gdb/go-valprint.c

   1 /* Support for printing Go values for GDB, the GNU debugger.
   2
   3    Copyright (C) 2012-2020 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
  39 static void
  40 print_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 = get_type_arch (type);
  47   struct type *elt_ptr_type = TYPE_FIELD_TYPE (type, 0);
  48   struct type *elt_type = TYPE_TARGET_TYPE (elt_ptr_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);
  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       fputs_filtered (paddress (gdbarch, addr), stream);
  70       fputs_filtered (" ", stream);
  71     }
  72
  73   if (length < 0)
  74     {
  75       printf_filtered (_("<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
  89 void
  90 go_value_print_inner (struct value *val, struct ui_file *stream,
  91                       int recurse, const struct value_print_options *options)
  92 {
  93   struct type *type = check_typedef (value_type (val));
  94
  95   switch (type->code ())
  96     {
  97       case TYPE_CODE_STRUCT:
  98         {
  99           enum go_type go_type = go_classify_struct_type (type);
 100
 101           switch (go_type)
 102             {
 103             case GO_TYPE_STRING:
 104               if (! options->raw)
 105                 {
 106                   print_go_string (type, value_embedded_offset (val),
 107                                    value_address (val),
 108                                    stream, recurse, val, options);
 109                   return;
 110                 }
 111               break;
 112             default:
 113               break;
 114             }
 115         }
 116         /* Fall through.  */
 117
 118       default:
 119         c_value_print_inner (val, stream, recurse, options);
 120         break;
 121     }
 122 }