blob: 4f7df1e0af8bec11599359007b11e5f0a3158e6c [file] [log] [blame]
// Copyright (c) 2012 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/print_backend_cups.h"
#include <cups/ppd.h>
#include <dlfcn.h>
#include <errno.h>
#include <pthread.h>
#include <string>
#include "base/files/file_util.h"
#include "base/lazy_instance.h"
#include "base/logging.h"
#include "base/no_destructor.h"
#include "base/strings/string_number_conversions.h"
#include "base/synchronization/lock.h"
#include "base/values.h"
#include "printing/backend/cups_helper.h"
#include "printing/backend/print_backend_consts.h"
#include "url/gurl.h"
namespace printing {
namespace {
const char kCUPSPrinterInfoOpt[] = "printer-info";
const char kCUPSPrinterStateOpt[] = "printer-state";
const char kCUPSPrinterTypeOpt[] = "printer-type";
bool PrinterBasicInfoFromCUPS(const cups_dest_t& printer,
PrinterBasicInfo* printer_info) {
// CUPS can have 'printers' that are actually scanners. (not MFC)
// At least on Mac. Check for scanners and skip them.
const char* type_str =
cupsGetOption(kCUPSPrinterTypeOpt, printer.num_options, printer.options);
if (type_str) {
int type;
if (base::StringToInt(type_str, &type) && (type & CUPS_PRINTER_SCANNER))
return false;
printer_info->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(kDriverNameTagName,
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] =
return true;
} // namespace
PrintBackendCUPS::PrintBackendCUPS(const GURL& print_server_url,
http_encryption_t encryption,
bool blocking)
: print_server_url_(print_server_url),
blocking_(blocking) {
bool PrintBackendCUPS::EnumeratePrinters(PrinterList* printer_list) {
cups_dest_t* destinations = nullptr;
int num_dests = GetDests(&destinations);
if (!num_dests && cupsLastError() > IPP_OK_EVENTS_COMPLETE) {
VLOG(1) << "CUPS: Error getting printers from CUPS server"
<< ", server: " << print_server_url_
<< ", error: " << static_cast<int>(cupsLastError());
return false;
for (int printer_index = 0; printer_index < num_dests; ++printer_index) {
const cups_dest_t& printer = destinations[printer_index];
PrinterBasicInfo printer_info;
if (PrinterBasicInfoFromCUPS(printer, &printer_info))
cupsFreeDests(num_dests, destinations);
VLOG(1) << "CUPS: Enumerated printers, server: " << print_server_url_
<< ", # of printers: " << printer_list->size();
return true;
std::string PrintBackendCUPS::GetDefaultPrinterName() {
// Not using cupsGetDefault() because it lies about the default printer.
cups_dest_t* dests;
int num_dests = GetDests(&dests);
cups_dest_t* dest = cupsGetDest(nullptr, nullptr, num_dests, dests);
std::string name = dest ? std::string(dest->name) : std::string();
cupsFreeDests(num_dests, dests);
return name;
bool PrintBackendCUPS::GetPrinterBasicInfo(const std::string& printer_name,
PrinterBasicInfo* printer_info) {
cups_dest_t* dest = GetNamedDest(printer_name);
if (!dest)
return false;
DCHECK_EQ(printer_name, dest->name);
bool ret = PrinterBasicInfoFromCUPS(*dest, printer_info);
cupsFreeDests(1, dest);
return ret;
bool PrintBackendCUPS::GetPrinterSemanticCapsAndDefaults(
const std::string& printer_name,
PrinterSemanticCapsAndDefaults* printer_info) {
PrinterCapsAndDefaults info;
if (!GetPrinterCapsAndDefaults(printer_name, &info) )
return false;
return ParsePpdCapabilities(
printer_name, info.printer_capabilities, printer_info);
bool PrintBackendCUPS::GetPrinterCapsAndDefaults(
const std::string& printer_name,
PrinterCapsAndDefaults* printer_info) {
VLOG(1) << "CUPS: Getting caps and defaults, printer name: " << printer_name;
base::FilePath ppd_path(GetPPD(printer_name.c_str()));
// In some cases CUPS failed to get ppd file.
if (ppd_path.empty()) {
LOG(ERROR) << "CUPS: Failed to get PPD, printer name: " << printer_name;
return false;
std::string content;
bool res = base::ReadFileToString(ppd_path, &content);
base::DeleteFile(ppd_path, false);
if (res) {
printer_info->caps_mime_type = "application/pagemaker";
// In CUPS, printer defaults is a part of PPD file. Nothing to upload here.
return res;
std::string PrintBackendCUPS::GetPrinterDriverInfo(
const std::string& printer_name) {
std::string result;
cups_dest_t* dest = GetNamedDest(printer_name);
if (!dest)
return result;
DCHECK_EQ(printer_name, dest->name);
const char* info =
cupsGetOption(kDriverNameTagName, dest->num_options, dest->options);
if (info)
result = *info;
cupsFreeDests(1, dest);
return result;
bool PrintBackendCUPS::IsValidPrinter(const std::string& printer_name) {
cups_dest_t* dest = GetNamedDest(printer_name);
if (!dest)
return false;
cupsFreeDests(1, dest);
return true;
#if !defined(OS_CHROMEOS)
scoped_refptr<PrintBackend> PrintBackend::CreateInstanceImpl(
const base::DictionaryValue* print_backend_settings) {
std::string print_server_url_str, cups_blocking;
int encryption = HTTP_ENCRYPT_NEVER;
if (print_backend_settings) {
print_backend_settings->GetInteger(kCUPSEncryption, &encryption);
GURL print_server_url(print_server_url_str);
return new PrintBackendCUPS(print_server_url,
cups_blocking == kValueTrue);
#endif // !defined(OS_CHROMEOS)
int PrintBackendCUPS::GetDests(cups_dest_t** dests) {
if (print_server_url_.is_empty()) // Use default (local) print server.
return cupsGetDests(dests);
HttpConnectionCUPS http(print_server_url_, cups_encryption_);
return cupsGetDests2(http.http(), dests);
base::FilePath PrintBackendCUPS::GetPPD(const char* name) {
// cupsGetPPD returns a filename stored in a static buffer in CUPS.
// Protect this code with lock.
static base::NoDestructor<base::Lock> ppd_lock;
base::AutoLock ppd_autolock(*ppd_lock);
base::FilePath ppd_path;
const char* ppd_file_path = nullptr;
if (print_server_url_.is_empty()) { // Use default (local) print server.
ppd_file_path = cupsGetPPD(name);
if (ppd_file_path)
ppd_path = base::FilePath(ppd_file_path);
} else {
// cupsGetPPD2 gets stuck sometimes in an infinite time due to network
// configuration/issues. To prevent that, use non-blocking http connection
// here.
// Note: After looking at CUPS sources, it looks like non-blocking
// connection will timeout after 10 seconds of no data period. And it will
// return the same way as if data was completely and successfully
// downloaded.
HttpConnectionCUPS http(print_server_url_, cups_encryption_);
ppd_file_path = cupsGetPPD2(http.http(), name);
// Check if the get full PPD, since non-blocking call may simply return
// normally after timeout expired.
if (ppd_file_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.
ppd_path = base::FilePath(ppd_file_path);
ipp_status_t error_code = cupsLastError();
int http_error = httpError(http.http());
if (error_code > IPP_OK_EVENTS_COMPLETE || http_error != 0) {
LOG(ERROR) << "Error downloading PPD file, name: " << name
<< ", CUPS error: " << static_cast<int>(error_code)
<< ", HTTP error: " << http_error;
base::DeleteFile(ppd_path, false);
return ppd_path;
cups_dest_t* PrintBackendCUPS::GetNamedDest(const std::string& printer_name) {
// Use default (local) print server.
if (print_server_url_.is_empty())
return cupsGetNamedDest(CUPS_HTTP_DEFAULT, printer_name.c_str(), nullptr);
HttpConnectionCUPS http(print_server_url_, cups_encryption_);
return cupsGetNamedDest(http.http(), printer_name.c_str(), nullptr);
} // namespace printing