This commits the result of running gdb/copyright.py as per our Start
of New Year procedure...
gdb/ChangeLog
Update copyright year range in copyright header of all GDB files.
This function allows to create a BFD handle using an accessible memory
range in a target memory. It is currently contained in a JIT module but
this functionality may be of wider usefullness - for example, reading
ELF binaries contained within a core dump.
gdb/ChangeLog:
2020-12-07 Mihails Strasuns <mihails.strasuns@intel.com>
* jit.c (mem_bfd*, bfd_open_from_target_memory): Removed.
* gdb_bfd.h (gdb_bfd_open_from_target_memory): New function.
* gdb_bfd.c (mem_bfd*, gdb_bfd_open_from_target_memory): New functions.
This adds a new overload of gdb_bfd_sections, that accepts a
gdb_bfd_ref_ptr. This also fixes the formatting of the existing
function, since I happened to notice it was mildly off.
gdb/ChangeLog
2020-09-19 Tom Tromey <tom@tromey.com>
* gdb_bfd.h (gdb_bfd_sections): New overload. Fix formatting of
existing function.
I wanted to make a nicer / type-safe interface for
bfd_map_over_sections, avoiding the `void *` data parameter.
My first shot was to make a wrapper for bfd_map_over_sections,
gdb_bfd_map_over_sections that took a gdb::function_view.
However, I think that a range adapter gives nicer and simpler code, as a
simple for loop is easier to read than a callback / lambda function. So
here it is, it uses next_iterator and next_adapter, so it's not much
code.
As an example, I ported maintenance_info_sections and friends to use it.
The maint_print_section_data type could probably be removed now, but I
didn't want to do too much in one patch.
gdb/ChangeLog:
* gdb_bfd.h (gdb_bfd_section_iterator, gdb_bfd_section_range,
gdb_bfd_sections): New.
* maint.c (print_bfd_section_info): Change param type to
maint_print_section_data.
(print_objfile_section_info): Likewise.
(print_bfd_section_info_maybe_relocated): Likewise.
(maintenance_info_sections): Use gdb_bfd_sections.
Change-Id: Ib496f6b0a0eb7aadb10da1dd381304014d934ea0
The patch makes GDB do exec-file-mismatch validation by comparing
build IDs instead of the current method of comparing filenames.
Currently, the exec-file-mismatch feature simply compares filenames to
decide whether the exec file loaded in gdb and the exec file the
target reports is running match. This causes false positives when
remote debugging, because it'll often be the case that the paths in
the host and the target won't match. And of course misses the case of
the files having the same name but being actually different files
(e.g., different builds).
This also broke many testcases when running against gdbserver, causing
tests to be skipped like (here native-extended-gdbserver):
(gdb) run
Starting program: /home/pedro/gdb/binutils-gdb/build/gdb/testsuite/outputs/gdb.base/argv0-symlink/argv0-symlink-filelink
warning: Mismatch between current exec-file /home/pedro/gdb/binutils-gdb/build/gdb/testsuite/outputs/gdb.base/argv0-symlink/argv0-symlink-filelink
and automatically determined exec-file /home/pedro/gdb/binutils-gdb/build/gdb/testsuite/outputs/gdb.base/argv0-symlink/argv0-symlink
exec-file-mismatch handling is currently "ask"
Load new symbol table from "/home/pedro/gdb/binutils-gdb/build/gdb/testsuite/outputs/gdb.base/argv0-symlink/argv0-symlink"? (y or n) UNTESTED: gdb.base/argv0-symlink.exp: could not run to main
or to fail like (here native-gdbserver):
(gdb) spawn /home/pedro/gdb/binutils-gdb/build/gdb/testsuite/../../gdbserver/gdbserver --once localhost:2346 /home/pedro/gdb/binutils-gdb/build/gdb/te
stsuite/outputs/gdb.btrace/buffer-size/skip_btrace_tests-19968.x
Process /home/pedro/gdb/binutils-gdb/build/gdb/testsuite/outputs/gdb.btrace/buffer-size/skip_btrace_tests-19968.x created; pid = 20040
Listening on port 2346
target remote localhost:2346
Remote debugging using localhost:2346
warning: Mismatch between current exec-file /home/pedro/gdb/binutils-gdb/build/gdb/testsuite/temp/19968/skip_btrace_tests-19968.x
and automatically determined exec-file /home/pedro/gdb/binutils-gdb/build/gdb/testsuite/outputs/gdb.btrace/buffer-size/skip_btrace_tests-19968.x
exec-file-mismatch handling is currently "ask"
Load new symbol table from "/home/pedro/gdb/binutils-gdb/build/gdb/testsuite/outputs/gdb.btrace/buffer-size/skip_btrace_tests-19968.x"? (y or n) Quit
(gdb) UNSUPPORTED: gdb.btrace/buffer-size.exp: target does not support record-btrace
The former case is about GDB not realizing the two files are the same,
because one of the them is a symlink to the other. The latter case is
about GDB realizing that one file is a copy of the other.
Over the years, the toolchain has settled on build ID matching being
the canonical method to match core dumps to executables, and
executables with no debug info to their debug info.
This patch makes us use build IDs to match the running image of a
binary with its version loaded in gdb, which may or may not have debug
info. This is very much like the core dump/executable matching.
The change to gdb_bfd_open is necessary to get rid of the "transfers
from remote targets can be slow" warning when we open the remote file
to read its build ID:
(gdb) r
Starting program: /home/pedro/gdb/binutils-gdb/build/gdb/testsuite/outputs/gdb.base/break/break
Reading /home/pedro/gdb/binutils-gdb/build/gdb/testsuite/outputs/gdb.base/argv0-symlink/argv0-symlink from remote target...
warning: File transfers from remote targets can be slow. Use "set sysroot" to access files locally instead.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
warning: Mismatch between current exec-file /home/pedro/gdb/binutils-gdb/build/gdb/testsuite/outputs/gdb.base/break/break
and automatically determined exec-file /home/pedro/gdb/binutils-gdb/build/gdb/testsuite/outputs/gdb.base/argv0-symlink/argv0-symlink
exec-file-mismatch handling is currently "ask"
Load new symbol table from "/home/pedro/gdb/binutils-gdb/build/gdb/testsuite/outputs/gdb.base/argv0-symlink/argv0-symlink"? (y or n)
While trying this out, I was worried that bfd would read a lot of
stuff from the binary in order to extract the build ID, making it
potentially slow, but turns out we don't read all that much. Maybe a
couple hundred bytes, and most of it seemingly is the read-ahead
cache. So I'm not worried about that. Otherwise I'd consider whether
a new qXfer:buildid:read would be better. But I'm happy that we
seemingly don't need to worry about it.
gdb/ChangeLog:
2020-05-19 Pedro Alves <palves@redhat.com>
* NEWS (set exec-file-mismatch): Adjust entry.
* exec.c: Include "build-id.h".
(validate_exec_file): Try to match build IDs instead of filenames.
* gdb_bfd.c (struct gdb_bfd_open_closure): New.
(gdb_bfd_iovec_fileio_open): Adjust to use gdb_bfd_open_closure
and pass down 'warn_if_slow'.
(gdb_bfd_open): Add 'warn_if_slow' parameter. Use
gdb_bfd_open_closure to pass it down.
* gdb_bfd.h (gdb_bfd_open): Add 'warn_if_slow' parameter.
gdb/doc/ChangeLog:
2020-05-19 Pedro Alves <palves@redhat.com>
* gdb.texinfo (Attach): Update exec-file-mismatch description to
mention build IDs.
(Separate Debug Files): Add "build id" anchor.
A following patch will add one more defaulted parameter.
gdb/ChangeLog:
2020-05-19 Pedro Alves <palves@redhat.com>
* gdb_bfd.h: (gdb_bfd_open): Default to 'fd' parameter to -1.
Adjust all callers.
The function is_linked_with_cygwin_dll currently uses
gdb_bfd_map_section to get some section contents. This is not ideal
because that memory, which is only used in this function, can't be
released. Instead, it was suggested to use
bfd_get_full_section_contents.
However, bfd_get_full_section_contents returns a newly allocated buffer,
which is not very practical to use with C++ automatic memory management
constructs. I decided to make gdb_bfd_get_full_section_contents, a
small alternative to bfd_get_full_section_contents. It is a small
wrapper around bfd_get_section_contents which returns the full contents
of the section in a gdb::byte_vector.
gdb_bfd_get_full_section_contents could be used at many places that
already allocate a vector of the size of the section and then call
bfd_get_section_contents. I think these call sites can be updated over
time.
gdb/ChangeLog:
* gdb_bfd.h: Include gdbsupport/byte-vector.h.
(gdb_bfd_get_full_section_contents): New declaration.
* gdb_bfd.c (gdb_bfd_get_full_section_contents): New function.
* windows-tdep.c (is_linked_with_cygwin_dll): Use
gdb_bfd_get_full_section_contents.
I noticed that gdb_bfd_fdopenr is no longer used, so this patch
removes it. Tested by rebuilding and by grep.
gdb/ChangeLog
2019-03-05 Tom Tromey <tromey@adacore.com>
* gdb_bfd.c (gdb_bfd_fdopenr): Remove.
* gdb_bfd.h (gdb_bfd_fdopenr): Don't declare.
This commit applies all changes made after running the gdb/copyright.py
script.
Note that one file was flagged by the script, due to an invalid
copyright header
(gdb/unittests/basic_string_view/element_access/char/empty.cc).
As the file was copied from GCC's libstdc++-v3 testsuite, this commit
leaves this file untouched for the time being; a patch to fix the header
was sent to gcc-patches first.
gdb/ChangeLog:
Update copyright year range in all GDB files.
For gdb_bfd_ref_ptr, gdb already had a convenience function like the
new gdb_ref_ptr::new_reference -- called new_bfd_ref. This patch
removes it in favor of the new common function.
While doing this I also noticed that the comment for gdb_bfd_open was
incorrect (in a way related to reference counting), so this patch
updates the comment as well.
ChangeLog
2018-04-30 Tom Tromey <tom@tromey.com>
* symfile-mem.c (symbol_file_add_from_memory): Use new_reference.
* gdb_bfd.h (new_bfd_ref): Remove.
(gdb_bfd_open): Update comment.
* gdb_bfd.c (gdb_bfd_open, gdb_bfd_fopen, gdb_bfd_openr)
(gdb_bfd_openw, gdb_bfd_openr_iovec, gdb_bfd_record_inclusion)
(gdb_bfd_fdopenr): Use new_reference.
* exec.c (exec_file_attach): Use new_reference.
This fixes PR 16577.
This patch changes gdb_bfd_map_section to issue a warning rather than an error
if it is unable to read the object file, and sets the size of the section/frame
that it attempted to read to 0 on error.
The description of gdb_bfd_map_section states that it will try to read or map
the contents of the section SECT, and if successful, the section data is
returned and *SIZE is set to the size of the section data. This function was
throwing an error and leaving *SIZE as-is. Setting the section size to 0
indicates to dwarf2_build_frame_info that there is no data to read, otherwise
it will try to read from an invalid frame pointer.
Changing the error to a warning allows this to be handled gracefully.
Additionally, the error was clobbering the breakpoint output indicating the
current frame (function name, arguments, source file, and line number). E.g.
Thread 3 "foo" hit Breakpoint 1, BFD: reopening /tmp/jna-1013829440/jna2973250704389291330.tmp: No such file or directory
BFD: reopening /tmp/jna-1013829440/jna2973250704389291330.tmp: No such file or directory
(gdb)
While the "BFD: reopening ..." messages will still appear interspersed in the
breakpoint output, the current frame info is now displayed:
Thread 3 "foo" hit Breakpoint 1, BFD: reopening /tmp/jna-1013829440/jna1875755897659885075.tmp: No such file or directory
BFD: reopening /tmp/jna-1013829440/jna1875755897659885075.tmp: No such file or directory
warning: Can't read data for section '.eh_frame' in file '/tmp/jna-1013829440/jna1875755897659885075.tmp'
do_something () at file.cpp:80
80 {
(gdb)
This introduces a helper function, new_bfd_ref, that calls gdb_bfd_ref
and returns a gdb_bfd_ref_ptr. Then it updates several places to use
this.
ChangeLog
2017-10-20 Tom Tromey <tom@tromey.com>
* exec.c (exec_file_attach): Use new_bfd_ref.
* symfile-mem.c (symbol_file_add_from_memory): Use new_bfd_ref.
* gdb_bfd.c (gdb_bfd_open, gdb_bfd_fopen, gdb_bfd_openr)
(gdb_bfd_openw, gdb_bfd_openr_iovec, gdb_bfd_fdopenr): Use
new_bfd_ref.
* gdb_bfd.h (new_bfd_ref): New function.
This introduces a new specialization of gdb::ref_ptr that can be used
to manage BFD reference counts. Then it changes most places in gdb to
use this new class, rather than explicit reference-counting or
cleanups. This patch removes make_cleanup_bfd_unref.
If you look you will see a couple of spots using "release" where a use
of gdb_bfd_ref_ptr would be cleaner. These will be fixed in the next
patch.
I think this patch fixes some latent bugs. For example, it seems to
me that previously objfpy_add_separate_debug_file leaked a BFD.
I'm not 100% certain that the macho_symfile_read_all_oso change is
correct. The existing code here is hard for me to follow. One goal
of this sort of automated reference counting, though, is to make it
more difficult to make logic errors; so hopefully the code is clear
now.
2017-01-10 Tom Tromey <tom@tromey.com>
* windows-tdep.c (windows_xfer_shared_library): Update.
* windows-nat.c (windows_make_so): Update.
* utils.h (make_cleanup_bfd_unref): Remove.
* utils.c (do_bfd_close_cleanup, make_cleanup_bfd_unref): Remove.
* symfile.h (symfile_bfd_open)
(find_separate_debug_file_in_section): Return gdb_bfd_ref_ptr.
* symfile.c (read_symbols, symbol_file_add)
(separate_debug_file_exists): Update.
(symfile_bfd_open): Return gdb_bfd_ref_ptr.
(generic_load, reread_symbols): Update.
* symfile-mem.c (symbol_file_add_from_memory): Update.
* spu-linux-nat.c (spu_bfd_open): Return gdb_bfd_ref_ptr.
(spu_symbol_file_add_from_memory): Update.
* solist.h (struct target_so_ops) <bfd_open>: Return
gdb_bfd_ref_ptr.
(solib_bfd_fopen, solib_bfd_open): Return gdb_bfd_ref_ptr.
* solib.c (solib_bfd_fopen, solib_bfd_open): Return
gdb_bfd_ref_ptr.
(solib_map_sections, reload_shared_libraries_1): Update.
* solib-svr4.c (enable_break): Update.
* solib-spu.c (spu_bfd_fopen): Return gdb_bfd_ref_ptr.
* solib-frv.c (enable_break2): Update.
* solib-dsbt.c (enable_break): Update.
* solib-darwin.c (gdb_bfd_mach_o_fat_extract): Return
gdb_bfd_ref_ptr.
(darwin_solib_get_all_image_info_addr_at_init): Update.
(darwin_bfd_open): Return gdb_bfd_ref_ptr.
* solib-aix.c (solib_aix_bfd_open): Return gdb_bfd_ref_ptr.
* record-full.c (record_full_save): Update.
* python/py-objfile.c (objfpy_add_separate_debug_file): Update.
* procfs.c (insert_dbx_link_bpt_in_file): Update.
* minidebug.c (find_separate_debug_file_in_section): Return
gdb_bfd_ref_ptr.
* machoread.c (macho_add_oso_symfile): Change abfd to
gdb_bfd_ref_ptr.
(macho_symfile_read_all_oso): Update.
(macho_check_dsym): Return gdb_bfd_ref_ptr.
(macho_symfile_read): Update.
* jit.c (bfd_open_from_target_memory): Return gdb_bfd_ref_ptr.
(jit_bfd_try_read_symtab): Update.
* gdb_bfd.h (gdb_bfd_open, gdb_bfd_fopen, gdb_bfd_openr)
(gdb_bfd_openw, gdb_bfd_openr_iovec)
(gdb_bfd_openr_next_archived_file, gdb_bfd_fdopenr): Return
gdb_bfd_ref_ptr.
(gdb_bfd_ref_policy): New struct.
(gdb_bfd_ref_ptr): New typedef.
* gdb_bfd.c (gdb_bfd_open, gdb_bfd_fopen, gdb_bfd_openr)
(gdb_bfd_openw, gdb_bfd_openr_iovec)
(gdb_bfd_openr_next_archived_file, gdb_bfd_fdopenr): Return
gdb_bfd_ref_ptr.
* gcore.h (create_gcore_bfd): Return gdb_bfd_ref_ptr.
* gcore.c (create_gcore_bfd): Return gdb_bfd_ref_ptr.
(gcore_command): Update.
* exec.c (exec_file_attach): Update.
* elfread.c (elf_symfile_read): Update.
* dwarf2read.c (dwarf2_get_dwz_file): Update.
(try_open_dwop_file, open_dwo_file): Return gdb_bfd_ref_ptr.
(open_and_init_dwo_file): Update.
(open_dwp_file): Return gdb_bfd_ref_ptr.
(open_and_init_dwp_file): Update.
* corelow.c (core_open): Update.
* compile/compile-object-load.c (compile_object_load): Update.
* common/gdb_ref_ptr.h (ref_ptr::operator->): New operator.
* coffread.c (coff_symfile_read): Update.
* cli/cli-dump.c (bfd_openr_or_error, bfd_openw_or_error): Return
gdb_bfd_ref_ptr. Rename.
(dump_bfd_file, restore_command): Update.
* build-id.h (build_id_to_debug_bfd): Return gdb_bfd_ref_ptr.
* build-id.c (build_id_to_debug_bfd): Return gdb_bfd_ref_ptr.
(find_separate_debug_file_by_buildid): Update.
This applies the second part of GDB's End of Year Procedure, which
updates the copyright year range in all of GDB's files.
gdb/ChangeLog:
Update copyright year range in all GDB files.
This commit updates gdb_bfd_open to access files using target
fileio functions if the supplied path starts with "target:"
and if the local and target filesystems are not the same.
This allows users to specify "set sysroot target:" and have
GDB access files locally or from the remote as appropriate.
The new functions in gdb_bfd.c are copies of functions from
remote.c. This duplication is intentional and will be removed
by the next commit in this series.
gdb/ChangeLog:
* gdb/gdb_bfd.h (TARGET_SYSROOT_PREFIX): New definition.
(is_target_filename): New declaration.
(gdb_bfd_has_target_filename): Likewise.
(gdb_bfd_open): Update documentation comment.
* gdb_bfd.c (target.h): New include.
(gdb/fileio.h): Likewise.
(is_target_filename): New function.
(gdb_bfd_has_target_filename): Likewise.
(fileio_errno_to_host): Likewise.
(gdb_bfd_iovec_fileio_open): Likewise.
(gdb_bfd_iovec_fileio_pread): Likewise.
(gdb_bfd_iovec_fileio_close): Likewise.
(gdb_bfd_iovec_fileio_fstat): Likewise.
(gdb_bfd_open): Use target fileio to access paths prefixed
with "target:" where necessary.
Right now we always share per-BFD data across objfiles, if there is a
BFD. This works fine. However, we're going to start sharing more
data, and sometimes this data will come directly from sections of the
BFD. If such a section has SEC_RELOC set, then the data coming from
that section will not be truly sharable -- the section will be
program-space-dependent, and re-read by gdb for each objfile.
This patch disallows per-BFD sharing in this case. This is a bit
"heavy" in that we could in theory examine each bit of shared data for
suitability. However, that is more complicated, and SEC_RELOC is rare
enough that I think we needn't bother.
Note that the "no sharing" case is equivalent to "gdb works as it
historically did". That is, the sharing is a new(-ish) optimization.
Built and regtested on x86-64 Fedora 18.
* gdb_bfd.c (struct gdb_bfd_data) <relocation_computed,
needs_relocations>: New fields.
(gdb_bfd_requires_relocations): New function.
* gdb_bfd.h (gdb_bfd_requires_relocations): Declare.
* objfiles.c (get_objfile_bfd_data): Disallow sharing if
the BFD needs relocations applied.
Two modifications:
1. The addition of 2013 to the copyright year range for every file;
2. The use of a single year range, instead of potentially multiple
year ranges, as approved by the FSF.
* solib-darwin.c (gdb_bfd_mach_o_fat_extract): New function.
(darwin_solib_get_all_image_info_addr_at_init, darwin_bfd_open):
Use it.
* gdb_bfd.h (gdb_bfd_mark_parent): Declare.
* gdb_bfd.c (gdb_bfd_mark_parent): New function.
(gdb_bfd_openr_next_archived_file): Use it.
gdb_bfd_unref.
(free_dwo_file): Use gdb_bfd_unref.
* cli/cli-dump.c: Include gdb_bfd.h.
(bfd_openw_with_cleanup): Use gdb_bfd_ref.
(bfd_openr_with_cleanup): Likewise.
* windows-nat.c (windows_make_so): Use gdb_bfd_ref,
gdb_bfd_unref.
* utils.c: Include gdb_bfd.h.
(do_bfd_close_cleanup): Use gdb_bfd_unref.
* symfile.c: Include gdb_bfd.h.
(separate_debug_file_exists): Use gdb_bfd_unref.
(bfd_open_maybe_remote): Use gdb_bfd_ref.
(symfile_bfd_open): Use gdb_bfd_ref, gdb_bfd_unref.
(generic_load): Use gdb_bfd_ref.
(reread_symbols): Use gdb_bfd_unref.
* symfile-mem.c: Include gdb_bfd.h.
(symbol_file_add_from_memory): Use make_cleanup_bfd_close.
* spu-linux-nat.c (spu_bfd_open): Use gdb_bfd_ref, gdb_bfd_unref.
* solib.c: Include gdb_bfd.h.
(solib_bfd_fopen): Use gdb_bfd_ref.
(solib_bfd_open): Use gdb_bfd_unref.
(free_so_symbols): Use gdb_bfd_unref.
(reload_shared_libraries_1): Use gdb_bfd_unref.
* solib-spu.c: Include gdb_bfd.h.
(spu_bfd_fopen): Use gdb_bfd_ref, gdb_bfd_unref.
* solib-pa64.c (pa64_solib_create_inferior_hook): Use gdb_bfd_ref,
gdb_bfd_unref.
* solib-frv.c: Include gdb_bfd.h.
(enable_break2): Use gdb_bfd_unref.
* solib-dsbt.c: Include gdb_bfd.h.
(enable_break2): Use gdb_bfd_unref.
* solib-darwin.c: Include gdb_bfd.h.
(darwin_solib_get_all_image_info_addr_at_init): Use gdb_bfd_ref,
gdb_bfd_unref.
(darwin_bfd_open): Use gdb_bfd_unref.
* rs6000-nat.c (add_vmap): Use gdb_bfd_ref, gdb_bfd_unref.
* remote-mips.c: Include gdb_bfd.h.
(mips_load_srec): Use gdb_bfd_ref.
(pmon_load_fast): Use gdb_bfd_ref.
* remote-m32r-sdi.c: Include gdb_bfd.h.
(m32r_load): Use gdb_bfd_ref.
* record.c: Include gdb_bfd.h.
(record_save_cleanups): Use gdb_bfd_unref.
(cmd_record_save): Use gdb_bfd_unref.
* procfs.c (insert_dbx_link_bpt_in_file): Use gdb_bfd_ref,
gdb_bfd_unref.
* objfiles.h (gdb_bfd_close_or_warn): Remove.
(gdb_bfd_ref, gdb_bfd_unref): Move to gdb_bfd.h.
* objfiles.c: Include gdb_bfd.h.
(free_objfile): Use gdb_bfd_unref.
(gdb_bfd_close_or_warn, gdb_bfd_ref, gdb_bfd_unref): Move to
gdb_bfd.c.
* machoread.c (macho_add_oso_symfile): Use gdb_bfd_unref.
(macho_symfile_read_all_oso): Use gdb_bfd_ref, gdb_bfd_unref.
(macho_check_dsym): Likewise.
* m32r-rom.c: Include gdb_bfd.h.
(m32r_load): Use gdb_bfd_ref.
(m32r_upload_command): Use gdb_bfd_ref.
* jit.c: Include gdb_bfd.h.
(jit_bfd_try_read_symtab): Use gdb_bfd_ref, gdb_bfd_unref.
* gdb_bfd.h: New file.
* gdb_bfd.c: New file.
* gcore.c: Include gdb_bfd.h.
(create_gcore_bfd): Use gdb_bfd_ref.
(do_bfd_delete_cleanup): Use gdb_bfd_unref.
(gcore_command): Use gdb_bfd_unref.
* exec.c: Include gdb_bfd.h.
(exec_close): Use gdb_bfd_unref.
(exec_close_1): Use gdb_bfd_unref.
(exec_file_attach): Use gdb_bfd_ref.
* elfread.c: Include gdb_bfd.h.
(build_id_verify): Use gdb_bfd_unref.
* dsrec.c: Include gdb_bfd.h.
(load_srec): Use gdb_bfd_ref.
* corelow.c: Include gdb_bfd.h.
(core_close): Use gdb_bfd_unref.
(core_open): Use gdb_bfd_ref.
* bfd-target.c: Include gdb_bfd.h.
(target_bfd_xclose): Use gdb_bfd_unref.
(target_bfd_reopen): Use gdb_bfd_ref.
* Makefile.in (SFILES): Add gdb_bfd.c.
(HFILES_NO_SRCDIR): Add gdb_bfd.h.
(COMMON_OBS): Add gdb_bfd.o.
