SkFontMgr::matchFamily should not crash on nullptr.

While all systems can resolve a font from just a style request
(without a name) almost no systems specify a default font family.

BUG=skia:6574

Change-Id: If7c81808b62cd5d8212bce2eb4d9c476c45af80a
Reviewed-on: https://skia-review.googlesource.com/14902
Commit-Queue: Ben Wagner <bungeman@google.com>
Reviewed-by: Mike Reed <reed@google.com>

5 files changed, 23 insertions, 4 deletions

diff --git a/include/ports/SkFontMgr.h b/include/ports/SkFontMgr.h
index b5879d35b8..b13e113a2e 100644
--- a/include/ports/SkFontMgr.h
+++ b/include/ports/SkFontMgr.h
@@ -45,7 +45,9 @@ public:
      *  The caller must call unref() on the returned object.
      *  Never returns NULL; will return an empty set if the name is not found.
      *
-     *  Passing |nullptr| as the parameter will return the default system font.
+     *  Passing nullptr as the parameter will return the default system family.
+     *  Note that most systems don't have a default system family, so passing nullptr will often
+     *  result in the empty set.
      *
      *  It is possible that this will return a style set not accessible from
      *  createStyleSet(int) due to hidden or auto-activated fonts.
diff --git a/src/ports/SkFontHost_mac.cpp b/src/ports/SkFontHost_mac.cpp
index b525ed597f..4774eab87f 100644
--- a/src/ports/SkFontHost_mac.cpp
+++ b/src/ports/SkFontHost_mac.cpp
@@ -2362,14 +2362,17 @@ protected:
     }
 
     SkFontStyleSet* onMatchFamily(const char familyName[]) const override {
+        if (!familyName) {
+            return nullptr;
+        }
         UniqueCFRef<CFStringRef> cfName = make_CFString(familyName);
         return CreateSet(cfName.get());
     }
 
     SkTypeface* onMatchFamilyStyle(const char familyName[],
-                                   const SkFontStyle& fontStyle) const override {
-        sk_sp<SkFontStyleSet> sset(this->matchFamily(familyName));
-        return sset->matchStyle(fontStyle);
+                                   const SkFontStyle& style) const override {
+        UniqueCFRef<CTFontDescriptorRef> desc = create_descriptor(familyName, style);
+        return create_from_desc(desc.get());
     }
 
     SkTypeface* onMatchFamilyStyleCharacter(const char familyName[],
diff --git a/src/ports/SkFontMgr_fontconfig.cpp b/src/ports/SkFontMgr_fontconfig.cpp
index bceb4de3bd..f27ad40da6 100644
--- a/src/ports/SkFontMgr_fontconfig.cpp
+++ b/src/ports/SkFontMgr_fontconfig.cpp
@@ -752,6 +752,9 @@ protected:
     }
 
     SkFontStyleSet* onMatchFamily(const char familyName[]) const override {
+        if (!familyName) {
+            return nullptr;
+        }
         FCLocker lock;
 
         SkAutoFcPattern pattern;
diff --git a/src/ports/SkFontMgr_win_dw.cpp b/src/ports/SkFontMgr_win_dw.cpp
index f985c4f245..1fd300ca1d 100644
--- a/src/ports/SkFontMgr_win_dw.cpp
+++ b/src/ports/SkFontMgr_win_dw.cpp
@@ -484,6 +484,10 @@ SkFontStyleSet* SkFontMgr_DirectWrite::onCreateStyleSet(int index) const {
 }
 
 SkFontStyleSet* SkFontMgr_DirectWrite::onMatchFamily(const char familyName[]) const {
+    if (!familyName) {
+        return nullptr;
+    }
+
     SkSMallocWCHAR dwFamilyName;
     HRN(sk_cstring_to_wchar(familyName, &dwFamilyName));
 
diff --git a/tests/FontMgrTest.cpp b/tests/FontMgrTest.cpp
index b6a0cc5a74..251eb154a0 100644
--- a/tests/FontMgrTest.cpp
+++ b/tests/FontMgrTest.cpp
@@ -114,6 +114,12 @@ static void test_fontiter(skiatest::Reporter* reporter, bool verbose) {
     }
 }
 
+static void test_match(skiatest::Reporter* reporter) {
+    sk_sp<SkFontMgr> fm(SkFontMgr::RefDefault());
+    sk_sp<SkFontStyleSet> styleSet(fm->matchFamily(nullptr));
+    REPORTER_ASSERT(reporter, styleSet);
+}
+
 static void test_matchStyleCSS3(skiatest::Reporter* reporter) {
     static const SkFontStyle invalidFontStyle(101, SkFontStyle::kNormal_Width, SkFontStyle::kUpright_Slant);
 
@@ -710,6 +716,7 @@ static void test_matchStyleCSS3(skiatest::Reporter* reporter) {
 DEFINE_bool(verboseFontMgr, false, "run verbose fontmgr tests.");
 
 DEF_TEST(FontMgr, reporter) {
+    test_match(reporter);
     test_matchStyleCSS3(reporter);
     test_fontiter(reporter, FLAGS_verboseFontMgr);
     test_alias_names(reporter);