Commit Graph

2 Commits

Author SHA1 Message Date
Jose E. Marchesi
a0486bac41 libctf: fix a number of build problems found on Solaris and NetBSD
- Use of nonportable <endian.h>
- Use of qsort_r
- Use of zlib without appropriate magic to pull in the binutils zlib
- Use of off64_t without checking (fixed by dropping the unused fields
  that need off64_t entirely)
- signedness problems due to long being too short a type on 32-bit
  platforms: ctf_id_t is now 'unsigned long', and CTF_ERR must be
  used only for functions that return ctf_id_t
- One lingering use of bzero() and of <sys/errno.h>

All fixed, using code from gnulib where possible.

Relatedly, set cts_size in a couple of places it was missed
(string table and symbol table loading upon ctf_bfdopen()).

binutils/
	* objdump.c (make_ctfsect): Drop cts_type, cts_flags, and
	cts_offset.
	* readelf.c (shdr_to_ctf_sect): Likewise.
include/
	* ctf-api.h (ctf_sect_t): Drop cts_type, cts_flags, and cts_offset.
	(ctf_id_t): This is now an unsigned type.
	(CTF_ERR): Cast it to ctf_id_t.  Note that it should only be used
	for ctf_id_t-returning functions.
libctf/
	* Makefile.am (ZLIB): New.
	(ZLIBINC): Likewise.
	(AM_CFLAGS): Use them.
	(libctf_a_LIBADD): New, for LIBOBJS.
	* configure.ac: Check for zlib, endian.h, and qsort_r.
	* ctf-endian.h: New, providing htole64 and le64toh.
	* swap.h: Code style fixes.
	(bswap_identity_64): New.
	* qsort_r.c: New, from gnulib (with one added #include).
	* ctf-decls.h: New, providing a conditional qsort_r declaration,
	and unconditional definitions of MIN and MAX.
	* ctf-impl.h: Use it.  Do not use <sys/errno.h>.
	(ctf_set_errno): Now returns unsigned long.
	* ctf-util.c (ctf_set_errno): Adjust here too.
	* ctf-archive.c: Use ctf-endian.h.
	(ctf_arc_open_by_offset): Use memset, not bzero.  Drop cts_type,
	cts_flags and cts_offset.
	(ctf_arc_write): Drop debugging dependent on the size of off_t.
	* ctf-create.c: Provide a definition of roundup if not defined.
	(ctf_create): Drop cts_type, cts_flags and cts_offset.
	(ctf_add_reftype): Do not check if type IDs are below zero.
	(ctf_add_slice): Likewise.
	(ctf_add_typedef): Likewise.
	(ctf_add_member_offset): Cast error-returning ssize_t's to size_t
	when known error-free.  Drop CTF_ERR usage for functions returning
	int.
	(ctf_add_member_encoded): Drop CTF_ERR usage for functions returning
	int.
	(ctf_add_variable): Likewise.
	(enumcmp): Likewise.
	(enumadd): Likewise.
	(membcmp): Likewise.
	(ctf_add_type): Likewise.  Cast error-returning ssize_t's to size_t
	when known error-free.
	* ctf-dump.c (ctf_is_slice): Drop CTF_ERR usage for functions
	returning int: use CTF_ERR for functions returning ctf_type_id.
	(ctf_dump_label): Likewise.
	(ctf_dump_objts): Likewise.
	* ctf-labels.c (ctf_label_topmost): Likewise.
	(ctf_label_iter): Likewise.
	(ctf_label_info): Likewise.
	* ctf-lookup.c (ctf_func_args): Likewise.
	* ctf-open.c (upgrade_types): Cast to size_t where appropriate.
	(ctf_bufopen): Likewise.  Use zlib types as needed.
	* ctf-types.c (ctf_member_iter): Drop CTF_ERR usage for functions
	returning int.
	(ctf_enum_iter): Likewise.
	(ctf_type_size): Likewise.
	(ctf_type_align): Likewise.  Cast to size_t where appropriate.
	(ctf_type_kind_unsliced): Likewise.
	(ctf_type_kind): Likewise.
	(ctf_type_encoding): Likewise.
	(ctf_member_info): Likewise.
	(ctf_array_info): Likewise.
	(ctf_enum_value): Likewise.
	(ctf_type_rvisit): Likewise.
	* ctf-open-bfd.c (ctf_bfdopen): Drop cts_type, cts_flags and
	cts_offset.
	(ctf_simple_open): Likewise.
	(ctf_bfdopen_ctfsect): Likewise.  Set cts_size properly.
	* Makefile.in: Regenerate.
	* aclocal.m4: Likewise.
	* config.h: Likewise.
	* configure: Likewise.
2019-05-31 11:10:51 +02:00
Nick Alcock
72f3392127 libctf: opening
This fills in the other half of the opening/creation puzzle: opening of
already-existing CTF files.  Such files are always read-only: if you
want to add to a CTF file opened with one of the opening functions in
this file, use ctf_add_type(), in a later commit, to copy appropriate
types into a newly ctf_create()d, writable container.

The lowest-level opening functions are in here: ctf_bufopen(), which
takes ctf_sect_t structures akin to ELF section headers, and
ctf_simple_open(), which can be used if you don't have an entire ELF
section header to work from.  Both will malloc() new space for the
buffers only if necessary, will mmap() directly from the file if
requested, and will mprotect() it afterwards to prevent accidental
corruption of the types. These functions are also used by ctf_update()
when converting types in a writable container into read-only types that
can be looked up using the lookup functions (in later commits).

The files are always of the native endianness of the system that created
them: at read time, the endianness of the header magic number is used to
determine whether or not the file needs byte-swapping, and the entire
thing is aggressively byte-swapped.

The agggressive nature of this swapping avoids complicating the rest of
the code with endianness conversions, while the native endianness
introduces no byte-swapping overhead in the common case. (The
endianness-independence code is also much newer than everything else in
this file, and deserves closer scrutiny.)

The accessors at the top of the file are there to transparently support
older versions of the CTF file format, allowing translation from older
formats that have different sizes for the structures in ctf.h:
currently, these older formats are intermingled with the newer ones in
ctf.h: they will probably migrate to a compatibility header in time, to
ease readability.  The ctf_set_base() function is split out for the same
reason: when conversion code to a newer format is written, it would need
to malloc() new storage for the entire ctf_file_t if a file format
change causes it to grow, and for that we need ctf_set_base() to be a
separate function.

One pair of linked data structures supported by this file has no
creation code in libctf yet: the data and function object sections read
by init_symtab(). These will probably arrive soon, when the linker comes
to need them. (init_symtab() has hardly been changed since 2009, but if
any code in libctf has rotted over time, this will.)

A few simple accessors are also present that can even be called on
read-only containers because they don't actually modify them, since the
relevant things are not stored in the container but merely change its
operation: ctf_setmodel(), which lets you specify whether a container is
LP64 or not (used to statically determine the sizes of a few types),
ctf_import(), which is the only way to associate a parent container with
a child container, and ctf_setspecific(), which lets the caller
associate an arbitrary pointer with the CTF container for any use. If
the user doesn't call these functions correctly, libctf will misbehave:
this is particularly important for ctf_import(), since a container built
against a given parent container will not be able to resolve types that
depend on types in the parent unless it is ctf_import()ed with a parent
container with the same set of types at the same IDs, or a superset.

Possible future extensions (also noted in the ctf-hash.c file) include
storing a count of things so that we don't need to do one pass over the
CTF file counting everything, and computing a perfect hash at CTF
creation time in some compact form, storing it in the CTF file, and
using it to hash things so we don't need to do a second pass over the
entire CTF file to set up the hashes used to go from names to type IDs.
(There are multiple such hashes, one for each C type namespace: types,
enums, structs, and unions.)

libctf/
	* ctf-open.c: New file.
	* swap.h: Likewise.
include/
	* ctf-api.h (ctf_file_close): New declaration.
	(ctf_getdatasect): Likewise.
	(ctf_parent_file): Likewise.
	(ctf_parent_name): Likewise.
	(ctf_parent_name_set): Likewise.
	(ctf_import): Likewise.
	(ctf_setmodel): Likewise.
	(ctf_getmodel): Likewise.
	(ctf_setspecific): Likewise.
	(ctf_getspecific): Likewise.
2019-05-28 17:07:46 +01:00