//go:build linux

package console

import (
	"fmt"
	"os"
	"strings"
	"testing"
	"time"
)

func plan9Fix2Boot(t *testing.T) string {
	t.Helper()
	raw, err := os.ReadFile("/proc/sys/kernel/random/boot_id")
	if err != nil {
		t.Fatal(err)
	}
	return strings.TrimSpace(string(raw))
}

func TestPlan9Fix4ContainerProcfsDoesNotProveLegacyPIDAbsent(t *testing.T) {
	boot := plan9Fix2Boot(t)
	const ns = "4026532999"
	priorNamespace := hostReportPIDNamespace
	t.Cleanup(func() { hostReportPIDNamespace = priorNamespace })
	hostReportPIDNamespace = func() (string, error) { return ns, nil }
	// A container with its own procfs sees itself and its init in the same
	// namespace, while a still-live host PID is absent from both procfs and
	// kill(0). That agreement is not evidence of the initial namespace.
	plan9Fix2RootNamespace(t, ns, nil)
	prior := hostReportProcReadFile
	t.Cleanup(func() { hostReportProcReadFile = prior })
	hostReportProcReadFile = func(path string) ([]byte, error) {
		if path == "/proc/999999999/stat" {
			return nil, os.ErrNotExist
		}
		return prior(path)
	}
	now := time.Now()
	if err := hostReportCollision(plan9Report(boot+":999999999", now), plan9Report(hostReportProcessID(boot), now), now); err == nil {
		t.Fatal("container procfs allowed takeover of a live host's legacy report")
	}
}

func plan9Fix2RootNamespace(t *testing.T, ns string, err error) {
	t.Helper()
	prior := hostReportRootPIDNamespace
	t.Cleanup(func() { hostReportRootPIDNamespace = prior })
	hostReportRootPIDNamespace = func() (string, error) { return ns, err }
}

func TestPlan9Fix2LegacyTwoPartIDProvedGoneInHostNamespace(t *testing.T) {
	boot := plan9Fix2Boot(t)
	const ns = hostReportInitialPIDNamespace
	priorNamespace := hostReportPIDNamespace
	t.Cleanup(func() { hostReportPIDNamespace = priorNamespace })
	hostReportPIDNamespace = func() (string, error) { return ns, nil }
	plan9Fix2RootNamespace(t, ns, nil)
	if !hostReportProcessGone(boot+":999999999", hostReportProcessID(boot)) {
		t.Fatal("main's absent boot:pid was not accepted during the roll")
	}
}

func TestPlan9Fix2LegacyTwoPartIDNeverProvedOutsideHostNamespace(t *testing.T) {
	boot := plan9Fix2Boot(t)
	ns, _ := hostReportPIDNamespace()
	next := hostReportProcessID(boot)
	plan9Fix2RootNamespace(t, ns+"0", nil)
	if hostReportProcessGone(boot+":999999999", next) {
		t.Fatal("legacy ID proved gone from a namespace that is not init's")
	}
	plan9Fix2RootNamespace(t, "", os.ErrPermission)
	if hostReportProcessGone(boot+":999999999", next) {
		t.Fatal("legacy ID proved gone with an unreadable init namespace")
	}
}

func TestPlan9Fix2LegacyTwoPartIDKeepsLivePIDAndBootChecks(t *testing.T) {
	boot := plan9Fix2Boot(t)
	const ns = hostReportInitialPIDNamespace
	priorNamespace := hostReportPIDNamespace
	t.Cleanup(func() { hostReportPIDNamespace = priorNamespace })
	hostReportPIDNamespace = func() (string, error) { return ns, nil }
	plan9Fix2RootNamespace(t, ns, nil)
	next := hostReportProcessID(boot)
	if hostReportProcessGone(fmt.Sprintf("%s:%d", boot, os.Getpid()), next) {
		t.Fatal("a live legacy PID was proved gone")
	}
	if hostReportProcessGone("other-boot:999999999", hostReportProcessID("other-boot")) {
		t.Fatal("a legacy ID from another boot was proved gone")
	}
	if hostReportProcessGone(boot+":999999999", hostReportProcessID("other-boot")) {
		t.Fatal("boot mismatch between reports was ignored")
	}
}