mock_printer: Nuance textproto parsing

This change modifies the "proto_test_utils" source set into a slightly
more specific "parse textproto" source set. The singular
`ParseTestProto()` function is split into two:
*   `ParseTextprotoOrDie()`, intended for use in unit tests, and
*   `ParseTextproto()`, intended for use in the main execution of
    virtual-usb-printer.

BUG=b:178649877
TEST=cros_run_unit_tests --board=octopus \
TEST=--packages=chromeos-base/virtual-usb-printer

Change-Id: If7f096eec47b9b9e314af5f324390e3857b640c8
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/virtual-usb-printer/+/2830014
Reviewed-by: Piotr Pawliczek <pawliczek@chromium.org>
Tested-by: Kalvin Lee <kdlee@chromium.org>
Commit-Queue: Kalvin Lee <kdlee@chromium.org>
7 files changed
tree: 35ab30dbd70d27d3c844c3e121287498aa0475fc
  1. config/
  2. docs/
  3. mock_printer/
  4. tools/
  5. .clang-format
  6. BUILD.gn
  7. CPPLINT.cfg
  8. cups_constants.cc
  9. cups_constants.h
  10. device_descriptors.cc
  11. device_descriptors.h
  12. escl_manager.cc
  13. escl_manager.h
  14. escl_manager_test.cc
  15. http_util.cc
  16. http_util.h
  17. http_util_test.cc
  18. ipp_manager.cc
  19. ipp_manager.h
  20. ipp_manager_test.cc
  21. ipp_util.cc
  22. ipp_util.h
  23. ipp_util_test.cc
  24. jpeg_util.cc
  25. jpeg_util.h
  26. jpeg_util_test.cc
  27. LICENSE
  28. load_config.cc
  29. load_config.h
  30. load_config_test.cc
  31. op_commands.cc
  32. op_commands.h
  33. OWNERS
  34. PRESUBMIT.cfg
  35. README.md
  36. server.cc
  37. server.h
  38. smart_buffer.cc
  39. smart_buffer.h
  40. smart_buffer_test.cc
  41. usb_printer.cc
  42. usb_printer.h
  43. usbip.cc
  44. usbip.h
  45. usbip_constants.h
  46. value_util.cc
  47. value_util.h
  48. virtual_usb_printer.cc
  49. xml_util.cc
  50. xml_util.h
README.md

Virtual USB Printer

Virtual USB Printer provides a server which can be used with USBIP in order to emulate a USB printing device and bind it to the system as if it were physically connected to a USB port.

Virtual USB Printer supports both regular USB printers as well as IPP-over-USB devices.

Motivation

This project was created in order to make on-device tests which check for any regressions in the native USB printing system.

Requirements

  • USBIP - userspace program for binding virtual device to system
  • USBIP kernel modules:
    • CONFIG_USBIP_CORE
    • CONFIG_USBIP_VHCI_HCD

In order to actually “connect” the virtual printer to the system the USBIP program is used.

USBIP is typically used to export real USB devices over a network so that other systems on the network can bind them and treat them as connected devices.

For the purposes of the virtual printer, only the client portion of USBIP is required so that the virtual device can be bound to the system.

Installation

Currently the USBIP program is only installed by default for the elm and betty boards.

In order to install it on your test image, you need to build an image with the usbip USE flag enabled. To do this, all you need to to is run build_packages with the USE flag enabled.

USE="usbip" ./build_packages --board=$BOARD

How to Use

virtual-usb-printer can behave like

  • a printer,
  • an eSCL scanner, or
  • a [scriptable mock printer][./mock_printer/README.md].

Before the first use you have to load a required kernel module:

modprobe vhci-hcd

Run the virtual-usb-printer program:

virtual-usb-printer --descriptors_path=<path>

(Optional) Check the list of exported printers with USBIP:

usbip list -r localhost

Should return something like this:

Exportable USB devices
======================
 - localhost
        1-1: Canon, Inc. : unknown product (04a9:27e8)
           : /sys/devices/pci0000:00/0000:00:01.2/usb1/1-1
           : (Defined at Interface level) (00/00/00)
           : 0 - Printer / Printer Bidirectional (07/01/02)

Bind the virtual printer to the system:

usbip attach -r localhost -b 1-1

Once the device has been attached it should appear in the list of connected USB devices (lsusb), and can be used with the native printing system in Chrome OS.

Configuration

The printer's USB descriptors and defined IPP attributes can be configured using a JSON file and are loaded at run-time using command line flags. Example configurations can be found in the config/ directory.

The configuration files can be loaded with the following flags:

  • --descriptors_path - full path to the JSON file which defines the USB descriptors
  • --attributes_path - full path to the JSON file which defines the supported IPP attributes
    • Only needed for IPP-over-USB printer configurations
  • --record_doc_path - full path to the file used to record documents received from print jobs

Using in Tast

Refer to these existing tast tests for examples of how to use the virtual-usb-printer to test the Chromium OS printing stack.

Print Tests

Scan Tests