[subset] Fix memory leak in hb-ot-{maxp,os2}. Plus some formatting.

src/hb-ot-maxp-table.hh

@@ -64,7 +64,7 @@ struct maxp
   inline bool subset (hb_subset_plan_t *plan) const
   {
     hb_blob_t *maxp_blob = OT::Sanitizer<OT::maxp>().sanitize (hb_face_reference_table (plan->source, HB_OT_TAG_maxp));
-    // TODO hb_blob_copy_writable_or_fail
+    // TODO(grieger): hb_blob_copy_writable_or_fail
     hb_blob_t *maxp_prime_blob = hb_blob_create_sub_blob (maxp_blob, 0, -1);
     hb_blob_destroy (maxp_blob);
 
@@ -76,7 +76,9 @@ struct maxp
 
     maxp_prime->set_num_glyphs (plan->gids_to_retain_sorted.len);
 
-    return hb_subset_plan_add_table(plan, HB_OT_TAG_maxp, maxp_prime_blob);
+    bool result = hb_subset_plan_add_table(plan, HB_OT_TAG_maxp, maxp_prime_blob);
+    hb_blob_destroy (maxp_prime_blob);
+    return result;
   }
 
   /* We only implement version 0.5 as none of the extra fields in version 1.0 are useful. */

src/hb-ot-os2-table.hh

@@ -53,6 +53,7 @@ struct os2
   {
     hb_blob_t *os2_blob = OT::Sanitizer<OT::os2>().sanitize (hb_face_reference_table (plan->source, HB_OT_TAG_os2));
     hb_blob_t *os2_prime_blob = hb_blob_create_sub_blob (os2_blob, 0, -1);
+    // TODO(grieger): move to hb_blob_copy_writable_or_fail
     hb_blob_destroy (os2_blob);
 
     OT::os2 *os2_prime = (OT::os2 *) hb_blob_get_data_writable (os2_prime_blob, nullptr);
@@ -62,27 +63,28 @@ struct os2
     }
 
     uint16_t min_cp, max_cp;
-    find_min_and_max_codepoint (plan, &min_cp, &max_cp);
+    find_min_and_max_codepoint (plan->codepoints, &min_cp, &max_cp);
     os2_prime->usFirstCharIndex.set (min_cp);
     os2_prime->usLastCharIndex.set (max_cp);
 
-    return hb_subset_plan_add_table(plan, HB_OT_TAG_os2, os2_prime_blob);
+    bool result = hb_subset_plan_add_table(plan, HB_OT_TAG_os2, os2_prime_blob);
+    hb_blob_destroy (os2_prime_blob);
+    return result;
   }
 
-  static inline void find_min_and_max_codepoint (hb_subset_plan_t *plan,
-                                                 uint16_t         *min_cp, /* OUT */
-                                                 uint16_t         *max_cp  /* OUT */)
+  static inline void find_min_and_max_codepoint (const hb_prealloced_array_t<hb_codepoint_t> &codepoints,
+                                                 uint16_t *min_cp, /* OUT */
+                                                 uint16_t *max_cp  /* OUT */)
   {
     hb_codepoint_t min = -1, max = 0;
 
-    for (int i = 0; i < plan->codepoints.len; i++) {
-      hb_codepoint_t cp = plan->codepoints[i];
-      if (cp < min) {
+    for (int i = 0; i < codepoints.len; i++)
+    {
+      hb_codepoint_t cp = codepoints[i];
+      if (cp < min)
         min = cp;
-      }
-      if (cp > max) {
+      if (cp > max)
         max = cp;
-      }
     }
 
     if (min > 0xFFFF)