directwrite: split out the inner loop of scan_fonts as a separate function

This has the side effect that the ASS_FontProviderMetaData instance is now
cleared for every font rather than only once at the start of the search,
which fixes some use-after-free scenarios and prevents the creation of
chimeric fonts using names left over from other fonts processed earlier.

This lays the groundwork for further code simplification and error handling
improvements within this function, which will come in a separate commit.

This commit is transparent to `git blame -w` except for return statements.

diff --git a/libass/ass_directwrite.c b/libass/ass_directwrite.c
index bf40cfbc0569d1652e8d020cd81bd0d157a448d4..be029e6b21fe6dc151fedb6188e0dd52b7fd9aba 100644 (file)
--- a/libass/ass_directwrite.c
+++ b/libass/ass_directwrite.c
@@ -500,6 +500,122 @@ static bool is_postscript(IDWriteFont *font)
            type == DWRITE_FONT_FACE_TYPE_TYPE1;
 }
 
+static void add_font(IDWriteFont *font, IDWriteFontFamily *fontFamily,
+                     ASS_FontProvider *provider)
+{
+    HRESULT hr = S_OK;
+    DWRITE_FONT_METRICS metrics;
+    DWRITE_FONT_STYLE style;
+    ASS_FontProviderMetaData meta = {0};
+    wchar_t temp_name[NAME_MAX_LENGTH];
+    int size_needed = 0;
+    IDWriteLocalizedStrings *familyNames = NULL;
+    IDWriteLocalizedStrings *fontNames = NULL;
+    IDWriteLocalizedStrings *psNames = NULL;
+    BOOL exists = FALSE;
+
+    meta.weight = IDWriteFont_GetWeight(font);
+    meta.width = map_width(IDWriteFont_GetStretch(font));
+    IDWriteFont_GetMetrics(font, &metrics);
+    style = IDWriteFont_GetStyle(font);
+    meta.slant = (style == DWRITE_FONT_STYLE_NORMAL) ? FONT_SLANT_NONE :
+                 (style == DWRITE_FONT_STYLE_OBLIQUE)? FONT_SLANT_OBLIQUE :
+                 (style == DWRITE_FONT_STYLE_ITALIC) ? FONT_SLANT_ITALIC : FONT_SLANT_NONE;
+
+    hr = IDWriteFont_GetInformationalStrings(font,
+            DWRITE_INFORMATIONAL_STRING_POSTSCRIPT_NAME, &psNames,&exists);
+    if (FAILED(hr)) {
+        IDWriteFont_Release(font);
+        return;
+    }
+
+    if (exists) {
+        hr = IDWriteLocalizedStrings_GetString(psNames, 0, temp_name, NAME_MAX_LENGTH);
+        if (FAILED(hr)) {
+            IDWriteLocalizedStrings_Release(psNames);
+            IDWriteFont_Release(font);
+            return;
+        }
+
+        temp_name[NAME_MAX_LENGTH-1] = 0;
+        size_needed = WideCharToMultiByte(CP_UTF8, 0, temp_name, -1, NULL, 0,NULL, NULL);
+        char *mbName = (char *) malloc(size_needed);
+        WideCharToMultiByte(CP_UTF8, 0, temp_name, -1, mbName, size_needed, NULL, NULL);
+        meta.postscript_name = mbName;
+
+        IDWriteLocalizedStrings_Release(psNames);
+    }
+
+    hr = IDWriteFont_GetInformationalStrings(font,
+            DWRITE_INFORMATIONAL_STRING_FULL_NAME, &fontNames,&exists);
+    if (FAILED(hr)) {
+        IDWriteFont_Release(font);
+        return;
+    }
+
+    if (exists) {
+        meta.n_fullname = IDWriteLocalizedStrings_GetCount(fontNames);
+        meta.fullnames = (char **) calloc(meta.n_fullname, sizeof(char *));
+        for (UINT32 k = 0; k < meta.n_fullname; ++k) {
+            hr = IDWriteLocalizedStrings_GetString(fontNames, k,
+                                                   temp_name,
+                                                   NAME_MAX_LENGTH);
+            if (FAILED(hr)) {
+                continue;
+            }
+
+            temp_name[NAME_MAX_LENGTH-1] = 0;
+            size_needed = WideCharToMultiByte(CP_UTF8, 0, temp_name, -1, NULL, 0, NULL, NULL);
+            char *mbName = (char *) malloc(size_needed);
+            WideCharToMultiByte(CP_UTF8, 0, temp_name, -1, mbName, size_needed, NULL, NULL);
+            meta.fullnames[k] = mbName;
+        }
+        IDWriteLocalizedStrings_Release(fontNames);
+    }
+
+    hr = IDWriteFont_GetInformationalStrings(font,
+            DWRITE_INFORMATIONAL_STRING_WIN32_FAMILY_NAMES, &familyNames, &exists);
+    if (!exists)
+        hr = IDWriteFontFamily_GetFamilyNames(fontFamily, &familyNames);
+    if (FAILED(hr)) {
+        IDWriteFont_Release(font);
+        return;
+    }
+
+    meta.n_family = IDWriteLocalizedStrings_GetCount(familyNames);
+    meta.families = (char **) calloc(meta.n_family, sizeof(char *));
+    for (UINT32 k = 0; k < meta.n_family; ++k) {
+        hr = IDWriteLocalizedStrings_GetString(familyNames, k,
+                                               temp_name,
+                                               NAME_MAX_LENGTH);
+        if (FAILED(hr)) {
+            continue;
+        }
+
+        temp_name[NAME_MAX_LENGTH-1] = 0;
+        size_needed = WideCharToMultiByte(CP_UTF8, 0, temp_name, -1, NULL, 0,NULL, NULL);
+        char *mbName = (char *) malloc(size_needed);
+        WideCharToMultiByte(CP_UTF8, 0, temp_name, -1, mbName, size_needed, NULL, NULL);
+        meta.families[k] = mbName;
+    }
+    IDWriteLocalizedStrings_Release(familyNames);
+
+    meta.is_postscript = is_postscript(font);
+
+    FontPrivate *font_priv = (FontPrivate *) calloc(1, sizeof(*font_priv));
+    font_priv->font = font;
+
+    ass_font_provider_add_font(provider, &meta, NULL, 0, font_priv);
+
+    for (UINT32 k = 0; k < meta.n_family; ++k)
+        free(meta.families[k]);
+    for (UINT32 k = 0; k < meta.n_fullname; ++k)
+        free(meta.fullnames[k]);
+    free(meta.fullnames);
+    free(meta.families);
+    free(meta.postscript_name);
+}
+
 /*
  * Scan every system font on the current machine and add it
  * to the libass lookup. Stores the FontPrivate as private data
@@ -511,12 +627,7 @@ static void scan_fonts(IDWriteFactory *factory,
     HRESULT hr = S_OK;
     IDWriteFontCollection *fontCollection = NULL;
     IDWriteFont *font = NULL;
-    DWRITE_FONT_METRICS metrics;
-    DWRITE_FONT_STYLE style;
-    ASS_FontProviderMetaData meta = {0};
     hr = IDWriteFactory_GetSystemFontCollection(factory, &fontCollection, FALSE);
-    wchar_t temp_name[NAME_MAX_LENGTH];
-    int size_needed = 0;
 
     if (FAILED(hr) || !fontCollection)
         return;
@@ -525,10 +636,6 @@ static void scan_fonts(IDWriteFactory *factory,
 
     for (UINT32 i = 0; i < familyCount; ++i) {
         IDWriteFontFamily *fontFamily = NULL;
-        IDWriteLocalizedStrings *familyNames = NULL;
-        IDWriteLocalizedStrings *fontNames = NULL;
-        IDWriteLocalizedStrings *psNames = NULL;
-        BOOL exists = FALSE;
 
         hr = IDWriteFontCollection_GetFontFamily(fontCollection, i, &fontFamily);
         if (FAILED(hr))
@@ -547,106 +654,7 @@ static void scan_fonts(IDWriteFactory *factory,
                 continue;
             }
 
-            meta.weight = IDWriteFont_GetWeight(font);
-            meta.width = map_width(IDWriteFont_GetStretch(font));
-            IDWriteFont_GetMetrics(font, &metrics);
-            style = IDWriteFont_GetStyle(font);
-            meta.slant = (style == DWRITE_FONT_STYLE_NORMAL) ? FONT_SLANT_NONE :
-                         (style == DWRITE_FONT_STYLE_OBLIQUE)? FONT_SLANT_OBLIQUE :
-                         (style == DWRITE_FONT_STYLE_ITALIC) ? FONT_SLANT_ITALIC : FONT_SLANT_NONE;
-
-            hr = IDWriteFont_GetInformationalStrings(font,
-                    DWRITE_INFORMATIONAL_STRING_POSTSCRIPT_NAME, &psNames,&exists);
-            if (FAILED(hr)) {
-                IDWriteFont_Release(font);
-                continue;
-            }
-
-            if (exists) {
-                hr = IDWriteLocalizedStrings_GetString(psNames, 0, temp_name, NAME_MAX_LENGTH);
-                if (FAILED(hr)) {
-                    IDWriteLocalizedStrings_Release(psNames);
-                    IDWriteFont_Release(font);
-                    continue;
-                }
-
-                temp_name[NAME_MAX_LENGTH-1] = 0;
-                size_needed = WideCharToMultiByte(CP_UTF8, 0, temp_name, -1, NULL, 0,NULL, NULL);
-                char *mbName = (char *) malloc(size_needed);
-                WideCharToMultiByte(CP_UTF8, 0, temp_name, -1, mbName, size_needed, NULL, NULL);
-                meta.postscript_name = mbName;
-
-                IDWriteLocalizedStrings_Release(psNames);
-            }
-
-            hr = IDWriteFont_GetInformationalStrings(font,
-                    DWRITE_INFORMATIONAL_STRING_FULL_NAME, &fontNames,&exists);
-            if (FAILED(hr)) {
-                IDWriteFont_Release(font);
-                continue;
-            }
-
-            if (exists) {
-                meta.n_fullname = IDWriteLocalizedStrings_GetCount(fontNames);
-                meta.fullnames = (char **) calloc(meta.n_fullname, sizeof(char *));
-                for (UINT32 k = 0; k < meta.n_fullname; ++k) {
-                    hr = IDWriteLocalizedStrings_GetString(fontNames, k,
-                                                           temp_name,
-                                                           NAME_MAX_LENGTH);
-                    if (FAILED(hr)) {
-                        continue;
-                    }
-
-                    temp_name[NAME_MAX_LENGTH-1] = 0;
-                    size_needed = WideCharToMultiByte(CP_UTF8, 0, temp_name, -1, NULL, 0, NULL, NULL);
-                    char *mbName = (char *) malloc(size_needed);
-                    WideCharToMultiByte(CP_UTF8, 0, temp_name, -1, mbName, size_needed, NULL, NULL);
-                    meta.fullnames[k] = mbName;
-                }
-                IDWriteLocalizedStrings_Release(fontNames);
-            }
-
-            hr = IDWriteFont_GetInformationalStrings(font,
-                    DWRITE_INFORMATIONAL_STRING_WIN32_FAMILY_NAMES, &familyNames, &exists);
-            if (!exists)
-                hr = IDWriteFontFamily_GetFamilyNames(fontFamily, &familyNames);
-            if (FAILED(hr)) {
-                IDWriteFont_Release(font);
-                continue;
-            }
-
-            meta.n_family = IDWriteLocalizedStrings_GetCount(familyNames);
-            meta.families = (char **) calloc(meta.n_family, sizeof(char *));
-            for (UINT32 k = 0; k < meta.n_family; ++k) {
-                hr = IDWriteLocalizedStrings_GetString(familyNames, k,
-                                                       temp_name,
-                                                       NAME_MAX_LENGTH);
-                if (FAILED(hr)) {
-                    continue;
-                }
-
-                temp_name[NAME_MAX_LENGTH-1] = 0;
-                size_needed = WideCharToMultiByte(CP_UTF8, 0, temp_name, -1, NULL, 0,NULL, NULL);
-                char *mbName = (char *) malloc(size_needed);
-                WideCharToMultiByte(CP_UTF8, 0, temp_name, -1, mbName, size_needed, NULL, NULL);
-                meta.families[k] = mbName;
-            }
-            IDWriteLocalizedStrings_Release(familyNames);
-
-            meta.is_postscript = is_postscript(font);
-
-            FontPrivate *font_priv = (FontPrivate *) calloc(1, sizeof(*font_priv));
-            font_priv->font = font;
-
-            ass_font_provider_add_font(provider, &meta, NULL, 0, font_priv);
-
-            for (UINT32 k = 0; k < meta.n_family; ++k)
-                free(meta.families[k]);
-            for (UINT32 k = 0; k < meta.n_fullname; ++k)
-                free(meta.fullnames[k]);
-            free(meta.fullnames);
-            free(meta.families);
-            free(meta.postscript_name);
+            add_font(font, fontFamily, provider);
         }
     }
 }