Harden allocation failure handling and size arithmetic

- check malloc/calloc/realloc results in constructors, the JSON and
  OpenStep writers, the XML text-part helpers and base64 decoding, and
  return PLIST_ERR_NO_MEM instead of asserting or dereferencing NULL
- guard size calculations against overflow in the UTF-8/UTF-16BE
  conversions, ptrarray, and bytearray
- make hash_table_insert() report failure instead of silently dropping
  the entry; writers propagate PLIST_ERR_NO_MEM, and dict lookup caches
  are discarded so lookups fall back to a linear search
- don't overwrite an earlier parse error code in the XML parser, and
  report PLIST_ERR_NO_MEM when reading text content fails for lack of memory
- OpenStep parser: check node/data/string allocations and dict/array
  insertion results

Based on #323 by bg0d-droid.

Co-authored-by: bg0d-droid <81825610+bg0d-droid@users.noreply.github.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/src/out-limd.c b/src/out-limd.c
index 259d036..dd4c252 100644
--- a/src/out-limd.c
+++ b/src/out-limd.c
@@ -293,7 +293,9 @@ static plist_err_t _node_estimate_size(node_t node, uint64_t *size, uint32_t dep
     }
 
     // mark as visited
-    hash_table_insert(visited, node, (void*)1);
+    if (hash_table_insert(visited, node, (void*)1) < 0) {
+        return PLIST_ERR_NO_MEM;
+    }
 
     data = plist_get_data(node);
     if (node->children) {