binutils-gdb/gdb/bfd-target.c
Tom Tromey 7fdc15218d remove pop_target
This patch fixes the target double-close problem (PR remote/15266),
and in the process removes pop_target entire (PR remote/15256).

The first issue is that pop_target calls target_close.  However, it
then calls unpush_target, which also calls target_close.  This means
targets must be able to be closed twice.  Not only is this strange,
but it also directly contradicts the contract of to_xclose targets.
(We currently have just a single such target, and it is never pushed;
but I plan to add more, and so this latent bug is triggered.)

The second issue is that it seems to me that calling pop_target is
often unsafe.  This is what cropped up in 15256, where the remote
target assumed that it could pop_target -- but there was another
target higher on the stack, leading to confusion.

But, it is always just as easy to call unpush_target as it is to call
pop_target; and it is also safer.  So, removing pop_target seemed like
an improvement.

Finally, this adds an assertion to target_close to ensure that no
currently-pushed target can be closed.

Built and regtested on x86-64 Fedora 18; both natively and using the
native-gdbserver board file.

	PR remote/15256, PR remote/15266:
	* bfd-target.c (target_bfd_reopen): Initialize to_magic.
	* monitor.c (monitor_detach): Use unpush_target.
	* remote-m32r-sdi.c (m32r_detach): Use unpush_target.
	* remote-mips.c (mips_detach): Use unpush_target.  Don't
	call mips_close.
	* remote-sim.c (gdbsim_detach): Use unpush_target.
	* target.c (pop_target): Remove.
	(pop_all_targets_above): Don't call target_close.
	(target_close): Assert that the target is unpushed.
	* target.h (pop_target): Don't declare.
	* tracepoint.c (tfile_open): Use unpush_target.
2013-07-25 14:34:51 +00:00

103 lines
2.8 KiB
C

/* Very simple "bfd" target, for GDB, the GNU debugger.
Copyright (C) 2003-2013 Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include "defs.h"
#include "target.h"
#include "bfd-target.h"
#include "exec.h"
#include "gdb_bfd.h"
/* The object that is stored in the target_ops->to_data field has this
type. */
struct target_bfd_data
{
/* The BFD we're wrapping. */
struct bfd *bfd;
/* The section table build from the ALLOC sections in BFD. Note
that we can't rely on extracting the BFD from a random section in
the table, since the table can be legitimately empty. */
struct target_section_table table;
};
static LONGEST
target_bfd_xfer_partial (struct target_ops *ops,
enum target_object object,
const char *annex, gdb_byte *readbuf,
const gdb_byte *writebuf,
ULONGEST offset, LONGEST len)
{
switch (object)
{
case TARGET_OBJECT_MEMORY:
{
struct target_bfd_data *data = ops->to_data;
return section_table_xfer_memory_partial (readbuf, writebuf,
offset, len,
data->table.sections,
data->table.sections_end,
NULL);
}
default:
return -1;
}
}
static struct target_section_table *
target_bfd_get_section_table (struct target_ops *ops)
{
struct target_bfd_data *data = ops->to_data;
return &data->table;
}
static void
target_bfd_xclose (struct target_ops *t)
{
struct target_bfd_data *data = t->to_data;
gdb_bfd_unref (data->bfd);
xfree (data->table.sections);
xfree (data);
xfree (t);
}
struct target_ops *
target_bfd_reopen (struct bfd *abfd)
{
struct target_ops *t;
struct target_bfd_data *data;
data = XZALLOC (struct target_bfd_data);
data->bfd = abfd;
gdb_bfd_ref (abfd);
build_section_table (abfd, &data->table.sections, &data->table.sections_end);
t = XZALLOC (struct target_ops);
t->to_shortname = "bfd";
t->to_longname = _("BFD backed target");
t->to_doc = _("You should never see this");
t->to_get_section_table = target_bfd_get_section_table;
t->to_xfer_partial = target_bfd_xfer_partial;
t->to_xclose = target_bfd_xclose;
t->to_data = data;
t->to_magic = OPS_MAGIC;
return t;
}