From 4acc1960e69fd5e86198e479088e7be50459337b Mon Sep 17 00:00:00 2001
From: Oleg Oshmyan <chortos@inbox.lv>
Date: Sat, 26 Jun 2021 15:21:55 +0300
Subject: directwrite: remove arbitrary 256-char name length limit

---
 libass/ass_directwrite.c | 38 ++++++++++++++++++++++++++++----------
 libass/dwrite_c.h        |  5 ++++-
 2 files changed, 32 insertions(+), 11 deletions(-)

diff --git a/libass/ass_directwrite.c b/libass/ass_directwrite.c
index 89e1099..deabb57 100644
--- a/libass/ass_directwrite.c
+++ b/libass/ass_directwrite.c
@@ -29,7 +29,6 @@
 #include "ass_directwrite.h"
 #include "ass_utils.h"
 
-#define NAME_MAX_LENGTH 256
 #define FALLBACK_DEFAULT_FONT L"Arial"
 
 static const ASS_FontMapping font_substitutions[] = {
@@ -428,19 +427,38 @@ static int encode_utf16(wchar_t *chars, uint32_t codepoint)
 
 static char *get_utf8_name(IDWriteLocalizedStrings *names, int k)
 {
-    wchar_t temp_name[NAME_MAX_LENGTH];
-    HRESULT hr = IDWriteLocalizedStrings_GetString(names, k,
-                                                   temp_name,
-                                                   NAME_MAX_LENGTH);
+    wchar_t *temp_name = NULL;
+    char *mbName = NULL;
+
+    UINT32 length;
+    HRESULT hr = IDWriteLocalizedStrings_GetStringLength(names, k, &length);
     if (FAILED(hr))
-        return NULL;
+        goto cleanup;
+
+    if (length >= (UINT32) -1 || length + (size_t) 1 > SIZE_MAX / sizeof(wchar_t))
+        goto cleanup;
 
-    temp_name[NAME_MAX_LENGTH-1] = 0;
-    int size_needed = WideCharToMultiByte(CP_UTF8, 0, temp_name, -1, NULL, 0, NULL, NULL);
-    char *mbName = (char *) malloc(size_needed);
+    temp_name = (wchar_t *) malloc((length + 1) * sizeof(wchar_t));
+    if (!temp_name)
+        goto cleanup;
+
+    hr = IDWriteLocalizedStrings_GetString(names, k, temp_name, length + 1);
+    if (FAILED(hr))
+        goto cleanup;
+
+    int size_needed =
+        WideCharToMultiByte(CP_UTF8, 0, temp_name, -1, NULL, 0, NULL, NULL);
+    if (!size_needed)
+        goto cleanup;
+
+    mbName = (char *) malloc(size_needed);
     if (!mbName)
-        return NULL;
+        goto cleanup;
+
     WideCharToMultiByte(CP_UTF8, 0, temp_name, -1, mbName, size_needed, NULL, NULL);
+
+cleanup:
+    free(temp_name);
     return mbName;
 }
 
diff --git a/libass/dwrite_c.h b/libass/dwrite_c.h
index 5612e9f..43930ca 100644
--- a/libass/dwrite_c.h
+++ b/libass/dwrite_c.h
@@ -506,8 +506,10 @@ DECLARE_INTERFACE_(IDWriteLocalizedStrings,IUnknown)
     STDMETHOD(dummy1)(THIS);
     STDMETHOD(dummy2)(THIS);
     STDMETHOD(dummy3)(THIS);
-    STDMETHOD(dummy4)(THIS);
 
+    STDMETHOD(GetStringLength)(THIS_
+        UINT32 index,
+        UINT32 *length) PURE;
     STDMETHOD(GetString)(THIS_
         UINT32 index,
         WCHAR *stringBuffer,
@@ -518,6 +520,7 @@ DECLARE_INTERFACE_(IDWriteLocalizedStrings,IUnknown)
 #ifdef COBJMACROS
 #define IDWriteLocalizedStrings_Release(This) (This)->lpVtbl->Release(This)
 #define IDWriteLocalizedStrings_GetCount(This) (This)->lpVtbl->GetCount(This)
+#define IDWriteLocalizedStrings_GetStringLength(This,index,length) (This)->lpVtbl->GetStringLength(This,index,length)
 #define IDWriteLocalizedStrings_GetString(This,index,stringBuffer,size) (This)->lpVtbl->GetString(This,index,stringBuffer,size)
 #endif /*COBJMACROS*/
 
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