
Stderr string
}
// IO holds the io information for a task or process
type IO interface {
// Config returns the IO configuration.
Config() IOConfig
// Cancel aborts all current io operations
Cancel()
// Wait blocks until all io copy operations have completed
Wait()
// Close cleans up all open io resources
Close() error
}
// cio is a basic container IO implementation.
type cio struct {
config IOConfig
closer *wgCloser
}
func (c *cio) Config() IOConfig {
return c.config
}
func (c *cio) Cancel() {
if c.closer == nil {
return
}
c.closer.Cancel()
}
func (c *cio) Wait() {
if c.closer == nil {
return
}
c.closer.Wait()
}
func (c *cio) Close() error {
if c.closer == nil {
return nil
}
return c.closer.Close()
}
// IOCreation creates new IO sets for a task
type IOCreation func(id string) (IO, error)
// IOAttach allows callers to reattach to running tasks
//
// There should only be one reader for a task's IO set
// because fifo's can only be read from one reader or the output
// will be sent only to the first reads
type IOAttach func(*FIFOSet) (IO, error)
// NewIO returns an IOCreation that will provide IO sets without a terminal
func NewIO(stdin io.Reader, stdout, stderr io.Writer) IOCreation {
return NewIOWithTerminal(stdin, stdout, stderr, false)
}
// NewIOWithTerminal creates a new io set with the provied io.Reader/Writers for use with a terminal
func NewIOWithTerminal(stdin io.Reader, stdout, stderr io.Writer, terminal bool) IOCreation {
return func(id string) (_ IO, err error) {
paths, err := NewFifos(id)
if err != nil {
return nil, err
}
defer func() {
if err != nil && paths.Dir != "" {
os.RemoveAll(paths.Dir)
}
}()
cfg := IOConfig{
Terminal: terminal,
Stdout: paths.Out,
Stderr: paths.Err,
Stdin: paths.In,
}
i := &cio{config: cfg}
set := &ioSet{
in: stdin,
out: stdout,
err: stderr,
}
closer, err := copyIO(paths, set, cfg.Terminal)
if err != nil {
return nil, err
}
i.closer = closer
return i, nil
}
}
// WithAttach attaches the existing io for a task to the provided io.Reader/Writers
func WithAttach(stdin io.Reader, stdout, stderr io.Writer) IOAttach {
return func(paths *FIFOSet) (IO, error) {
if paths == nil {
return nil, fmt.Errorf("cannot attach to existing fifos")
}
cfg := IOConfig{
Terminal: paths.Terminal,
Stdout: paths.Out,
Stderr: paths.Err,
Stdin: paths.In,
}
i := &cio{config: cfg}
set := &ioSet{
in: stdin,
out: stdout,
err: stderr,
}
closer, err := copyIO(paths, set, cfg.Terminal)
if err != nil {
return nil, err
}
i.closer = closer
return i, nil
}
}
// Stdio returns an IO set to be used for a task
// that outputs the container's IO as the current processes Stdio
func Stdio(id string) (IO, error) {
return NewIO(os.Stdin, os.Stdout, os.Stderr)(id)
}
// StdioTerminal will setup the IO for the task to use a terminal
func StdioTerminal(id string) (IO, error) {
return NewIOWithTerminal(os.Stdin, os.Stdout, os.Stderr, true)(id)
}
// NullIO redirects the container's IO into /dev/null
func NullIO(id string) (IO, error) {
return &cio{}, nil
}
// FIFOSet is a set of fifos for use with tasks
type FIFOSet struct {
// Dir is the directory holding the task fifos
Dir string
// In, Out, and Err fifo paths
In, Out, Err string
// Terminal returns true if a terminal is being used for the task
Terminal bool
}
type ioSet struct {
in io.Reader
out, err io.Writer
}
type wgCloser struct {
wg *sync.WaitGroup
dir string
set []io.Closer
cancel context.CancelFunc
}
func (g *wgCloser) Wait() {
g.wg.Wait()
}
func (g *wgCloser) Close() error {
for _, f := range g.set {
f.Close()
}
if g.dir != "" {
return os.RemoveAll(g.dir)
}
return nil
}
func (g *wgCloser) Cancel() {
g.cancel()
}