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C

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/* Support for printing C values for GDB, the GNU debugger.
Copyright (C) 1986-2022 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 (true_type->code () == TYPE_CODE_CHAR)
return 1;
/* Any other character-like types must be integral. */
if (true_type->code () != 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 (iter_type->name () && textual_name (iter_type->name ()))
return 1;
if (iter_type->code () != 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 (true_type->code () == 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 (true_type->code () == 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 = type->arch ();
if (elttype->code () == 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)
{
gdb_puts (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)
gdb_puts (" ", 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 == msymbol.value_address ()))
{
if (want_space)
gdb_puts (" ", stream);
gdb_puts (" <", stream);
gdb_puts (msymbol.minsym->print_name (), stream);
gdb_puts (">", stream);
want_space = 1;
}
if (vt_address && options->vtblprint)
{
struct value *vt_val;
struct symbol *wsym = NULL;
struct type *wtype;
if (want_space)
gdb_puts (" ", stream);
if (msymbol.minsym != NULL)
{
const char *search_name = msymbol.minsym->search_name ();
wsym = lookup_symbol_search_name (search_name, NULL,
VAR_DOMAIN).symbol;
}
if (wsym)
{
wtype = wsym->type ();
}
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)
{
gdb_printf (stream, "\n");
print_spaces (2 + 2 * recurse, stream);
}
}
}
}
/* c_value_print helper for TYPE_CODE_ARRAY. */
static void
c_value_print_array (struct value *val,
struct ui_file *stream, int recurse,
const struct value_print_options *options)
{
struct type *type = check_typedef (value_type (val));
CORE_ADDR address = value_address (val);
const gdb_byte *valaddr = value_contents_for_printing (val).data ();
struct type *unresolved_elttype = TYPE_TARGET_TYPE (type);
struct type *elttype = check_typedef (unresolved_elttype);
if (TYPE_LENGTH (type) > 0 && TYPE_LENGTH (unresolved_elttype) > 0)
{
LONGEST low_bound, high_bound;
int eltlen, len;
enum bfd_endian byte_order = type_byte_order (type);
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;
/* 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 (val, 0, TYPE_LENGTH (type))
&& !value_bits_any_optimized_out (val, 0,
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 + temp_len * eltlen,
eltlen, byte_order) != 0);
++temp_len)
;
/* Force printstr 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 ival
= extract_unsigned_integer (valaddr + temp_len * eltlen,
eltlen, byte_order);
if (ival != 0)
force_ellipses = 1;
}
len = temp_len;
}
current_language->printstr (stream, unresolved_elttype, valaddr, len,
NULL, force_ellipses, options);
}
else
{
unsigned int i = 0;
gdb_printf (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;
gdb_printf (stream, _("%d vtable entries"),
len - 1);
}
value_print_array_elements (val, stream, recurse, options, i);
gdb_printf (stream, "}");
}
}
else
{
/* Array of unspecified length: treat like pointer to first elt. */
print_unpacked_pointer (type, elttype, unresolved_elttype, valaddr,
0, address, stream, recurse, options);
}
}
/* c_value_print_inner helper for TYPE_CODE_PTR. */
static void
c_value_print_ptr (struct value *val, struct ui_file *stream, int recurse,
const struct value_print_options *options)
{
if (options->format && options->format != 's')
{
value_print_scalar_formatted (val, options, 0, stream);
return;
}
struct type *type = check_typedef (value_type (val));
const gdb_byte *valaddr = value_contents_for_printing (val).data ();
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, type);
print_function_pointer_address (options, type->arch (), 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);
print_unpacked_pointer (type, elttype, unresolved_elttype, valaddr,
0, addr, stream, recurse, options);
}
}
/* c_value_print helper for TYPE_CODE_STRUCT and TYPE_CODE_UNION. */
static void
c_value_print_struct (struct value *val, struct ui_file *stream, int recurse,
const struct value_print_options *options)
{
struct type *type = check_typedef (value_type (val));
if (type->code () == TYPE_CODE_UNION && recurse && !options->unionprint)
gdb_printf (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 NOT using
-fvtable_thunks. (Otherwise, look under
TYPE_CODE_PTR.) */
int offset = type->field (VTBL_FNADDR_OFFSET).loc_bitpos () / 8;
struct type *field_type = type->field (VTBL_FNADDR_OFFSET).type ();
const gdb_byte *valaddr = value_contents_for_printing (val).data ();
CORE_ADDR addr = extract_typed_address (valaddr + offset, field_type);
print_function_pointer_address (options, type->arch (), addr, stream);
}
else
cp_print_value_fields (val, stream, recurse, options, NULL, 0);
}
/* c_value_print helper for TYPE_CODE_INT. */
static void
c_value_print_int (struct value *val, struct ui_file *stream,
const struct value_print_options *options)
{
if (options->format || options->output_format)
{
struct value_print_options opts = *options;
opts.format = (options->format ? options->format
: options->output_format);
value_print_scalar_formatted (val, &opts, 0, stream);
}
else
{
value_print_scalar_formatted (val, 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. */
struct type *type = value_type (val);
const gdb_byte *valaddr = value_contents_for_printing (val).data ();
if (c_textual_element_type (type, options->format))
{
gdb_puts (" ", stream);
current_language->printchar (unpack_long (type, valaddr), type,
stream);
}
}
}
/* See c-lang.h. */
void
c_value_print_inner (struct value *val, struct ui_file *stream, int recurse,
const struct value_print_options *options)
{
struct type *type = value_type (val);
type = check_typedef (type);
switch (type->code ())
{
case TYPE_CODE_ARRAY:
c_value_print_array (val, stream, recurse, options);
break;
case TYPE_CODE_PTR:
c_value_print_ptr (val, stream, recurse, options);
break;
case TYPE_CODE_UNION:
case TYPE_CODE_STRUCT:
c_value_print_struct (val, stream, recurse, options);
break;
case TYPE_CODE_CHAR:
case TYPE_CODE_INT:
c_value_print_int (val, stream, options);
break;
case TYPE_CODE_METHODPTR:
case TYPE_CODE_MEMBERPTR:
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:
default:
generic_value_print (val, stream, recurse, options, &c_decorations);
break;
}
}
void
c_value_print (struct value *val, struct ui_file *stream,
const struct value_print_options *options)
{
struct type *type, *real_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. */
type = check_typedef (value_type (val));
if (type->is_pointer_or_reference ())
{
struct type *original_type = value_type (val);
/* 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 (original_type->code () == TYPE_CODE_PTR
&& original_type->name () == NULL
&& TYPE_TARGET_TYPE (original_type)->name () != NULL
&& (strcmp (TYPE_TARGET_TYPE (original_type)->name (),
"char") == 0
|| textual_name (TYPE_TARGET_TYPE (original_type)->name ())))
{
/* Print nothing. */
}
else if (options->objectprint
&& (TYPE_TARGET_TYPE (type)->code () == 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 ();
}
/* Pointer to class, check real type of object. */
gdb_printf (stream, "(");
if (value_entirely_available (val))
{
real_type = value_rtti_indirect_type (val, &full, &top,
&using_enc);
if (real_type)
{
/* RTTI entry found. */
/* 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);
gdb_printf (stream, ") ");
}
else
{
/* normal case */
gdb_printf (stream, "(");
type_print (value_type (val), "", stream, -1);
gdb_printf (stream, ") ");
}
}
if (!value_initialized (val))
gdb_printf (stream, " [uninitialized] ");
if (options->objectprint && (type->code () == 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);
/* In a destructor we might see a real type that is a
superclass of the object's type. In this case it is
better to leave the object as-is. */
if (!(full
&& (TYPE_LENGTH (real_type)
< TYPE_LENGTH (value_enclosing_type (val)))))
val = value_cast (real_type, val);
gdb_printf (stream, "(%s%s) ",
real_type->name (),
full ? "" : _(" [incomplete object]"));
}
else if (type != check_typedef (value_enclosing_type (val)))
{
/* No RTTI information, so let's do our best. */
gdb_printf (stream, "(%s ?) ",
value_enclosing_type (val)->name ());
val = value_cast (value_enclosing_type (val), val);
}
}
common_val_print (val, stream, 0, &opts, current_language);
}