test(agentcompat): add process supervision harness

Co-authored-by: naiba/CloudCode <hi+cloudcode@nai.ba>

integration/agentcompat/internal/process/sqlite_journal_identity.go

@@ -0,0 +1,76 @@
+//go:build linux
+
+package process
+
+import (
+	"errors"
+	"sync"
+
+	"golang.org/x/sys/unix"
+)
+
+var (
+	ErrSQLiteJournalUnsupported      = errors.New("sqlite journal identity unsupported")
+	ErrSQLiteJournalIdentityMismatch = errors.New("sqlite journal identity mismatch")
+)
+
+type SQLiteJournalUnsupportedError struct{ Missing uint32 }
+
+func (err *SQLiteJournalUnsupportedError) Error() string { return ErrSQLiteJournalUnsupported.Error() }
+func (err *SQLiteJournalUnsupportedError) Unwrap() error { return ErrSQLiteJournalUnsupported }
+
+type SQLiteJournalIdentity struct {
+	MountID     uint64
+	DeviceMajor uint32
+	DeviceMinor uint32
+	Inode       uint64
+	BirthTime   unix.StatxTimestamp
+}
+
+func (identity SQLiteJournalIdentity) equal(other SQLiteJournalIdentity) bool {
+	return identity == other
+}
+
+func sqliteJournalIdentity(stat unix.Statx_t) (SQLiteJournalIdentity, error) {
+	required := uint32(unix.STATX_MNT_ID | unix.STATX_BTIME)
+	if stat.Mask&required != required {
+		return SQLiteJournalIdentity{}, &SQLiteJournalUnsupportedError{Missing: required &^ stat.Mask}
+	}
+	return SQLiteJournalIdentity{
+		MountID:     stat.Mnt_id,
+		DeviceMajor: stat.Dev_major,
+		DeviceMinor: stat.Dev_minor,
+		Inode:       stat.Ino,
+		BirthTime:   stat.Btime,
+	}, nil
+}
+
+func readSQLiteJournalIdentity(fd int) (SQLiteJournalIdentity, error) {
+	var stat unix.Statx_t
+	err := unix.Statx(fd, "", unix.AT_EMPTY_PATH, unix.STATX_BASIC_STATS|unix.STATX_MNT_ID|unix.STATX_BTIME, &stat)
+	if err != nil {
+		if errors.Is(err, unix.ENOSYS) || errors.Is(err, unix.EINVAL) || errors.Is(err, unix.EPERM) {
+			return SQLiteJournalIdentity{}, &SQLiteJournalUnsupportedError{Missing: unix.STATX_MNT_ID | unix.STATX_BTIME}
+		}
+		return SQLiteJournalIdentity{}, err
+	}
+	if stat.Mode&unix.S_IFMT != unix.S_IFREG {
+		return SQLiteJournalIdentity{}, &SQLiteJournalUnsupportedError{}
+	}
+	return sqliteJournalIdentity(stat)
+}
+
+type SQLiteJournalIdentityError struct {
+	Expected SQLiteJournalIdentity
+	Actual   SQLiteJournalIdentity
+}
+
+func (err *SQLiteJournalIdentityError) Error() string {
+	return ErrSQLiteJournalIdentityMismatch.Error()
+}
+func (err *SQLiteJournalIdentityError) Unwrap() error { return ErrSQLiteJournalIdentityMismatch }
+
+type sqliteJournalCloser struct {
+	once sync.Once
+	err  error
+}