binutils-gdb/gdb/c-valprint.c

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

   Copyright (C) 1986-2015 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"
};

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

void
c_val_print (struct type *type, const gdb_byte *valaddr,
	     int embedded_offset, CORE_ADDR address,
	     struct ui_file *stream, int recurse,
	     const struct value *original_value,
	     const struct value_print_options *options)
{
  struct gdbarch *gdbarch = get_type_arch (type);
  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  unsigned int i = 0;	/* Number of characters printed.  */
  unsigned len;
  struct type *elttype, *unresolved_elttype;
  struct type *unresolved_type = type;
  unsigned eltlen;
  CORE_ADDR addr;

  CHECK_TYPEDEF (type);
  switch (TYPE_CODE (type))
    {
    case TYPE_CODE_ARRAY:
      unresolved_elttype = TYPE_TARGET_TYPE (type);
      elttype = check_typedef (unresolved_elttype);
      if (TYPE_LENGTH (type) > 0 && TYPE_LENGTH (unresolved_elttype) > 0)
	{
          LONGEST low_bound, high_bound;

          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
						     + 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
						    + temp_len * eltlen,
						    eltlen, byte_order);
		      if (val != 0)
			force_ellipses = 1;
		    }

		  len = temp_len;
		}

	      LA_PRINT_STRING (stream, unresolved_elttype,
			       valaddr + embedded_offset, 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, valaddr, embedded_offset,
					address, stream,
					recurse, original_value, options, i);
	      fprintf_filtered (stream, "}");
	    }
	  break;
	}
      /* Array of unspecified length: treat like pointer to first
	 elt.  */
      addr = address + embedded_offset;
      goto print_unpacked_pointer;

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

    case TYPE_CODE_PTR:
      if (options->format && options->format != 's')
	{
	  val_print_scalar_formatted (type, valaddr, embedded_offset,
				      original_value, options, 0, stream);
	  break;
	}
      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);

	  print_function_pointer_address (options, gdbarch, addr, stream);
	  break;
	}
      unresolved_elttype = TYPE_TARGET_TYPE (type);
      elttype = check_typedef (unresolved_elttype);
	{
	  int want_space;

	  addr = unpack_pointer (type, valaddr + embedded_offset);
	print_unpacked_pointer:

	  want_space = 0;

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

	  if (options->symbol_print)
	    want_space = print_address_demangle (options, gdbarch, addr,
						 stream, demangle);
	  else if (options->addressprint)
	    {
	      fputs_filtered (paddress (gdbarch, addr), 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)
	      && addr != 0)
	    {
	      if (want_space)
		fputs_filtered (" ", stream);
	      i = val_print_string (unresolved_elttype, NULL,
				    addr, -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 = (struct symbol *) NULL;
		  struct type *wtype;
		  struct block *block = (struct block *) NULL;
		  struct field_of_this_result is_this_fld;

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

		  if (msymbol.minsym != NULL)
		    wsym = lookup_symbol (MSYMBOL_LINKAGE_NAME (msymbol.minsym),
					  block, VAR_DOMAIN,
					  &is_this_fld);

		  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);
		    }
		}
	    }
	  return;
	}
      break;

    case TYPE_CODE_UNION:
      if (recurse && !options->unionprint)
	{
	  fprintf_filtered (stream, "{...}");
	  break;
	}
      /* Fall through.  */
    case TYPE_CODE_STRUCT:
      /*FIXME: Abstract this away.  */
      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.)  */
	  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);
      break;

    case TYPE_CODE_INT:
      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, valaddr, embedded_offset,
				      original_value, &opts, 0, stream);
	}
      else
	{
	  val_print_type_code_int (type, valaddr + embedded_offset,
				   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),
			     unresolved_type, stream);
	    }
	}
      break;

    case TYPE_CODE_MEMBERPTR:
      if (!options->format)
	{
	  cp_print_class_member (valaddr + embedded_offset, type, stream, "&");
	  break;
	}
      /* FALLTHROUGH */

    case TYPE_CODE_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, valaddr, 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, top, using_enc;
  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_CODE (type) == TYPE_CODE_REF)
    {
      /* 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_CODE (type) == TYPE_CODE_REF;

	  if (is_ref)
	    val = value_addr (val);

	  /* 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);

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

		  /* Note: When we look up RTTI entries, we don't get
		     any information on const or volatile
		     attributes.  */
		}
	    }
          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),
		     value_contents_for_printing (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),
		     value_contents_for_printing (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_contents_for_printing (val),
	     value_embedded_offset (val),
	     value_address (val),
	     stream, 0,
	     val, &opts, current_language);
}