json_patch_apply_move_copy() checks that "from" is not a proper prefix
of "path" per RFC 6902 section 4.4 (a location cannot be moved into one
of its own children), but it did so with a plain strncmp() over the raw
pointer strings, without checking that the shared run of characters
actually ends on a JSON Pointer reference-token boundary in "path".
As a result, moving or copying between two sibling object keys where
one name is a textual prefix of the other, e.g. "/aa" to "/aab", was
rejected with "Invalid attempt to move parent under a child" even
though "/aa" is not an ancestor pointer of "/aab" at all, just an
unrelated key that happens to share a few leading characters.
The fix requires that the character in "path" right after the shared
"from" prefix be either the end of the string (equal paths, a no-op)
or a '/' (a genuine nested reference token), before treating it as an
attempt to move a location under its own descendant.
Added two cases to json_patch_tests.json covering the move and copy
operations between such sibling keys, and refreshed the corresponding
golden test_json_patch.expected output.
Initially I wanted to also do a function that generates the JSON patch from
two JSON documents, but even just applying the JSON patch was a bit of
work, especially when needing to satisfy all the test-cases.
This change defines all the operation in the RFC6902. The addition isn't
too big (for the json_patch_apply() function), as part of the heavy lifting
is also done by JSON pointer logic.
All the ops were tested with the test-cases defined at:
https://github.com/json-patch/json-patch-tests
RFC6902: https://tools.ietf.org/html/rfc6902
Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>