The recent change to detect duplicate enum values and return ECTF_DUPLICATE
when found turns out to perturb a great many callers. In particular, the
pahole-created kernel BTF has the same problem we historically did, and
gleefully emits duplicated enum constants in profusion. Handling the
resulting duplicate errors from BTF -> CTF converters reasonably is
unreasonably difficult (it amounts to forcing them to skip some types or
reimplement the deduplicator).
So let's step back a bit. What we care about mostly is that the
deduplicator treat enums with conflicting enumeration constants as
conflicting types: programs that want to look up enumeration constant ->
value mappings using the new APIs to do so might well want the same checks
to apply to any ctf_add_* operations they carry out (and since they're
*using* the new APIs, added at the same time as this restriction was
imposed, there is likely to be no negative consequence of this).
So we want some way to allow processes that know about duplicate detection
to opt into it, while allowing everyone else to stay clear of it: but we
want ctf_link to get this behaviour even if its caller has opted out.
So add a new concept to the API: dict-wide CTF flags, set via
ctf_dict_set_flag, obtained via ctf_dict_get_flag. They are not bitflags
but simple arbitrary integers and an on/off value, stored in an unspecified
manner (the one current flag, we translate into an LCTF_* flag value in the
internal ctf_dict ctf_flags word). If you pass in an invalid flag or value
you get a new ECTF_BADFLAG error, so the caller can easily tell whether
flags added in future are valid with a particular libctf or not.
We check this flag in ctf_add_enumerator, and set it around the link
(including on child per-CU dicts). The newish enumerator-iteration test is
souped up to check the semantics of the flag as well.
The fact that the flag can be set and unset at any time has curious
consequences. You can unset the flag, insert a pile of duplicates, then set
it and expect the new duplicates to be detected, not only by
ctf_add_enumerator but also by ctf_lookup_enumerator. This means we now
have to maintain the ctf_names and conflicting_enums enum-duplication
tracking as new enums are added, not purely as the dict is opened.
Move that code out of init_static_types_internal and into a new
ctf_track_enumerator function that addition can also call.
(None of this affects the file format or serialization machinery, which has
to be able to handle duplicate enumeration constants no matter what.)
include/
* ctf-api.h (CTF_ERRORS) [ECTF_BADFLAG]: New.
(ECTF_NERR): Update.
(CTF_STRICT_NO_DUP_ENUMERATORS): New flag.
(ctf_dict_set_flag): New function.
(ctf_dict_get_flag): Likewise.
libctf/
* ctf-impl.h (LCTF_STRICT_NO_DUP_ENUMERATORS): New flag.
(ctf_track_enumerator): Declare.
* ctf-dedup.c (ctf_dedup_emit_type): Set it.
* ctf-link.c (ctf_create_per_cu): Likewise.
(ctf_link_deduplicating_per_cu): Likewise.
(ctf_link): Likewise.
(ctf_link_write): Likewise.
* ctf-subr.c (ctf_dict_set_flag): New function.
(ctf_dict_get_flag): New function.
* ctf-open.c (init_static_types_internal): Move enum tracking to...
* ctf-create.c (ctf_track_enumerator): ... this new function.
(ctf_add_enumerator): Call it.
* libctf.ver: Add the new functions.
* testsuite/libctf-lookup/enumerator-iteration.c: Test them.
Most of these are harmless, but some of the type confusions and especially
a missing ctf_strerror() on an error path were actual bugs that could
have resulted in test failures crashing rather than printing an error
message.
libctf/
* testsuite/libctf-lookup/enumerator-iteration.c: Fix type
confusion, signedness confusion and a missing ctf_errmsg().
* testsuite/libctf-regression/libctf-repeat-cu-main.c: Return 0 from
the test function.
* testsuite/libctf-regression/open-error-free.c: Fix signedness
confusion.
* testsuite/libctf-regression/zrewrite.c: Remove unused label.
Three new functions for looking up the enum type containing a given
enumeration constant, and optionally that constant's value.
The simplest, ctf_lookup_enumerator, looks up a root-visible enumerator by
name in one dict: if the dict contains multiple such constants (which is
possible for dicts created by older versions of the libctf deduplicator),
ECTF_DUPLICATE is returned.
The next simplest, ctf_lookup_enumerator_next, is an iterator which returns
all enumerators with a given name in a given dict, whether root-visible or
not.
The most elaborate, ctf_arc_lookup_enumerator_next, finds all
enumerators with a given name across all dicts in an entire CTF archive,
whether root-visible or not, starting looking in the shared parent dict;
opened dicts are cached (as with all other ctf_arc_*lookup functions) so
that repeated use does not incur repeated opening costs.
All three of these return enumerator values as int64_t: unfortunately, API
compatibility concerns prevent us from doing the same with the other older
enum-related functions, which all return enumerator constant values as ints.
We may be forced to add symbol-versioning compatibility aliases that fix the
other functions in due course, bumping the soname for platforms that do not
support such things.
ctf_arc_lookup_enumerator_next is implemented as a nested ctf_archive_next
iterator, and inside that, a nested ctf_lookup_enumerator_next iterator
within each dict. To aid in this, add support to ctf_next_t iterators for
iterators that are implemented in terms of two simultaneous nested iterators
at once. (It has always been possible for callers to use as many nested or
semi-overlapping ctf_next_t iterators as they need, which is one of the
advantages of this style over the _iter style that calls a function for each
thing iterated over: the iterator change here permits *ctf_next_t iterators
themselves* to be implemented by iterating using multiple other iterators as
part of their internal operation, transparently to the caller.)
Also add a testcase that tests all these functions (which is fairly easy
because ctf_arc_lookup_enumerator_next is implemented in terms of
ctf_lookup_enumerator_next) in addition to enumeration addition in
ctf_open()ed dicts, ctf_add_enumerator duplicate enumerator addition, and
conflicting enumerator constant deduplication.
include/
* ctf-api.h (ctf_lookup_enumerator): New.
(ctf_lookup_enumerator_next): Likewise.
(ctf_arc_lookup_enumerator_next): Likewise.
libctf/
* libctf.ver: Add them.
* ctf-impl.h (ctf_next_t) <ctn_next_inner>: New.
* ctf-util.c (ctf_next_copy): Copy it.
(ctf_next_destroy): Destroy it.
* ctf-lookup.c (ctf_lookup_enumerator): New.
(ctf_lookup_enumerator_next): New.
* ctf-archive.c (ctf_arc_lookup_enumerator_next): New.
* testsuite/libctf-lookup/enumerator-iteration.*: New test.
* testsuite/libctf-lookup/enum-ctf-2.c: New test CTF, used by the
above.
