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The root-visible flag we're dealing with here is directly out of the dict,
not a flag passed in to the API, so it does not have the values CTF_ADD_ROOT
or CTF_ADD_NONROOT: instead it's simply zero for non-root-visible, nonzero
otherwise. Fix the test.
libctf/
* ctf-create.c (ctf_add_enumerator): Fix root-visibility test.
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If you add a non-root type to a dict, you should always get a new, unique
type ID back, even if a root-visible type with the same name already exists.
Unfortunately, if the root-visible type is a forward, and you're adding a
non-root-visible struct, union, or enum, the machinery to detect forwards
and promote them to the concrete type fires in this case and returns the
root-visible type! If this is an enum being inserted hidden because its
enumerands conflict with some other enum, this will lead to failure later
on: in any case, it's seriously counterintuitive to add a non-root- visible
type and get a root-visible one instead.
Fix this by checking the root-visible flag properly and only checking for
forwards if this type is root-visible. (This may lead to a certain degree
of proliferation of non-root-visible forwards: we can add a cleanup pass for
those later if needed.)
libctf/
* ctf-create.c (ctf_add_sou_sized): Check the root-visible flag when
doing forward promotion.
(ctf_add_enum_internal): Likewise.
(ctf_add_enum_encoded_internal): Likewise.
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The new serializer is quite a lot more customizable than the old, because it
can write out BTF as well as CTF: you can ask to write out BTF or fail,
write out CTF if required to avoid information loss, otherwise BTF, or
always write out CTF.
Callers often need to find out whether a dict could be written out as BTF
before deciding how to write it out (because a dict can never be written out
as BTF if it is compressed, a caller might well want to ask if there is
anything else that prevents BTF writeout -- say, slices, conflicting types,
or CTF_K_BIG -- before deciding whether to compress it). GNU ld will do
this whenever it is passed only BTF sections on the input.
Figuring out whether a dict can be written out as BTF is quite expensive: we
have to traverse all the types and check them, including every member of
every struct. So we'd rather do that work only once. This means making a
lot of state once private to ctf_preserialize public enough that another
function can initialize it; and since the whole API is available after
calling this function and before serializing, we should probably arrange
that if we do things we know will invalidate the results of all this
checking, we are forced to do it again.
This commit does that, moving all the existing serialization state into a
new ctf_serialize_t and adding to it. Several functions grow force_ctf
arguments that allow the caller to force CTF emission even if the type
section looks BTFish: the writeout code and archive creation use this to
force CTF emission if we are compressing, and archive creation uses it
to force CTF emission if a CTF multi-member archive is in use, because
BTF doesn't support archives at all so there's no point maintaining
BTF compatibility in that case. The ctf_write* functions gain support for
writing out BTF headers as well as CTF, depending on whether what was
ultimately written out was actually BTF or not.
Even more than most commits in this series, there is no way this is
going to compile right now: we're in the middle of a major transition,
completed in the next few commits.
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Just as for typedefs, this is just catching up with API changes on the
type-addition side.
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Nothing here but adjustment to internal API changes. Typedefs have no
special properties that need querying, so there are no changes to
ctf-types.c at all.
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Nothing difficult for this CTF-specific type kind, just the usual adjustment
to internal API changes.
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The same internal API changes for arrays. There is one ABI change here,
to ctf_arinfo_t:
- uint32_t ctr_nelems; /* Number of elements. */
+ size_t ctr_nelems; /* Number of elements. */
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This is pure adjustment for internal API changes, and a change to the
type-compatibility of pointers to type 0 now that it can be void as well as
"unrepresentable".
By now this dance should be quite familiar.
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The conflicting type kind is a CTF-specific prefix kind consisting purely of
an optional translation unit name. It takes the place of the old hidden
bit: we have already seen it used to prefix types added with a
CTF_ADD_NONROOT flag. The deduplicator will also use them to label
conflicting types from different TUs smushed into the same dict by the
CU-mapping mechanism: unlike the hidden bit, with this scheme users can tell
which CUs the conflicting types came from.
New API:
+int ctf_type_conflicting (ctf_dict_t *, ctf_id_t, const char **cuname);
+int ctf_set_conflicting (ctf_dict_t *, ctf_id_t, const char *);
(Frankly I expect ctf_set_conflicting to be used only by deduplicators and
things like that, but if we provide an option to query something we should
also provide an option to produce it...)
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These are a little more fiddly than previous kinds, because their
namespacing rules are odd: they have names (so presumably we want an API to
look them up by name), but the names are not unique (they don't need to be,
because they are not entities you can refer to from C), so many distinct
tags in the same TU can have the same name. Type tags only refer to a type
ID: decl tags refer to a specific function parameter or structure member via
a zero-indexed "component index".
The name tables for these things are a hash of name to a set of type IDs;
rather different from all the other named entities in libctf. As a
consequence, they can presently be looked up only using their own dedicated
functions, not using ctf_lookup_by_name et al. (It's not clear if this
restriction could ever be lifted: ctf_lookup_by_name and friends return a
type ID, not a set of them.)
They are similar enough to each other that we can at least have one function
to look up both type and decl tags if you don't care about their
component_idx and only want a type ID: ctf_tag. (And one to iterate over
them, ctf_tag_next).
(A caveat: because tags aren't widely used or generated yet, much of this is
more or less untested and/or supposition and will need testing later.)
New API, more or less the minimum needed because it's not entirely clear how
these things will be used:
+ctf_id_t ctf_tag (ctf_dict_t *, ctf_id_t tag);
+ctf_id_t ctf_decl_tag (ctf_dict_t *, ctf_id_t decl_tag,
+ int64_t *component_idx);
+ctf_id_t ctf_tag_next (ctf_dict_t *, const char *tag, ctf_next_t **);
+ctf_id_t ctf_add_type_tag (ctf_dict_t *, uint32_t, ctf_id_t, const char *);
+ctf_id_t ctf_add_decl_type_tag (ctf_dict_t *, uint32_t, ctf_id_t, const char *);
+ctf_id_t ctf_add_decl_tag (ctf_dict_t *, uint32_t, ctf_id_t, const char *,
+ int component_idx);
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Functions change in CTFv4 by growing argument names as well as argument
types; the representation changes into a two-element array of (type, string
offset) rather than a simple array of arg types. Functions also gain an
explicit linkage in a different type kind (CTF_K_FUNC_LINKAGE, which
corresponds to BTF_KIND_FUNC).
New API:
typedef struct ctf_funcinfo {
/* ... */
- uint32_t ctc_argc; /* Number of typed arguments to function. */
+ size_t ctc_argc; /* Number of typed arguments to function. */
};
int ctf_func_arg_names (ctf_dict_t *, unsigned long, uint32_t, const char **);
int ctf_func_type_arg_names (ctf_dict_t *, ctf_id_t, uint32_t,
const char **names);
+extern int ctf_type_linkage (ctf_dict_t *, ctf_id_t);
-extern ctf_id_t ctf_add_function (ctf_dict_t *, uint32_t,
- const ctf_funcinfo_t *, const ctf_id_t *);
+extern ctf_id_t ctf_add_function (ctf_dict_t *, uint32_t,
+ const ctf_funcinfo_t *, const ctf_id_t *,
+ const char **arg_names);
+extern ctf_id_t ctf_add_function_linkage (ctf_dict_t *, uint32_t,
+ ctf_id_t, const char *, int linkage);
Adding this is fairly straightforward; the only annoying part is the way the
callers need to allocate space for the arg name and type arrays. Maybe we
should rethink these into something like ctf_type_aname(), allocating
space for the caller so the caller doesn't need to? It would certainly
make all the callers in libctf much less complex...
While we're at it, adjust ctf_type_reference, ctf_type_align, and
ctf_type_size for the new internal API changes (they also all have
special-case code for functions).
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This is an area of significant difference from CTFv3. The API changes
significantly, with quite a few additions to allow creation and querying of
these new datasec entities:
-typedef int ctf_variable_f (const char *name, ctf_id_t type, void *arg);
+typedef int ctf_variable_f (ctf_dict_t *, const char *name, ctf_id_t type,
+ void *arg);
+typedef int ctf_datasec_var_f (ctf_dict_t *fp, ctf_id_t type, size_t offset,
+ size_t datasec_size, void *arg);
+/* Search a datasec for a variable covering a given offset.
+
+ Errors with ECTF_NODATASEC if not found. */
+
+ctf_id_t ctf_datasec_var_offset (ctf_dict_t *fp, ctf_id_t datasec,
+ uint32_t offset);
+
+/* Return the datasec that a given variable appears in, or ECTF_NODATASEC if
+ none. */
+
+ctf_id_t ctf_variable_datasec (ctf_dict_t *fp, ctf_id_t var);
+int ctf_datasec_var_iter (ctf_dict_t *, ctf_id_t, ctf_datasec_var_f *,
+ void *);
+ctf_id_t ctf_datasec_var_next (ctf_dict_t *, ctf_id_t, ctf_next_t **,
+ size_t *size, size_t *offset);
-int ctf_add_variable (ctf_dict_t *, const char *, ctf_id_t);
+/* ctf_add_variable adds variables to no datasec at all;
+ ctf_add_section_variable adds them to the given datasec, or to no datasec at
+ all if the datasec is NULL. */
+
+ctf_id_t ctf_add_variable (ctf_dict_t *, const char *, int linkage, ctf_id_t);
+ctf_id_t ctf_add_section_variable (ctf_dict_t *, uint32_t,
+ const char *datasec, const char *name,
+ int linkage, ctf_id_t type,
+ size_t size, size_t offset);
We tie datasecs quite closely to variables at addition (and, as should
become clear later, dedup) time: you never create datasecs, you only create
variables *in* datasecs, and the datasec springs into existence when you do
so: datasecs are always found in the same dict as the variables they contain
(the variables are never in the parent if the datasec is in a child or
anything). We keep track of the variable->datasec mapping in
ctf_var_datasecs (populating it at addition and open time), to allow
ctf_variable_datasec to work at reasonable speed. (But, as yet, there are
no tests of this function at all.)
The datasecs are created unsorted (to avoid variable addition becoming
O(n^2)) and sorted at serialization time, and when ctf_datasec_var_offset is
invoked.
We reuse the natural-alignment code from struct addition to get a plausible
offset in datasecs if an alignment of -1 is specified: maybe this is
unnecessary now (it was originally added when ctf_add_variable added
variables to a "default datasec", while now it just leaves them out of
all datasecs, like externs are).
One constraint of this is that we currently prohibit the addition of
nonrepresentable-typed variables, because we can't tell what their natural
alignment is: if we dropped the whole "align" and just required everyone
adding a variable to a datasec to specify an offset, we could drop that
restriction. WDYT?
One additional caveat: right now, ctf_lookup_variable() looks up the type of
a variable (because when it was invented, variables were not entities in
themselves that you could look up). This name is confusing as hell as a
result. It might be less confusing to make it return the CTF_K_VAR, but
that would be awful to adapt callers to, since both are represented with
ctf_id_t's, so the compiler wouldn't warn about the needed change at all...
I've vacillated on this three or four times now.
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This adds support for the nearly useless BTF_KIND_FLOAT, under the name
CTF_K_BTF_FLOAT. At the same time we fix up the ctf_add_encoding and
ctf_type_encoding machinery for the new API changes.
I expect this to change a bit: Ali Bahrami reckons I've oversimplified the
CTFv4 encoding representation and need to reintroduce at least a width.
New API:
ctf_id_t ctf_add_btf_float (ctf_dict_t *, uint32_t,
const char *, const ctf_encoding_t *);
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This commit adapts most aspects of enum handling: querying and iteration,
enumerator querying and iteration, ctf_type_add, etc. We have to adapt to
enum64s and to signed versus unsigned enums, to our vlen and DTD changes and
other internal API changes to handle prefix types etc, and fix the types of
things to allow for 64-bit enumerators. We can also (finally!) get useful
info on enum size rather than being restricted to a value hardwired into
libctf.
We also adjust all the type-encoding functions for the internal API changes,
since enums are the first encodable entities we have covered.
API changes:
-typedef int ctf_enum_f (const char *name, int val, void *arg);
+typedef int ctf_enum_f (const char *name, int64_t val, void *arg);
+typedef int ctf_unsigned_enum_f (const char *name, uint64_t val, void *arg);
-extern const char *ctf_enum_name (ctf_dict_t *, ctf_id_t, int);
-extern int ctf_enum_value (ctf_dict_t *, ctf_id_t, const char *, int *);
+extern const char *ctf_enum_name (ctf_dict_t *, ctf_id_t, int64_t);
+extern int ctf_enum_value (ctf_dict_t *, ctf_id_t, const char *, int64_t *);
+extern int ctf_enum_unsigned_value (ctf_dict_t *, ctf_id_t, const char *, uint64_t *);
+
+/* Return 1 if this enum's contents are unsigned, so you can tell which of the
+ above functions to use. */
+
+extern int ctf_enum_unsigned (ctf_dict_t *, ctf_id_t);
-/* Return all enumeration constants in a given enum type. */
-extern int ctf_enum_iter (ctf_dict_t *, ctf_id_t, ctf_enum_f *, void *);
+/* Return all enumeration constants in a given enum type. The return value, and
+ VAL argument, may need to be cast to uint64_t: see ctf_enum_unsigned(). */
+extern int64_t ctf_enum_iter (ctf_dict_t *, ctf_id_t, ctf_enum_f *, void *);
extern const char *ctf_enum_next (ctf_dict_t *, ctf_id_t, ctf_next_t **,
- int *);
+ int64_t *);
+
+/* enums are created signed by default. If you want an unsigned enum,
+ use ctf_add_enum_encoded() with an encoding of 0 (CTF_INT_SIGNED and
+ everything else off). This will not create a slice, unlike all other
+ uses of ctf_add_enum_encoded(), and the result is still representable
+ as BTF. */
+
+extern ctf_id_t ctf_add_enum64_encoded (ctf_dict_t *, uint32_t, const char *,
+ const ctf_encoding_t *);
+extern ctf_id_t ctf_add_enum64 (ctf_dict_t *, uint32_t, const char *);
-extern int ctf_add_enumerator (ctf_dict_t *, ctf_id_t, const char *, int);
+extern int ctf_add_enumerator (ctf_dict_t *, ctf_id_t, const char *, int64_t);
The only aspects of enums that are not now handled are forwards to enums,
dumping of enums, and deduplication of enums.
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This adapts ctf_add_type a little, adding support for prefix types, shifting
away from hardwired things towards API functions that can adapt to the CTFv4
changes, adapting to the structure/union API changes, and adding bitfielded
structures and structure members as needed.
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There is one API addition here:
int ctf_add_member_bitfield (ctf_dict_t *, ctf_id_t souid,
const char *, ctf_id_t type,
unsigned long bit_offset,
int bit_width);
SoU addition handles the representational changes for bitfields and for
CTF_K_BIG structs (i.e. all structs you can add members to), errors out if
you add bitfields to structs that aren't created with the
CTF_ADD_STRUCT_BITFIELDS flag, and arranges to add padding as needed if
there is too much of a gap for the offsets to encode in one hop (that
part is still untested).
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There's one API addition here: the existing CTF_ADD_ROOT / CTF_ADD_NONROOT
flags can have a new flag ORed with them, CTF_ADD_STRUCT_BITFIELDS,
indicating that the newly-added struct/union is capable of having bitfields
added to it via the new ctf_add_member_bitfield function (see a later
commit).
Without this, you can only add bitfields via the deprecated slice or base
type encoding representations (the former will force CTF output).
Implementation notes: structs and unions are always added with a CTF_K_BIG
prefix: if promoting from a forward, one is added. These are elided at
serialization time if they are not needed to encode this size of struct /
this number of members. (This means you don't have to figure out in advance
if your struct will be too big for BTF: you can just add members to it,
and libctf will figure it out and upgrade the dict as needed, or tell you
it can't if you've forbidden such things.)
We take advantage of this to merge a couple of very similar functions,
saving a bit of code.
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DTD deletion changes mostly relate to the changes to the ctf_dtdef_t, but
also we no longer nede to have special handling for forwards (we can just
use ctf_type_kind_forwarded like everyone else).
Rollback no longer needs to delete things by hand (it hasn't needed to for
years): it can just call ctf_dtd_delete.
ctf_add_generic changes substantially, mostly to allow for the ctf_dtdef_t
changes. Rather than returning a type ID it now returns the DTD it just
allocated: it can also be asked to add some prefixes, and return the first
prefix added (which may not be the first prefix in the type, because if it
is asked to add a non-root-visible type it will additionally allocate a
CTF_K_CONFLICTING prefix to encode that).
Finally, duplicate name detection is suppressed for type and decl tags.
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Variable handling in BTF and CTFv4 works quite differently from in CTFv3.
Rather than a separate section containing sorted, bsearchable variables,
they are simply named entities like types, stored in CTF_K_VARs.
As a first stage towards migrating to this, delete most references to
the ctf_varent_t and ctf_dvdef_t, including the DVD lookup code, all
the linking code, and quite a lot of the serialization code.
Note: CTF_LINK_OMIT_VARIABLES_SECTION, and the whole "delete variables that
already exist in the symtypetabs section" stuff, has yet to be
reimplemented. We can implement CTF_LINK_OMIT_VARIABLES_SECTION by simply
excising all CTF_K_VARs at deduplication time if requested. (Note:
symtypetabs should still point directly at the type, not at the CTF_K_VAR.)
(Symtypetabs in general need a bit more thought -- perhaps we can now store
them in a separate .ctf.symtypetab section with its own little four-entry
header for the symtypetabs and their indexes, making .ctf even more like
.BTF; the only difference would then be that .ctf could include prefix
types, CTF_K_FLOAT, and external string refs. For later discussion.)
We also add ctf_lookup_by_kind() at this stage (because it is hopelessly
diff-entangled with ctf_lookup_variable): this looks up a type of a
particular kind, without needing a per-kind lookup function for it,
nor needing to hack around adding string prefixes (so you can do
ctf_lookup_by_kind (fp, CTF_K_STRUCT, "foo") rather than having to
do ctf_lookup_by_name (fp, "struct foo"): often this is more convenient, and
anything that reduces string buffer manipulation in C is good.)
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This commit modifies ctf_grow_vlen to account for the recent changes to
ctf_dtdef_t, and adds a new ctf_add_prefix function to add a prefix to an
existing type, moving the dtd_data and dtd_vlen up accordinly.
It deserves close review, since this is probably the single greatest bug
cluster in libctf: the number of times I added to a variable of type
ctf_type_t and assumed it would move it in bytes rather than ctf_type_t
units is hard to believe.
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The majority of this commit rejigs the core type table opening
code for CTFv4: there are a few ancillary bits it drags in,
indicated below.
The internal definition of a child dict (that may not have type or string
lookups performed in it until ctf_open time) used to be 'has a
cth_parent_name', but since BTF doesn't have one of those at all, we add
an additional check: a dict the first byte of whose strtab is not 0 must
be a child. (If *either* is true, this is a child dict, which allows for
the possibility of CTF dicts with non-deduplicated strtabs -- thus with
leading \0's -- to exist in future.)
The initial sweep through the type table in init_static_types (to size
the name-table lookup hashes) also now checks for various types which
indicate that this must be a CTF dict, in addition to being adjusted
to cater for new CTFv4 representations of things like forwards. (At
this early stage, we cannot rely on the functions in ctf-type.c to
abstract over this for us.)
We make some new hashtables for new namespace-like things: datasecs
and type and decl tags.
The main name-population loop in init_static_types_names_internal
takes prefixes into account, looking for the name on the suffix type
(where the name is always found). LSTRUCT handling is removed (they
no longer exist); ENUM64s, enum forwards, VARs, datasecs, and type
and decl tags get their names suitably populated. Some buggy code
which tried to populate the name tables for cvr-quals (which are
nameless) was dropped.
We add an extra pass which traverses all datasecs and keeps track of which
datasec each var is instantiated in (if any) in a new ctf_var_datasecs hash
table. (This uses a number of type-querying functions which don't yet
exist: they'll be added in the upcoming commits.)
We handle the type 0 == void case by pointing the first element of
ctf_txlate at a type read in named "void" (making type 0 an alias to it),
or, if one doesn't exist, creating a new one (outside the type table and dtd
arrays), and pointing type 0 at that. Since it is numbered 0 and not in the
type table or dtd arrays, it will never be written out at serialization
time, but since it is *present*, libctf consumers who expect the void type
to have an integral definition rather than being a magic number will get
what they expect.
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A few places with inadequate error checking have fallen out of the
ctf_id_t work:
- ctf_add_slice doesn't make sure that the type it is slicing
actually exists
- ctf_add_member_offset doesn't check that the type of the member
exists (though it will often fail if it doesn't, it doesn't
explicitly check, so if you're unlucky it can sometimes succeed,
giving you a corrupted dict)
- ctf_type_encoding doesn't check whether its slied type exists:
it should verify it so it can return a decent error, rather than
a thoroughly misleading one
- ctf_type_compat has the same problem with respect to both of its
arguments. It would definitely be nicer if we could call
ctf_type_compat and just get a boolean answer, but it's not
clear to me whether a type can be said to be compatible *or*
incompatible with a nonexistent one, and we should probably alert
the users to a likely bug regardless. C error checking, sigh...
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This change modifies type ID assignment in CTF so that it works like BTF:
rather than flipping the high bit on for types in child dicts, types ascend
directly from IDs in the parent to IDs in the child, without interruption
(so type 0x4 in the parent is immediately followed by 0x5 in all children).
Doing this while retaining useful semantics for modification of parents is
challenging. By definition, child type IDs are not known until the parent
is written out, but we don't want to find ourselves constrained to adding
types to the parent in one go, followed by all child types: that would make
the deduplicator a nightmare and would frankly make the entire ctf_add*()
interface next to useless: all existing clients that add types at all
add types to both parents and children without regard for ordering, and
breaking that would probably necessitate redesigning all of them.
So we have to be a litle cleverer.
We approach this the same way as we approach strings in the recent refs
rework: if a parent has children attached (or has ever had them attached
since it was created or last read in), any new types created in the parent
are assigned provisional IDs starting at the very top of the type space and
working down. (Their indexes in the internal libctf arrays remain
unchanged, so we don't suddenly need multigigabyte indexes!). At writeout
(preserialization) time, we traverse the type table (and all other table
containing type IDs) and assign refs to every type ID in exactly the same
way we assign refs to every string offset (just a different set of refs --
we don't want to update type IDs with string offset values!).
For a parent dict with children, these refs are real entities in memory:
pointers to the memory locations where type IDs are stored, tracked in the
DTD of each type. As we traverse the type table, we assign real IDs to each
type (by simple incrementation), storing those IDs in a new dtd_final_type
field in the DTD for each type. Once the type table and all other tables
containing type IDs are fully traversed, we update all the refs and
overwrite the IDs currently residing in each with the final IDs for each
type.
That fixes up IDs in the parent dict itself (including forward references in
structs and the like: that's why the ref updates only happen at the end);
but what about child dicts' references, both to parent types and to their
own? We add armouring to enforce that parent dicts are always serialized
before their children (which ctf-link.c already does, because it's a
precondition for strtab deduplication), and then arrange that when a ref is
added to a type whose ID has been assigned (has a dtd_final_type), we just
immediately do an update rather than storing a ref for later updating.
Since the parent is already serialized, all parent type IDs have a
dtd_final_type by this point, and all parent IDs in the children are
properly updated. The child types can now be renumbered now we now the
number of types in the parent, and their refs updated identically to what
was just done with the parent.
One wrinkle: before the child refs are updated, while we are working over
the child's type section, the type IDs in the child start from 1 (or
something like that), which might seem to overlap the parent IDs. But this
is not the case: when you serialize the parent, the IDs written out to disk
are changed, but the only change to the representation in memory is that we
remember a dtd_final_type for each type (and use it to update all the child
type refs): its ID in memory is the same as it always was, a nonoverlapping
provisional ID higher than any other valid ID. We enforce all of this by
asserting that when you add a ref to a type, the memory location that is
modified must be in the buffer being serialized: the code will not let you
accidentally modify the actual DTDs in memory.
We track the number of types in the parent in a new CTFv4 (not BTF) header
field (the dumper is updated): we will also use this to open CTFv3 child
dicts without change by simply declaring for them that the parent dict has
2^31 types in it (or 2^15, for v2 and below): the IDs in the children then
naturally come out right with no other changes needed. (Right now, opening
CTFv3 child dicts requires extra compatibility code that has not been
written, but that code will no longer need to worry about type ID
differences.)
Various things are newly forbidden:
- you cannot ctf_import() a child into a parent if you already ctf_add()ed
types to the child, because all its IDs would change (and since you
already cannot ctf_add() types to a child that hasn't had its parent
imported, this in practice means only that ctf_create() must be followed
immediately by a ctf_import() if this is a new child, which all sane
clients were doing anyway).
- You cannot import a child into a parent which has the wrong number of
(non-provisional) types, again because all its IDs would be wrong:
because parents only add types in the provisional space if children are
attached to it, this would break the not unknown case of opening an
archive, adding types to the parent, and only then importing children
into it, so we add a special case: archive members which are not children
in an archive with more than one member always pretend to have at least
one child, so type additions in them are always provisional even before
you ctf_import anything. In practice, this does exactly what we want,
since all archives so far are created by the linker and have one parent
and N children of that parent.
Because this introduces huge gaps between index and type ID for provisional
types, some extra assertions are added to ensure that the internal
ctf_type_to_index() is only ever called on types in the current dict (never
a parent dict): before now, this was just taken on trust, and it was often
wrong (which at best led to wrong results, as wrong array indexes were used,
and at worst to a buffer overflow). When hash debugging is on (suggesting
that the user doesn't mind expensive checks), every ctf_type_to_index()
triggers a ctf_index_to_type() to make sure that the operations are proper
inverses.
Lots and lots of tests are added to verify that assignment works and that
updating of every type kind works fine -- existing tests suffice for
type IDs in the variable and symtypetab sections.
The ld-ctf tests get a bunch of largely display-based updates: various
tests refer to 0x8... type IDs, which no longer exist, and because the
IDs are shorter all the spacing and alignment has changed.
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Slices had a bunch of horrible usability problems. In particular, while
towers of cv-quals are resolved away by functions that need to do it, towers
of cv-quals with slices in the middle are not resolved away by functions
like ctf_enum_value that can see through slices: resolving volatile -> slice
-> const -> enum will leave it with a 'const', which will error pointlessly,
annoying callers, who reasonably expect slices to be more invisible than
this. (The user-callable ctf_type_resolve still does not resolve away
slices, because this is the only way users can see that the slices are there
at all.)
This is induced by a fix for another wart: ctf_add_enumerator does not
resolve anything away at all, so you can't even add enumerators to const or
volatile enums -- and more problematically, you can't add enumerators to
enums with an explicit encoding without resolving away the types by hand,
since ctf_add_enum_encoded works by returning a slice! ctf_add_enumerator
now resolves away all of those, so any cvr-or-typedef-or-slice-qual
terminating in an enum can be added to, exactly as callers likely expect.
(New tests added.)
libctf/
* ctf-create.c (ctf_add_enumerator): Resolve away cvr-qualness.
* ctf-types.c (ctf_type_resolve_unsliced): Don't terminate at
the first slice.
* testsuite/libctf-writable/slice-of-slice.*: New test.
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This commit moves provisional (not-yet-serialized) string refs towards the
scheme to be used for CTF IDs in the future. In particular
- provisional string offsets now count downwards from just under the
external string offset space (all bits on but the high bit). This makes
it possible to detect an overflowing strtab, and also makes it trivial to
determine whether any string offset (ref) updates were missed -- where
before we might get a slightly corrupted or incorrect string, we now get
a huge high strtab offset corresponding to no string, and an error is
emitted at read time.
- refs are emitted at serialization time during the pass through the types.
They are strictly associated with the newly-written-out buffer: the
existing opened CTF dict is not changed, though it does still get the new
strtab so that new refs to the same string can just refer directly to it.
The provisional strtab hash table that contains these strings is not
deleted after serialization (because we might serialize again): instead,
we keep track in the parent of the lowest-yet-used ("latest") provisional
strtab offset, and any strtab offset above that, but not external
(high-bit-on) is considered provisional.
This is sort-of-enforced by moving most of the ref-addition function
declarations (including ctf_str_add_ref) to a new ctf-ref.h, which is
not included by ctf-create.c or ctf-open.c.
- because we don't add refs when adding types, we don't need to handle the
case where we add things to expanding vlens (enums, struct members) and
have to realloc() them. So the entire painful movable refs system can
just be deleted, along with the ability to remove refs piecemeal at all
(purging all of them is still possible). Strings added during type
addition are added via ctf_str_add(), which adds no refs: the strings are
picked up at serialization time and refs to their final, serialized
resting place added. The DTDs never have any refs in them, and their
provisional strtab offsets are never updated by the ref system.
This caused several bugs to fall out of the earlier work and get fixed.
In particular, attempts to look up a string in a child dict now search
the parent's provisional strtab too: we add some extra special casing
for the null string so we don't need to worry about deduplication
moving it somewhere other than offset zero.
Finally, the optimization that removes an unreferenced synthetic external
strtab (the record of the strings the linker has told us about, kept around
internally for lookup during late serialization) is faulty: references to a
strtab entry will only produce CTF-level refs if their value might change,
and an external string's offset won't change, so it produces no refs: worse
yet, even if we did get a ref (say, if the string was originally believed
to be internal and only later were we told that the linker knew about it
too), when we serialize a strtab, all its refs are dropped (since they've
been updated and can no longer change); so if we serialized it a second
time, its synthetic external strtab would be considered empty and dropped,
even though the same external strings as before still exist, referencing
it. We must keep the synthetic external strtab around as long as external
strings exist that reference it, i.e. for the life of the dict.
One benefit of all this: now we're emitting provisional string offsets at
a really high value, it's out of the way of the consecutive, deduplicated
string offsets in child dicts. So we can drop the constraint that you
cannot add strings to a dict with children, which allows us to add types
freely to parent dicts again. What you can't do is write that dict out
again: when we serialize, we currently update the dict being serialized
with the updated strtabs: when you write a dict out, its provisional
strings become real strings, and suddenly the offsets would overlap once
more. But opening a dict and its children, adding to it, and then
writing it out again is rare indeed, and we have a workaround: anyone
wanting to do this can just use ctf_link instead.
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The initial_vlen parameter to ctf_add_generic is misnamed: it's not the
initial vlen (the initial number of members of a struct, etc), but rather
the initial size of the vlen region. We have a term for that, vbytes: use
it.
Amazingly this doesn't seem to have caused any bugs to creep in.
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Making these functions is unnecessary right now, but will become much
clearer shortly.
While we're at it, we can drop the third child argument to
LCTF_INDEX_TO_TYPE: it's only used for nontrivial purposes that aren't
literally the same as getting the result from the fp in one place,
in ctf_lookup_by_name_internal, and that place is easily fixed by just
looking in the right dictionary in the first place.
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They're meant to be inverses, which makes it unfortunate that
they check different bounds. No visible effect yet, since
ctf_typemax and ctf_stypes currently cover the entire type ID
space, but will have an effect shortly.
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Parent/child determination is about to become rather more complex, making a
macro impractical. Use the ctf_type_isparent/ischild function calls
everywhere and remove the macro. Make them more const-correct too, to
make them more widely usable.
While we're about it, change several places that hand-implemented
ctf_get_dict() to call it instead, and armour several functions against
the null returns that were always possible in this case (but previously
unprotected-against).
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Despite the removal of the separate movable ref list, the ref system as
a whole is more than complex enough to be worth generalizing now that
we are adding different kinds of ref.
Refs now are lists of uint32_t * which can be updated through the
pointer for all entries in the list and moved to new sites for all
pointers in a given range: they are no longer references to string
offsets in particular and can be references to other uint32_t-sized
things instead (note that ctf_id_t is a typedef to a uint32_t).
ctf-string.c has been adjusted accordingly (the adjustments are tiny,
more or less just turning a bunch of references to atom into
&atom->csa_refs).
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Pending refs haven't been a thing for a while now.
libctf/
* ctf-create.c (ctf_add_member_offset): Fix comment.
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We are about to add machinery that deduplicates a child dict's strtab
against its parent. Obviously if you open such a dict but do not import its
parent, all strtab lookups must fail: so add an LCTF_NO_STR flag that is set
in that window and make most operations fail if it's not set. (Two more
that will be set in future commits are serialization and string lookup
itself.)
Notably, not all symbol lookup is impossible in this window: you can still
look up by symbol index, as long as this dict is not using an indexed
strtypetab (which obviously requires string lookups to get the symbol name).
include/
* ctf-api.h (_CTF_ERRORS) [ECTF_HASPARENT]: New.
[ECTF_WRONGPARENT]: Likewise.
(ECTF_NERR): Update.
Update comments to note the new limitations on ctf_import et al.
libctf/
* ctf-impl.h (LCTF_NO_STR): New.
* ctf-create.c (ctf_rollback): Error out when LCTF_NO_STR.
(ctf_add_generic): Likewise.
(ctf_add_struct_sized): Likewise.
(ctf_add_union_sized): Likewise.
(ctf_add_enum): Likewise.
(ctf_add_forward): Likewise.
(ctf_add_unknown): Likewise.
(ctf_add_enumerator): Likewise.
(ctf_add_member_offset): Likewise.
(ctf_add_variable): Likewise.
(ctf_add_funcobjt_sym_forced): Likewise.
(ctf_add_type): Likewise (on either dict).
* ctf-dump.c (ctf_dump): Likewise.
* ctf-lookup.c (ctf_lookup_by_name): Likewise.
(ctf_lookup_variable): Likewise. Likewise.
(ctf_lookup_enumerator): Likewise.
(ctf_lookup_enumerator_next): Likewise.
(ctf_symbol_next): Likewise.
(ctf_lookup_by_sym_or_name): Likewise, if doing indexed lookups.
* ctf-types.c (ctf_member_next): Likewise.
(ctf_enum_next): Likewise.
(ctf_type_aname): Likewise.
(ctf_type_name_raw): Likewise.
(ctf_type_compat): Likewise, for either dict.
(ctf_member_info): Likewise.
(ctf_enum_name): Likewise.
(ctf_enum_value): Likewise.
(ctf_type_rvisit): Likewise.
(ctf_variable_next): Note that we don't need to test LCTF_NO_STR.
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A bug in ctf_dtd_delete led to refs in the string table to the
names of non-root-visible types not being removed when the DTD
was. This seems harmless, but actually it would lead to a write
down a pointer into freed memory if such a type was ctf_rollback()ed
over and then the dict was serialized (updating all the refs as the
strtab was serialized in turn).
Bug introduced in commit fe4c2d55634c700ba527ac4183e05c66e9f93c62
("libctf: create: non-root-visible types should not appear in name tables")
which is included in binutils 2.35.
libctf/
* ctf-create.c (ctf_dtd_delete): Remove refs for all types
with names, not just root-visible ones.
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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.
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libctf has long prohibited addition of enums with overlapping constants in a
single enum, but now that we are properly considering enums with overlapping
constants to be conflciting types, we can go further and prohibit addition
of enumeration constants to a dict if they already exist in any enum in that
dict: the same rules as C itself.
We do this in a fashion vaguely similar to what we just did in the
deduplicator, by considering enumeration constants as identifiers and adding
them to the core type/identifier namespace, ctf_dict_t.ctf_names. This is a
little fiddly, because we do not want to prohibit opening of existing dicts
into which the deduplicator has stuffed enums with overlapping constants!
We just want to prohibit the addition of *new* enumerators that violate that
rule. Even then, it's fine to add overlapping enumerator constants as long
as at least one of them is in a non-root type. (This is essential for
proper deduplicator operation in cu-mapped mode, where multiple compilation
units can be smashed into one dict, with conflicting types marked as
hidden: these types may well contain overlapping enumerators.)
So, at open time, keep track of all enums observed, then do a third pass
through the enums alone, adding each enumerator either to the ctf_names
table as a mapping from the enumerator name to the enum it is part of (if
not already present), or to a new ctf_conflicting_enums hashtable that
tracks observed duplicates. (The latter is not used yet, but will be soon.)
(We need to do a third pass because it's quite possible to have an enum
containing an enumerator FOO followed by a type FOO: since they're processed
in order, the enumerator would be processed before the type, and at that
stage it seems nonconflicting. The easiest fix is to run through the
enumerators after all type names are interned.)
At ctf_add_enumerator time, if the enumerator to which we are adding a type
is root-visible, check for an already-present name and error out if found,
then intern the new name in the ctf_names table as is done at open time.
(We retain the existing code which scans the enum itself for duplicates
because it is still an error to add an enumerator twice to a
non-root-visible enum type; but we only need to do this if the enum is
non-root-visible, so the cost of enum addition is reduced.)
Tested in an upcoming commit.
libctf/
* ctf-impl.h (ctf_dict_t) <ctf_names>: Augment comment.
<ctf_conflicting_enums>: New.
(ctf_dynset_elements): New.
* ctf-hash.c (ctf_dynset_elements): Implement it.
* ctf-open.c (init_static_types): Split body into...
(init_static_types_internal): ... here. Count enumerators;
keep track of observed enums in pass 2; populate ctf_names and
ctf_conflicting_enums with enumerators in a third pass.
(ctf_dict_close): Free ctf_conflicting_enums.
* ctf-create.c (ctf_add_enumerator): Prohibit addition of duplicate
enumerators in root-visible enum types.
include/
* ctf-api.h (CTF_ADD_NONROOT): Describe what non-rootness
means for enumeration constants.
(ctf_add_enumerator): The name is not a misnomer.
We now require that enumerators have unique names.
Document the non-rootness of enumerators.
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If ctf_add_type failed in the middle of enumerator addition, the
destination would end up containing the source enum type and some
but not all of its enumerator constants.
Use snapshots to roll back the enum addition as a whole if this happens.
Before now, it's been pretty unlikely, but in an upcoming commit we will ban
addition of enumerators that already exist in a given dict, making failure
of ctf_add_enumerator and thus of this part of ctf_add_type much more
likely.
libctf/
* ctf-create.c (ctf_add_type_internal): Roll back if enum or
enumerator addition fails.
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ctf_serialize() evolved from the old ctf_update(), which mutated the
in-memory CTF dict to make all the dynamic in-memory types into static,
unchanging written-to-the-dict types (by deserializing and reserializing
it): back in the days when you could only do type lookups on static types,
this meant you could see all the types you added recently, at the small,
small cost of making it impossible to change those older types ever again
and inducing an amortized O(n^2) cost if you actually wanted to add
references to types you added at arbitrary times to later types.
It also reset things so that ctf_discard() would throw away only types you
added after the most recent ctf_update() call.
Some time ago this was all changed so that you could look up dynamic types
just as easily as static types: ctf_update() changed so that only its
visible side-effect of affecting ctf_discard() remained: the old
ctf_update() was renamed to ctf_serialize(), made internal to libctf, and
called from the various functions that wrote files out.
... but it was still working by serializing and deserializing the entire
dict, swapping out its guts with the newly-serialized copy in an invasive
and horrible fashion that coupled ctf_serialize() to almost every field in
the ctf_dict_t. This is totally useless, and fixing it is easy: just rip
all that code out and have ctf_serialize return a serialized representation,
and let everything use that directly. This simplifies most of its callers
significantly.
(It also points up another bug: ctf_gzwrite() failed to call ctf_serialize()
at all, so it would only ever work for a dict you just ctf_write_mem()ed
yourself, just for its invisible side-effect of serializing the dict!)
This lets us simplify away a bunch of internal-only open-side functionality
for overriding the syn_ext_strtab and some just-added functionality for
forcing in an existing atoms table, without loss of functionality, and lets
us lift the restriction on reserializing a dict that was ctf_open()ed rather
than being ctf_create()d: it's now perfectly OK to open a dict, modify it
(except for adding members to existing structs, unions, or enums, which
fails with -ECTF_RDONLY), and write it out again, just as one would expect.
libctf/
* ctf-serialize.c (ctf_symtypetab_sect_sizes): Fix typos.
(ctf_type_sect_size): Add static type sizes too.
(ctf_serialize): Return the new dict rather than updating the
existing dict. No longer fail for dicts with static types;
copy them onto the start of the new types table.
(ctf_gzwrite): Actually serialize before gzwriting.
(ctf_write_mem): Improve forced (test-mode) endian-flipping:
flip dicts even if they are too small to be compressed.
Improve confusing variable naming.
* ctf-archive.c (arc_write_one_ctf): Don't bother to call
ctf_serialize: both the functions we call do so.
* ctf-string.c (ctf_str_create_atoms): Drop serializing case
(atoms arg).
* ctf-open.c (ctf_simple_open): Call ctf_bufopen directly.
(ctf_simple_open_internal): Delete.
(ctf_bufopen_internal): Delete/rename to ctf_bufopen: no
longer bother with syn_ext_strtab or forced atoms table,
serialization no longer needs them.
* ctf-create.c (ctf_create): Call ctf_bufopen directly.
* ctf-impl.h (ctf_str_create_atoms): Drop atoms arg.
(ctf_simple_open_internal): Delete.
(ctf_bufopen_internal): Likewise.
(ctf_serialize): Adjust.
* testsuite/libctf-lookup/add-to-opened.c: Adjust now that
this is supposed to work.
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This commit finally adjusts strtab writeout so that repeated writeouts, or
writeouts of a dict that was read in earlier, only sorts the portion of the
strtab that was newly added.
There are three intertwined changes here:
- pull the contents of strtabs from newly ctf_bufopened dicts into the
atoms table, so that future additions will reuse the existing offset etc
rather than adding new identical strings
- allow the internal ctf_bufopen done by serialization to contribute its
existing atoms table, so that existing atoms can be used for the
remainder of the open process (like name table construction): this atoms
table currente gets thrown away in the mass reassignment done later in
ctf_serialize in any case, but it needs to be there during the open.
- rewrite ctf_str_write_strtab so that a) it uses iterators rather than
ctf_*_iter, reducing pointless structures which serve no other purpose
than to implement ordinary variable scope, but more clunkily, and b)
retains the existing strtab on the front of the new one, with its sort
retained, rather than resorting, so all existing already-written strtab
offsets remain valid across the call.
This latter change finally permits repeated serializations, and
reserializations of ctf_open()ed dicts, to work, but for now we keep the
code that prevents that because serialization is about to change again in a
way that will make it more obvious that doing such things is safe, and we
can take it out then.
(There are also some smaller changes like moving the purge of the refs table
into ctf_str_write_strtab(), since that's where the changes happen that
invalidate it, rather than doing it in ctf_serialize(). We also prohibit
something that has never worked, opening a dict and then reporting symbols
to it via ctf_link_add_strtab() et al: you must do that to newly-created
dicts which have had stuff ctf_link()ed into them. This is very unlikely
ever to be a problem in practice: linkers just don't do that sort of thing.)
libctf/
* ctf-create.c (ctf_create): Add (temporary) atoms arg.
* ctf-impl.h (struct ctf_dict.ctf_dynstrtab): New.
(ctf_str_create_atoms): Adjust.
(ctf_str_write_strtab): Likewise.
(ctf_simple_open_internal): Likewise.
* ctf-open.c (ctf_simple_open_internal): Add atoms arg.
(ctf_bufopen): Likewise.
(ctf_bufopen_internal): Initialize just enough of an
atoms table: pre-init from the atoms arg if supplied.
(ctf_simple_open): Adjust.
* ctf-serialize.c (ctf_serialize): Constify the strtab.
Move ref list purging into ctf_str_write_strtab.
Initialize the new dict with the old dict's atoms table.
Accept the new strtab from ctf_str_write_strtab.
Adjust for addition of ctf_dynstrtab.
* ctf-string.c (ctf_strraw_explicit): Improve comments.
(ctf_str_create_atoms): Prepopulate from an existing atoms table,
or alternatively pull in all strings from the strtab and turn
them into atoms.
(ctf_str_free_atoms): Free the dynstrtab and its strtab.
(struct ctf_strtab_write_state): Remove.
(ctf_str_count_strtab): Fold this...
(ctf_str_populate_sorttab): ... and this...
(ctf_str_write_strtab): ... into this. Prepend existing strings
to the strtab rather than resorting them (and wrecking their
offsets). Keep the dynstrtab updated. Update refs for all
atoms with refs, whether or not they are strings newly added
to the strtab.
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A few years ago we introduced a 'pending refs' abstraction to fix one
problem: serializing a dict, then changing it would tend to corrupt the dict
because the strtab sort we do on strtab writeout (to improve compression
efficiency) would modify the offset of any strings that sorted
lexicographically earlier in the strtab: so we added a new restriction that
all strings are added only at serialization time, and maintained a set of
'pending' refs that were added earlier, whose offsets we could update (like
other refs) at writeout time.
This was in hindsight seriously problematic for maintenance (because
serialization has to traverse all strings in all datatypes in the entire
dict), and has become impossible to sustain now that we can read in existing
dicts, modify them, and reserialize them again. We really don't want to
have to dig through the entire dict we jut read in just in order to dig out
all its strtab offsets, then *change* it, just for the sake of a sort that
adds a frankly trivial amount of compression efficiency.
Sorting *is* still worthwhile -- but it sacrifices very little to only sort
newly-added portions of the strtab, reusing older portions as necessary.
As a first stage in this, discard the whole "pending refs" abstraction and
replace it with "movable" refs, which are exactly like all other refs
(addresses containing the strtab offset of some string, which are updated
wiht the final strtab offset on serialization) except that we track them in
a reverse dict so that we can move the refs around (which we do whenever we
realloc() a buffer containing a bunch of structure members or something when
we add members to the structure).
libctf/
* ctf-create.c (ctf_add_enumerator): Call ctf_str_move_refs; add
a movable ref.
(ctf_add_member_offset): Likewise.
* ctf-util.c (ctf_realloc): Delete.
* ctf-serialize.c (ctf_serialize): No longer use it. Adjust to
new fields.
* ctf-string.c (ctf_str_purge_atom_refs): Purge movable refs.
(ctf_str_free_atom): Free freeable atoms' strings.
(ctf_str_create_atoms): Create the movable refs dynhash if needed.
(ctf_str_free_atoms): Destroy it.
(CTF_STR_MOVABLE): Switch (back) from ints to flags (see previous
reversion). Add new flag.
(aref_create): New, populate movable refs if need be.
(ctf_str_add_ref_internal): Switch back to flags, update refs
directly for nonprovisional strings (with already-known fixed offsets);
create refs via aref_create. Allocate strings only if not within an
mmapped strtab.
(ctf_str_add_movable_ref): New.
(ctf_str_add): Adjust to CTF_STR_* reintroduction.
(ctf_str_add_external): LIkewise.
(ctf_str_move_refs): New, move refs via ctf_str_movable_refs
backpointer.
(ctf_str_purge_refs): Drop ctf_str_num_refs.
(ctf_str_update_refs): Fix indentation.
* ctf-impl.h (struct ctf_str_atom_movable): New.
(struct ctf_dict.ctf_str_num_refs): Drop.
(struct ctf_dict.ctf_str_movable_refs): New.
(ctf_str_add_movable_ref): Declare.
(ctf_str_move_refs): Likewise.
(ctf_realloc): Drop.
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This reverts commit 986e9e3aa03f854bedacef7fac38fe8f009a416c.
(We do not revert the testcase -- it remains valid -- but we are
taking a different, less complex and more robust approach.)
This also deletes the pending refs abstraction without (yet)
replacing it, so some tests will fail for a commit or two.
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This flag was meant as an optimization to avoid reserializing dicts
unnecessarily. It was critically necessary back when serialization was
done by ctf_update() and you had to call that every time you wanted any
new modifications to the type table to be usable by other types, but
that has been unnecessary for years now, and serialization is only done
once when writing out, which one would naturally assume would always
serialize the dict. Worse, it never really worked: it only tracked
newly-added types, not things like added symbols which might equally
well require reserialization, and it gets in the way of an upcoming
change. Delete entirely.
libctf/
* ctf-create.c (ctf_create): Drop LCTF_DIRTY.
(ctf_discard): Likewise.
(ctf_rollback): Likewise.
(ctf_add_generic): Likewise.
(ctf_set_array): Likewise.
(ctf_add_enumerator): Likewise.
(ctf_add_member_offset): Likewise.
(ctf_add_variable_forced): Likewise.
* ctf-link.c (ctf_link_intern_extern_string): Likewise.
(ctf_link_add_strtab): Likewise.
* ctf-serialize.c (ctf_serialize): Likewise.
* ctf-impl.h (LCTF_DIRTY): Likewise.
(LCTF_LINKING): Renumber.
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libctf has long declared deserialized dictionaries (out of files or ELF
sections or memory buffers or whatever) to be read-only: back in the
furthest prehistory this was not the case, in that you could add a
few sorts of type to such dicts, but attempting to do so often caused
horrible memory corruption, so I banned the lot.
But it turns out real consumers want it (notably DTrace, which
synthesises pointers to types that don't have them and adds them to the
ctf_open()ed dicts if it needs them). Let's bring it back again, but
without the memory corruption and without the massive code duplication
required in days of yore to distinguish between static and dynamic
types: the representation of both types has been identical for a few
years, with the only difference being that types as a whole are stored in
a big buffer for types read in via ctf_open and per-type hashtables for
newly-added types.
So we discard the internally-visible concept of "readonly dictionaries"
in favour of declaring the *range of types* that were already present
when the dict was read in to be read-only: you can't modify them (say,
by adding members to them if they're structs, or calling ctf_set_array
on them), but you can add more types and point to them. (The API
remains the same, with calls sometimes returning ECTF_RDONLY, but now
they do so less often.)
This is a fairly invasive change, mostly because code written since the
ban was introduced didn't take the possibility of a static/dynamic split
into account. Some of these irregularities were hard to define as
anything but bugs.
Notably:
- The symbol handling was assuming that symbols only needed to be
looked for in dynamic hashtabs or static linker-laid-out indexed/
nonindexed layouts, but now we want to check both in case people
added more symbols to a dict they opened.
- The code that handles type additions wasn't checking to see if types
with the same name existed *at all* (so you could do
ctf_add_typedef (fp, "foo", bar) repeatedly without error). This
seems reasonable for types you just added, but we probably *do* want
to ban addition of types with names that override names we already
used in the ctf_open()ed portion, since that would probably corrupt
existing type relationships. (Doing things this way also avoids
causing new errors for any existing code that was doing this sort of
thing.)
- ctf_lookup_variable entirely failed to work for variables just added
by ctf_add_variable: you had to write the dict out and read it back
in again before they appeared.
- The symbol handling remembered what symbols you looked up but didn't
remember their types, so you could look up an object symbol and then
find it popping up when you asked for function symbols, which seems
less than ideal. Since we had to rejig things enough to be able to
distinguish function and object symbols internally anyway (in order
to give suitable errors if you try to add a symbol with a name that
already existed in the ctf_open()ed dict), this bug suddenly became
more visible and was easily fixed.
We do not (yet) support writing out dicts that have been previously read
in via ctf_open() or other deserializer (you can look things up in them,
but not write them out a second time). This never worked, so there is
no incompatibility; if it is needed at a later date, the serializer is a
little bit closer to having it work now (the only table we don't deal
with is the types table, and that's because the upcoming CTFv4 changes
are likely to make major changes to the way that table is represented
internally, so adding more code that depends on its current form seems
like a bad idea).
There is a new testcase that tests much of this, in particular that
modification of existing types is still banned and that you can add new
ones and chase them without error.
libctf/
* ctf-impl.h (struct ctf_dict.ctf_symhash): Split into...
(ctf_dict.ctf_symhash_func): ... this and...
(ctf_dict.ctf_symhash_objt): ... this.
(ctf_dict.ctf_stypes): New, counts static types.
(LCTF_INDEX_TO_TYPEPTR): Use it instead of CTF_RDWR.
(LCTF_RDWR): Deleted.
(LCTF_DIRTY): Renumbered.
(LCTF_LINKING): Likewise.
(ctf_lookup_variable_here): New.
(ctf_lookup_by_sym_or_name): Likewise.
(ctf_symbol_next_static): Likewise.
(ctf_add_variable_forced): Likewise.
(ctf_add_funcobjt_sym_forced): Likewise.
(ctf_simple_open_internal): Adjust.
(ctf_bufopen_internal): Likewise.
* ctf-create.c (ctf_grow_ptrtab): Adjust a lot to start with.
(ctf_create): Migrate a bunch of initializations into bufopen.
Force recreation of name tables. Do not forcibly override the
model, let ctf_bufopen do it.
(ctf_static_type): New.
(ctf_update): Drop LCTF_RDWR check.
(ctf_dynamic_type): Likewise.
(ctf_add_function): Likewise.
(ctf_add_type_internal): Likewise.
(ctf_rollback): Check ctf_stypes, not LCTF_RDWR.
(ctf_set_array): Likewise.
(ctf_add_struct_sized): Likewise.
(ctf_add_union_sized): Likewise.
(ctf_add_enum): Likewise.
(ctf_add_enumerator): Likewise (only on the target dict).
(ctf_add_member_offset): Likewise.
(ctf_add_generic): Drop LCTF_RDWR check. Ban addition of types
with colliding names.
(ctf_add_forward): Note safety under the new rules.
(ctf_add_variable): Split all but the existence check into...
(ctf_add_variable_forced): ... this new function.
(ctf_add_funcobjt_sym): Likewise...
(ctf_add_funcobjt_sym_forced): ... for this new function.
* ctf-link.c (ctf_link_add_linker_symbol): Ban calling on dicts
with any stypes.
(ctf_link_add_strtab): Likewise.
(ctf_link_shuffle_syms): Likewise.
(ctf_link_intern_extern_string): Note pre-existing prohibition.
* ctf-lookup.c (ctf_lookup_by_id): Drop LCTF_RDWR check.
(ctf_lookup_variable): Split out looking in a dict but not
its parent into...
(ctf_lookup_variable_here): ... this new function.
(ctf_lookup_symbol_idx): Track whether looking up a function or
object: cache them separately.
(ctf_symbol_next): Split out looking in non-dynamic symtypetab
entries to...
(ctf_symbol_next_static): ... this new function. Don't get confused
by the simultaneous presence of static and dynamic symtypetab entries.
(ctf_try_lookup_indexed): Don't waste time looking up symbols by
index before there can be any idea how symbols are numbered.
(ctf_lookup_by_sym_or_name): Distinguish between function and
data object lookups. Drop LCTF_RDWR.
(ctf_lookup_by_symbol): Adjust.
(ctf_lookup_by_symbol_name): Likewise.
* ctf-open.c (init_types): Rename to...
(init_static_types): ... this. Drop LCTF_RDWR. Populate ctf_stypes.
(ctf_simple_open): Drop writable arg.
(ctf_simple_open_internal): Likewise.
(ctf_bufopen): Likewise.
(ctf_bufopen_internal): Populate fields only used for writable dicts.
Drop LCTF_RDWR.
(ctf_dict_close): Cater for symhash cache split.
* ctf-serialize.c (ctf_serialize): Use ctf_stypes, not LCTF_RDWR.
* ctf-types.c (ctf_variable_next): Drop LCTF_RDWR.
* testsuite/libctf-lookup/add-to-opened*: New test.
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libctf internally maintains a set of hash tables for type name lookups,
one for each valid C type namespace (struct, union, enum, and everything
else).
Or, rather, it maintains *two* sets of hash tables: one, a ctf_hash *,
is meant for lookups in ctf_(buf)open()ed dicts with fixed content; the
other, a ctf_dynhash *, is meant for lookups in ctf_create()d dicts.
This distinction was somewhat valuable in the far pre-binutils past when
two different hashtable implementations were used (one expanding, the
other fixed-size), but those days are long gone: the hash table
implementations are almost identical, both wrappers around the libiberty
hashtab. The ctf_dynhash has many more capabilities than the ctf_hash
(iteration, deletion, etc etc) and has no downsides other than starting
at a fixed, arbitrary small size.
That limitation is easy to lift (via a new ctf_dynhash_create_sized()),
following which we can throw away nearly all the ctf_hash
implementation, and all the code to choose between readable and writable
hashtabs; the few convenience functions that are still useful (for
insertion of name -> type mappings) can also be generalized a bit so
that the extra string verification they do is potentially available to
other string lookups as well.
(libctf still has two hashtable implementations, ctf_dynhash, above,
and ctf_dynset, which is a key-only hashtab that can avoid a great many
malloc()s, used for high-volume applications in the deduplicator.)
libctf/
* ctf-create.c (ctf_create): Eliminate ctn_writable.
(ctf_dtd_insert): Likewise.
(ctf_dtd_delete): Likewise.
(ctf_rollback): Likewise.
(ctf_name_table): Eliminate ctf_names_t.
* ctf-hash.c (ctf_dynhash_create): Comment update.
Reimplement in terms of...
(ctf_dynhash_create_sized): ... this new function.
(ctf_hash_create): Remove.
(ctf_hash_size): Remove.
(ctf_hash_define_type): Remove.
(ctf_hash_destroy): Remove.
(ctf_hash_lookup_type): Rename to...
(ctf_dynhash_lookup_type): ... this.
(ctf_hash_insert_type): Rename to...
(ctf_dynhash_insert_type): ... this, moving validation to...
* ctf-string.c (ctf_strptr_validate): ... this new function.
* ctf-impl.h (struct ctf_names): Extirpate.
(struct ctf_lookup.ctl_hash): Now a ctf_dynhash_t.
(struct ctf_dict): All ctf_names_t fields are now ctf_dynhash_t.
(ctf_name_table): Now returns a ctf_dynhash_t.
(ctf_lookup_by_rawhash): Remove.
(ctf_hash_create): Likewise.
(ctf_hash_insert_type): Likewise.
(ctf_hash_define_type): Likewise.
(ctf_hash_lookup_type): Likewise.
(ctf_hash_size): Likewise.
(ctf_hash_destroy): Likewise.
(ctf_dynhash_create_sized): New.
(ctf_dynhash_insert_type): New.
(ctf_dynhash_lookup_type): New.
(ctf_strptr_validate): New.
* ctf-lookup.c (ctf_lookup_by_name_internal): Adapt.
* ctf-open.c (init_types): Adapt.
(ctf_set_ctl_hashes): Adapt.
(ctf_dict_close): Adapt.
* ctf-serialize.c (ctf_serialize): Adapt.
* ctf-types.c (ctf_lookup_by_rawhash): Remove.
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Seen with every compiler I have if using -fno-inline:
home/alan/src/binutils-gdb/libctf/ctf-create.c: In function ‘ctf_add_encoded’:
/home/alan/src/binutils-gdb/libctf/ctf-create.c:555:3: warning: ‘encoding’ may be used uninitialized [-Wmaybe-uninitialized]
555 | memcpy (dtd->dtd_vlen, &encoding, sizeof (encoding));
Seen with gcc-4.9 and probably others at lower optimisation levels:
home/alan/src/binutils-gdb/libctf/ctf-serialize.c: In function 'symtypetab_density':
/home/alan/src/binutils-gdb/libctf/ctf-serialize.c:211:18: warning: 'sym' may be used uninitialized in this function [-Wmaybe-uninitialized]
if (*max < sym->st_symidx)
Seen with gcc-4.5 and probably others at lower optimisation levels:
/home/alan/src/binutils-gdb/libctf/ctf-types.c:1649:21: warning: 'tp' may be used uninitialized in this function
/home/alan/src/binutils-gdb/libctf/ctf-link.c:765:16: warning: 'parent_i' may be used uninitialized in this function
Also with gcc-4.5:
In file included from /home/alan/src/binutils-gdb/libctf/ctf-endian.h:25:0,
from /home/alan/src/binutils-gdb/libctf/ctf-archive.c:24:
/home/alan/src/binutils-gdb/libctf/swap.h:70:0: warning: "_Static_assert" redefined
/usr/include/sys/cdefs.h:568:0: note: this is the location of the previous definition
* swap.h (_Static_assert): Don't define if already defined.
* ctf-serialize.c (symtypetab_density): Merge two
CTF_SYMTYPETAB_FORCE_INDEXED blocks.
* ctf-create.c (ctf_add_encoded): Avoid "encoding" may be used
uninitialized warning.
* ctf-link.c (ctf_link_deduplicating_open_inputs): Avoid
"parent_i" may be used uninitialized warning.
* ctf-types.c (ctf_type_rvisit): Avoid "tp" may be used
uninitialized warning.
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Adds two new external authors to etc/update-copyright.py to cover
bfd/ax_tls.m4, and adds gprofng to dirs handled automatically, then
updates copyright messages as follows:
1) Update cgen/utils.scm emitted copyrights.
2) Run "etc/update-copyright.py --this-year" with an extra external
author I haven't committed, 'Kalray SA.', to cover gas testsuite
files (which should have their copyright message removed).
3) Build with --enable-maintainer-mode --enable-cgen-maint=yes.
4) Check out */po/*.pot which we don't update frequently.
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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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Made sure there is no implicit conversion between signed and unsigned
return value for functions setting the ctf_errno value.
An example of the problem is that in ctf_member_next, the "offset" value
is either 0L or (ctf_id_t)-1L, but it should have been 0L or -1L.
The issue was discovered while building a 64 bit ld binary to be
executed on the Windows platform.
Example object file that demonstrates the issue is attached in the PR.
libctf/
Affected functions adjusted.
Signed-off-by: Torbjörn SVENSSON <torbjorn.svensson@foss.st.com>
Co-Authored-By: Yvan ROUX <yvan.roux@foss.st.com>
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CTF dicts have per-dict errno values: as with other errno values these
are set on error and left unchanged on success. This means that all
errors *must* set the CTF errno: if a call leaves it unchanged, the
caller is apt to find a previous, lingering error and misinterpret
it as the real error.
There are many places in libctf where we carry out operations on parent
dicts as a result of carrying out other user-requested operations on
child dicts (e.g. looking up information on a pointer to a type will
look up the type as well: the pointer might well be in a child and the
type it's a pointer to in the parent). Those operations on the parent
might fail; if they do, the error must be correctly reflected on the
child that the user-visible operation was carried out on. In many
places this was not happening.
So, audit and fix all those places. Add tests for as many of those
cases as possible so they don't regress.
libctf/
* ctf-create.c (ctf_add_slice): Use the original dict.
* ctf-lookup.c (ctf_lookup_variable): Propagate errors.
(ctf_lookup_symbol_idx): Likewise.
* ctf-types.c (ctf_member_next): Likewise.
(ctf_type_resolve_unsliced): Likewise.
(ctf_type_aname): Likewise.
(ctf_member_info): Likewise.
(ctf_type_rvisit): Likewise.
(ctf_func_type_info): Set the error on the right dict.
(ctf_type_encoding): Use the original dict.
* testsuite/libctf-writable/error-propagation.*: New test.
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