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|
package main
import (
"errors"
"io"
"log"
"os"
"os/exec"
"reflect"
"github.com/google/shlex"
)
type pager interface {
io.WriteCloser
Running() bool
IsDone(any, int) bool
}
var pagerDone error = errors.New("paging is done")
func newPager(expected int) pager {
if !isStdoutTerminal || expected != 0 {
return &staticPager{os.Stdout, expected, 0}
}
name, ok := os.LookupEnv("PAGER")
if !ok {
name = "/usr/bin/pager"
}
commandSplit, err := shlex.Split(name)
if err != nil {
log.Fatalf("Failed to parse pager command: %v", err)
}
cmd := exec.Command(commandSplit[0], commandSplit[1:]...)
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
cmd.Env = append(os.Environ(), "LESS=FRX")
w, err := cmd.StdinPipe()
if err != nil {
log.Fatalf("Failed to create stdin pipe for pager: %v", err)
}
if err := cmd.Start(); err != nil {
log.Fatalf("Failed to start pager %q: %v", cmd.Args[0], err)
}
done := make(chan struct{})
go func() {
defer close(done)
if err := cmd.Wait(); err != nil {
log.Fatalf("Failed to run pager: %v", err)
}
}()
return &cmdPager{w, done}
}
type pagerifyFn func(p pager) error
func pagerify(fn pagerifyFn, expected int) error {
pager := newPager(expected)
defer pager.Close()
for pager.Running() {
err := fn(pager)
if err == pagerDone {
return nil
} else if err != nil {
return err
}
}
return nil
}
type staticPager struct {
io.WriteCloser
objectsExpected int
objectsGot int
}
func (p *staticPager) Write(b []byte) (int, error) {
return p.WriteCloser.Write(b)
}
func (p *staticPager) Running() bool {
return true
}
func (p *staticPager) IsDone(cursor any, objectsGot int) bool {
v := reflect.ValueOf(cursor)
if v.Kind() == reflect.Pointer && v.IsNil() {
return true
}
// TODO: Use API to request number of objects
p.objectsGot += objectsGot
return p.objectsGot >= p.objectsExpected
}
type cmdPager struct {
io.WriteCloser
done <-chan struct{}
}
func (p *cmdPager) Close() error {
if err := p.WriteCloser.Close(); err != nil {
return err
}
<-p.done
return nil
}
func (p *cmdPager) Running() bool {
select {
case <-p.done:
return false
default:
return true
}
}
func (p *cmdPager) IsDone(cursor any, _ int) bool {
v := reflect.ValueOf(cursor)
if v.Kind() == reflect.Pointer && v.IsNil() {
return true
}
return false
}
|
