From 64a72a1f7bd0d4d76d35c49d631806a10c4fbfbc Mon Sep 17 00:00:00 2001
From: Emilio Cobos Alvarez <emilio@mozilla.com>
Date: Thu, 10 Sep 2020 17:25:21 +0000
Subject: [PATCH] Bug 1659470 - Handle printing with an empty file name in
 nsDeviceContextSpecWin. r=jwatt

Ideally print preview and co. shouldn't need a PrintTarget at all, I'd think...
Though that's a bigger refactoring.

Differential Revision: https://phabricator.services.mozilla.com/D89452
---
 widget/windows/nsDeviceContextSpecWin.cpp | 19 ++++++++++++++++---
 widget/windows/nsDeviceContextSpecWin.h   |  5 +++++
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/widget/windows/nsDeviceContextSpecWin.cpp b/widget/windows/nsDeviceContextSpecWin.cpp
index fa020b66b8df..7e25eab02878 100644
--- a/widget/windows/nsDeviceContextSpecWin.cpp
+++ b/widget/windows/nsDeviceContextSpecWin.cpp
@@ -12,6 +12,7 @@
 #include "mozilla/Preferences.h"
 #include "mozilla/RefPtr.h"
 #include "mozilla/Telemetry.h"
+#include "nsAnonymousTemporaryFile.h"
 
 #include <wchar.h>
 #include <windef.h>
@@ -74,6 +75,10 @@ NS_IMPL_ISUPPORTS(nsDeviceContextSpecWin, nsIDeviceContextSpec)
 nsDeviceContextSpecWin::~nsDeviceContextSpecWin() {
   SetDevMode(nullptr);
 
+  if (mTempFile) {
+    mTempFile->Remove(/* recursive = */ false);
+  }
+
   if (nsCOMPtr<nsIPrintSettingsWin> ps = do_QueryInterface(mPrintSettings)) {
     ps->SetDeviceName(EmptyString());
     ps->SetDriverName(EmptyString());
@@ -287,9 +292,17 @@ already_AddRefed<PrintTarget> nsDeviceContextSpecWin::MakePrintTarget() {
     width /= TWIPS_PER_POINT_FLOAT;
     height /= TWIPS_PER_POINT_FLOAT;
 
-    nsCOMPtr<nsIFile> file = do_CreateInstance("@mozilla.org/file/local;1");
-    nsresult rv = file->InitWithPath(filename);
-    if (NS_FAILED(rv)) {
+    nsCOMPtr<nsIFile> file;
+    nsresult rv;
+    if (!filename.IsEmpty()) {
+      file = do_CreateInstance("@mozilla.org/file/local;1");
+      rv = file->InitWithPath(filename);
+    } else {
+      rv = NS_OpenAnonymousTemporaryNsIFile(getter_AddRefs(mTempFile));
+      file = mTempFile;
+    }
+
+    if (NS_WARN_IF(NS_FAILED(rv))) {
       return nullptr;
     }
 
diff --git a/widget/windows/nsDeviceContextSpecWin.h b/widget/windows/nsDeviceContextSpecWin.h
index 686ef73ccfc7..8363e52cbe09 100644
--- a/widget/windows/nsDeviceContextSpecWin.h
+++ b/widget/windows/nsDeviceContextSpecWin.h
@@ -14,6 +14,7 @@
 #include "mozilla/Attributes.h"
 #include "mozilla/RefPtr.h"
 
+class nsIFile;
 class nsIWidget;
 
 class nsDeviceContextSpecWin : public nsIDeviceContextSpec {
@@ -71,6 +72,10 @@ class nsDeviceContextSpecWin : public nsIDeviceContextSpec {
   nsCOMPtr<nsIPrintSettings> mPrintSettings;
   int16_t mOutputFormat = nsIPrintSettings::kOutputFormatNative;
 
+  // A temporary file to create an "anonymous" print target. See bug 1664253,
+  // this should ideally not be needed.
+  nsCOMPtr<nsIFile> mTempFile;
+
 #ifdef MOZ_ENABLE_SKIA_PDF
 
   // This variable is independant of nsIPrintSettings::kOutputFormatPDF.