Files
fn_registry/functions/infra/pty_capture_idle.go
T
2026-06-04 23:44:39 +02:00

150 lines
3.3 KiB
Go

package infra
import (
"bytes"
"context"
"fmt"
"os/exec"
"sync"
"syscall"
"time"
"github.com/creack/pty"
)
// PTYCaptureIdle launches a command inside a pseudo-terminal (PTY) and captures
// all output until the terminal has been idle for at least idle duration, or
// maxDur has elapsed. Before sending inputs it waits warmup to let the process
// initialize. Between each input step it waits stepDelay.
//
// The returned string is the raw PTY output, ANSI escape sequences included.
// To turn it into plain text: use vt_render_go_tui to reconstruct the 2D screen
// layout for TUIs with absolute cursor positioning (claude, htop), or
// strip_ansi_go_core for sequential, log-like output.
func PTYCaptureIdle(
ctx context.Context,
name string,
args []string,
warmup time.Duration,
inputs []string,
stepDelay time.Duration,
idle time.Duration,
maxDur time.Duration,
) (string, error) {
cmd := exec.CommandContext(ctx, name, args...)
ptmx, err := pty.Start(cmd)
if err != nil {
return "", fmt.Errorf("pty_capture_idle: pty.Start: %w", err)
}
// Set a reasonable terminal size so TUIs render without truncating.
if szErr := pty.Setsize(ptmx, &pty.Winsize{Rows: 40, Cols: 120}); szErr != nil {
// Non-fatal: continue even if resize fails.
_ = szErr
}
var (
mu sync.Mutex
buf bytes.Buffer
lastByte = time.Now()
)
// Reader goroutine: copy PTY output into buf and track last-byte time.
readDone := make(chan struct{})
go func() {
defer close(readDone)
tmp := make([]byte, 4096)
for {
n, rerr := ptmx.Read(tmp)
if n > 0 {
mu.Lock()
buf.Write(tmp[:n])
lastByte = time.Now()
mu.Unlock()
}
if rerr != nil {
// EIO/EOF is normal on Linux when the PTY master is closed
// after the child exits. Not a real error.
return
}
}
}()
start := time.Now()
// Wait for warmup so the TUI/CLI has time to initialize.
select {
case <-time.After(warmup):
case <-ctx.Done():
_ = ptmx.Close()
<-readDone
mu.Lock()
out := buf.String()
mu.Unlock()
return out, fmt.Errorf("pty_capture_idle: context cancelled during warmup: %w", ctx.Err())
}
// Send inputs one by one with stepDelay between them.
for _, in := range inputs {
if _, werr := ptmx.Write([]byte(in)); werr != nil {
// PTY may have closed already; stop sending.
break
}
select {
case <-time.After(stepDelay):
case <-ctx.Done():
goto done
}
}
done:
// Poll until idle or maxDur.
ticker := time.NewTicker(100 * time.Millisecond)
defer ticker.Stop()
for {
select {
case <-ticker.C:
mu.Lock()
sinceLastByte := time.Since(lastByte)
mu.Unlock()
elapsed := time.Since(start)
if sinceLastByte >= idle || elapsed >= maxDur {
goto shutdown
}
case <-ctx.Done():
goto shutdown
}
}
shutdown:
// Close the PTY master. This signals EOF to the reader goroutine.
_ = ptmx.Close()
// Graceful shutdown: SIGTERM first, then SIGKILL after 2s.
if cmd.Process != nil {
_ = cmd.Process.Signal(syscall.SIGTERM)
killTimer := time.NewTimer(2 * time.Second)
waitCh := make(chan error, 1)
go func() { waitCh <- cmd.Wait() }()
select {
case <-waitCh:
// Process exited cleanly.
case <-killTimer.C:
_ = cmd.Process.Kill()
<-waitCh
}
killTimer.Stop()
}
<-readDone
mu.Lock()
out := buf.String()
mu.Unlock()
return out, nil
}