/tmp/gdb-8.1/gdb/c-valprint.c

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/* Support for printing C values for GDB, the GNU debugger.

   Copyright (C) 1986-2018 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 "symtab.h"
#include "gdbtypes.h"
#include "expression.h"
#include "value.h"
#include "valprint.h"
#include "language.h"
#include "c-lang.h"
#include "cp-abi.h"
#include "target.h"
#include "objfiles.h"


/* A helper for c_textual_element_type.  This checks the name of the
   typedef.  This is bogus but it isn't apparent that the compiler
   provides us the help we may need.  */

static int
textual_name (const char *name)
{
  return (!strcmp (name, "wchar_t")
      || !strcmp (name, "char16_t")
      || !strcmp (name, "char32_t"));
}

/* Apply a heuristic to decide whether an array of TYPE or a pointer
   to TYPE should be printed as a textual string.  Return non-zero if
   it should, or zero if it should be treated as an array of integers
   or pointer to integers.  FORMAT is the current format letter, or 0
   if none.

   We guess that "char" is a character.  Explicitly signed and
   unsigned character types are also characters.  Integer data from
   vector types is not.  The user can override this by using the /s
   format letter.  */

int
c_textual_element_type (struct type *type, char format)
{
  struct type *true_type, *iter_type;

  if (format != 0 && format != 's')
    return 0;

  /* We also rely on this for its side effect of setting up all the
     typedef pointers.  */
  true_type = check_typedef (type);

  /* TYPE_CODE_CHAR is always textual.  */
  if (TYPE_CODE (true_type) == TYPE_CODE_CHAR)
    return 1;

  /* Any other character-like types must be integral.  */
  if (TYPE_CODE (true_type) != TYPE_CODE_INT)
    return 0;

  /* We peel typedefs one by one, looking for a match.  */
  iter_type = type;
  while (iter_type)
    {
      /* Check the name of the type.  */
      if (TYPE_NAME (iter_type) && textual_name (TYPE_NAME (iter_type)))
    return 1;

      if (TYPE_CODE (iter_type) != TYPE_CODE_TYPEDEF)
    break;

      /* Peel a single typedef.  If the typedef doesn't have a target
     type, we use check_typedef and hope the result is ok -- it
     might be for C++, where wchar_t is a built-in type.  */
      if (TYPE_TARGET_TYPE (iter_type))
    iter_type = TYPE_TARGET_TYPE (iter_type);
      else
    iter_type = check_typedef (iter_type);
    }

  if (format == 's')
    {
      /* Print this as a string if we can manage it.  For now, no wide
     character support.  */
      if (TYPE_CODE (true_type) == TYPE_CODE_INT
      && TYPE_LENGTH (true_type) == 1)
    return 1;
    }
  else
    {
      /* If a one-byte TYPE_CODE_INT is missing the not-a-character
     flag, then we treat it as text; otherwise, we assume it's
     being used as data.  */
      if (TYPE_CODE (true_type) == TYPE_CODE_INT
      && TYPE_LENGTH (true_type) == 1
      && !TYPE_NOTTEXT (true_type))
    return 1;
    }

  return 0;
}

/* Decorations for C.  */

static const struct generic_val_print_decorations c_decorations =
{
  "",
  " + ",
  " * I",
  "true",
  "false",
  "void",
  "{",
  "}"
};

/* Print a pointer based on the type of its target.

   Arguments to this functions are roughly the same as those in c_val_print.
   A difference is that ADDRESS is the address to print, with embedded_offset
   already added.  UNRESOLVED_ELTTYPE and ELTTYPE represent the pointed type,
   respectively before and after check_typedef.  */

static void
print_unpacked_pointer (struct type *type, struct type *elttype,
            struct type *unresolved_elttype,
            const gdb_byte *valaddr, int embedded_offset,
            CORE_ADDR address, struct ui_file *stream, int recurse,
            const struct value_print_options *options)
{
  int want_space = 0;
  struct gdbarch *gdbarch = get_type_arch (type);

  if (TYPE_CODE (elttype) == TYPE_CODE_FUNC)
    {
      /* Try to print what function it points to.  */
      print_function_pointer_address (options, gdbarch, address, stream);
      return;
    }

  if (options->symbol_print)
    want_space = print_address_demangle (options, gdbarch, address, stream,
                     demangle);
  else if (options->addressprint)
    {
      fputs_filtered (paddress (gdbarch, address), stream);
      want_space = 1;
    }

  /* For a pointer to a textual type, also print the string
     pointed to, unless pointer is null.  */

  if (c_textual_element_type (unresolved_elttype, options->format)
      && address != 0)
    {
      if (want_space)
    fputs_filtered (" ", stream);
      val_print_string (unresolved_elttype, NULL, address, -1, stream, options);
    }
  else if (cp_is_vtbl_member (type))
    {
      /* Print vtbl's nicely.  */
      CORE_ADDR vt_address = unpack_pointer (type, valaddr + embedded_offset);
      struct bound_minimal_symbol msymbol =
    lookup_minimal_symbol_by_pc (vt_address);

      /* If 'symbol_print' is set, we did the work above.  */
      if (!options->symbol_print
      && (msymbol.minsym != NULL)
      && (vt_address == BMSYMBOL_VALUE_ADDRESS (msymbol)))
    {
      if (want_space)
        fputs_filtered (" ", stream);
      fputs_filtered (" <", stream);
      fputs_filtered (MSYMBOL_PRINT_NAME (msymbol.minsym), stream);
      fputs_filtered (">", stream);
      want_space = 1;
    }

      if (vt_address && options->vtblprint)
    {
      struct value *vt_val;
      struct symbol *wsym = NULL;
      struct type *wtype;
      struct block *block = NULL;

      if (want_space)
        fputs_filtered (" ", stream);

      if (msymbol.minsym != NULL)
        {
          const char *search_name
        = MSYMBOL_SEARCH_NAME (msymbol.minsym);
          wsym = lookup_symbol_search_name (search_name, block,
                        VAR_DOMAIN).symbol;
        }

      if (wsym)
        {
          wtype = SYMBOL_TYPE (wsym);
        }
      else
        {
          wtype = unresolved_elttype;
        }
      vt_val = value_at (wtype, vt_address);
      common_val_print (vt_val, stream, recurse + 1, options,
                current_language);
      if (options->prettyformat)
        {
          fprintf_filtered (stream, "\n");
          print_spaces_filtered (2 + 2 * recurse, stream);
        }
    }
    }
}

/* c_val_print helper for TYPE_CODE_ARRAY.  */

static void
c_val_print_array (struct type *type, const gdb_byte *valaddr,
           int embedded_offset, CORE_ADDR address,
           struct ui_file *stream, int recurse,
           struct value *original_value,
           const struct value_print_options *options)
{
  struct type *unresolved_elttype = TYPE_TARGET_TYPE (type);
  struct type *elttype = check_typedef (unresolved_elttype);
  struct gdbarch *arch = get_type_arch (type);
  int unit_size = gdbarch_addressable_memory_unit_size (arch);

  if (TYPE_LENGTH (type) > 0 && TYPE_LENGTH (unresolved_elttype) > 0)
    {
      LONGEST low_bound, high_bound;
      int eltlen, len;
      struct gdbarch *gdbarch = get_type_arch (type);
      enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
      unsigned int i = 0;   /* Number of characters printed.  */

      if (!get_array_bounds (type, &low_bound, &high_bound))
    error (_("Could not determine the array high bound"));

      eltlen = TYPE_LENGTH (elttype);
      len = high_bound - low_bound + 1;
      if (options->prettyformat_arrays)
    {
      print_spaces_filtered (2 + 2 * recurse, stream);
    }

      /* Print arrays of textual chars with a string syntax, as
     long as the entire array is valid.  */
      if (c_textual_element_type (unresolved_elttype,
                  options->format)
      && value_bytes_available (original_value, embedded_offset,
                    TYPE_LENGTH (type))
      && !value_bits_any_optimized_out (original_value,
                        TARGET_CHAR_BIT * embedded_offset,
                        TARGET_CHAR_BIT * TYPE_LENGTH (type)))
    {
      int force_ellipses = 0;

      /* If requested, look for the first null char and only
         print elements up to it.  */
      if (options->stop_print_at_null)
        {
          unsigned int temp_len;

          for (temp_len = 0;
           (temp_len < len
            && temp_len < options->print_max
            && extract_unsigned_integer (valaddr
                         + embedded_offset * unit_size
                         + temp_len * eltlen,
                         eltlen, byte_order) != 0);
           ++temp_len)
        ;

          /* Force LA_PRINT_STRING to print ellipses if
         we've printed the maximum characters and
         the next character is not \000.  */
          if (temp_len == options->print_max && temp_len < len)
        {
          ULONGEST val
            = extract_unsigned_integer (valaddr
                        + embedded_offset * unit_size
                        + temp_len * eltlen,
                        eltlen, byte_order);
          if (val != 0)
            force_ellipses = 1;
        }

          len = temp_len;
        }

      LA_PRINT_STRING (stream, unresolved_elttype,
               valaddr + embedded_offset * unit_size, len,
               NULL, force_ellipses, options);
      i = len;
    }
      else
    {
      fprintf_filtered (stream, "{");
      /* If this is a virtual function table, print the 0th
         entry specially, and the rest of the members
         normally.  */
      if (cp_is_vtbl_ptr_type (elttype))
        {
          i = 1;
          fprintf_filtered (stream, _("%d vtable entries"),
                len - 1);
        }
      else
        {
          i = 0;
        }
      val_print_array_elements (type, embedded_offset,
                    address, stream,
                    recurse, original_value, options, i);
      fprintf_filtered (stream, "}");
    }
    }
  else
    {
      /* Array of unspecified length: treat like pointer to first elt.  */
      print_unpacked_pointer (type, elttype, unresolved_elttype, valaddr,
                  embedded_offset, address + embedded_offset,
                  stream, recurse, options);
    }
}

/* c_val_print helper for TYPE_CODE_PTR.  */

static void
c_val_print_ptr (struct type *type, const gdb_byte *valaddr,
         int embedded_offset, struct ui_file *stream, int recurse,
         struct value *original_value,
         const struct value_print_options *options)
{
  struct gdbarch *arch = get_type_arch (type);
  int unit_size = gdbarch_addressable_memory_unit_size (arch);

  if (options->format && options->format != 's')
    {
      val_print_scalar_formatted (type, embedded_offset,
                  original_value, options, 0, stream);
    }
  else if (options->vtblprint && cp_is_vtbl_ptr_type (type))
    {
      /* Print the unmangled name if desired.  */
      /* Print vtable entry - we only get here if we ARE using
     -fvtable_thunks.  (Otherwise, look under
     TYPE_CODE_STRUCT.)  */
      CORE_ADDR addr
    = extract_typed_address (valaddr + embedded_offset, type);
      struct gdbarch *gdbarch = get_type_arch (type);

      print_function_pointer_address (options, gdbarch, addr, stream);
    }
  else
    {
      struct type *unresolved_elttype = TYPE_TARGET_TYPE (type);
      struct type *elttype = check_typedef (unresolved_elttype);
      CORE_ADDR addr = unpack_pointer (type,
                       valaddr + embedded_offset * unit_size);

      print_unpacked_pointer (type, elttype, unresolved_elttype, valaddr,
                  embedded_offset, addr, stream, recurse, options);
    }
}

/* c_val_print helper for TYPE_CODE_STRUCT.  */

static void
c_val_print_struct (struct type *type, const gdb_byte *valaddr,
            int embedded_offset, CORE_ADDR address,
            struct ui_file *stream, int recurse,
            struct value *original_value,
            const struct value_print_options *options)
{
  if (options->vtblprint && cp_is_vtbl_ptr_type (type))
    {
      /* Print the unmangled name if desired.  */
      /* Print vtable entry - we only get here if NOT using
     -fvtable_thunks.  (Otherwise, look under
     TYPE_CODE_PTR.)  */
      struct gdbarch *gdbarch = get_type_arch (type);
      int offset = (embedded_offset
            + TYPE_FIELD_BITPOS (type,
                     VTBL_FNADDR_OFFSET) / 8);
      struct type *field_type = TYPE_FIELD_TYPE (type, VTBL_FNADDR_OFFSET);
      CORE_ADDR addr = extract_typed_address (valaddr + offset, field_type);

      print_function_pointer_address (options, gdbarch, addr, stream);
    }
  else
    cp_print_value_fields_rtti (type, valaddr,
                embedded_offset, address,
                stream, recurse,
                original_value, options,
                NULL, 0);
}

/* c_val_print helper for TYPE_CODE_UNION.  */

static void
c_val_print_union (struct type *type, const gdb_byte *valaddr,
           int embedded_offset, CORE_ADDR address,
           struct ui_file *stream, int recurse,
           struct value *original_value,
           const struct value_print_options *options)
{
  if (recurse && !options->unionprint)
    {
      fprintf_filtered (stream, "{...}");
     }
  else
    {
      c_val_print_struct (type, valaddr, embedded_offset, address, stream,
              recurse, original_value, options);
    }
}

/* c_val_print helper for TYPE_CODE_INT.  */

static void
c_val_print_int (struct type *type, struct type *unresolved_type,
         const gdb_byte *valaddr, int embedded_offset,
         struct ui_file *stream, struct value *original_value,
         const struct value_print_options *options)
{
  struct gdbarch *arch = get_type_arch (type);
  int unit_size = gdbarch_addressable_memory_unit_size (arch);

  if (options->format || options->output_format)
    {
      struct value_print_options opts = *options;

      opts.format = (options->format ? options->format
             : options->output_format);
      val_print_scalar_formatted (type, embedded_offset,
                  original_value, &opts, 0, stream);
    }
  else
    {
      val_print_scalar_formatted (type, embedded_offset,
                  original_value, options, 0, stream);
      /* C and C++ has no single byte int type, char is used
     instead.  Since we don't know whether the value is really
     intended to be used as an integer or a character, print
     the character equivalent as well.  */
      if (c_textual_element_type (unresolved_type, options->format))
    {
      fputs_filtered (" ", stream);
      LA_PRINT_CHAR (unpack_long (type,
                      valaddr + embedded_offset * unit_size),
             unresolved_type, stream);
    }
    }
}

/* c_val_print helper for TYPE_CODE_MEMBERPTR.  */

static void
c_val_print_memberptr (struct type *type, const gdb_byte *valaddr,
               int embedded_offset, CORE_ADDR address,
               struct ui_file *stream, int recurse,
               struct value *original_value,
               const struct value_print_options *options)
{
  if (!options->format)
    {
      cp_print_class_member (valaddr + embedded_offset, type, stream, "&");
    }
  else
    {
      generic_val_print (type, embedded_offset, address, stream,
             recurse, original_value, options, &c_decorations);
    }
}

/* See val_print for a description of the various parameters of this
   function; they are identical.  */

void
c_val_print (struct type *type,
         int embedded_offset, CORE_ADDR address,
         struct ui_file *stream, int recurse,
         struct value *original_value,
         const struct value_print_options *options)
{
  struct type *unresolved_type = type;
  const gdb_byte *valaddr = value_contents_for_printing (original_value);

  type = check_typedef (type);
  switch (TYPE_CODE (type))
    {
    case TYPE_CODE_ARRAY:
      c_val_print_array (type, valaddr, embedded_offset, address, stream,
             recurse, original_value, options);
      break;

    case TYPE_CODE_METHODPTR:
      cplus_print_method_ptr (valaddr + embedded_offset, type, stream);
      break;

    case TYPE_CODE_PTR:
      c_val_print_ptr (type, valaddr, embedded_offset, stream, recurse,
               original_value, options);
      break;

    case TYPE_CODE_UNION:
      c_val_print_union (type, valaddr, embedded_offset, address, stream,
             recurse, original_value, options);
      break;

    case TYPE_CODE_STRUCT:
      c_val_print_struct (type, valaddr, embedded_offset, address, stream,
              recurse, original_value, options);
      break;

    case TYPE_CODE_INT:
      c_val_print_int (type, unresolved_type, valaddr, embedded_offset, stream,
               original_value, options);
      break;

    case TYPE_CODE_MEMBERPTR:
      c_val_print_memberptr (type, valaddr, embedded_offset, address, stream,
                 recurse, original_value, options);
      break;

    case TYPE_CODE_REF:
    case TYPE_CODE_RVALUE_REF:
    case TYPE_CODE_ENUM:
    case TYPE_CODE_FLAGS:
    case TYPE_CODE_FUNC:
    case TYPE_CODE_METHOD:
    case TYPE_CODE_BOOL:
    case TYPE_CODE_RANGE:
    case TYPE_CODE_FLT:
    case TYPE_CODE_DECFLOAT:
    case TYPE_CODE_VOID:
    case TYPE_CODE_ERROR:
    case TYPE_CODE_UNDEF:
    case TYPE_CODE_COMPLEX:
    case TYPE_CODE_CHAR:
    default:
      generic_val_print (type, embedded_offset, address,
             stream, recurse, original_value, options,
             &c_decorations);
      break;
    }
  gdb_flush (stream);
}

void
c_value_print (struct value *val, struct ui_file *stream, 
           const struct value_print_options *options)
{
  struct type *type, *real_type, *val_type;
  int full, using_enc;
  LONGEST top;
  struct value_print_options opts = *options;

  opts.deref_ref = 1;

  /* If it is a pointer, indicate what it points to.

     Print type also if it is a reference.

     C++: if it is a member pointer, we will take care
     of that when we print it.  */

  /* Preserve the original type before stripping typedefs.  We prefer
     to pass down the original type when possible, but for local
     checks it is better to look past the typedefs.  */
  val_type = value_type (val);
  type = check_typedef (val_type);

  if (TYPE_CODE (type) == TYPE_CODE_PTR || TYPE_IS_REFERENCE (type))
    {
      /* Hack:  remove (char *) for char strings.  Their
         type is indicated by the quoted string anyway.
         (Don't use c_textual_element_type here; quoted strings
         are always exactly (char *), (wchar_t *), or the like.  */
      if (TYPE_CODE (val_type) == TYPE_CODE_PTR
      && TYPE_NAME (val_type) == NULL
      && TYPE_NAME (TYPE_TARGET_TYPE (val_type)) != NULL
      && (strcmp (TYPE_NAME (TYPE_TARGET_TYPE (val_type)),
              "char") == 0
          || textual_name (TYPE_NAME (TYPE_TARGET_TYPE (val_type)))))
    {
      /* Print nothing.  */
    }
      else if (options->objectprint
           && (TYPE_CODE (TYPE_TARGET_TYPE (type)) == TYPE_CODE_STRUCT))
    {
      int is_ref = TYPE_IS_REFERENCE (type);
      enum type_code refcode = TYPE_CODE_UNDEF;

      if (is_ref)
        {
          val = value_addr (val);
          refcode = TYPE_CODE (type);
        }

      /* Pointer to class, check real type of object.  */
      fprintf_filtered (stream, "(");

      if (value_entirely_available (val))
        {
          real_type = value_rtti_indirect_type (val, &full, &top,
                            &using_enc);
          if (real_type)
        {
          /* RTTI entry found.  */
          type = real_type;

          /* Need to adjust pointer value.  */
          val = value_from_pointer (real_type,
                        value_as_address (val) - top);

          /* Note: When we look up RTTI entries, we don't get
             any information on const or volatile
             attributes.  */
        }
        }

      if (is_ref)
        {
          val = value_ref (value_ind (val), refcode);
          type = value_type (val);
        }

      type_print (type, "", stream, -1);
      fprintf_filtered (stream, ") ");
      val_type = type;
    }
      else
    {
      /* normal case */
      fprintf_filtered (stream, "(");
      type_print (value_type (val), "", stream, -1);
      fprintf_filtered (stream, ") ");
    }
    }

  if (!value_initialized (val))
    fprintf_filtered (stream, " [uninitialized] ");

  if (options->objectprint && (TYPE_CODE (type) == TYPE_CODE_STRUCT))
    {
      /* Attempt to determine real type of object.  */
      real_type = value_rtti_type (val, &full, &top, &using_enc);
      if (real_type)
    {
      /* We have RTTI information, so use it.  */
      val = value_full_object (val, real_type, 
                   full, top, using_enc);
      fprintf_filtered (stream, "(%s%s) ",
                TYPE_NAME (real_type),
                full ? "" : _(" [incomplete object]"));
      /* Print out object: enclosing type is same as real_type if
         full.  */
      val_print (value_enclosing_type (val),
             0,
             value_address (val), stream, 0,
             val, &opts, current_language);
      return;
          /* Note: When we look up RTTI entries, we don't get any
             information on const or volatile attributes.  */
    }
      else if (type != check_typedef (value_enclosing_type (val)))
    {
      /* No RTTI information, so let's do our best.  */
      fprintf_filtered (stream, "(%s ?) ",
                TYPE_NAME (value_enclosing_type (val)));
      val_print (value_enclosing_type (val),
             0,
             value_address (val), stream, 0,
             val, &opts, current_language);
      return;
    }
      /* Otherwise, we end up at the return outside this "if".  */
    }

  val_print (val_type,
         value_embedded_offset (val),
         value_address (val),
         stream, 0,
         val, &opts, current_language);
}