binutils-gdb/gdb/go-valprint.c
Simon Marchi 50888e42dc gdb: change functions returning value contents to use gdb::array_view
The bug fixed by this [1] patch was caused by an out-of-bounds access to
a value's content.  The code gets the value's content (just a pointer)
and then indexes it with a non-sensical index.

This made me think of changing functions that return value contents to
return array_views instead of a plain pointer.  This has the advantage
that when GDB is built with _GLIBCXX_DEBUG, accesses to the array_view
are checked, making bugs more apparent / easier to find.

This patch changes the return types of these functions, and updates
callers to call .data() on the result, meaning it's not changing
anything in practice.  Additional work will be needed (which can be done
little by little) to make callers propagate the use of array_view and
reap the benefits.

[1] https://sourceware.org/pipermail/gdb-patches/2021-September/182306.html

Change-Id: I5151f888f169e1c36abe2cbc57620110673816f3
2021-10-25 14:51:44 -04:00

124 lines
3.6 KiB
C

/* Support for printing Go values for GDB, the GNU debugger.
Copyright (C) 2012-2021 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/>.
NOTE: This currently only provides special support for printing gccgo
strings. 6g objects are handled in Python.
The remaining gccgo types may also be handled in Python.
Strings are handled specially here, at least for now, in case the Python
support is unavailable. */
#include "defs.h"
#include "gdbtypes.h"
#include "gdbcore.h"
#include "go-lang.h"
#include "c-lang.h"
#include "valprint.h"
#include "cli/cli-style.h"
/* Print a Go string.
Note: We assume
gdb_assert (go_classify_struct_type (type) == GO_TYPE_STRING). */
static void
print_go_string (struct type *type,
LONGEST embedded_offset, CORE_ADDR address,
struct ui_file *stream, int recurse,
struct value *val,
const struct value_print_options *options)
{
struct gdbarch *gdbarch = type->arch ();
struct type *elt_ptr_type = type->field (0).type ();
struct type *elt_type = TYPE_TARGET_TYPE (elt_ptr_type);
LONGEST length;
/* TODO(dje): The encapsulation of what a pointer is belongs in value.c.
I.e. If there's going to be unpack_pointer, there should be
unpack_value_field_as_pointer. Do this until we can get
unpack_value_field_as_pointer. */
LONGEST addr;
const gdb_byte *valaddr = value_contents_for_printing (val).data ();
if (! unpack_value_field_as_long (type, valaddr, embedded_offset, 0,
val, &addr))
error (_("Unable to read string address"));
if (! unpack_value_field_as_long (type, valaddr, embedded_offset, 1,
val, &length))
error (_("Unable to read string length"));
/* TODO(dje): Print address of struct or actual string? */
if (options->addressprint)
{
fputs_filtered (paddress (gdbarch, addr), stream);
fputs_filtered (" ", stream);
}
if (length < 0)
{
printf_filtered (_("<invalid length: %ps>"),
styled_string (metadata_style.style (),
plongest (addr)));
return;
}
/* TODO(dje): Perhaps we should pass "UTF8" for ENCODING.
The target encoding is a global switch.
Either choice is problematic. */
val_print_string (elt_type, NULL, addr, length, stream, options);
}
/* See go-lang.h. */
void
go_language::value_print_inner (struct value *val, struct ui_file *stream,
int recurse,
const struct value_print_options *options) const
{
struct type *type = check_typedef (value_type (val));
switch (type->code ())
{
case TYPE_CODE_STRUCT:
{
enum go_type go_type = go_classify_struct_type (type);
switch (go_type)
{
case GO_TYPE_STRING:
if (! options->raw)
{
print_go_string (type, value_embedded_offset (val),
value_address (val),
stream, recurse, val, options);
return;
}
break;
default:
break;
}
}
/* Fall through. */
default:
c_value_print_inner (val, stream, recurse, options);
break;
}
}