From c889bc5ce1b8cbbbc057dc629eb1d1a45c171ada Mon Sep 17 00:00:00 2001
From: Cameron Kaiser <classilla@floodgap.com>
Date: Wed, 19 Apr 2023 21:55:52 -0700
Subject: [PATCH] #659: initial support for per-host CSS grid whitelist

---
 layout/base/nsLayoutUtils.cpp |  3 +++
 layout/style/nsCSSParser.cpp  | 31 +++++++++++++++++++++++++++++++
 modules/libpref/init/all.js   |  7 +++----
 3 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/layout/base/nsLayoutUtils.cpp b/layout/base/nsLayoutUtils.cpp
index f5a89763b..9a3278ed6 100644
--- a/layout/base/nsLayoutUtils.cpp
+++ b/layout/base/nsLayoutUtils.cpp
@@ -174,6 +174,9 @@ static ContentMap& GetContentMap() {
 // When the pref "layout.css.grid.enabled" changes, this function is invoked
 // to let us update kDisplayKTable, to selectively disable or restore the
 // entries for "grid" and "inline-grid" in that table.
+//
+// NB: as of TenFourFox issue 659, a whitelist entry per host is also required
+// to enable (but turning it off turns it off globally).
 static void
 GridEnabledPrefChangeCallback(const char* aPrefName, void* aClosure)
 {
diff --git a/layout/style/nsCSSParser.cpp b/layout/style/nsCSSParser.cpp
index 2e77eae0d..a4f598fa4 100644
--- a/layout/style/nsCSSParser.cpp
+++ b/layout/style/nsCSSParser.cpp
@@ -1439,6 +1439,10 @@ protected:
   // Value to make sure our resolved variable results stay within sane limits.
   const uint32_t MAX_CSS_VAR_LENGTH = 10240;
 
+  // TenFourFox issue 659
+  // If this host is whitelisted, turn on CSS grid and inline grid.
+  bool mHostCSSGridOK : 1;
+
 public:
   // Used from nsCSSParser constructors and destructors
   CSSParserImpl* mNextFree;
@@ -1587,6 +1591,25 @@ CSSParserImpl::InitScanner(nsCSSScanner& aScanner,
   mSheetURI = aSheetURI;
   mSheetPrincipal = aSheetPrincipal;
   mHavePushBack = false;
+
+  mHostCSSGridOK = false;
+  if (MOZ_LIKELY(mBaseURI)) {
+    nsCString host;
+
+    nsresult rv = mBaseURI->GetHost(host);
+    if (NS_SUCCEEDED(rv)) {
+      nsCString pref;
+
+      pref.AssignLiteral("layout.css.grid.host.");
+      pref.SetCapacity(pref.Length() + host.Length());
+      pref += host;
+      mHostCSSGridOK = Preferences::GetBool(pref.get(), false);
+#if DEBUG
+      if (mHostCSSGridOK)
+        fprintf(stderr, "CSS grid enabled for %s\n", pref.get());
+#endif
+    }
+  }
 }
 
 void
@@ -7586,6 +7609,14 @@ CSSParserImpl::ParseVariant(nsCSSValue& aValue,
       }
       if ((aVariantMask & VARIANT_KEYWORD) != 0) {
         int32_t value;
+
+        // TenFourFox issue 659
+        if (MOZ_UNLIKELY(!mHostCSSGridOK &&
+             aKeywordTable == nsCSSProps::kDisplayKTable &&
+             (keyword == eCSSKeyword_grid ||
+              keyword == eCSSKeyword_inline_grid))) {
+          // pretend the keyword wasn't found
+        } else
         if (nsCSSProps::FindKeyword(keyword, aKeywordTable, value)) {
           aValue.SetIntValue(value, eCSSUnit_Enumerated);
           return CSSParseResult::Ok;
diff --git a/modules/libpref/init/all.js b/modules/libpref/init/all.js
index a32f996d8..6953a792b 100644
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -2395,11 +2395,10 @@ pref("layout.css.variables.enabled", true);
 pref("layout.css.overflow-clip-box.enabled", false);
 
 // Is support for CSS grid enabled?
-#ifdef RELEASE_BUILD
-pref("layout.css.grid.enabled", false);
-#else
+// TenFourFox issue 659 makes this into a per-host whitelist.
 pref("layout.css.grid.enabled", true);
-#endif
+// Whitelist by default:
+pref("layout.css.grid.host.developer.mozilla.org", true);
 
 // Is support for CSS "grid-template-{columns,rows}: subgrid X" enabled?
 pref("layout.css.grid-template-subgrid-value.enabled", false);