2016-11-21 01:48:31 +01:00
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/* Reference-counted smart pointer class
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2020-01-01 07:20:01 +01:00
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Copyright (C) 2016-2020 Free Software Foundation, Inc.
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2016-11-21 01:48:31 +01:00
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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2019-01-27 20:51:36 +01:00
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#ifndef COMMON_GDB_REF_PTR_H
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#define COMMON_GDB_REF_PTR_H
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2016-11-21 01:48:31 +01:00
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#include <cstddef>
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namespace gdb
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{
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/* An instance of this class either holds a reference to a
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reference-counted object or is "NULL". Reference counting is
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handled externally by a policy class. If the object holds a
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reference, then when the object is destroyed, the reference is
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decref'd.
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Normally an instance is constructed using a pointer. This sort of
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initialization lets this class manage the lifetime of that
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reference.
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Assignment and copy construction will make a new reference as
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appropriate. Assignment from a plain pointer is disallowed to
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avoid confusion about whether this acquires a new reference;
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instead use the "reset" method -- which, like the pointer
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constructor, transfers ownership.
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The policy class must provide two static methods:
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void incref (T *);
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void decref (T *);
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*/
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template<typename T, typename Policy>
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class ref_ptr
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{
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public:
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/* Create a new NULL instance. */
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ref_ptr ()
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: m_obj (NULL)
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{
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}
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/* Create a new NULL instance. Note that this is not explicit. */
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ref_ptr (const std::nullptr_t)
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: m_obj (NULL)
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{
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}
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/* Create a new instance. OBJ is a reference, management of which
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is now transferred to this class. */
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explicit ref_ptr (T *obj)
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: m_obj (obj)
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{
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}
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/* Copy another instance. */
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ref_ptr (const ref_ptr &other)
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: m_obj (other.m_obj)
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{
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if (m_obj != NULL)
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Policy::incref (m_obj);
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}
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/* Transfer ownership from OTHER. */
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2020-04-20 19:45:06 +02:00
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ref_ptr (ref_ptr &&other) noexcept
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2016-11-21 01:48:31 +01:00
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: m_obj (other.m_obj)
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{
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other.m_obj = NULL;
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}
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/* Destroy this instance. */
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~ref_ptr ()
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{
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if (m_obj != NULL)
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Policy::decref (m_obj);
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}
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/* Copy another instance. */
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ref_ptr &operator= (const ref_ptr &other)
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{
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/* Do nothing on self-assignment. */
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if (this != &other)
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{
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reset (other.m_obj);
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if (m_obj != NULL)
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Policy::incref (m_obj);
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}
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return *this;
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}
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/* Transfer ownership from OTHER. */
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ref_ptr &operator= (ref_ptr &&other)
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{
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/* Do nothing on self-assignment. */
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if (this != &other)
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{
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reset (other.m_obj);
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other.m_obj = NULL;
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}
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return *this;
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}
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/* Change this instance's referent. OBJ is a reference, management
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of which is now transferred to this class. */
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void reset (T *obj)
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{
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if (m_obj != NULL)
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Policy::decref (m_obj);
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m_obj = obj;
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}
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/* Return this instance's referent without changing the state of
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this class. */
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T *get () const
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{
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return m_obj;
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}
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/* Return this instance's referent, and stop managing this
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reference. The caller is now responsible for the ownership of
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the reference. */
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2019-02-26 22:59:47 +01:00
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ATTRIBUTE_UNUSED_RESULT T *release ()
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2016-11-21 01:48:31 +01:00
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{
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T *result = m_obj;
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m_obj = NULL;
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return result;
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}
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Use class to manage BFD reference counts
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.
2016-11-21 19:12:23 +01:00
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/* Let users refer to members of the underlying pointer. */
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T *operator-> () const
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{
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return m_obj;
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}
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2018-04-30 04:59:21 +02:00
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/* Acquire a new reference and return a ref_ptr that owns it. */
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static ref_ptr<T, Policy> new_reference (T *obj)
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{
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Policy::incref (obj);
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return ref_ptr<T, Policy> (obj);
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}
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2016-11-21 01:48:31 +01:00
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private:
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T *m_obj;
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};
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template<typename T, typename Policy>
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inline bool operator== (const ref_ptr<T, Policy> &lhs,
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const ref_ptr<T, Policy> &rhs)
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{
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return lhs.get () == rhs.get ();
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}
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template<typename T, typename Policy>
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inline bool operator== (const ref_ptr<T, Policy> &lhs, const T *rhs)
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{
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return lhs.get () == rhs;
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}
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template<typename T, typename Policy>
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inline bool operator== (const ref_ptr<T, Policy> &lhs, const std::nullptr_t)
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{
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return lhs.get () == nullptr;
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}
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template<typename T, typename Policy>
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inline bool operator== (const T *lhs, const ref_ptr<T, Policy> &rhs)
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{
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return lhs == rhs.get ();
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}
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template<typename T, typename Policy>
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inline bool operator== (const std::nullptr_t, const ref_ptr<T, Policy> &rhs)
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{
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return nullptr == rhs.get ();
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}
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template<typename T, typename Policy>
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inline bool operator!= (const ref_ptr<T, Policy> &lhs,
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const ref_ptr<T, Policy> &rhs)
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{
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return lhs.get () != rhs.get ();
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}
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template<typename T, typename Policy>
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inline bool operator!= (const ref_ptr<T, Policy> &lhs, const T *rhs)
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{
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return lhs.get () != rhs;
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}
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template<typename T, typename Policy>
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inline bool operator!= (const ref_ptr<T, Policy> &lhs, const std::nullptr_t)
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{
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return lhs.get () != nullptr;
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}
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template<typename T, typename Policy>
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inline bool operator!= (const T *lhs, const ref_ptr<T, Policy> &rhs)
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{
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return lhs != rhs.get ();
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}
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template<typename T, typename Policy>
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inline bool operator!= (const std::nullptr_t, const ref_ptr<T, Policy> &rhs)
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{
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return nullptr != rhs.get ();
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}
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}
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2019-01-27 20:51:36 +01:00
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#endif /* COMMON_GDB_REF_PTR_H */
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