sklad/ql/ql.go

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2019-04-12 02:15:28 +02:00
// Package ql is a Linux driver for Brother QL-series printers.
package ql
// Resources:
// http://www.undocprint.org/formats/page_description_languages/brother_p-touch
import (
"errors"
"io"
"os"
"path/filepath"
"regexp"
"strings"
"syscall"
"time"
"unsafe"
)
// #include <linux/ioctl.h>
import "C"
// -----------------------------------------------------------------------------
func _IOC(dir, typ, nr, size int) uintptr {
return (uintptr(dir) << C._IOC_DIRSHIFT) |
(uintptr(typ) << C._IOC_TYPESHIFT) |
(uintptr(nr) << C._IOC_NRSHIFT) |
(uintptr(size) << C._IOC_SIZESHIFT)
}
const (
iocnrGetDeviceID = 1
)
// lpiocGetDeviceID reads the IEEE-1284 Device ID string of a printer.
func lpiocGetDeviceID(fd uintptr) ([]byte, error) {
var buf [1024]byte
if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, fd,
_IOC(C._IOC_READ, 'P', iocnrGetDeviceID, len(buf)),
uintptr(unsafe.Pointer(&buf))); err != 0 {
return nil, err
}
// In theory it might get trimmed along the way.
length := int(buf[0])<<8 | int(buf[1])
if 2+length > len(buf) {
return buf[2:], errors.New("the device ID string got trimmed")
}
return buf[2 : 2+length], nil
}
// -----------------------------------------------------------------------------
var deviceIDRegexp = regexp.MustCompile(
`(?s:\s*([^:,;]+?)\s*:\s*([^:;]*)\s*(?:;|$))`)
type deviceID map[string][]string
// parseIEEE1284DeviceID leniently parses an IEEE 1284 Device ID string
// and returns a map containing a slice of values for each key.
//
// See e.g. http://www.undocprint.org/formats/communication_protocols/ieee_1284
func parseIEEE1284DeviceID(id []byte) deviceID {
m := make(deviceID)
for _, kv := range deviceIDRegexp.FindAllStringSubmatch(string(id), -1) {
var values []string
for _, v := range strings.Split(kv[2], ",") {
values = append(values, strings.Trim(v, "\t\n\v\f\r "))
}
m[kv[1]] = values
}
return m
}
func (id deviceID) Find(key, abbreviation string) []string {
if values, ok := id[key]; ok {
return values
}
if values, ok := id[abbreviation]; ok {
return values
}
return nil
}
// -----------------------------------------------------------------------------
type Printer struct {
File *os.File
}
func compatible(id deviceID) bool {
for _, commandSet := range id.Find("COMMAND SET", "CMD") {
if commandSet == "PT-CBP" {
return true
}
}
return false
}
// Open finds and initializes the first USB printer found supporting
// the appropriate protocol. Returns nil if no printer could be found.
func Open() (*Printer, error) {
// Linux usblp module, located in /drivers/usb/class/usblp.c
paths, err := filepath.Glob("/dev/usb/lp[0-9]*")
if err != nil {
return nil, err
}
for _, candidate := range paths {
f, err := os.OpenFile(candidate, os.O_RDWR, 0)
if err != nil {
continue
}
// Filter out obvious non-printers.
deviceID, err := lpiocGetDeviceID(f.Fd())
if err != nil {
f.Close()
continue
}
// Filter out printers that wouldn't understand the protocol.
if !compatible(parseIEEE1284DeviceID(deviceID)) {
f.Close()
continue
}
return &Printer{File: f}, nil
}
return nil, nil
}
// Initialize initializes the printer for further operations.
func (p *Printer) Initialize() error {
// Clear the print buffer.
invalidate := make([]byte, 400)
if _, err := p.File.Write(invalidate); err != nil {
return err
}
// Initialize.
if _, err := p.File.WriteString("\x1b\x40"); err != nil {
return err
}
// Flush any former responses in the printer's queue.
//
// I'm not sure if this is necessary, or rather whether the kernel driver
// does any buffering that could cause data to be returned at this point.
/*
for {
dummy := make([]byte, 32)
if _, err := f.Read(dummy); err == io.EOF {
break
}
}
*/
return nil
}
// GetStatus retrieves the printer's status as raw data. The printer must be
// in an appropriate mode, i.e. on-line and not currently printing.
func (p *Printer) GetStatus() ([]byte, error) {
// Request status information.
if _, err := p.File.WriteString("\x1b\x69\x53"); err != nil {
return nil, err
}
// We need to poll the device a bit.
status := make([]byte, 32)
start := time.Now()
for {
if n, err := p.File.Read(status); err == io.EOF {
time.Sleep(10 * time.Millisecond)
} else if err != nil {
return nil, err
} else if n < 32 {
return nil, errors.New("invalid read")
} else {
return status, nil
}
if time.Now().Sub(start) > time.Second {
return nil, errors.New("timeout")
}
}
}
// Close closes the underlying file.
func (p *Printer) Close() error {
return p.File.Close()
}
// -----------------------------------------------------------------------------
type Status struct {
errors []string
}
func decodeBitfieldErrors(b byte, errors [8]string) []string {
var result []string
for i := uint(0); i < 8; i++ {
if b&(1<<i) != 0 {
result = append(result, errors[i])
}
}
return result
}
// TODO: What exactly do we need? Probably extend as needed.
func decodeStatusInformation(d []byte) Status {
var status Status
status.errors = append(status.errors, decodeBitfieldErrors(d[8], [8]string{
"no media", "end of media", "cutter jam", "?", "printer in use",
"printer turned off", "high-voltage adapter", "fan motor error"})...)
status.errors = append(status.errors, decodeBitfieldErrors(d[9], [8]string{
"replace media", "expansion buffer full", "communication error",
"communication buffer full", "cover open", "cancel key",
"media cannot be fed", "system error"})...)
return status
}