Create a new print backend for the updated CUPS APIs

printing/backend/cups_printer.cc

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "printing/backend/cups_printer.h"
+
+#include <cups/cups.h>
+
+#include <string>
+#include <utility>
+
+#include "base/files/file.h"
+#include "base/files/file_path.h"
+#include "base/files/file_util.h"
+#include "base/strings/string_number_conversions.h"
+#include "printing/backend/cups_connection.h"
+#include "printing/backend/print_backend.h"
+
+namespace {
+
+const char kDriverInfoTagName[] = "system_driverinfo";
+
+const char kCUPSPrinterInfoOpt[] = "printer-info";
+const char kCUPSPrinterStateOpt[] = "printer-state";
+const char kCUPSPrinterMakeModelOpt[] = "printer-make-and-model";
+
+}  // namespace
+
+namespace printing {
+
+CupsPrinter::CupsPrinter(http_t* http,
+                         std::unique_ptr<cups_dest_t, DestinationDeleter> dest,
+                         std::unique_ptr<cups_dinfo_t, DestInfoDeleter> info)
+    : cups_http_(http),
+      destination_(std::move(dest)),
+      dest_info_(std::move(info)) {}
+
+CupsPrinter::CupsPrinter(CupsPrinter&& printer)
+    : cups_http_(printer.cups_http_),
+      destination_(std::move(printer.destination_)),
+      dest_info_(std::move(printer.dest_info_)) {}
+
+CupsPrinter::~CupsPrinter() {}
+
+bool CupsPrinter::is_default() const {
+  return destination_->is_default;
+}
+
+ipp_attribute_t* CupsPrinter::GetSupportedOptionValues(
+    base::StringPiece option_name) const {
+  if (!InitializeDestInfo())
+    return nullptr;
+
+  return cupsFindDestSupported(cups_http_, destination_.get(), dest_info_.get(),
+                               option_name.as_string().c_str());
+}
+
+std::vector<base::StringPiece> CupsPrinter::GetSupportedOptionValueStrings(
+    base::StringPiece option_name) const {
+  ipp_attribute_t* attr = GetSupportedOptionValues(option_name);
+  std::vector<base::StringPiece> values;
+  if (!attr) {
+    return values;
+  }
+
+  base::StringPiece value;
+  int num_options = ippGetCount(attr);
+  for (int i = 0; i < num_options; ++i) {
+    value.set(ippGetString(attr, i, nullptr));
+    values.push_back(value);
+  }
+
+  return values;
+}
+
+ipp_attribute_t* CupsPrinter::GetDefaultOptionValue(
+    base::StringPiece option_name) const {
+  if (!InitializeDestInfo())
+    return nullptr;
+
+  return cupsFindDestDefault(cups_http_, destination_.get(), dest_info_.get(),
+                             option_name.as_string().c_str());
+}
+
+bool CupsPrinter::CheckOptionSupported(base::StringPiece name,
+                                       base::StringPiece value) const {
+  int supported = cupsCheckDestSupported(
+      cups_http_, destination_.get(), dest_info_.get(),
+      name.as_string().c_str(), value.as_string().c_str());
+  return supported == 1;
+}
+
+bool CupsPrinter::ToPrinterInfo(PrinterBasicInfo* printer_info) const {
+  const cups_dest_t* printer = destination_.get();
+
+  printer_info->printer_name = printer->name;
+  printer_info->is_default = printer->is_default;
+
+  const char* info = cupsGetOption(kCUPSPrinterInfoOpt, printer->num_options,
+                                   printer->options);
+  if (info)
+    printer_info->printer_description = info;
+
+  const char* state = cupsGetOption(kCUPSPrinterStateOpt, printer->num_options,
+                                    printer->options);
+  if (state)
+    base::StringToInt(state, &printer_info->printer_status);
+
+  const char* drv_info = cupsGetOption(kCUPSPrinterMakeModelOpt,
+                                       printer->num_options, printer->options);
+  if (drv_info)
+    printer_info->options[kDriverInfoTagName] = *drv_info;
+
+  // Store printer options.
+  for (int opt_index = 0; opt_index < printer->num_options; ++opt_index) {
+    printer_info->options[printer->options[opt_index].name] =
+        printer->options[opt_index].value;
+  }
+
+  return true;
+}
+
+base::FilePath CupsPrinter::GetPPD() const {
+  base::StringPiece printer_name = destination_->name;
+  const char* ppd_path =
+      cupsGetPPD2(cups_http_, printer_name.as_string().c_str());
+  base::FilePath path(ppd_path);
+
+  if (ppd_path) {
+    // There is no reliable way right now to detect full and complete PPD
+    // get downloaded. If we reach http timeout, it may simply return
+    // downloaded part as a full response. It might be good enough to check
+    // http->data_remaining or http->_data_remaining, unfortunately http_t
+    // is an internal structure and fields are not exposed in CUPS headers.
+    // httpGetLength or httpGetLength2 returning the full content size.
+    // Comparing file size against that content length might be unreliable
+    // since some http reponses are encoded and content_length > file size.
+    // Let's just check for the obvious CUPS and http errors here.
+    ipp_status_t error_code = cupsLastError();
+    int http_error = httpError(cups_http_);
+    if (error_code > IPP_OK_EVENTS_COMPLETE || http_error != 0) {
+      LOG(ERROR) << "Error downloading PPD file, name: " << destination_->name
+                 << ", CUPS error: " << static_cast<int>(error_code)
+                 << ", HTTP error: " << http_error;
+      base::DeleteFile(path, false);
+      path.clear();
+    }
+  }
+
+  return path;
+}
+
+const std::string CupsPrinter::GetName() const {
+  return std::string(destination_->name);
+}
+
+const std::string CupsPrinter::GetMakeAndModel() const {
+  const char* make_and_model =
+      cupsGetOption(kCUPSPrinterMakeModelOpt, destination_->num_options,
+                    destination_->options);
+
+  return make_and_model ? std::string(make_and_model) : std::string();
+}
+
+bool CupsPrinter::IsAvailable() const {
+  return cups_http_ && destination_ && InitializeDestInfo();
+}
+
+bool CupsPrinter::InitializeDestInfo() const {
+  if (dest_info_)
+    return true;
+
+  cups_dinfo_t* info = cupsCopyDestInfo(cups_http_, destination_.get());

[Lei Zhang, 2016/07/21 00:46:20]

Same pattern, dest_info_.reset(cupsFoo()); return !!dest_info_;

[skau, 2016/07/21 20:07:32]

Done.

+
+  if (!info)
+    return false;
+
+  dest_info_.reset(info);
+  return true;
+}
+
+ipp_status_t CupsPrinter::CreateJob(int* job_id,
+                                    base::StringPiece title,
+                                    const std::vector<cups_option_t>& options) {
+  cups_option_t* data = const_cast<cups_option_t*>(
+      options.data());  // createDestJob will not modify the data
+  ipp_status_t create_status = cupsCreateDestJob(
+      cups_http_, destination_.get(), dest_info_.get(), job_id,
+      title.as_string().c_str(), options.size(), data);
+
+  return create_status;
+}
+
+bool CupsPrinter::StartDocument(int job_id,
+                                base::StringPiece document_name,
+                                bool last_document,
+                                const std::vector<cups_option_t>& options) {
+  cups_option_t* data = const_cast<cups_option_t*>(
+      options.data());  // createStartDestDocument will not modify the data
+  http_status_t start_doc_status = cupsStartDestDocument(
+      cups_http_, destination_.get(), dest_info_.get(), job_id,
+      document_name.as_string().c_str(), CUPS_FORMAT_PDF, options.size(), data,
+      last_document ? 0 : 1);
+
+  return start_doc_status == HTTP_CONTINUE;
+}
+
+bool CupsPrinter::StreamData(const std::vector<char>& buffer) {
+  http_status_t status =
+      cupsWriteRequestData(cups_http_, buffer.data(), buffer.size());
+  return status == HTTP_STATUS_CONTINUE;
+}
+
+bool CupsPrinter::FinishDocument() {
+  DCHECK(cups_http_);

[Lei Zhang, 2016/07/21 00:46:20]

Given cups_http_ can be "http_t* const", if you want this DCHECK, then do it in
the ctor.

[skau, 2016/07/21 20:07:33]

Done.

+  DCHECK(destination_);

[Lei Zhang, 2016/07/21 00:46:20]

BTW, we use |destination_| and |dest_info_| all over. Why do we only DCHECK
here?

[skau, 2016/07/21 20:07:32]

The code was moved from where there were different guarantees.  It's fixed now.

+  DCHECK(dest_info_);
+
+  ipp_status_t status =
+      cupsFinishDestDocument(cups_http_, destination_.get(), dest_info_.get());
+
+  return status == IPP_STATUS_OK;
+}
+
+ipp_status_t CupsPrinter::CloseJob(int job_id) {
+  return cupsCloseDestJob(cups_http_, destination_.get(), dest_info_.get(),
+                          job_id);
+}
+
+}  // namespace printing