When sanitizing, delay making writable

Before, as soon as we needed to make an edit, we tried to make the blob
writable inplace.  That grows code unnecessarily though.  We can simply
fail, make writable, then start again.  That's indeed what the fallback
was doing anyway.

diff --git a/src/hb-open-type-private.hh b/src/hb-open-type-private.hh
index 3a89425..a4b76c5 100644 (file)
--- a/src/hb-open-type-private.hh
+++ b/src/hb-open-type-private.hh
@@ -166,7 +166,8 @@ typedef struct _hb_sanitize_context_t hb_sanitize_context_t;
 struct _hb_sanitize_context_t
 {
   const char *start, *end;
-  int edit_count;
+  hb_bool_t writable;
+  unsigned int edit_count;
   hb_blob_t *blob;
 };
 
@@ -177,6 +178,7 @@ _hb_sanitize_init (hb_sanitize_context_t *context,
   context->blob = blob;
   context->start = hb_blob_lock (blob);
   context->end = context->start + hb_blob_get_length (blob);
+  context->writable = hb_blob_is_writable (blob);
   context->edit_count = 0;
 
 #if HB_DEBUG_SANITIZE
@@ -236,6 +238,7 @@ _hb_sanitize_array (SANITIZE_ARG_DEF,
             context->start, context->end,
             !overflows ? "does not overflow" : "OVERFLOWS FAIL");
 #endif
+
   return HB_LIKELY (!overflows) && _hb_sanitize_check (SANITIZE_ARG, base, record_size * len);
 }
 
@@ -244,7 +247,6 @@ _hb_sanitize_edit (SANITIZE_ARG_DEF,
                   const char *base HB_GNUC_UNUSED,
                   unsigned int len HB_GNUC_UNUSED)
 {
-  bool perm = hb_blob_try_writable_inplace (context->blob);
   context->edit_count++;
 
 #if HB_DEBUG_SANITIZE
@@ -254,9 +256,10 @@ _hb_sanitize_edit (SANITIZE_ARG_DEF,
           context->edit_count,
           base, base+len, len,
           context->start, context->end,
-          perm ? "granted" : "REJECTED");
+          context->writable ? "granted" : "REJECTED");
 #endif
-  return perm;
+
+  return context->writable;
 }
 
 #define SANITIZE(X) HB_LIKELY ((X).sanitize (SANITIZE_ARG))