1/* Support for printing Go values for GDB, the GNU debugger.
2
3   Copyright (C) 2012-2023 Free Software Foundation, Inc.
4
5   This file is part of GDB.
6
7   This program is free software; you can redistribute it and/or modify
8   it under the terms of the GNU General Public License as published by
9   the Free Software Foundation; either version 3 of the License, or
10   (at your option) any later version.
11
12   This program is distributed in the hope that it will be useful,
13   but WITHOUT ANY WARRANTY; without even the implied warranty of
14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15   GNU General Public License for more details.
16
17   You should have received a copy of the GNU General Public License
18   along with this program.  If not, see <http://www.gnu.org/licenses/>.
19
20   NOTE: This currently only provides special support for printing gccgo
21   strings.  6g objects are handled in Python.
22   The remaining gccgo types may also be handled in Python.
23   Strings are handled specially here, at least for now, in case the Python
24   support is unavailable.  */
25
26#include "defs.h"
27#include "gdbtypes.h"
28#include "gdbcore.h"
29#include "go-lang.h"
30#include "c-lang.h"
31#include "valprint.h"
32#include "cli/cli-style.h"
33
34/* Print a Go string.
35
36   Note: We assume
37   gdb_assert (go_classify_struct_type (type) == GO_TYPE_STRING).  */
38
39static void
40print_go_string (struct type *type,
41		 LONGEST embedded_offset, CORE_ADDR address,
42		 struct ui_file *stream, int recurse,
43		 struct value *val,
44		 const struct value_print_options *options)
45{
46  struct gdbarch *gdbarch = type->arch ();
47  struct type *elt_ptr_type = type->field (0).type ();
48  struct type *elt_type = elt_ptr_type->target_type ();
49  LONGEST length;
50  /* TODO(dje): The encapsulation of what a pointer is belongs in value.c.
51     I.e. If there's going to be unpack_pointer, there should be
52     unpack_value_field_as_pointer.  Do this until we can get
53     unpack_value_field_as_pointer.  */
54  LONGEST addr;
55  const gdb_byte *valaddr = value_contents_for_printing (val).data ();
56
57
58  if (! unpack_value_field_as_long (type, valaddr, embedded_offset, 0,
59				    val, &addr))
60    error (_("Unable to read string address"));
61
62  if (! unpack_value_field_as_long (type, valaddr, embedded_offset, 1,
63				    val, &length))
64    error (_("Unable to read string length"));
65
66  /* TODO(dje): Print address of struct or actual string?  */
67  if (options->addressprint)
68    {
69      gdb_puts (paddress (gdbarch, addr), stream);
70      gdb_puts (" ", stream);
71    }
72
73  if (length < 0)
74    {
75      gdb_printf (_("<invalid length: %ps>"),
76		  styled_string (metadata_style.style (),
77				 plongest (addr)));
78      return;
79    }
80
81  /* TODO(dje): Perhaps we should pass "UTF8" for ENCODING.
82     The target encoding is a global switch.
83     Either choice is problematic.  */
84  val_print_string (elt_type, NULL, addr, length, stream, options);
85}
86
87/* See go-lang.h.  */
88
89void
90go_language::value_print_inner (struct value *val, struct ui_file *stream,
91				int recurse,
92				const struct value_print_options *options) const
93{
94  struct type *type = check_typedef (value_type (val));
95
96  switch (type->code ())
97    {
98      case TYPE_CODE_STRUCT:
99	{
100	  enum go_type go_type = go_classify_struct_type (type);
101
102	  switch (go_type)
103	    {
104	    case GO_TYPE_STRING:
105	      if (! options->raw)
106		{
107		  print_go_string (type, value_embedded_offset (val),
108				   value_address (val),
109				   stream, recurse, val, options);
110		  return;
111		}
112	      break;
113	    default:
114	      break;
115	    }
116	}
117	/* Fall through.  */
118
119      default:
120	c_value_print_inner (val, stream, recurse, options);
121	break;
122    }
123}
124