byte_array_grow() assigned the result of realloc() directly to
ba->data and increased the capacity even if realloc() failed, so the
following memcpy() in byte_array_append() wrote to NULL + len.

On failure, free the old buffer and leave the byte array in a failed
state (data == NULL), which byte_array_append() already ignores. The
callers check for that state:

- the writers (bin, xml, json, openstep and the text output formats)
  return PLIST_ERR_NO_MEM instead of handing out a NULL/truncated buffer
- node_to_xml() base64-encodes <data> directly into the grown buffer,
  so it must bail out there (only guarded by assert() before)
- the OpenStep parser returns PLIST_ERR_NO_MEM for <hex data> instead of
  silently returning truncated data

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Avoid undefined behavior when serializing malformed PLIST_DATE values
containing NaN, infinity, or values outside the Time64_T range. Add a
shared helper for checked date conversion and use it across writer paths.

Ensure that XML property lists contain exactly one root value inside the <plist> element and reject any additional value nodes before </plist>.

Add tests covering root value handling and nested CF$UID conversion behavior.

Co-authored-by: Sami Kortelainen <sami.kortelainen@piceasoft.com>
Co-authored-by: Nikias Bassen <nikias@gmx.li>

Convert single-entry { "CF$UID" : <integer> } dictionaries to PLIST_UID
nodes when closing a dict in the XML parser.

Refactor node cleanup logic:
- Split plist_free_data() into internal _plist_free_data()
- Introduce plist_free_children() to release child nodes separately
- Update plist_set_element_val() to free children before changing
  container node types
- Ensure PLIST_DICT hashtables do not free values (assert + force
  free_func = NULL)

This avoids in-place container mutation issues and ensures child
nodes and container metadata are released correctly before
changing node type.

Co-authored-by: Sami Kortelainen <sami.kortelainen@piceasoft.com>
Co-authored-by: Nikias Bassen <nikias@gmx.li>

This change adds stricter validation for numeric and date nodes,
including full-input consumption, overflow/range checks, and rejection
of invalid floating-point values. Whitespace handling is clarified by
explicitly trimming trailing XML whitespace for value nodes.

This removes the necessity for malloc failures and reduces overhead