third_party_cups/ohos-usb-print.patch

diff --git a/backend/usb-oh.c b/backend/usb-oh.c
new file mode 100644
index 0000000..668ea73
--- /dev/null
+++ b/backend/usb-oh.c
@@ -0,0 +1,1818 @@
+/*
+ * Copyright (c) 2024 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ * OH USB interface code for CUPS.
+ */
+
+/*
+ * Include necessary headers.
+ */
+
+#include "usb_manager.h"
+#include <cups/cups-private.h>
+#include <cups/ppd-private.h>
+#include <cups/dir.h>
+#include <pthread.h>
+#include <sys/select.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <unistd.h>
+
+/*
+ * WAIT_EOF_DELAY is number of seconds we'll wait for responses from
+ * the printer after we've finished sending all the data
+ */
+
+#define WAIT_EOF			0
+#define WAIT_EOF_DELAY			7
+#define WAIT_SIDE_DELAY			3
+
+/*
+ * Quirks: various printer quirks are handled by this structure and its flags.
+ *
+ * The quirks table used to be compiled into the backend but is now loaded from
+ * one or more files in the /usr/share/cups/usb directory.
+ */
+
+#define USB_QUIRK_BLACKLIST	0x0001	/* Does not conform to the spec */
+#define USB_QUIRK_NO_REATTACH	0x0002	/* After printing we cannot re-attach
+					   the usblp kernel module */
+#define USB_QUIRK_SOFT_RESET	0x0004	/* After printing do a soft reset
+					   for clean-up */
+#define USB_QUIRK_UNIDIR	0x0008	/* Requires unidirectional mode */
+#define USB_QUIRK_USB_INIT	0x0010	/* Needs vendor USB init string */
+#define USB_QUIRK_VENDOR_CLASS	0x0020	/* Descriptor uses vendor-specific
+					   Class or SubClass */
+#define USB_QUIRK_DELAY_CLOSE	0x0040	/* Delay close */
+#define USB_QUIRK_WHITELIST	0x0000	/* no quirks */
+
+/*
+ * Local types...
+ */
+
+typedef struct usb_printer_s		/**** USB Printer Data ****/
+{
+  ohusb_device_descriptor   *device;	/* Device info */
+  int   conf,		/* Configuration */
+			  origconf,	/* Original configuration */
+			  iface,		/* Interface */
+			  altset,		/* Alternate setting */
+			  write_endp,	/* Write endpoint */
+			  read_endp,	/* Read endpoint */
+			  protocol,	/* Protocol: 1 = Uni-di, 2 = Bi-di. */
+			  usblp_attached,	/* "usblp" kernel module attached? */
+			  reset_after_job;/* Set to 1 by print_device() */
+  unsigned   quirks;		/* Quirks flags */
+  ohusb_pipe *pipe;	/* Open pipe to device */
+} usb_printer_t;
+
+typedef struct usb_quirk_s		/* USB "quirk" information */
+{
+  int vendor_id,		/* Affected vendor ID */
+      product_id;		/* Affected product ID or 0 for all */
+  unsigned quirks;			/* Quirks bitfield */
+} usb_quirk_t;
+
+typedef int (*usb_cb_t)(usb_printer_t *, const char *, const char *, const void *);
+
+typedef struct usb_globals_s		/* Global USB printer information */
+{
+  usb_printer_t   *printer;	/* Printer */
+
+  pthread_mutex_t	read_thread_mutex;
+  pthread_cond_t	read_thread_cond;
+  int			read_thread_stop;
+  int			read_thread_done;
+
+  pthread_mutex_t	readwrite_lock_mutex;
+  pthread_cond_t	readwrite_lock_cond;
+  int			readwrite_lock;
+
+  int			print_fd;	/* File descriptor to print */
+  ssize_t		print_bytes;	/* Print bytes read */
+
+  int			wait_eof;
+  int			drain_output;	/* Drain all pending output */
+  int			bidi_flag;	/* 0=unidirectional, 1=bidirectional */
+
+  pthread_mutex_t	sidechannel_thread_mutex;
+  pthread_cond_t	sidechannel_thread_cond;
+  int			sidechannel_thread_stop;
+  int			sidechannel_thread_done;
+} usb_globals_t;
+
+/*
+ * Globals...
+ */
+
+cups_array_t    *all_quirks;	/* Array of printer quirks */
+usb_globals_t   g = { 0 };	/* Globals */
+ohusb_device_descriptor   **all_list;	/* List of connected USB devices */
+
+/*
+ * Local functions...
+ */
+
+static int		close_device(usb_printer_t *printer);
+static int		compare_quirks(usb_quirk_t *a, usb_quirk_t *b);
+static usb_printer_t  *find_device(usb_cb_t cb, const void *data);
+static unsigned   find_quirks(int vendor_id, int product_id);
+static int		get_device_id(usb_printer_t *printer, char *buffer, size_t bufsize);
+static int		list_cb(usb_printer_t *printer, const char *device_uri, const char *device_id, const void *data);
+static void		load_quirks(void);
+static char		*make_device_uri(usb_printer_t *printer, const char *device_id, char *uri, size_t uri_size);
+static int		open_device(usb_printer_t *printer, int verbose);
+static int		print_cb(usb_printer_t *printer, const char *device_uri, const char *device_id, const void *data);
+static void		*read_thread(void *reference);
+static void		*sidechannel_thread(void *reference);
+static void		soft_reset(void);
+static int		soft_reset_printer(usb_printer_t *printer);
+
+/*
+ * 'list_devices()' - List the available printers.
+ */
+
+void
+list_devices(void)
+{
+  load_quirks();
+
+  fputs("DEBUG: list_devices\n", stderr);
+  find_device(list_cb, NULL);
+  fputs("DEBUG: list_devices out\n", stderr);
+}
+
+int					/* O - Exit status */
+print_device(const char *uri,		/* I - Device URI */
+             const char *hostname,	/* I - Hostname/manufacturer */
+             const char *resource,	/* I - Resource/modelname */
+	     char       *options,	/* I - Device options/serial number */
+	     int        print_fd,	/* I - File descriptor to print */
+	     int        copies,		/* I - Copies to print */
+	     int	argc,		/* I - Number of command-line arguments (6 or 7) */
+	     char	*argv[])	/* I - Command-line arguments */
+{
+  int	        bytes;			/* Bytes written */
+  ssize_t	total_bytes;		/* Total bytes written */
+  struct sigaction action;		/* Actions for POSIX signals */
+  int		status = CUPS_BACKEND_OK,   /* Function results */
+		    iostatus;		/* Current IO status */
+  pthread_t	read_thread_id,		/* Read thread */
+		        sidechannel_thread_id;	/* Side-channel thread */
+  int		have_sidechannel = 0,	/* Was the side-channel thread started? */
+		    have_backchannel = 0;   /* Do we have a back channel? */
+  struct stat   sidechannel_info;	/* Side-channel file descriptor info */
+  unsigned char	print_buffer[8192],	/* Print data buffer */
+		            *print_ptr;		/* Pointer into print data buffer */
+  fd_set	input_set;		/* Input set for select() */
+  int		nfds;			/* Number of file descriptors */
+  struct timeval  *timeout,		/* Timeout pointer */
+		              tv;			/* Time value */
+  struct timespec cond_timeout;		/* pthread condition timeout */
+  int		num_opts;		/* Number of options */
+  cups_option_t	*opts;			/* Options */
+  const char	*val;			/* Option value */
+
+  fputs("DEBUG: print_device\n", stderr);
+
+  load_quirks();
+
+ /*
+  * See if the side-channel descriptor is valid...
+  */
+
+  have_sidechannel = !fstat(CUPS_SC_FD, &sidechannel_info) &&
+                     S_ISSOCK(sidechannel_info.st_mode);
+
+  g.wait_eof = WAIT_EOF;
+
+ /*
+  * Connect to the printer...
+  */
+
+  fprintf(stderr, "DEBUG: Printing on printer with URI: %s\n", uri);
+  while ((g.printer = find_device(print_cb, uri)) == NULL)
+  {
+    _cupsLangPrintFilter(stderr, "INFO", _("Waiting for printer to become available."));
+    sleep(5);
+  }
+
+  g.print_fd = print_fd;
+
+ /*
+  * Some devices need a reset after finishing a job, these devices are
+  * marked with the USB_QUIRK_SOFT_RESET quirk.
+  */
+  g.printer->reset_after_job = (g.printer->quirks & USB_QUIRK_SOFT_RESET ? 1 : 0);
+
+ /*
+  * If we are printing data from a print driver on stdin, ignore SIGTERM
+  * so that the driver can finish out any page data, e.g. to eject the
+  * current page.  We only do this for stdin printing as otherwise there
+  * is no way to cancel a raw print job...
+  */
+
+  if (!print_fd)
+  {
+    memset(&action, 0, sizeof(action));
+
+    sigemptyset(&action.sa_mask);
+    action.sa_handler = SIG_IGN;
+    sigaction(SIGTERM, &action, NULL);
+  }
+
+ /*
+  * Start the side channel thread if the descriptor is valid...
+  */
+
+  pthread_mutex_init(&g.readwrite_lock_mutex, NULL);
+  pthread_cond_init(&g.readwrite_lock_cond, NULL);
+  g.readwrite_lock = 1;
+
+  if (have_sidechannel)
+  {
+    g.sidechannel_thread_stop = 0;
+    g.sidechannel_thread_done = 0;
+
+    pthread_cond_init(&g.sidechannel_thread_cond, NULL);
+    pthread_mutex_init(&g.sidechannel_thread_mutex, NULL);
+
+    if (pthread_create(&sidechannel_thread_id, NULL, sidechannel_thread, NULL))
+    {
+      fprintf(stderr, "DEBUG: Fatal USB error.\n");
+      _cupsLangPrintFilter(stderr, "ERROR", _("There was an unrecoverable USB error."));
+      fputs("DEBUG: Couldn't create side-channel thread.\n", stderr);
+      close_device(g.printer);
+      return (CUPS_BACKEND_STOP);
+    }
+  }
+
+ /*
+  * Debug mode: If option "usb-unidir" is given, always deactivate
+  * backchannel
+  */
+
+  num_opts = cupsParseOptions(argv[5], 0, &opts);
+  val = cupsGetOption("usb-unidir", num_opts, opts);
+  if (val && strcasecmp(val, "no") && strcasecmp(val, "off") && strcasecmp(val, "false"))
+  {
+    g.printer->read_endp = -1;
+    fprintf(stderr, "DEBUG: Forced uni-directional communication "
+	    "via \"usb-unidir\" option.\n");
+  }
+
+ /*
+  * Debug mode: If option "usb-no-reattach" is given, do not re-attach
+  * the usblp kernel module after the job has completed.
+  */
+
+  val = cupsGetOption("usb-no-reattach", num_opts, opts);
+  if (val && strcasecmp(val, "no") && strcasecmp(val, "off") && strcasecmp(val, "false"))
+  {
+    g.printer->usblp_attached = 0;
+    fprintf(stderr, "DEBUG: Forced not re-attaching the usblp kernel module "
+	    "after the job via \"usb-no-reattach\" option.\n");
+  }
+
+ /*
+  * Get the read thread going...
+  */
+
+  if (g.printer->read_endp != -1)
+  {
+    have_backchannel = 1;
+
+    g.read_thread_stop = 0;
+    g.read_thread_done = 0;
+
+    pthread_cond_init(&g.read_thread_cond, NULL);
+    pthread_mutex_init(&g.read_thread_mutex, NULL);
+
+    if (pthread_create(&read_thread_id, NULL, read_thread, NULL))
+    {
+      fprintf(stderr, "DEBUG: Fatal USB error.\n");
+      _cupsLangPrintFilter(stderr, "ERROR", _("There was an unrecoverable USB error."));
+      fputs("DEBUG: Couldn't create read thread.\n", stderr);
+      close_device(g.printer);
+      return (CUPS_BACKEND_STOP);
+    }
+  }
+  else
+    fprintf(stderr, "DEBUG: Uni-directional device/mode, back channel "
+	    "deactivated.\n");
+
+ /*
+  * The main thread sends the print file...
+  */
+
+  g.drain_output = 0;
+  g.print_bytes	 = 0;
+  total_bytes	 = 0;
+  print_ptr	 = print_buffer;
+
+  while (status == CUPS_BACKEND_OK && copies-- > 0)
+  {
+    _cupsLangPrintFilter(stderr, "INFO", _("Sending data to printer."));
+
+    if (print_fd != STDIN_FILENO)
+    {
+      fputs("PAGE: 1 1\n", stderr);
+      lseek(print_fd, 0, SEEK_SET);
+    }
+
+    while (status == CUPS_BACKEND_OK)
+    {
+      FD_ZERO(&input_set);
+
+      if (!g.print_bytes)
+	      FD_SET(print_fd, &input_set);
+
+     /*
+      * Calculate select timeout...
+      *   If we have data waiting to send timeout is 100ms.
+      *   else if we're draining print_fd timeout is 0.
+      *   else we're waiting forever...
+      */
+
+      if (g.print_bytes)
+      {
+	      tv.tv_sec  = 0;
+	      tv.tv_usec = 100000;		/* 100ms */
+	      timeout    = &tv;
+      }
+      else if (g.drain_output)
+      {
+	      tv.tv_sec  = 0;
+	      tv.tv_usec = 0;
+	      timeout    = &tv;
+      }
+      else
+	      timeout = NULL;
+
+     /*
+      * I/O is unlocked around select...
+      */
+
+      pthread_mutex_lock(&g.readwrite_lock_mutex);
+      g.readwrite_lock = 0;
+      pthread_cond_signal(&g.readwrite_lock_cond);
+      pthread_mutex_unlock(&g.readwrite_lock_mutex);
+
+      nfds = select(print_fd + 1, &input_set, NULL, NULL, timeout);
+
+     /*
+      * Reacquire the lock...
+      */
+
+      pthread_mutex_lock(&g.readwrite_lock_mutex);
+      while (g.readwrite_lock)
+	      pthread_cond_wait(&g.readwrite_lock_cond, &g.readwrite_lock_mutex);
+      g.readwrite_lock = 1;
+      pthread_mutex_unlock(&g.readwrite_lock_mutex);
+
+      if (nfds < 0)
+      {
+	      if (errno == EINTR && total_bytes == 0)
+	      {
+	        fputs("DEBUG: Received an interrupt before any bytes were "
+	              "written, aborting.\n", stderr);
+	        close_device(g.printer);
+          return (CUPS_BACKEND_OK);
+	      }
+	      else if (errno != EAGAIN && errno != EINTR)
+	      {
+	        _cupsLangPrintFilter(stderr, "ERROR", _("Unable to read print data."));
+	        perror("DEBUG: select");
+	        close_device(g.printer);
+          return (CUPS_BACKEND_FAILED);
+	      }
+      }
+
+     /*
+      * If drain output has finished send a response...
+      */
+
+      if (g.drain_output && !nfds && !g.print_bytes)
+      {
+	      /* Send a response... */
+	      cupsSideChannelWrite(CUPS_SC_CMD_DRAIN_OUTPUT, CUPS_SC_STATUS_OK, NULL, 0, 1.0);
+	      g.drain_output = 0;
+      }
+
+     /*
+      * Check if we have print data ready...
+      */
+
+      if (FD_ISSET(print_fd, &input_set))
+      {
+	      g.print_bytes = read(print_fd, print_buffer, sizeof(print_buffer));
+
+	      if (g.print_bytes < 0)
+	      {
+	       /*
+	        * Read error - bail if we don't see EAGAIN or EINTR...
+	        */
+
+	        if (errno != EAGAIN && errno != EINTR)
+	        {
+	          _cupsLangPrintFilter(stderr, "ERROR", _("Unable to read print data."));
+	          perror("DEBUG: read");
+	          close_device(g.printer);
+	          return (CUPS_BACKEND_FAILED);
+	        }
+
+	        g.print_bytes = 0;
+	      }
+	      else if (g.print_bytes == 0)
+	      {
+	       /*
+	        * End of file, break out of the loop...
+	        */
+
+	        break;
+	      }
+
+	      print_ptr = print_buffer;
+
+	      fprintf(stderr, "DEBUG: Read %d bytes of print data...\n", (int)g.print_bytes);
+      }
+
+      if (g.print_bytes)
+      {
+        ohusb_transfer_pipe tpipe = {
+          g.printer->iface,
+          g.printer->write_endp
+        };
+	      iostatus = OH_BulkTransferWrite(g.printer->pipe, &tpipe,
+          print_buffer, g.print_bytes, &bytes, 0);
+       /*
+	      * Ignore timeout errors, but retain the number of bytes written to
+	      * avoid sending duplicate data...
+	      */
+
+	      if (iostatus == OHUSB_ERROR_TIMEOUT)
+	      {
+	        fputs("DEBUG: Got USB transaction timeout during write.\n", stderr);
+	        iostatus = 0;
+	      }
+
+       /*
+	      * Retry a write after an aborted write since we probably just got
+	      * SIGTERM...
+	      */
+
+	      else if (iostatus == OHUSB_ERROR_NO_DEVICE)
+	      {
+	        fputs("DEBUG: Got USB return aborted during write.\n", stderr);
+
+	        iostatus = OH_BulkTransferWrite(g.printer->pipe, &tpipe,
+            print_buffer, g.print_bytes, &bytes, 0);
+        }
+
+	      if (iostatus)
+	      {
+	       /*
+	        * Write error - bail if we don't see an error we can retry...
+	        */
+
+	        _cupsLangPrintFilter(stderr, "ERROR", _("Unable to send data to printer."));
+	        fprintf(stderr, "DEBUG: ohusb write operation returned %x.\n", iostatus);
+
+	        status = CUPS_BACKEND_FAILED;
+	        break;
+	      }
+	      else if (bytes > 0)
+	      {
+	        fprintf(stderr, "DEBUG: Wrote %d bytes of print data...\n", (int)bytes);
+
+	        g.print_bytes -= bytes;
+	        print_ptr   += bytes;
+	        total_bytes += bytes;
+	      }
+        fprintf(stderr, "DEBUG: %d bytes left to write...\n", (int)g.print_bytes);
+      }
+
+      if (print_fd != 0 && status == CUPS_BACKEND_OK)
+	      fprintf(stderr, "DEBUG: Sending print file, " CUPS_LLFMT " bytes...\n",
+	      	CUPS_LLCAST total_bytes);
+    }
+  }
+
+  fprintf(stderr, "DEBUG: Sent " CUPS_LLFMT " bytes...\n",
+          CUPS_LLCAST total_bytes);
+
+ /*
+  * Signal the side channel thread to exit...
+  */
+
+  if (have_sidechannel)
+  {
+    close(CUPS_SC_FD);
+    pthread_mutex_lock(&g.readwrite_lock_mutex);
+    g.readwrite_lock = 0;
+    pthread_cond_signal(&g.readwrite_lock_cond);
+    pthread_mutex_unlock(&g.readwrite_lock_mutex);
+
+    g.sidechannel_thread_stop = 1;
+    pthread_mutex_lock(&g.sidechannel_thread_mutex);
+
+    if (!g.sidechannel_thread_done)
+    {
+      gettimeofday(&tv, NULL);
+      cond_timeout.tv_sec  = tv.tv_sec + WAIT_SIDE_DELAY;
+      cond_timeout.tv_nsec = tv.tv_usec * 1000;
+
+      while (!g.sidechannel_thread_done)
+      {
+	      if (pthread_cond_timedwait(&g.sidechannel_thread_cond,
+				   &g.sidechannel_thread_mutex,
+				   &cond_timeout) != 0)
+	      break;
+      }
+    }
+
+    pthread_mutex_unlock(&g.sidechannel_thread_mutex);
+  }
+
+ /*
+  * Signal the read thread to exit then wait 7 seconds for it to complete...
+  */
+
+  if (have_backchannel)
+  {
+    g.read_thread_stop = 1;
+
+    pthread_mutex_lock(&g.read_thread_mutex);
+
+    if (!g.read_thread_done)
+    {
+      fputs("DEBUG: Waiting for read thread to exit...\n", stderr);
+
+      gettimeofday(&tv, NULL);
+      cond_timeout.tv_sec  = tv.tv_sec + WAIT_EOF_DELAY;
+      cond_timeout.tv_nsec = tv.tv_usec * 1000;
+
+      while (!g.read_thread_done)
+      {
+	      if (pthread_cond_timedwait(&g.read_thread_cond, &g.read_thread_mutex,
+				   &cond_timeout) != 0)
+	      break;
+      }
+
+      /*
+       * If it didn't exit abort the pending read and wait an additional
+       * second...
+       */
+
+      if (!g.read_thread_done)
+      {
+	      fputs("DEBUG: Read thread still active, aborting the pending read...\n", stderr);
+
+	      g.wait_eof = 0;
+
+	      gettimeofday(&tv, NULL);
+	      cond_timeout.tv_sec  = tv.tv_sec + 1;
+	      cond_timeout.tv_nsec = tv.tv_usec * 1000;
+
+	      while (!g.read_thread_done)
+	      {
+	        if (pthread_cond_timedwait(&g.read_thread_cond, &g.read_thread_mutex,
+	      		&cond_timeout) != 0)
+	        break;
+	      }
+      }
+    }
+
+    pthread_mutex_unlock(&g.read_thread_mutex);
+  }
+
+ /*
+  * Close the connection and input file and general clean up...
+  */
+
+  if (g.printer->quirks & USB_QUIRK_DELAY_CLOSE)
+    sleep(1);
+
+  close_device(g.printer);
+
+  fputs("DEBUG: print_device out\n", stderr);
+  return (status);
+}
+
+/*
+ * 'find_device()' - Find or enumerate USB printers.
+ */
+
+static usb_printer_t *			/* O - Found printer */
+find_device(usb_cb_t   cb,		/* I - Callback function */
+            const void *data)		/* I - User data for callback */
+{
+  ohusb_device_descriptor           *list = NULL;      /* List of connected USB devices */
+  ohusb_device_descriptor           *device = NULL;	    /* Current device */
+  ohusb_config_descriptor           *confptr = NULL;    /* Pointer to current configuration */
+  const ohusb_interface             *ifaceptr = NULL;   /* Pointer to current interface */
+  const ohusb_interface_descriptor  *altptr = NULL;     /* Pointer to current alternate setting */
+  const ohusb_endpoint_descriptor   *endpptr = NULL;    /* Pointer to current endpoint */
+  ssize_t               numdevs,        /* number of connected devices */
+                        i = 0;
+  uint8_t		conf,		    /* Current configuration */
+			      iface,		  /* Current interface */
+			      altset,		  /* Current alternate setting */
+			      protocol,	  /* Current protocol */
+			      endp,		    /* Current endpoint */
+			      read_endp,	/* Current read endpoint */
+			      write_endp;	/* Current write endpoint */
+  char			device_id[1024],  /* IEEE-1284 device ID */
+			      device_uri[1024]; /* Device URI */
+  static usb_printer_t	printer;	/* Current printer */
+  int32_t ret;
+
+ /*
+  * get ohusb devices...
+  */
+
+  fputs("DEBUG: find_device\n", stderr);
+  ret = OH_GetDevices(&list, &numdevs);
+  if (ret != OHUSB_SUCCESS) {
+    fprintf(stderr, "DEBUG: find_device OH_GetDevices fail\n");
+    return (NULL);
+  }
+  fprintf(stderr, "DEBUG: find_device OH_GetDevices numdevs=%d\n", (int)numdevs);
+
+ /*
+  * Then loop through the devices it found...
+  */
+
+  if (numdevs > 0)
+    for (i = 0; i < numdevs; i++)
+    {
+      device = list + i;
+
+     /*
+      * Ignore devices with no configuration data and anything that is not
+      * a printer...
+      */
+
+      if (device == NULL)
+	      continue;
+
+      fprintf(stderr, "DEBUG: OH_GetDevices index=%zd, busNum=%d, devAddr=%d, idVendor=%d, idProduct=%d\n",
+        i, device->busNum, device->devAddr, device->idVendor, device->idProduct);
+
+      if (!device->bNumConfigurations || !device->idVendor || !device->idProduct)
+	      continue;
+
+      printer.quirks = find_quirks(device->idVendor, device->idProduct);
+      fprintf(stderr, "DEBUG: find_device quirks=%d\n", printer.quirks);
+
+     /*
+      * Ignore blacklisted printers...
+      */
+
+      if (printer.quirks & USB_QUIRK_BLACKLIST)
+        continue;
+
+      for (conf = 0, confptr = device->config; conf < device->bNumConfigurations; conf ++, confptr ++)
+      {
+	      if (confptr == NULL)
+	        continue;
+        for (iface = 0, ifaceptr = confptr->interface;
+	           iface < confptr->bNumInterfaces;
+	           iface ++, ifaceptr ++)
+        {
+	       /*
+	        * Some printers offer multiple interfaces...
+	        */
+
+          protocol   = 0;
+          if (ifaceptr == NULL)
+            continue;
+
+	        for (altset = 0, altptr = ifaceptr->altsetting;
+	             altset < ifaceptr->num_altsetting;
+	             altset ++, altptr ++)
+          {
+            if (altptr == NULL)
+              continue;
+	         /*
+	          * Currently we only support unidirectional and bidirectional
+	          * printers.  Future versions of this code will support the
+	          * 1284.4 (packet mode) protocol as well.
+	          */
+            fprintf(stderr, "DEBUG: find_device class=%x, subclass=%x, protocol=%x\n",
+              altptr->bInterfaceClass, altptr->bInterfaceSubClass, altptr->bInterfaceProtocol);
+	          if (((altptr->bInterfaceClass != OHUSB_CLASS_PRINTER || altptr->bInterfaceSubClass != 1) &&
+		              ((printer.quirks & USB_QUIRK_VENDOR_CLASS) == 0)) ||
+		            (altptr->bInterfaceProtocol != 1 &&	/* Unidirectional */
+		              altptr->bInterfaceProtocol != 2) ||	/* Bidirectional */
+		            altptr->bInterfaceProtocol < protocol)
+            {
+              fprintf(stderr, "DEBUG: Not a usb printer.\n");
+	            continue;
+            }
+
+	          if (printer.quirks & USB_QUIRK_VENDOR_CLASS)
+	            fprintf(stderr, "DEBUG: Printer does not report class 7 and/or "
+		            "subclass 1 but works as a printer anyway\n");
+
+	          read_endp  = 0xff;
+	          write_endp = 0xff;
+
+	          for (endp = 0, endpptr = altptr->endpoint;
+	               endp < altptr->bNumEndpoints;
+		             endp ++, endpptr ++)
+            {
+              if ((endpptr->bmAttributes & OHUSB_TRANSFER_TYPE_MASK) == OHUSB_TRANSFER_TYPE_BULK)
+	            {
+	              if (endpptr->bEndpointAddress & OHUSB_ENDPOINT_DIR_MASK)
+		              read_endp = endp;
+		            else
+		              write_endp = endp;
+	            }
+            }
+
+            if (write_endp != 0xff)
+	          {
+	           /*
+	            * Save the best match so far...
+	            */
+
+              protocol           = altptr->bInterfaceProtocol;
+	            printer.altset     = altset;
+	            printer.write_endp = write_endp;
+	            if (protocol > 1)
+		            printer.read_endp = read_endp;
+	            else
+		            printer.read_endp = -1;
+	          }
+	        }
+
+	        if (protocol > 0)
+	        {
+	          printer.device   = device;
+	          printer.conf     = conf;
+	          printer.iface    = iface;
+	          printer.protocol = protocol;
+            printer.pipe     = NULL;
+
+            if (!open_device(&printer, data != NULL))
+	          {
+	            get_device_id(&printer, device_id, sizeof(device_id));
+	            make_device_uri(&printer, device_id, device_uri, sizeof(device_uri));
+
+	            fprintf(stderr, "DEBUG2: Printer found with device ID: %s "
+		            "Device URI: %s\n",
+		            device_id, device_uri);
+
+	            if ((*cb)(&printer, device_uri, device_id, data))
+	            {
+		            fprintf(stderr, "DEBUG: Device protocol: %d\n", printer.protocol);
+		            if (printer.quirks & USB_QUIRK_UNIDIR)
+		            {
+		              printer.read_endp = -1;
+		              fprintf(stderr, "DEBUG: Printer reports bi-di support "
+		            	  "but in reality works only uni-directionally\n");
+		            }
+		            if (printer.read_endp != -1)
+		            {
+		              printer.read_endp = confptr->interface[printer.iface].
+		            			                altsetting[printer.altset].
+		            			                endpoint[printer.read_endp].
+		            			                bEndpointAddress;
+		            }
+		            else
+		              fprintf(stderr, "DEBUG: Uni-directional USB communication "
+		            	  "only!\n");
+		            printer.write_endp = confptr->interface[printer.iface].
+		            			               altsetting[printer.altset].
+		            			               endpoint[printer.write_endp].
+		            			               bEndpointAddress;
+		            if (printer.quirks & USB_QUIRK_NO_REATTACH)
+		            {
+		              printer.usblp_attached = 0;
+		              fprintf(stderr, "DEBUG: Printer does not like usblp "
+		            	  "kernel module to be re-attached after job\n");
+		            }
+		            return (&printer);
+              }
+
+              close_device(&printer);
+	          }
+	        }
+	      }
+      }
+    }
+
+  fputs("DEBUG: find_device out\n", stderr);
+  return (NULL);
+}
+
+/*
+ * 'open_device()' - Open a connection to the USB printer.
+ */
+
+static int				/* O - 0 on success, -1 on error */
+open_device(usb_printer_t *printer,	/* I - Printer */
+            int           verbose)	/* I - Update connecting-to-device state? */
+{
+  ohusb_config_descriptor confptr;
+                                        /* Pointer to current configuration */
+  int	  number1 = -1,			/* Configuration/interface/altset */
+        number2 = -1,			/* numbers */
+        errcode = 0;
+  char	current;			/* Current configuration */
+
+  fprintf(stderr, "DEBUG: open_device\n");
+
+ /*
+  * Return immediately if we are already connected...
+  */
+
+  if (printer->pipe)
+    return (0);
+
+ /*
+  * Try opening the printer...
+  */
+
+  if ((errcode = OH_OpenDevice(printer->device, &(printer->pipe))) < 0)
+  {
+    fprintf(stderr, "DEBUG: Failed to open device, code: %d\n", errcode);
+    return (-1);
+  }
+  fprintf(stderr, "DEBUG: OH_OpenDevice success busNum=%d, devAddr=%d\n",
+    printer->pipe->busNum, printer->pipe->devAddr);
+
+  printer->usblp_attached = 0;
+  printer->reset_after_job = 0;
+
+  if (verbose)
+    fputs("STATE: +connecting-to-device\n", stderr);
+  if (printer->device == NULL)
+  {
+    fprintf(stderr, "DEBUG: Failed to get device descriptor, code: %d\n", errcode);
+    goto error;
+  }
+
+ /*
+  * Set the desired configuration, but only if it needs changing. Some
+  * printers (e.g., Samsung) don't like OH_SetConfiguration. It will
+  * succeed, but the following print job is sometimes silently lost by the
+  * printer.
+  */
+
+  ohusb_control_transfer_parameter ctrlParam = {
+    OHUSB_REQUEST_TYPE_STANDARD | OHUSB_ENDPOINT_IN | OHUSB_RECIPIENT_DEVICE,
+    8, 0, 0, 5000
+  };
+
+  if (OH_ControlTransferRead(printer->pipe, &ctrlParam, (unsigned char *)&current, 1) < 0)
+  {
+    current = 0;			/* Assume not configured */
+  }
+
+  printer->origconf = current;
+  fprintf(stderr, "DEBUG: open_device OH_ControlTransferRead current = %c, printer->origconf = %d\n",
+    current, printer->origconf);
+
+  confptr = printer->device->config[printer->conf];
+  number1 = confptr.iConfiguration;
+
+  if (number1 != current)
+  {
+    fprintf(stderr, "DEBUG: Switching USB device configuration: %d -> %d\n",
+	    current, number1);
+    if ((errcode = OH_SetConfiguration(printer->pipe, number1)) < 0)
+    {
+     /*
+      * If the set fails, chances are that the printer only supports a
+      * single configuration.  Technically these printers don't conform to
+      * the USB printer specification, but otherwise they'll work...
+      */
+
+      if (errcode != OHUSB_ERROR_BUSY)
+        fprintf(stderr, "DEBUG: Failed to set configuration %d for %04x:%04x\n",
+		      number1, printer->device->idVendor, printer->device->idProduct);
+    }
+  }
+
+ /*
+  * Claim interfaces as needed...
+  */
+
+  number1 = confptr.interface[printer->iface].altsetting[printer->altset].bInterfaceNumber;
+
+  if ((errcode = OH_ClaimInterface(printer->pipe, number1, true)) < 0)
+  {
+    fprintf(stderr,
+            "DEBUG: Failed to claim interface %d for %04x:%04x: %s\n",
+            number1, printer->device->idVendor, printer->device->idProduct, strerror(errno));
+
+    goto error;
+  }
+
+ /*
+  * Set alternate setting, but only if there is more than one option.  Some
+  * printers (e.g., Samsung) don't like usb_set_altinterface.
+  */
+
+  if (confptr.interface[printer->iface].num_altsetting > 1)
+  {
+    number1 = confptr.interface[printer->iface].
+                 altsetting[printer->altset].bInterfaceNumber;
+    number2 = confptr.interface[printer->iface].
+                 altsetting[printer->altset].bAlternateSetting;
+    while ((errcode = OH_SetInterface(printer->pipe, number1, number2)) < 0)
+    {
+      if (errcode != OHUSB_ERROR_BUSY)
+      {
+        fprintf(stderr,
+                "DEBUG: Failed to set alternate interface %d for %04x:%04x: "
+                "%s\n",
+                number2, printer->device->idVendor, printer->device->idProduct, strerror(errno));
+
+	      goto error;
+      }
+    }
+  }
+
+  if (verbose)
+    fputs("STATE: -connecting-to-device\n", stderr);
+
+  return (0);
+
+ /*
+  * If we get here, there was a hard error...
+  */
+
+  error:
+
+  if (verbose)
+    fputs("STATE: -connecting-to-device\n", stderr);
+
+  OH_CloseDevice(printer->pipe);
+  printer->pipe = NULL;
+
+  return (-1);
+}
+
+/*
+ * 'get_device_id()' - Get the IEEE-1284 device ID for the printer.
+ */
+
+static int				/* O - 0 on success, -1 on error */
+get_device_id(usb_printer_t *printer,	/* I - Printer */
+              char          *buffer,	/* I - String buffer */
+              size_t        bufsize)	/* I - Number of bytes in buffer */
+{
+  fprintf(stderr, "DEBUG: get_device_id\n");
+
+  int	length;				/* Length of device ID */
+
+  ohusb_control_transfer_parameter ctrlParam = {
+    OHUSB_REQUEST_TYPE_CLASS | OHUSB_ENDPOINT_IN | OHUSB_RECIPIENT_INTERFACE,
+    0, printer->conf, (printer->iface << 8) | printer->altset, 5000
+  };
+
+  if (OH_ControlTransferRead(printer->pipe, &ctrlParam, (unsigned char *)buffer, bufsize) < 0)
+  {
+    *buffer = '\0';
+    return (-1);
+  }
+
+ /*
+  * Extract the length of the device ID string from the first two
+  * bytes.  The 1284 spec says the length is stored MSB first...
+  */
+
+  length = (int)((((unsigned)buffer[0] & 255) << 8) | ((unsigned)buffer[1] & 255));
+
+ /*
+  * Check to see if the length is larger than our buffer or less than 14 bytes
+  * (the minimum valid device ID is "MFG:x;MDL:y;" with 2 bytes for the length).
+  *
+  * If the length is out-of-range, assume that the vendor incorrectly
+  * implemented the 1284 spec and re-read the length as LSB first,..
+  */
+
+  if (length > bufsize || length < 14)
+    length = (int)((((unsigned)buffer[1] & 255) << 8) | ((unsigned)buffer[0] & 255));
+
+  if (length > bufsize)
+    length = bufsize;
+
+  if (length < 14)
+  {
+   /*
+    * Invalid device ID, clear it!
+    */
+
+    *buffer = '\0';
+    fprintf(stderr, "DEBUG: get_device_id Invalid device ID\n");
+    return (-1);
+  }
+
+  length -= 2;
+  fprintf(stderr, "DEBUG: get_device_id length = %d\n", length);
+
+ /*
+  * Copy the device ID text to the beginning of the buffer and
+  * nul-terminate.
+  */
+
+  memmove(buffer, buffer + 2, (size_t)length);
+  buffer[length] = '\0';
+
+  return (0);
+}
+
+/*
+ * 'make_device_uri()' - Create a device URI for a USB printer.
+ */
+
+static char *				/* O - Device URI */
+make_device_uri(
+    usb_printer_t *printer,		/* I - Printer */
+    const char    *device_id,		/* I - IEEE-1284 device ID */
+    char          *uri,			/* I - Device URI buffer */
+    size_t        uri_size)		/* I - Size of device URI buffer */
+{
+  char		options[1024];		/* Device URI options */
+  int		num_values;		/* Number of 1284 parameters */
+  cups_option_t	*values;		/* 1284 parameters */
+  const char	*mfg,			/* Manufacturer */
+		          *mdl,			/* Model */
+		          *des = NULL,		/* Description */
+		          *sern = NULL;		/* Serial number */
+  size_t	mfglen;			/* Length of manufacturer string */
+  char		tempmdl[256],		/* Temporary model string */
+		      tempmfg[256],		/* Temporary manufacturer string */
+		      tempsern[256],	/* Temporary serial number string */
+		      *tempptr;		    /* Pointer into temp string */
+
+  fprintf(stderr, "DEBUG: make_device_uri\n");
+
+ /*
+  * Get the make, model, and serial numbers...
+  */
+
+  num_values = _cupsGet1284Values(device_id, &values);
+
+  if (printer->device != NULL && printer->device->iSerialNumber)
+  {
+    // Try getting the serial number from the device itself...
+    int length = OH_GetStringDescriptor(printer->pipe, printer->device->iSerialNumber, (unsigned char *)tempsern, sizeof(tempsern) - 1);
+    if (length > 0)
+    {
+      tempsern[length] = '\0';
+      sern             = tempsern;
+    }
+    else
+      fputs("DEBUG2: iSerialNumber could not be read.\n", stderr);
+  }
+  else
+    fputs("DEBUG2: iSerialNumber is not present.\n", stderr);
+
+  if ((mfg = cupsGetOption("MANUFACTURER", num_values, values)) == NULL)
+  {
+    if ((mfg = cupsGetOption("MFG", num_values, values)) == NULL && printer->device->iManufacturer)
+    {
+      int length = OH_GetStringDescriptor(printer->pipe, printer->device->iManufacturer, (unsigned char *)tempmfg, sizeof(tempmfg) - 1);
+      if (length > 0)
+      {
+	      tempmfg[length] = '\0';
+	      mfg             = tempmfg;
+      }
+    }
+  }
+
+  if ((mdl = cupsGetOption("MODEL", num_values, values)) == NULL)
+  {
+    if ((mdl = cupsGetOption("MDL", num_values, values)) == NULL && printer->device->iProduct)
+    {
+      int length = OH_GetStringDescriptor(printer->pipe, printer->device->iProduct, (unsigned char *)tempmdl, sizeof(tempmdl) - 1);
+      if (length > 0)
+      {
+	      tempmdl[length] = '\0';
+	      mdl             = tempmdl;
+      }
+    }
+  }
+
+ /*
+  * To maintain compatibility with the original character device backend on
+  * Linux and *BSD, map manufacturer names...
+  */
+
+  if (mfg)
+  {
+    if (!_cups_strcasecmp(mfg, "Hewlett-Packard"))
+      mfg = "HP";
+    else if (!_cups_strcasecmp(mfg, "Lexmark International"))
+      mfg = "Lexmark";
+  }
+  else
+  {
+   /*
+    * No manufacturer?  Use the model string or description...
+    */
+
+    if (mdl)
+      _ppdNormalizeMakeAndModel(mdl, tempmfg, sizeof(tempmfg));
+    else if ((des = cupsGetOption("DESCRIPTION", num_values, values)) != NULL ||
+             (des = cupsGetOption("DES", num_values, values)) != NULL)
+      _ppdNormalizeMakeAndModel(des, tempmfg, sizeof(tempmfg));
+    else
+      strlcpy(tempmfg, "Unknown", sizeof(tempmfg));
+
+    if ((tempptr = strchr(tempmfg, ' ')) != NULL)
+      *tempptr = '\0';
+
+    mfg = tempmfg;
+  }
+
+  if (!mdl)
+  {
+   /*
+    * No model?  Use description...
+    */
+    if (des)
+      mdl = des; /* We remove the manufacturer name below */
+    else if (!strncasecmp(mfg, "Unknown", 7))
+      mdl = "Printer";
+    else
+      mdl = "Unknown Model";
+  }
+
+  mfglen = strlen(mfg);
+
+  if (!strncasecmp(mdl, mfg, mfglen) && _cups_isspace(mdl[mfglen]))
+  {
+    mdl += mfglen + 1;
+
+    while (_cups_isspace(*mdl))
+      mdl ++;
+  }
+
+ /*
+  * Generate the device URI from the manufacturer, model, serial number,
+  * and interface number...
+  */
+
+  if (sern)
+  {
+    if (printer->iface > 0)
+      snprintf(options, sizeof(options), "?serial=%s&interface=%d", sern, printer->iface);
+    else
+      snprintf(options, sizeof(options), "?serial=%s", sern);
+  }
+  else if (printer->iface > 0)
+    snprintf(options, sizeof(options), "?interface=%d", printer->iface);
+  else
+    options[0] = '\0';
+
+  httpAssembleURIf(HTTP_URI_CODING_ALL, uri, uri_size, "usb", NULL, mfg, 0, "/%s%s", mdl, options);
+
+  fprintf(stderr, "DEBUG2: make_device_uri sern=\"%s\", mfg=\"%s\", mdl=\"%s\"\n", sern, mfg, mdl);
+
+  cupsFreeOptions(num_values, values);
+
+  return (uri);
+}
+
+/*
+ * 'close_device()' - Close the connection to the USB printer.
+ */
+
+static int				/* I - 0 on success, -1 on failure */
+close_device(usb_printer_t *printer)	/* I - Printer */
+{
+  ohusb_config_descriptor confptr;    /* Pointer to current configuration */
+
+  if (printer->pipe)
+  {
+   /*
+    * Release interfaces before closing so that we know all data is written
+    * to the device...
+    */
+
+    int errcode;			/* Return value of ohusb function */
+    int number1,			/* Interface number */
+	      number2;			/* Configuration number */
+
+    if (printer->device != NULL && printer->device->config != NULL)
+    {
+      confptr = printer->device->config[printer->conf];
+      number1 = confptr.interface[printer->iface].
+	              altsetting[printer->altset].bInterfaceNumber;
+      OH_ReleaseInterface(printer->pipe, number1);
+
+      number2 = confptr.iConfiguration;
+
+     /*
+      * If we have changed the configuration from one valid configuration
+      * to another, restore the old one
+      */
+      if (printer->origconf > 0 && printer->origconf != number2)
+      {
+	      fprintf(stderr, "DEBUG: Restoring USB device configuration: %d -> %d\n",
+	      	number2, printer->origconf);
+	      if ((errcode = OH_SetConfiguration(printer->pipe, printer->origconf)) < 0)
+	      {
+	        fprintf(stderr,
+            "DEBUG: Failed to set configuration %d for %04x:%04x\n",
+	          printer->origconf, printer->device->idVendor, printer->device->idProduct);
+	      }
+      }
+    }
+    else
+      fprintf(stderr,
+	      "DEBUG: Failed to get configuration descriptor %d\n",
+	      printer->conf);
+
+   /*
+    * Close the interface and return...
+    */
+
+    if (OH_CloseDevice(printer->pipe) == OHUSB_SUCCESS)
+      printer->pipe = NULL;
+  }
+
+  return (0);
+}
+
+/*
+ * 'read_thread()' - Thread to read the backchannel data on.
+ */
+
+static void *read_thread(void *reference)
+{
+  unsigned char		readbuffer[512];
+  int			rbytes;
+  int			readstatus;
+  ohusb_transfer_pipe tpipe = {
+    g.printer->iface,
+    g.printer->read_endp
+  };
+
+
+  (void)reference;
+
+  do
+  {
+   /*
+    * Try reading from the OUT (to host) endpoint...
+    */
+
+    rbytes     = sizeof(readbuffer);
+    readstatus = OH_BulkTransferRead(g.printer->pipe,
+				         &tpipe, readbuffer, rbytes, &rbytes);
+    if (readstatus == OHUSB_SUCCESS && rbytes > 0)
+    {
+      fprintf(stderr, "DEBUG: Read %d bytes of back-channel data...\n", (int)rbytes);
+      cupsBackChannelWrite((const char *)readbuffer, (size_t)rbytes, 1.0);
+    }
+    else
+      fprintf(stderr, "DEBUG: Got USB transaction error during read, errorcode=%d\n", readstatus);
+
+   /*
+    * Make sure this loop executes no more than once every 250 miliseconds...
+    */
+
+    if ((readstatus != OHUSB_SUCCESS || rbytes == 0) && (g.wait_eof || !g.read_thread_stop))
+      usleep(250000);
+  }
+  while (g.wait_eof || !g.read_thread_stop);
+
+ /*
+  * Let the main thread know that we have completed the read thread...
+  */
+
+  pthread_mutex_lock(&g.read_thread_mutex);
+  g.read_thread_done = 1;
+  pthread_cond_signal(&g.read_thread_cond);
+  pthread_mutex_unlock(&g.read_thread_mutex);
+
+  return (NULL);
+}
+
+/*
+ * 'sidechannel_thread()' - Handle side-channel requests.
+ */
+
+static void*
+sidechannel_thread(void *reference)
+{
+  cups_sc_command_t	command;	/* Request command */
+  cups_sc_status_t	status;		/* Request/response status */
+  char			data[2048];	/* Request/response data */
+  int			datalen;	/* Request/response data size */
+
+
+  (void)reference;
+
+  do
+  {
+    datalen = sizeof(data);
+
+    if (cupsSideChannelRead(&command, &status, data, &datalen, 1.0))
+    {
+      if (status == CUPS_SC_STATUS_TIMEOUT)
+	      continue;
+      else
+	      break;
+    }
+
+    switch (command)
+    {
+      case CUPS_SC_CMD_SOFT_RESET:	/* Do a soft reset */
+	      fputs("DEBUG: CUPS_SC_CMD_SOFT_RESET received from driver...\n", stderr);
+
+	      soft_reset();
+	      cupsSideChannelWrite(command, CUPS_SC_STATUS_OK, NULL, 0, 1.0);
+	      fputs("DEBUG: Returning status CUPS_STATUS_OK with no bytes...\n",
+		    stderr);
+	      break;
+
+      case CUPS_SC_CMD_DRAIN_OUTPUT:	/* Drain all pending output */
+	      fputs("DEBUG: CUPS_SC_CMD_DRAIN_OUTPUT received from driver...\n", stderr);
+
+	      g.drain_output = 1;
+	      break;
+
+      case CUPS_SC_CMD_GET_BIDI:	/* Is the connection bidirectional? */
+	      fputs("DEBUG: CUPS_SC_CMD_GET_BIDI received from driver...\n", stderr);
+
+	      data[0] = (g.printer->protocol >= 2 ? 1 : 0);
+	      cupsSideChannelWrite(command, CUPS_SC_STATUS_OK, data, 1, 1.0);
+
+	      fprintf(stderr,
+	              "DEBUG: Returned CUPS_SC_STATUS_OK with 1 byte (%02X)...\n",
+		      data[0]);
+	      break;
+
+      case CUPS_SC_CMD_GET_DEVICE_ID:	/* Return IEEE-1284 device ID */
+	      fputs("DEBUG: CUPS_SC_CMD_GET_DEVICE_ID received from driver...\n", stderr);
+
+	      datalen = sizeof(data);
+	      if (get_device_id(g.printer, data, sizeof(data)))
+	      {
+	        status  = CUPS_SC_STATUS_IO_ERROR;
+	        datalen = 0;
+	      }
+	      else
+	      {
+	        status  = CUPS_SC_STATUS_OK;
+	        datalen = strlen(data);
+	      }
+	      cupsSideChannelWrite(command, CUPS_SC_STATUS_OK, data, datalen, 1.0);
+
+        if (datalen < sizeof(data))
+	        data[datalen] = '\0';
+	      else
+	        data[sizeof(data) - 1] = '\0';
+
+	      fprintf(stderr,
+	              "DEBUG: Returning CUPS_SC_STATUS_OK with %d bytes (%s)...\n",
+		      datalen, data);
+	      break;
+
+      case CUPS_SC_CMD_GET_STATE:	/* Return device state */
+	      fputs("DEBUG: CUPS_SC_CMD_GET_STATE received from driver...\n", stderr);
+
+	      data[0] = CUPS_SC_STATE_ONLINE;
+	      cupsSideChannelWrite(command, CUPS_SC_STATUS_OK, data, 1, 1.0);
+
+	      fprintf(stderr,
+	              "DEBUG: Returned CUPS_SC_STATUS_OK with 1 byte (%02X)...\n",
+		      data[0]);
+	      break;
+
+      case CUPS_SC_CMD_GET_CONNECTED:	/* Return whether device is
+					   connected */
+	      fputs("DEBUG: CUPS_SC_CMD_GET_CONNECTED received from driver...\n", stderr);
+
+	      data[0] = (g.printer->device ? 1 : 0);
+	      cupsSideChannelWrite(command, CUPS_SC_STATUS_OK, data, 1, 1.0);
+
+	      fprintf(stderr,
+	              "DEBUG: Returned CUPS_SC_STATUS_OK with 1 byte (%02X)...\n",
+		      data[0]);
+	      break;
+
+      default:
+	      fprintf(stderr, "DEBUG: Unknown side-channel command (%d) received "
+		    	  "from driver...\n", command);
+
+	      cupsSideChannelWrite(command, CUPS_SC_STATUS_NOT_IMPLEMENTED, NULL, 0, 1.0);
+
+	      fputs("DEBUG: Returned CUPS_SC_STATUS_NOT_IMPLEMENTED with no bytes...\n", stderr);
+	      break;
+    }
+  }
+  while (!g.sidechannel_thread_stop);
+
+  pthread_mutex_lock(&g.sidechannel_thread_mutex);
+  g.sidechannel_thread_done = 1;
+  pthread_cond_signal(&g.sidechannel_thread_cond);
+  pthread_mutex_unlock(&g.sidechannel_thread_mutex);
+
+  return (NULL);
+}
+
+/*
+ * 'load_quirks()' - Load all quirks files in the /usr/share/cups/usb directory.
+ */
+
+static void
+load_quirks(void)
+{
+  const char	*datadir;		/* CUPS_DATADIR environment variable */
+  char		filename[1024],		/* Filename */
+		      line[1024];		    /* Line from file */
+  cups_dir_t	*dir;			/* Directory */
+  cups_dentry_t	*dent;			/* Directory entry */
+  cups_file_t	*fp;			/* Quirks file */
+  usb_quirk_t	*quirk;			/* New quirk */
+
+
+  all_quirks = cupsArrayNew((cups_array_func_t)compare_quirks, NULL);
+
+  if ((datadir = getenv("CUPS_DATADIR")) == NULL)
+    datadir = CUPS_DATADIR;
+
+  snprintf(filename, sizeof(filename), "%s/usb", datadir);
+  if ((dir = cupsDirOpen(filename)) == NULL)
+  {
+    perror(filename);
+    return;
+  }
+
+  fprintf(stderr, "DEBUG: Loading USB quirks from \"%s\".\n", filename);
+
+  while ((dent = cupsDirRead(dir)) != NULL)
+  {
+    if (!S_ISREG(dent->fileinfo.st_mode))
+      continue;
+
+    snprintf(filename, sizeof(filename), "%s/usb/%s", datadir, dent->filename);
+    if ((fp = cupsFileOpen(filename, "r")) == NULL)
+    {
+      perror(filename);
+      continue;
+    }
+
+    while (cupsFileGets(fp, line, sizeof(line)))
+    {
+     /*
+      * Skip blank and comment lines...
+      */
+
+      if (line[0] == '#' || !line[0])
+        continue;
+
+     /*
+      * Add a quirk...
+      */
+
+      if ((quirk = calloc(1, sizeof(usb_quirk_t))) == NULL)
+      {
+        perror("DEBUG: Unable to allocate memory for quirk");
+        break;
+      }
+
+      if (sscanf(line, "%x%x", &quirk->vendor_id, &quirk->product_id) < 1)
+      {
+        fprintf(stderr, "DEBUG: Bad line: %s\n", line);
+        free(quirk);
+        continue;
+      }
+
+      if (strstr(line, " blacklist"))
+        quirk->quirks |= USB_QUIRK_BLACKLIST;
+
+      if (strstr(line, " delay-close"))
+        quirk->quirks |= USB_QUIRK_DELAY_CLOSE;
+
+      if (strstr(line, " no-reattach"))
+        quirk->quirks |= USB_QUIRK_NO_REATTACH;
+
+      if (strstr(line, " soft-reset"))
+        quirk->quirks |= USB_QUIRK_SOFT_RESET;
+
+      if (strstr(line, " unidir"))
+        quirk->quirks |= USB_QUIRK_UNIDIR;
+
+      if (strstr(line, " usb-init"))
+        quirk->quirks |= USB_QUIRK_USB_INIT;
+
+      if (strstr(line, " vendor-class"))
+        quirk->quirks |= USB_QUIRK_VENDOR_CLASS;
+
+      cupsArrayAdd(all_quirks, quirk);
+    }
+
+    cupsFileClose(fp);
+  }
+
+  fprintf(stderr, "DEBUG: Loaded %d quirks.\n", cupsArrayCount(all_quirks));
+
+  cupsDirClose(dir);
+}
+
+/*
+ * 'find_quirks()' - Find the quirks for the given printer, if any.
+ *
+ * First looks for an exact match, then looks for the vendor ID wildcard match.
+ */
+
+static unsigned				/* O - Quirks flags */
+find_quirks(int vendor_id,		/* I - Vendor ID */
+            int product_id)		/* I - Product ID */
+{
+  usb_quirk_t	key,			  /* Search key */
+		          *match;			/* Matching quirk entry */
+
+
+  key.vendor_id  = vendor_id;
+  key.product_id = product_id;
+
+  if ((match = cupsArrayFind(all_quirks, &key)) != NULL)
+    return (match->quirks);
+
+  key.product_id = 0;
+
+  if ((match = cupsArrayFind(all_quirks, &key)) != NULL)
+    return (match->quirks);
+
+  return (USB_QUIRK_WHITELIST);
+}
+
+/*
+ * 'compare_quirks()' - Compare two quirks entries.
+ */
+
+static int				/* O - Result of comparison */
+compare_quirks(usb_quirk_t *a,		/* I - First quirk entry */
+               usb_quirk_t *b)		/* I - Second quirk entry */
+{
+  int result;				/* Result of comparison */
+
+  if ((result = b->vendor_id - a->vendor_id) == 0)
+    result = b->product_id - a->product_id;
+
+  return (result);
+}
+
+/*
+ * 'print_cb()' - Find a USB printer for printing.
+ */
+
+static int				/* O - 0 to continue, 1 to stop (found) */
+print_cb(usb_printer_t *printer,	/* I - Printer */
+         const char    *device_uri,	/* I - Device URI */
+         const char    *device_id,	/* I - IEEE-1284 device ID */
+         const void    *data)		/* I - User data (make, model, S/N) */
+{
+  char	requested_uri[1024],		/* Requested URI */
+	      *requested_ptr,			    /* Pointer into requested URI */
+	      detected_uri[1024],		  /* Detected URI */
+	      *detected_ptr;			    /* Pointer into detected URI */
+
+
+ /*
+  * If we have an exact match, stop now...
+  */
+
+  if (!strcmp((char *)data, device_uri))
+    return (1);
+
+ /*
+  * Work on copies of the URIs...
+  */
+
+  strlcpy(requested_uri, (char *)data, sizeof(requested_uri));
+  strlcpy(detected_uri, device_uri, sizeof(detected_uri));
+
+ /*
+  * ohusb-discovered URIs can have an "interface" specification and this
+  * never happens for usblp-discovered URIs, so remove the "interface"
+  * specification from the URI which we are checking currently. This way a
+  * queue for a usblp-discovered printer can now be accessed via ohusb.
+  *
+  * Similarly, strip "?serial=NNN...NNN" as needed.
+  */
+
+  if ((requested_ptr = strstr(requested_uri, "?interface=")) == NULL)
+    requested_ptr = strstr(requested_uri, "&interface=");
+  if ((detected_ptr = strstr(detected_uri, "?interface=")) == NULL)
+    detected_ptr = strstr(detected_uri, "&interface=");
+
+  if (!requested_ptr && detected_ptr)
+  {
+   /*
+    * Strip "[?&]interface=nnn" from the detected printer.
+    */
+
+    *detected_ptr = '\0';
+  }
+  else if (requested_ptr && !detected_ptr)
+  {
+   /*
+    * Strip "[?&]interface=nnn" from the requested printer.
+    */
+
+    *requested_ptr = '\0';
+  }
+
+  if ((requested_ptr = strstr(requested_uri, "?serial=?")) != NULL)
+  {
+   /*
+    * Strip "?serial=?" from the requested printer.  This is a special
+    * case, as "?serial=?" means no serial number and not the serial
+    * number '?'.  This is not covered by the checks below...
+    */
+
+    *requested_ptr = '\0';
+  }
+
+  if ((requested_ptr = strstr(requested_uri, "?serial=")) == NULL &&
+      (detected_ptr = strstr(detected_uri, "?serial=")) != NULL)
+  {
+   /*
+    * Strip "?serial=nnn" from the detected printer.
+    */
+
+    *detected_ptr = '\0';
+  }
+  else if (requested_ptr && !detected_ptr)
+  {
+   /*
+    * Strip "?serial=nnn" from the requested printer.
+    */
+
+    *requested_ptr = '\0';
+  }
+
+  return (!strcmp(requested_uri, detected_uri));
+}
+
+/*
+ * 'list_cb()' - List USB printers for discovery.
+ */
+
+static int				/* O - 0 to continue, 1 to stop */
+list_cb(usb_printer_t *printer,		/* I - Printer */
+        const char    *device_uri,	/* I - Device URI */
+        const char    *device_id,	/* I - IEEE-1284 device ID */
+        const void    *data)		/* I - User data (not used) */
+{
+  char	make_model[1024];		/* Make and model */
+
+
+ /*
+  * Get the device URI and make/model strings...
+  */
+
+  if (backendGetMakeModel(device_id, make_model, sizeof(make_model)))
+    strlcpy(make_model, "Unknown", sizeof(make_model));
+
+ /*
+  * Report the printer...
+  */
+
+  cupsBackendReport("direct", device_uri, make_model, make_model, device_id, NULL);
+
+ /*
+  * Keep going...
+  */
+
+  return (0);
+}
+
+/*
+ * 'soft_reset()' - Send a soft reset to the device.
+ */
+
+static void
+soft_reset(void)
+{
+  fd_set	  input_set;		/* Input set for select() */
+  struct timeval  tv;			/* Time value */
+  char		  buffer[2048];		/* Buffer */
+  struct timespec cond_timeout;		/* pthread condition timeout */
+
+
+ /*
+  * Send an abort once a second until the I/O lock is released by the main
+  * thread...
+  */
+
+  pthread_mutex_lock(&g.readwrite_lock_mutex);
+  while (g.readwrite_lock)
+  {
+    gettimeofday(&tv, NULL);
+    cond_timeout.tv_sec  = tv.tv_sec + 1;
+    cond_timeout.tv_nsec = tv.tv_usec * 1000;
+
+    while (g.readwrite_lock)
+    {
+      if (pthread_cond_timedwait(&g.readwrite_lock_cond,
+				 &g.readwrite_lock_mutex,
+				 &cond_timeout) != 0)
+	      break;
+    }
+  }
+
+  g.readwrite_lock = 1;
+  pthread_mutex_unlock(&g.readwrite_lock_mutex);
+
+ /*
+  * Flush bytes waiting on print_fd...
+  */
+
+  g.print_bytes = 0;
+
+  FD_ZERO(&input_set);
+  FD_SET(g.print_fd, &input_set);
+
+  tv.tv_sec  = 0;
+  tv.tv_usec = 0;
+
+  while (select(g.print_fd+1, &input_set, NULL, NULL, &tv) > 0)
+    if (read(g.print_fd, buffer, sizeof(buffer)) <= 0)
+      break;
+
+ /*
+  * Send the reset...
+  */
+
+  soft_reset_printer(g.printer);
+
+ /*
+  * Release the I/O lock...
+  */
+
+  pthread_mutex_lock(&g.readwrite_lock_mutex);
+  g.readwrite_lock = 0;
+  pthread_cond_signal(&g.readwrite_lock_cond);
+  pthread_mutex_unlock(&g.readwrite_lock_mutex);
+}
+
+
+/*
+ * 'soft_reset_printer()' - Do the soft reset request specific to printers
+ *
+ * This soft reset is specific to the printer device class and is much less
+ * invasive than the general USB reset OH_ResetDevice(). Especially it
+ * does never happen that the USB addressing and configuration changes. What
+ * is actually done is that all buffers get flushed and the bulk IN and OUT
+ * pipes get reset to their default states. This clears all stall conditions.
+ * See http://cholla.mmto.org/computers/linux/usb/usbprint11.pdf
+ */
+
+static int				/* O - 0 on success, < 0 on error */
+soft_reset_printer(
+    usb_printer_t *printer)		/* I - Printer */
+{
+  ohusb_config_descriptor confptr;    /* Pointer to current configuration */
+  int interface,			/* Interface to reset */
+      errcode;				/* Error code */
+
+
+  if (printer->device == NULL) {
+    interface = printer->iface;
+  } else {
+    confptr = printer->device->config[printer->conf];
+    interface = confptr.interface[printer->iface].
+                altsetting[printer->altset].bInterfaceNumber;
+  }
+    
+  ohusb_control_transfer_parameter ctrlParam = {
+    OHUSB_REQUEST_TYPE_CLASS | OHUSB_ENDPOINT_OUT | OHUSB_RECIPIENT_OTHER,
+    2, 0, interface, 5000
+  };
+
+  if ((errcode = OH_ControlTransferWrite(printer->pipe, &ctrlParam, NULL, 0)) < 0)
+  {
+    ctrlParam.requestType = OHUSB_REQUEST_TYPE_CLASS | OHUSB_ENDPOINT_OUT | OHUSB_RECIPIENT_INTERFACE;
+    errcode = OH_ControlTransferWrite(printer->pipe, &ctrlParam, NULL, 0);
+  }
+    
+
+  return (errcode);
+}
\ No newline at end of file
diff --git a/backend/usb.c b/backend/usb.c
index e1b2c03..50c1bc3 100644
--- a/backend/usb.c
+++ b/backend/usb.c
@@ -42,7 +42,9 @@ int	print_device(const char *uri, const char *hostname,
  * Include the vendor-specific USB implementation...
  */
 
-#ifdef HAVE_LIBUSB
+#ifdef HAVE_OPENHARMONY
+#  include "usb-oh.c"
+#elif defined(HAVE_LIBUSB)
 #  include "usb-libusb.c"
 #elif defined(__APPLE__)
 #  include "usb-darwin.c"