/* Support for printing C values for GDB, the GNU debugger. Copyright (C) 1986-2020 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.minsym->print_name (), stream); fputs_filtered (">", stream); want_space = 1; } if (vt_address && options->vtblprint) { struct value *vt_val; struct symbol *wsym = NULL; struct type *wtype; if (want_space) fputs_filtered (" ", 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 = 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_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); 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; 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 (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 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 ival = extract_unsigned_integer (valaddr + temp_len * eltlen, eltlen, byte_order); if (ival != 0) force_ellipses = 1; } len = temp_len; } LA_PRINT_STRING (stream, unresolved_elttype, valaddr, len, NULL, force_ellipses, options); } else { unsigned int i = 0; 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); } value_print_array_elements (val, stream, recurse, options, i); fprintf_filtered (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)); struct gdbarch *arch = get_type_arch (type); const gdb_byte *valaddr = value_contents_for_printing (val); 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, 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) == TYPE_CODE_UNION && recurse && !options->unionprint) fprintf_filtered (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.) */ struct gdbarch *gdbarch = get_type_arch (type); int offset = TYPE_FIELD_BITPOS (type, VTBL_FNADDR_OFFSET) / 8; struct type *field_type = TYPE_FIELD_TYPE (type, VTBL_FNADDR_OFFSET); const gdb_byte *valaddr = value_contents_for_printing (val); CORE_ADDR addr = extract_typed_address (valaddr + offset, field_type); print_function_pointer_address (options, gdbarch, 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); if (c_textual_element_type (type, options->format)) { fputs_filtered (" ", stream); LA_PRINT_CHAR (unpack_long (type, valaddr), type, stream); } } } /* c_value_print helper for TYPE_CODE_MEMBERPTR. */ static void c_value_print_memberptr (struct value *val, struct ui_file *stream, int recurse, const struct value_print_options *options) { if (!options->format) { struct type *type = check_typedef (value_type (val)); const gdb_byte *valaddr = value_contents_for_printing (val); cp_print_class_member (valaddr, type, stream, "&"); } else generic_value_print (val, stream, recurse, options, &c_decorations); } /* 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); const gdb_byte *valaddr = value_contents_for_printing (val); type = check_typedef (type); switch (TYPE_CODE (type)) { case TYPE_CODE_ARRAY: c_value_print_array (val, stream, recurse, options); break; case TYPE_CODE_METHODPTR: cplus_print_method_ptr (valaddr, type, stream); 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_INT: c_value_print_int (val, stream, options); break; case TYPE_CODE_MEMBERPTR: c_value_print_memberptr (val, stream, recurse, 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_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_CODE (type) == TYPE_CODE_PTR || TYPE_IS_REFERENCE (type)) { 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 (TYPE_CODE (original_type) == TYPE_CODE_PTR && TYPE_NAME (original_type) == NULL && TYPE_NAME (TYPE_TARGET_TYPE (original_type)) != NULL && (strcmp (TYPE_NAME (TYPE_TARGET_TYPE (original_type)), "char") == 0 || textual_name (TYPE_NAME (TYPE_TARGET_TYPE (original_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. */ /* 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, ") "); } 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); /* 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); fprintf_filtered (stream, "(%s%s) ", TYPE_NAME (real_type), full ? "" : _(" [incomplete object]")); } 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 = value_cast (value_enclosing_type (val), val); } } common_val_print (val, stream, 0, &opts, current_language); }