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Bug 1694104: Add a Mutex to nsPrinterWin and lock around most driver calls. r=jfkthame

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This also removes the fix from bug 1677388, which worked in some circumstances,
but is effectively superseded by this one. Removing that fix also reduces
potential contention for copying the default DEVMODE.

Differential Revision: https://phabricator.services.mozilla.com/D112635
This commit is contained in:
Bob Owen 2021-05-07 07:04:38 +00:00
parent ba1380d84b
commit c33509f455
2 changed files with 37 additions and 46 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

77
widget/windows/nsPrinterWin.cpp
View File

@ -37,7 +37,7 @@ already_AddRefed<nsPrinterWin> nsPrinterWin::Create(
template <class T>
static nsTArray<T> GetDeviceCapabilityArray(const LPWSTR aPrinterName,
WORD aCapabilityID,
const DEVMODEW* aDevmodeW,
mozilla::Mutex& aDriverMutex,
int& aCount) {
MOZ_ASSERT(aCount >= 0, "Possibly passed aCount from previous error case.");
@ -59,8 +59,9 @@ static nsTArray<T> GetDeviceCapabilityArray(const LPWSTR aPrinterName,
// sense. Also, the printer set-up seems to stop you from having two
// printers with the same name. Note: this (and the call below) are blocking
// calls, which could be slow.
MutexAutoLock autoLock(aDriverMutex);
aCount = ::DeviceCapabilitiesW(aPrinterName, nullptr, aCapabilityID,
nullptr, aDevmodeW);
nullptr, nullptr);
if (aCount <= 0) {
return caps;
}
@ -69,9 +70,10 @@ static nsTArray<T> GetDeviceCapabilityArray(const LPWSTR aPrinterName,
// As DeviceCapabilitiesW doesn't take a size, there is a greater risk of the
// buffer being overflowed, so we over-allocate for safety.
caps.SetLength(aCount * 2);
int count = ::DeviceCapabilitiesW(aPrinterName, nullptr, aCapabilityID,
reinterpret_cast<LPWSTR>(caps.Elements()),
aDevmodeW);
MutexAutoLock autoLock(aDriverMutex);
int count =
::DeviceCapabilitiesW(aPrinterName, nullptr, aCapabilityID,
reinterpret_cast<LPWSTR>(caps.Elements()), nullptr);
if (count <= 0) {
caps.Clear();
return caps;
@ -100,29 +102,15 @@ nsPrinterWin::GetSystemName(nsAString& aName) {
}
bool nsPrinterWin::SupportsDuplex() const {
// Some printer drivers have threading issues around using their default
// DEVMODE, so we use a copy of our cached one.
nsTArray<uint8_t> devmodeWStorage = CopyDefaultDevmodeW();
if (devmodeWStorage.IsEmpty()) {
return false;
}
auto* devmode = reinterpret_cast<DEVMODEW*>(devmodeWStorage.Elements());
MutexAutoLock autoLock(mDriverMutex);
return ::DeviceCapabilitiesW(mName.get(), nullptr, DC_DUPLEX, nullptr,
devmode) == 1;
nullptr) == 1;
}
bool nsPrinterWin::SupportsColor() const {
// Some printer drivers have threading issues around using their default
// DEVMODE, so we use a copy of our cached one.
nsTArray<uint8_t> devmodeWStorage = CopyDefaultDevmodeW();
if (devmodeWStorage.IsEmpty()) {
return false;
}
auto* devmode = reinterpret_cast<DEVMODEW*>(devmodeWStorage.Elements());
MutexAutoLock autoLock(mDriverMutex);
return ::DeviceCapabilitiesW(mName.get(), nullptr, DC_COLORDEVICE, nullptr,
devmode) == 1;
nullptr) == 1;
}
bool nsPrinterWin::SupportsMonochrome() const {
@ -148,6 +136,7 @@ bool nsPrinterWin::SupportsMonochrome() const {
// Try to modify the devmode settings and see if the setting sticks.
//
// This has been the only reliable way to detect it that we've found.
MutexAutoLock autoLock(mDriverMutex);
LONG ret =
::DocumentPropertiesW(nullptr, autoPrinter.get(), mName.get(), devmode,
devmode, DM_IN_BUFFER | DM_OUT_BUFFER);
@ -159,16 +148,9 @@ bool nsPrinterWin::SupportsMonochrome() const {
}
bool nsPrinterWin::SupportsCollation() const {
// Some printer drivers have threading issues around using their default
// DEVMODE, so we use a copy of our cached one.
nsTArray<uint8_t> devmodeWStorage = CopyDefaultDevmodeW();
if (devmodeWStorage.IsEmpty()) {
return false;
}
auto* devmode = reinterpret_cast<DEVMODEW*>(devmodeWStorage.Elements());
MutexAutoLock autoLock(mDriverMutex);
return ::DeviceCapabilitiesW(mName.get(), nullptr, DC_COLLATE, nullptr,
devmode) == 1;
nullptr) == 1;
}
nsPrinterBase::PrinterInfo nsPrinterWin::CreatePrinterInfo() const {
@ -188,7 +170,12 @@ mozilla::gfx::MarginDouble nsPrinterWin::GetMarginsForPaper(
devmode->dmFields = DM_PAPERSIZE;
devmode->dmPaperSize = _wtoi((const wchar_t*)aPaperId.BeginReading());
nsAutoHDC printerDc(::CreateICW(nullptr, mName.get(), nullptr, devmode));
HDC dc;
{
MutexAutoLock autoLock(mDriverMutex);
dc = ::CreateICW(nullptr, mName.get(), nullptr, devmode);
}
nsAutoHDC printerDc(dc);
MOZ_ASSERT(printerDc, "CreateICW failed");
if (!printerDc) {
return margin;
@ -215,6 +202,7 @@ nsTArray<uint8_t> nsPrinterWin::CopyDefaultDevmodeW() const {
}
nsAutoPrinter autoPrinter(hPrinter);
// Allocate devmode storage of the correct size.
MutexAutoLock autoLock(mDriverMutex);
LONG bytesNeeded = ::DocumentPropertiesW(nullptr, autoPrinter.get(),
mName.get(), nullptr, nullptr, 0);
// Note that we must cast the sizeof() to a signed type so that comparison
@ -244,25 +232,17 @@ nsTArray<uint8_t> nsPrinterWin::CopyDefaultDevmodeW() const {
}
nsTArray<mozilla::PaperInfo> nsPrinterWin::PaperList() const {
// Some printer drivers have threading issues around using their default
// DEVMODE, so we use a copy of our cached one.
nsTArray<uint8_t> devmodeWStorage = CopyDefaultDevmodeW();
if (devmodeWStorage.IsEmpty()) {
return {};
}
auto* devmode = reinterpret_cast<DEVMODEW*>(devmodeWStorage.Elements());
// Paper IDs are returned as WORDs.
int requiredArrayCount = 0;
auto paperIds = GetDeviceCapabilityArray<WORD>(mName.get(), DC_PAPERS,
devmode, requiredArrayCount);
auto paperIds = GetDeviceCapabilityArray<WORD>(
mName.get(), DC_PAPERS, mDriverMutex, requiredArrayCount);
if (!paperIds.Length()) {
return {};
}
// Paper names are returned in 64 long character buffers.
auto paperNames = GetDeviceCapabilityArray<Array<wchar_t, 64>>(
mName.get(), DC_PAPERNAMES, devmode, requiredArrayCount);
mName.get(), DC_PAPERNAMES, mDriverMutex, requiredArrayCount);
// Check that we have the same number of names as IDs.
if (paperNames.Length() != paperIds.Length()) {
return {};
@ -271,7 +251,7 @@ nsTArray<mozilla::PaperInfo> nsPrinterWin::PaperList() const {
// Paper sizes are returned as POINT structs with a tenth of a millimeter as
// the unit.
auto paperSizes = GetDeviceCapabilityArray<POINT>(
mName.get(), DC_PAPERSIZE, devmode, requiredArrayCount);
mName.get(), DC_PAPERSIZE, mDriverMutex, requiredArrayCount);
// Check that we have the same number of sizes as IDs.
if (paperSizes.Length() != paperIds.Length()) {
return {};
@ -333,7 +313,12 @@ PrintSettingsInitializer nsPrinterWin::DefaultSettings() const {
color = devmode->dmColor != DMCOLOR_MONOCHROME;
}
nsAutoHDC printerDc(::CreateICW(nullptr, mName.get(), nullptr, devmode));
HDC dc;
{
MutexAutoLock autoLock(mDriverMutex);
dc = ::CreateICW(nullptr, mName.get(), nullptr, devmode);
}
nsAutoHDC printerDc(dc);
MOZ_ASSERT(printerDc, "CreateICW failed");
if (!printerDc) {
return {};

6
widget/windows/nsPrinterWin.h
View File

@ -37,6 +37,12 @@ class nsPrinterWin final : public nsPrinterBase {
const nsString mName;
mutable mozilla::DataMutex<nsTArray<uint8_t>> mDefaultDevmodeWStorage;
// Even though some documentation seems to suggest that you should be able to
// use printer drivers on separate threads if you have separate handles, we
// see threading issues with multiple drivers. This Mutex is used to lock
// around all calls to DeviceCapabilitiesW, DocumentPropertiesW and
// CreateICW/DCW, to hopefully prevent these issues.
mutable mozilla::Mutex mDriverMutex{"nsPrinterWin::Driver"};
};
#endif // nsPrinterWin_h_