From 0b1642e4713f23f88eec98aeeb939d4c6f17ee4d Mon Sep 17 00:00:00 2001
From: Jonathan Kew <jkew@mozilla.com>
Date: Fri, 27 Jun 2014 16:19:28 +0100
Subject: [PATCH] bug 1030067 - ignore the principal when caching data-URI
 fonts, to allow sharing across pages with the same CSS. r=bzbarsky

---
 gfx/thebes/gfxUserFontSet.cpp | 70 ++++++++++++++++++++++++++---------
 gfx/thebes/gfxUserFontSet.h   | 10 +++--
 2 files changed, 58 insertions(+), 22 deletions(-)

diff --git a/gfx/thebes/gfxUserFontSet.cpp b/gfx/thebes/gfxUserFontSet.cpp
index 8fbc908b7c5..487efac812b 100644
--- a/gfx/thebes/gfxUserFontSet.cpp
+++ b/gfx/thebes/gfxUserFontSet.cpp
@@ -876,16 +876,32 @@ gfxUserFontSet::UserFontCache::Flusher::Observe(nsISupports* aSubject,
     return NS_OK;
 }
 
+static bool
+IgnorePrincipal(nsIURI *aURI)
+{
+    nsresult rv;
+    bool inherits = false;
+    rv = NS_URIChainHasFlags(aURI,
+                             nsIProtocolHandler::URI_INHERITS_SECURITY_CONTEXT,
+                             &inherits);
+    return NS_SUCCEEDED(rv) && inherits;
+}
+
 bool
 gfxUserFontSet::UserFontCache::Entry::KeyEquals(const KeyTypePointer aKey) const
 {
-    bool equal;
-    if (NS_FAILED(mURI->Equals(aKey->mURI, &equal)) || !equal) {
+    bool result;
+    if (NS_FAILED(mURI->Equals(aKey->mURI, &result)) || !result) {
         return false;
     }
 
-    if (NS_FAILED(mPrincipal->Equals(aKey->mPrincipal, &equal)) || !equal) {
-        return false;
+    // For data: URIs, we don't care about the principal; otherwise, check it.
+    if (!IgnorePrincipal(mURI)) {
+        NS_ASSERTION(mPrincipal && aKey->mPrincipal,
+                     "only data: URIs are allowed to omit the principal");
+        if (NS_FAILED(mPrincipal->Equals(aKey->mPrincipal, &result)) || !result) {
+            return false;
+        }
     }
 
     if (mPrivate != aKey->mPrivate) {
@@ -925,7 +941,16 @@ gfxUserFontSet::UserFontCache::CacheFont(gfxFontEntry *aFontEntry)
     }
 
     gfxUserFontData *data = aFontEntry->mUserFontData;
-    sUserFonts->PutEntry(Key(data->mURI, data->mPrincipal, aFontEntry,
+    // For data: URIs, the principal is ignored; anyone who has the same
+    // data: URI is able to load it and get an equivalent font.
+    // Otherwise, the principal is used as part of the cache key.
+    nsIPrincipal *principal;
+    if (IgnorePrincipal(data->mURI)) {
+        principal = nullptr;
+    } else {
+        principal = data->mPrincipal;
+    }
+    sUserFonts->PutEntry(Key(data->mURI, principal, aFontEntry,
                              data->mPrivate));
 
 #ifdef DEBUG_USERFONT_CACHE
@@ -965,7 +990,15 @@ gfxUserFontSet::UserFontCache::GetFont(nsIURI            *aSrcURI,
         return nullptr;
     }
 
-    Entry* entry = sUserFonts->GetEntry(Key(aSrcURI, aPrincipal, aProxy,
+    // Ignore principal when looking up a data: URI.
+    nsIPrincipal *principal;
+    if (IgnorePrincipal(aSrcURI)) {
+        principal = nullptr;
+    } else {
+        principal = aPrincipal;
+    }
+
+    Entry* entry = sUserFonts->GetEntry(Key(aSrcURI, principal, aProxy,
                                             aPrivate));
     if (entry) {
         return entry->GetFontEntry();
@@ -990,20 +1023,21 @@ gfxUserFontSet::UserFontCache::Entry::DumpEntry(Entry* aEntry, void* aUserData)
 {
     nsresult rv;
 
-    nsAutoCString principalURISpec;
-
-    nsCOMPtr<nsIURI> principalURI;
-    rv = aEntry->mPrincipal->GetURI(getter_AddRefs(principalURI));
-    if (NS_SUCCEEDED(rv)) {
-        principalURI->GetSpec(principalURISpec);
-    }
-
+    nsAutoCString principalURISpec("(null)");
     bool setDomain = false;
-    nsCOMPtr<nsIURI> domainURI;
 
-    aEntry->mPrincipal->GetDomain(getter_AddRefs(domainURI));
-    if (domainURI) {
-        setDomain = true;
+    if (aEntry->mPrincipal) {
+        nsCOMPtr<nsIURI> principalURI;
+        rv = aEntry->mPrincipal->GetURI(getter_AddRefs(principalURI));
+        if (NS_SUCCEEDED(rv)) {
+            principalURI->GetSpec(principalURISpec);
+        }
+
+        nsCOMPtr<nsIURI> domainURI;
+        aEntry->mPrincipal->GetDomain(getter_AddRefs(domainURI));
+        if (domainURI) {
+            setDomain = true;
+        }
     }
 
     NS_ASSERTION(aEntry->mURI, "null URI in userfont cache entry");
diff --git a/gfx/thebes/gfxUserFontSet.h b/gfx/thebes/gfxUserFontSet.h
index f5068a8c4db..446e236ee88 100644
--- a/gfx/thebes/gfxUserFontSet.h
+++ b/gfx/thebes/gfxUserFontSet.h
@@ -294,7 +294,7 @@ public:
         // entry and the corresponding "real" font entry.
         struct Key {
             nsCOMPtr<nsIURI>        mURI;
-            nsCOMPtr<nsIPrincipal>  mPrincipal;
+            nsCOMPtr<nsIPrincipal>  mPrincipal; // use nullptr with data: URLs
             gfxFontEntry           *mFontEntry;
             bool                    mPrivate;
 
@@ -333,8 +333,10 @@ public:
             static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }
 
             static PLDHashNumber HashKey(const KeyTypePointer aKey) {
-                uint32_t principalHash;
-                aKey->mPrincipal->GetHashValue(&principalHash);
+                uint32_t principalHash = 0;
+                if (aKey->mPrincipal) {
+                    aKey->mPrincipal->GetHashValue(&principalHash);
+                }
                 return mozilla::HashGeneric(principalHash + int(aKey->mPrivate),
                                             nsURIHashKey::HashKey(aKey->mURI),
                                             HashFeatures(aKey->mFontEntry->mFeatureSettings),
@@ -365,7 +367,7 @@ public:
             }
 
             nsCOMPtr<nsIURI>       mURI;
-            nsCOMPtr<nsIPrincipal> mPrincipal;
+            nsCOMPtr<nsIPrincipal> mPrincipal; // or nullptr for data: URLs
 
             // The "real" font entry corresponding to this downloaded font.
             // The font entry MUST notify the cache when it is destroyed