[Bug libctf/30985] ctf_add_member_encoded of a type on a parent dumps core

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30985

--- Comment #2 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot 
gnu.org> ---
The master branch has been updated by Nick Alcock <nix@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=cd4a8fc4f0bc3c4013756404bc06ad1bdddced59

commit cd4a8fc4f0bc3c4013756404bc06ad1bdddced59
Author: Nick Alcock <nick.alcock@oracle.com>
Date:   Wed Oct 18 18:34:57 2023 +0100

    libctf: fix creation-time parent/child dict confusions

    The fixes applied a few years ago to resolve confusions between parent and
    child dicts at lookup time also apply in various forms to creation.  In
    general, if you have a type in a parent dict ctf_imported into a child and
    you do something to it, and the parent dict is writable (created via
    ctf_create, not opened via ctf_open*) it should work just the same to make
    changes to that type via a child dict as it does to make the change
    to the parent dict directly -- and nothing you're prohibited from doing
    to the parent dict when done directly should be allowed just because
    you're doing it via a child.

    Specifically, the following don't work when doing things from the child,
but
    should:

     - adding a member of a type in the parent to a struct or union in the
       parent via ctf_add_member or ctf_add_member_offset: this yields
       ECTF_BADID

     - adding a member of a type in the parent to a struct or union in the
       parent via ctf_add_member_encoded: this dumps core (!).

     - adding an enumerand to an enumerator in the parent: this yields
       ECTF_BADID

     - setting the properties of an array in the parent via ctf_set_array;
       this yields ECTF_BADID

    Relatedly, some things work when doing things via a child that should fail,
    yielding a CTF dictionary with invalid content (readable, but meaningless):
    in particular, you can add a child type to a struct in the parent via
    any of the ctf_add_member* family and nothing complains at all, even though
    you should never be able to add references to children to parents (since
any
    given parent can be associated with many different children).

    A family of tests is added to check each of these cases independently,
since
    some can result in coredumps and it would be nice to test the other cases
    even if some dump core.  They use a common library to do all the actual
    work.  The set of affected API calls was determined by code inspection
    (auditing all calls to ctf_dtd_lookup): it's possible that I missed a few,
    but I doubt it, since other cases use ctf_lookup* functions, which already
    climb to the parent where appropriate.

    libctf/ChangeLog:

            PR libctf/30985
            * ctf-create.c (ctf_dtd_lookup): Traverse to parents if necessary.
            (ctf_set_array): Likewise.  Report errors on the child; require
            both parent and child to be writable.
            (ctf_add_enumerator): Likewise.
            (ctf_add_member_offset): Likewise.  Prohibit addition of child
types
            to structs in the parent.
            (ctf_add_member_encoded): Do not dereference a NULL dtd: report
            ECTF_BADID instead.
            * ctf-string.c (ctf_str_add_ref_internal): Report ENOMEM on the
            dict if addition of a string ref fails.
            * testsuite/libctf-writable/parent-child-dtd-crash-lib.c: New
library.
            * testsuite/libctf-writable/parent-child-dtd-enum.*: New test.
            * testsuite/libctf-writable/parent-child-dtd-enumerator.*: New
test.
            * testsuite/libctf-writable/parent-child-dtd-member-encoded.*: New
test.
            * testsuite/libctf-writable/parent-child-dtd-member-offset.*: New
test.
            * testsuite/libctf-writable/parent-child-dtd-set-array.*: New test.
            * testsuite/libctf-writable/parent-child-dtd-struct.*: New test.
            * testsuite/libctf-writable/parent-child-dtd-union.*: New test.

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