These functions allow you to look up types given a name in a simple
subset of C declarator syntax (no function pointers), to look up the
types of variables given a name, and to look up the types of data
objects and the type signatures of functions given symbol table offsets.
(Despite its name, one function in this commit, ctf_lookup_symbol_name(),
is for the internal use of libctf only, and does not appear in any
public header files.)
libctf/
* ctf-lookup.c (isqualifier): New.
(ctf_lookup_by_name): Likewise.
(struct ctf_lookup_var_key): Likewise.
(ctf_lookup_var): Likewise.
(ctf_lookup_variable): Likewise.
(ctf_lookup_symbol_name): Likewise.
(ctf_lookup_by_symbol): Likewise.
(ctf_func_info): Likewise.
(ctf_func_args): Likewise.
include/
* ctf-api.h (ctf_func_info): New.
(ctf_func_args): Likewise.
(ctf_lookup_by_symbol): Likewise.
(ctf_lookup_by_symbol): Likewise.
(ctf_lookup_variable): Likewise.
Finally we get to the functions used to actually look up and enumerate
properties of types in a container (names, sizes, members, what type a
pointer or cv-qual references, determination of whether two types are
assignment-compatible, etc).
With a very few exceptions these do not work for types newly added via
ctf_add_*(): they only work on types in read-only containers, or types
added before the most recent call to ctf_update().
This also adds support for lookup of "variables" (string -> type ID
mappings) and for generation of C type names corresponding to a type ID.
libctf/
* ctf-decl.c: New file.
* ctf-types.c: Likewise.
* ctf-impl.h: New declarations.
include/
* ctf-api.h (ctf_visit_f): New definition.
(ctf_member_f): Likewise.
(ctf_enum_f): Likewise.
(ctf_variable_f): Likewise.
(ctf_type_f): Likewise.
(ctf_type_isparent): Likewise.
(ctf_type_ischild): Likewise.
(ctf_type_resolve): Likewise.
(ctf_type_aname): Likewise.
(ctf_type_lname): Likewise.
(ctf_type_name): Likewise.
(ctf_type_sizee): Likewise.
(ctf_type_align): Likewise.
(ctf_type_kind): Likewise.
(ctf_type_reference): Likewise.
(ctf_type_pointer): Likewise.
(ctf_type_encoding): Likewise.
(ctf_type_visit): Likewise.
(ctf_type_cmp): Likewise.
(ctf_type_compat): Likewise.
(ctf_member_info): Likewise.
(ctf_array_info): Likewise.
(ctf_enum_name): Likewise.
(ctf_enum_value): Likewise.
(ctf_member_iter): Likewise.
(ctf_enum_iter): Likewise.
(ctf_type_iter): Likewise.
(ctf_variable_iter): Likewise.
These functions let you open an ELF file with a customarily-named CTF
section in it, automatically opening the CTF file or archive and
associating the symbol and string tables in the ELF file with the CTF
container, so that you can look up the types of symbols in the ELF file
via ctf_lookup_by_symbol(), and so that strings can be shared between
the ELF file and CTF container, to save space.
It uses BFD machinery to do so. This has now been lightly tested and
seems to work. In particular, if you already have a bfd you can pass
it in to ctf_bfdopen(), and if you want a bfd made for you you can
call ctf_open() or ctf_fdopen(), optionally specifying a target (or
try once without a target and then again with one if you get
ECTF_BFD_AMBIGUOUS back).
We use a forward declaration for the struct bfd in ctf-api.h, so that
ctf-api.h users are not required to pull in <bfd.h>. (This is mostly
for the sake of readelf.)
libctf/
* ctf-open-bfd.c: New file.
* ctf-open.c (ctf_close): New.
* ctf-impl.h: Include bfd.h.
(ctf_file): New members ctf_data_mmapped, ctf_data_mmapped_len.
(ctf_archive_internal): New members ctfi_abfd, ctfi_data,
ctfi_bfd_close.
(ctf_bfdopen_ctfsect): New declaration.
(_CTF_SECTION): likewise.
include/
* ctf-api.h (struct bfd): New forward.
(ctf_fdopen): New.
(ctf_bfdopen): Likewise.
(ctf_open): Likewise.
(ctf_arc_open): Likewise.
If you need to store a large number of CTF containers somewhere, this
provides a dedicated facility for doing so: an mmappable archive format
like a very simple tar or ar without all the system-dependent format
horrors or need for heavy file copying, with built-in compression of
files above a particular size threshold.
libctf automatically mmap()s uncompressed elements of these archives, or
uncompresses them, as needed. (If the platform does not support mmap(),
copying into dynamically-allocated buffers is used.)
Archive iteration operations are partitioned into raw and non-raw
forms. Raw operations pass thhe raw archive contents to the callback:
non-raw forms open each member with ctf_bufopen() and pass the resulting
ctf_file_t to the iterator instead. This lets you manipulate the raw
data in the archive, or the contents interpreted as a CTF file, as
needed.
It is not yet known whether we will store CTF archives in a linked ELF
object in one of these (akin to debugdata) or whether they'll get one
section per TU plus one parent container for types shared between them.
(In the case of ELF objects with very large numbers of TUs, an archive
of all of them would seem preferable, so we might just use an archive,
and add lzma support so you can assume that .gnu_debugdata and .ctf are
compressed using the same algorithm if both are present.)
To make usage easier, the ctf_archive_t is not the on-disk
representation but an abstraction over both ctf_file_t's and archives of
many ctf_file_t's: users see both CTF archives and raw CTF files as
ctf_archive_t's upon opening, the only difference being that a raw CTF
file has only a single "archive member", named ".ctf" (the default if a
null pointer is passed in as the name). The next commit will make use
of this facility, in addition to providing the public interface to
actually open archives. (In the future, it should be possible to have
all CTF sections in an ELF file appear as an "archive" in the same
fashion.)
This machinery is also used to allow library-internal creators of
ctf_archive_t's (such as the next commit) to stash away an ELF string
and symbol table, so that all opens of members in a given archive will
use them. This lets CTF archives exploit the ELF string and symbol
table just like raw CTF files can.
(All this leads to somewhat confusing type naming. The ctf_archive_t is
a typedef for the opaque internal type, struct ctf_archive_internal: the
non-internal "struct ctf_archive" is the on-disk structure meant for
other libraries manipulating CTF files. It is probably clearest to use
the struct name for struct ctf_archive_internal inside the program, and
the typedef names outside.)
libctf/
* ctf-archive.c: New.
* ctf-impl.h (ctf_archive_internal): New type.
(ctf_arc_open_internal): New declaration.
(ctf_arc_bufopen): Likewise.
(ctf_arc_close_internal): Likewise.
include/
* ctf.h (CTFA_MAGIC): New.
(struct ctf_archive): New.
(struct ctf_archive_modent): Likewise.
* ctf-api.h (ctf_archive_member_f): New.
(ctf_archive_raw_member_f): Likewise.
(ctf_arc_write): Likewise.
(ctf_arc_close): Likewise.
(ctf_arc_open_by_name): Likewise.
(ctf_archive_iter): Likewise.
(ctf_archive_raw_iter): Likewise.
(ctf_get_arc): Likewise.
We now enter a series of commits that are sufficiently tangled that
avoiding forward definitions is almost impossible: no attempt is made to
make individual commits compilable (which is why the build system does
not reference any of them yet): the only important thing is that they
should form something like conceptual groups.
But first, some definitions, including the core ctf_file_t itself. Uses
of these definitions will be introduced in later commits.
libctf/
* ctf-impl.h: New definitions and declarations for type creation
and lookup.
libctf maintains two distinct hash ADTs, one (ctf_dynhash) for wrapping
dynamically-generated unknown-sized hashes during CTF file construction,
one (ctf_hash) for wrapping unchanging hashes whose size is known at
creation time for reading CTF files that were previously created.
In the binutils implementation, these are both fairly thin wrappers
around libiberty hashtab.
Unusually, this code is not kept synchronized with libdtrace-ctf,
due to its dependence on libiberty hashtab.
libctf/
* ctf-hash.c: New file.
* ctf-impl.h: New declarations.
These utilities are a bit of a ragbag of small things needed by more
than one TU: list manipulation, ELF32->64 translators, routines to look
up strings in string tables, dynamically-allocated string appenders, and
routines to set the specialized errno values previously committed in
<ctf-api.h>.
We do still need to dig around in raw ELF symbol tables in places,
because libctf allows the caller to pass in the contents of string and
symbol sections without telling it where they come from, so we cannot
use BFD to get the symbols (BFD reasonably demands the entire file). So
extract minimal ELF definitions from glibc into a private header named
libctf/elf.h: later, we use those to get symbols. (The start-of-
copyright range on elf.h reflects this glibc heritage.)
libctf/
* ctf-util.c: New file.
* elf.h: Likewise.
* ctf-impl.h: Include it, and add declarations.
The memory-allocation wrappers are simple things to allow malloc
interposition: they are only used inconsistently at present, usually
where malloc debugging was required in the past.
These provide a default implementation that is environment-variable
triggered (initialized on the first call to the libctf creation and
file-opening functions, the first functions people will use), and
a ctf_setdebug()/ctf_getdebug() pair that allows the caller to
explicitly turn debugging off and on. If ctf_setdebug() is called,
the automatic setting from an environment variable is skipped.
libctf/
* ctf-impl.h: New file.
* ctf-subr.c: New file.
include/
* ctf-api.h (ctf_setdebug): New.
(ctf_getdebug): Likewise.
