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binutils-gdb/gdb/language.h
Andrew Burgess baab375361 gdb: building inferior strings from within GDB 
History Of This Patch
=====================

This commit aims to address PR gdb/21699.  There have now been a
couple of attempts to fix this issue.  Simon originally posted two
patches back in 2021:

  https://sourceware.org/pipermail/gdb-patches/2021-July/180894.html
  https://sourceware.org/pipermail/gdb-patches/2021-July/180896.html

Before Pedro then posted a version of his own:

  https://sourceware.org/pipermail/gdb-patches/2021-July/180970.html

After this the conversation halted.  Then in 2023 I (Andrew) also took
a look at this bug and posted two versions:

  https://sourceware.org/pipermail/gdb-patches/2023-April/198570.html
  https://sourceware.org/pipermail/gdb-patches/2023-April/198680.html

The approach taken in my first patch was pretty similar to what Simon
originally posted back in 2021.  My second attempt was only a slight
variation on the first.

Pedro then pointed out his older patch, and so we arrive at this
patch.  The GDB changes here are mostly Pedro's work, but updated by
me (Andrew), any mistakes are mine.

The tests here are a combinations of everyone's work, and the commit
message is new, but copies bits from everyone's earlier work.

Problem Description
===================

Bug PR gdb/21699 makes the observation that using $_as_string with
GDB's printf can cause GDB to print unexpected data from the
inferior.  The reproducer is pretty simple:

  #include <stddef.h>
  static char arena[100];

  /* Override malloc() so value_coerce_to_target() gets a known
     pointer, and we know we"ll see an error if $_as_string() gives
     a string that isn't null terminated. */
  void
  *malloc (size_t size)
  {
      memset (arena, 'x', sizeof (arena));
      if (size > sizeof (arena))
          return NULL;
      return arena;
  }

  int
  main ()
  {
    return 0;
  }

And then in a GDB session:

  $ gdb -q test
  Reading symbols from /tmp/test...
  (gdb) start
  Temporary breakpoint 1 at 0x4004c8: file test.c, line 17.
  Starting program: /tmp/test

  Temporary breakpoint 1, main () at test.c:17
  17        return 0;
  (gdb) printf "%s\n", $_as_string("hello")
  "hello"xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
  (gdb) quit

The problem above is caused by how value_cstring is used within
py-value.c, but once we understand the issue then it turns out that
value_cstring is used in an unexpected way in many places within GDB.

Within py-value.c we have a null-terminated C-style string.  We then
pass a pointer to this string, along with the length of this
string (so not including the null-character) to value_cstring.

In value_cstring GDB allocates an array value of the given character
type, and copies in requested number of characters.  However
value_cstring does not add a null-character of its own.  This means
that the value created by calling value_cstring is only
null-terminated if the null-character is included in the passed in
length.  In py-value.c this is not the case, and indeed, in most uses
of value_cstring, this is not the case.

When GDB tries to print one of these strings the value contents are
pushed to the inferior, and then read back as a C-style string, that
is, GDB reads inferior memory until it finds a null-terminator.  For
the py-value.c case, no null-terminator is pushed into the inferior,
so GDB will continue reading inferior memory until a null-terminator
is found, with unpredictable results.

Patch Description
=================

The first thing this patch does is better define what the arguments
for the two function value_cstring and value_string should represent.
The comments in the header file are updated to describe whether the
length argument should, or should not, include a null-character.
Also, the data argument is changed to type gdb_byte.  The functions as
they currently exist will handle wide-characters, in which case more
than one 'char' would be needed for each character.  As such using
gdb_byte seems to make more sense.

To avoid adding casts throughout GDB, I've also added an overload that
still takes a 'char *', but asserts that the character type being used
is of size '1'.

The value_cstring function is now responsible for adding a null
character at the end of the string value it creates.

However, once we start looking at how value_cstring is used, we
realise there's another, related, problem.  Not every language's
strings are null terminated.  Fortran and Ada strings, for example,
are just an array of characters, GDB already has the function
value_string which can be used to create such values.

Consider this example using current GDB:

  (gdb) set language ada
  (gdb) p $_gdb_setting("arch")
  $1 = (97, 117, 116, 111)
  (gdb) ptype $
  type = array (1 .. 4) of char
  (gdb) p $_gdb_maint_setting("test-settings string")
  $2 = (0)
  (gdb) ptype $
  type = array (1 .. 1) of char

This shows two problems, first, the $_gdb_setting and
$_gdb_maint_setting functions are calling value_cstring using the
builtin_char character, rather than a language appropriate type.  In
the first call, the 'arch' case, the value_cstring call doesn't
include the null character, so the returned array only contains the
expected characters.  But, in the $_gdb_maint_setting example we do
end up including the null-character, even though this is not expected
for Ada strings.

This commit adds a new language method language_defn::value_string,
this function takes a pointer and length and creates a language
appropriate value that represents the string.  For C, C++, etc this
will be a null-terminated string (by calling value_cstring), and for
Fortran and Ada this can be a bounded array of characters with no null
terminator.  Additionally, this new language_defn::value_string
function is responsible for selecting a language appropriate character
type.

After this commit the only calls to value_cstring are from the C
expression evaluator and from the default language_defn::value_string.

And the only calls to value_string are from Fortan, Ada, and ObjectC
related code.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=21699

Co-Authored-By: Simon Marchi <simon.marchi@efficios.com>
Co-Authored-By: Andrew Burgess <aburgess@redhat.com>
Co-Authored-By: Pedro Alves <pedro@palves.net>
Approved-By: Simon Marchi <simon.marchi@efficios.com>
2023-06-05 13:25:08 +01:00

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/* Source-language-related definitions for GDB.
Copyright (C) 1991-2023 Free Software Foundation, Inc.
Contributed by the Department of Computer Science at the State University
of New York at Buffalo.
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/>. */
#if !defined (LANGUAGE_H)
#define LANGUAGE_H 1
#include "symtab.h"
#include "gdbsupport/function-view.h"
#include "expression.h"
/* Forward decls for prototypes. */
struct value;
struct objfile;
class frame_info_ptr;
struct ui_file;
struct value_print_options;
struct type_print_options;
struct lang_varobj_ops;
struct parser_state;
class compile_instance;
struct completion_match_for_lcd;
class innermost_block_tracker;
#define MAX_FORTRAN_DIMS 7 /* Maximum number of F77 array dims. */
/* range_check ==
range_check_on: Ranges are checked in GDB expressions, producing errors.
range_check_warn: Ranges are checked, producing warnings.
range_check_off: Ranges are not checked in GDB expressions. */
extern enum range_check
{
range_check_off, range_check_warn, range_check_on
}
range_check;
/* array_ordering ==
array_row_major: Arrays are in row major order.
array_column_major: Arrays are in column major order. */
extern enum array_ordering
{
array_row_major, array_column_major
}
array_ordering;
/* case_sensitivity ==
case_sensitive_on: Case sensitivity in name matching is used.
case_sensitive_off: Case sensitivity in name matching is not used. */
extern enum case_sensitivity
{
case_sensitive_on, case_sensitive_off
}
case_sensitivity;
/* macro_expansion ==
macro_expansion_no: No macro expansion is available.
macro_expansion_c: C-like macro expansion is available. */
enum macro_expansion
{
macro_expansion_no, macro_expansion_c
};
/* Per architecture (OS/ABI) language information. */
struct language_arch_info
{
/* A default constructor. */
language_arch_info () = default;
DISABLE_COPY_AND_ASSIGN (language_arch_info);
/* Set the default boolean type to be TYPE. If NAME is not nullptr then
before using TYPE a symbol called NAME will be looked up, and the type
of this symbol will be used instead. Should only be called once when
performing setup for a particular language in combination with a
particular gdbarch. */
void set_bool_type (struct type *type, const char *name = nullptr)
{
gdb_assert (m_bool_type_default == nullptr);
gdb_assert (m_bool_type_name == nullptr);
gdb_assert (type != nullptr);
m_bool_type_default = type;
m_bool_type_name = name;
}
/* Set the type to be used for characters within a string. Should only
be called once when performing setup for a particular language in
combination with a particular gdbarch. */
void set_string_char_type (struct type *type)
{
gdb_assert (m_string_char_type == nullptr);
gdb_assert (type != nullptr);
m_string_char_type = type;
}
/* Return the type for characters within a string. */
struct type *string_char_type () const
{ return m_string_char_type; }
/* Return the type to be used for booleans. */
struct type *bool_type () const;
/* Add TYPE to the list of primitive types for this particular language,
with this OS/ABI combination. */
void add_primitive_type (struct type *type)
{
gdb_assert (type != nullptr);
primitive_types_and_symbols.push_back (type_and_symbol (type));
}
/* Lookup a primitive type called NAME. Will return nullptr if no
matching type is found. */
struct type *lookup_primitive_type (const char *name);
/* Lookup a primitive type for which FILTER returns true. Will return
nullptr if no matching type is found. */
struct type *lookup_primitive_type
(gdb::function_view<bool (struct type *)> filter);
/* Lookup a primitive type called NAME and return the type as a symbol.
LANG is the language for which type is being looked up. */
struct symbol *lookup_primitive_type_as_symbol (const char *name,
enum language lang);
private:
/* A structure storing a type and a corresponding symbol. The type is
defined at construction time, while the symbol is lazily created only
when asked for, but is then cached for future use. */
struct type_and_symbol
{
/* Constructor. */
explicit type_and_symbol (struct type *type)
: m_type (type)
{ /* Nothing. */ }
/* Default move constructor. */
type_and_symbol (type_and_symbol&&) = default;
DISABLE_COPY_AND_ASSIGN (type_and_symbol);
/* Return the type from this object. */
struct type *type () const
{ return m_type; }
/* Create and return a symbol wrapping M_TYPE from this object. */
struct symbol *symbol (enum language lang)
{
if (m_symbol == nullptr)
m_symbol = alloc_type_symbol (lang, m_type);
return m_symbol;
}
private:
/* The type primitive type. */
struct type *m_type = nullptr;
/* A symbol wrapping M_TYPE, only created when first asked for. */
struct symbol *m_symbol = nullptr;
/* Helper function for type lookup as a symbol. Create the symbol
corresponding to type TYPE in language LANG. */
static struct symbol *alloc_type_symbol (enum language lang,
struct type *type);
};
/* Lookup a type_and_symbol entry from the primitive_types_and_symbols
vector for a type matching NAME. Return a pointer to the
type_and_symbol object from the vector. This will return nullptr if
there is no type matching NAME found. */
type_and_symbol *lookup_primitive_type_and_symbol (const char *name);
/* Vector of the primitive types added through add_primitive_type. These
types can be specified by name in parsing types in expressions,
regardless of whether the program being debugged actually defines such
a type.
Within the vector each type is paired with a lazily created symbol,
which can be fetched by the symbol lookup machinery, should they be
needed. */
std::vector<type_and_symbol> primitive_types_and_symbols;
/* Type of elements of strings. */
struct type *m_string_char_type = nullptr;
/* Symbol name of type to use as boolean type, if defined. */
const char *m_bool_type_name = nullptr;
/* Otherwise, this is the default boolean builtin type. */
struct type *m_bool_type_default = nullptr;
};
/* In a language (particularly C++) a function argument of an aggregate
type (i.e. class/struct/union) may be implicitly passed by reference
even though it is declared a call-by-value argument in the source.
The struct below puts together necessary information for GDB to be
able to detect and carry out pass-by-reference semantics for a
particular type. This type is referred as T in the inlined comments
below.
The default values of the fields are chosen to give correct semantics
for primitive types and for simple aggregate types, such as
class T {
int x;
}; */
struct language_pass_by_ref_info
{
/* True if an argument of type T can be passed to a function by value
(i.e. not through an implicit reference). False, otherwise. */
bool trivially_copyable = true;
/* True if a copy of a value of type T can be initialized by
memcpy'ing the value bit-by-bit. False, otherwise.
E.g. If T has a user-defined copy ctor, this should be false. */
bool trivially_copy_constructible = true;
/* True if a value of type T can be destructed simply by reclaiming
the memory area occupied by the value. False, otherwise.
E.g. If T has a user-defined destructor, this should be false. */
bool trivially_destructible = true;
/* True if it is allowed to create a copy of a value of type T.
False, otherwise.
E.g. If T has a deleted copy ctor, this should be false. */
bool copy_constructible = true;
/* True if a value of type T can be destructed. False, otherwise.
E.g. If T has a deleted destructor, this should be false. */
bool destructible = true;
};
/* Splitting strings into words. */
extern const char *default_word_break_characters (void);
/* Base class from which all other language classes derive. */
struct language_defn
{
language_defn (enum language lang)
: la_language (lang)
{
/* We should only ever create one instance of each language. */
gdb_assert (languages[lang] == nullptr);
languages[lang] = this;
}
/* Which language this is. */
const enum language la_language;
/* Name of the language. */
virtual const char *name () const = 0;
/* Natural or official name of the language. */
virtual const char *natural_name () const = 0;
/* Digit separator of the language. */
virtual const char *get_digit_separator () const
{
return " ";
}
/* Return a vector of file extensions for this language. The extension
must include the ".", like ".c". If this language doesn't need to
provide any filename extensions, this may be an empty vector (which is
the default). */
virtual const std::vector<const char *> &filename_extensions () const
{
static const std::vector<const char *> no_extensions;
return no_extensions;
}
/* Print the index of an element of an array. This default
implementation prints using C99 syntax. */
virtual void print_array_index (struct type *index_type,
LONGEST index_value,
struct ui_file *stream,
const value_print_options *options) const;
/* Given a symbol VAR, the corresponding block VAR_BLOCK (if any) and a
stack frame id FRAME, read the value of the variable and return (pointer
to a) struct value containing the value.
VAR_BLOCK is needed if there's a possibility for VAR to be outside
FRAME. This is what happens if FRAME correspond to a nested function
and VAR is defined in the outer function. If callers know that VAR is
located in FRAME or is global/static, NULL can be passed as VAR_BLOCK.
Throw an error if the variable cannot be found. */
virtual struct value *read_var_value (struct symbol *var,
const struct block *var_block,
frame_info_ptr frame) const;
/* Return information about whether TYPE should be passed
(and returned) by reference at the language level. The default
implementation returns a LANGUAGE_PASS_BY_REF_INFO initialised in its
default state. */
virtual struct language_pass_by_ref_info pass_by_reference_info
(struct type *type) const
{
return {};
}
/* Return true if SYMBOL represents an entity that is not
supposed to be seen by the user. To be used to filter symbols
during printing. */
virtual bool symbol_printing_suppressed (struct symbol *symbol) const
{
return false;
}
/* The per-architecture (OS/ABI) language information. */
virtual void language_arch_info (struct gdbarch *,
struct language_arch_info *) const = 0;
/* Find the definition of the type with the given name. */
virtual struct type *lookup_transparent_type (const char *name) const
{
return basic_lookup_transparent_type (name);
}
/* Find all symbols in the current program space matching NAME in
DOMAIN, according to this language's rules.
The search is done in BLOCK only.
The caller is responsible for iterating up through superblocks
if desired.
For each one, call CALLBACK with the symbol. If CALLBACK
returns false, the iteration ends at that point.
This field may not be NULL. If the language does not need any
special processing here, 'iterate_over_symbols' should be
used as the definition. */
virtual bool iterate_over_symbols
(const struct block *block, const lookup_name_info &name,
domain_enum domain,
gdb::function_view<symbol_found_callback_ftype> callback) const
{
return ::iterate_over_symbols (block, name, domain, callback);
}
/* Return a pointer to the function that should be used to match a
symbol name against LOOKUP_NAME, according to this language's
rules. The matching algorithm depends on LOOKUP_NAME. For
example, on Ada, the matching algorithm depends on the symbol
name (wild/full/verbatim matching), and on whether we're doing
a normal lookup or a completion match lookup.
As Ada wants to capture symbol matching for all languages in some
cases, then this method is a non-overridable interface. Languages
should override GET_SYMBOL_NAME_MATCHER_INNER if they need to. */
symbol_name_matcher_ftype *get_symbol_name_matcher
(const lookup_name_info &lookup_name) const;
/* If this language allows compilation from the gdb command line,
then this method will return an instance of struct gcc_context
appropriate to the language. If compilation for this language is
generally supported, but something goes wrong then an exception
is thrown. If compilation is not supported for this language
then this method returns NULL. */
virtual std::unique_ptr<compile_instance> get_compile_instance () const;
/* This method must be overridden if 'get_compile_instance' is
overridden.
This takes the user-supplied text and returns a new bit of code
to compile.
INST is the compiler instance being used.
INPUT is the user's input text.
GDBARCH is the architecture to use.
EXPR_BLOCK is the block in which the expression is being
parsed.
EXPR_PC is the PC at which the expression is being parsed. */
virtual std::string compute_program (compile_instance *inst,
const char *input,
struct gdbarch *gdbarch,
const struct block *expr_block,
CORE_ADDR expr_pc) const
{
gdb_assert_not_reached ("language_defn::compute_program");
}
/* Hash the given symbol search name. */
virtual unsigned int search_name_hash (const char *name) const;
/* Demangle a symbol according to this language's rules. Unlike
la_demangle, this does not take any options.
*DEMANGLED will be set by this function.
If this function returns false, then *DEMANGLED must always be set
to NULL.
If this function returns true, the implementation may set this to
a xmalloc'd string holding the demangled form. However, it is
not required to. The string, if any, is owned by the caller.
The resulting string should be of the form that will be
installed into a symbol. */
virtual bool sniff_from_mangled_name
(const char *mangled, gdb::unique_xmalloc_ptr<char> *demangled) const
{
*demangled = nullptr;
return false;
}
/* Return demangled language symbol version of MANGLED, or NULL. */
virtual gdb::unique_xmalloc_ptr<char> demangle_symbol (const char *mangled,
int options) const
{
return nullptr;
}
/* Return true if this class' implementation of print_type can
handle the /o modifier. */
virtual bool can_print_type_offsets () const
{
return false;
}
/* Print TYPE to STREAM using syntax appropriate for this language.
LEVEL is the depth to indent lines by. VARSTRING, if not NULL or the
empty string, is the name of a variable and TYPE should be printed in
the form of a declaration of a variable named VARSTRING. */
virtual void print_type (struct type *type, const char *varstring,
struct ui_file *stream, int show, int level,
const struct type_print_options *flags) const = 0;
/* PC is possibly an unknown languages trampoline.
If that PC falls in a trampoline belonging to this language, return
the address of the first pc in the real function, or 0 if it isn't a
language tramp for this language. */
virtual CORE_ADDR skip_trampoline (const frame_info_ptr &fi, CORE_ADDR pc) const
{
return (CORE_ADDR) 0;
}
/* Return class name of a mangled method name or NULL. */
virtual char *class_name_from_physname (const char *physname) const
{
return nullptr;
}
/* The list of characters forming word boundaries. */
virtual const char *word_break_characters (void) const
{
return default_word_break_characters ();
}
/* Add to the completion tracker all symbols which are possible
completions for TEXT. WORD is the entire command on which the
completion is being made. If CODE is TYPE_CODE_UNDEF, then all
symbols should be examined; otherwise, only STRUCT_DOMAIN symbols
whose type has a code of CODE should be matched. */
virtual void collect_symbol_completion_matches
(completion_tracker &tracker,
complete_symbol_mode mode,
symbol_name_match_type name_match_type,
const char *text,
const char *word,
enum type_code code) const
{
return default_collect_symbol_completion_matches_break_on
(tracker, mode, name_match_type, text, word, "", code);
}
/* This is a function that lookup_symbol will call when it gets to
the part of symbol lookup where C looks up static and global
variables. This default implements the basic C lookup rules. */
virtual struct block_symbol lookup_symbol_nonlocal
(const char *name,
const struct block *block,
const domain_enum domain) const;
/* Return an expression that can be used for a location
watchpoint. TYPE is a pointer type that points to the memory
to watch, and ADDR is the address of the watched memory. */
virtual gdb::unique_xmalloc_ptr<char> watch_location_expression
(struct type *type, CORE_ADDR addr) const;
/* List of all known languages. */
static const struct language_defn *languages[nr_languages];
/* Print a top-level value using syntax appropriate for this language. */
virtual void value_print (struct value *val, struct ui_file *stream,
const struct value_print_options *options) const;
/* Print a value using syntax appropriate for this language. RECURSE is
the recursion depth. It is zero-based. */
virtual void value_print_inner
(struct value *val, struct ui_file *stream, int recurse,
const struct value_print_options *options) const;
/* Parser function. */
virtual int parser (struct parser_state *ps) const;
/* Print the character CH (of type CHTYPE) on STREAM as part of the
contents of a literal string whose delimiter is QUOTER. */
virtual void emitchar (int ch, struct type *chtype,
struct ui_file *stream, int quoter) const;
virtual void printchar (int ch, struct type *chtype,
struct ui_file * stream) const;
/* Print the character string STRING, printing at most LENGTH characters.
Printing stops early if the number hits print_max_chars; repeat counts
are printed as appropriate. Print ellipses at the end if we
had to stop before printing LENGTH characters, or if FORCE_ELLIPSES. */
virtual void printstr (struct ui_file *stream, struct type *elttype,
const gdb_byte *string, unsigned int length,
const char *encoding, int force_ellipses,
const struct value_print_options *options) const;
/* Print a typedef using syntax appropriate for this language.
TYPE is the underlying type. NEW_SYMBOL is the symbol naming
the type. STREAM is the output stream on which to print. */
virtual void print_typedef (struct type *type, struct symbol *new_symbol,
struct ui_file *stream) const;
/* Return true if TYPE is a string type. */
virtual bool is_string_type_p (struct type *type) const;
/* Return a string that is used by the 'set print max-depth' setting.
When GDB replaces a struct or union (during value printing) that is
"too deep" this string is displayed instead. The default value here
suits most languages. If overriding then the string here should
ideally be similar in style to the default; an opener, three '.', and
a closer. */
virtual const char *struct_too_deep_ellipsis () const
{ return "{...}"; }
/* If this returns non-NULL then the string returned specifies the name
of the implicit local variable that refers to the current object
instance. Return NULL (the default) for languages that have no name
for the current object instance. */
virtual const char *name_of_this () const
{ return nullptr; }
/* Return false if the language has first-class arrays. Return true if
there are no array values, and array objects decay to pointers, as in
C. The default is true as currently most supported languages behave
in this manner. */
virtual bool c_style_arrays_p () const
{ return true; }
/* Return the index to use for extracting the first element of a string,
or as the lower bound when creating a new string. The default of
choosing 0 or 1 based on C_STYLE_ARRAYS_P works for all currently
supported languages except Modula-2. */
virtual char string_lower_bound () const
{ return c_style_arrays_p () ? 0 : 1; }
/* Return the LEN characters long string at PTR as a value suitable for
this language. GDBARCH is used to infer the character type. The
default implementation returns a null-terminated C string. */
virtual struct value *value_string (struct gdbarch *gdbarch,
const char *ptr, ssize_t len) const;
/* Returns true if the symbols names should be stored in GDB's data
structures for minimal/partial/full symbols using their linkage (aka
mangled) form; false if the symbol names should be demangled first.
Most languages implement symbol lookup by comparing the demangled
names, in which case it is advantageous to store that information
already demangled, and so would return false, which is the default.
On the other hand, some languages have opted for doing symbol lookups
by comparing mangled names instead, for reasons usually specific to
the language. Those languages should override this function and
return true.
And finally, other languages such as C or Asm do not have the concept
of mangled vs demangled name, so those languages should also override
this function and return true, to prevent any accidental demangling
through an unrelated language's demangler. */
virtual bool store_sym_names_in_linkage_form_p () const
{ return false; }
/* Default range checking preference. The return value from this
function provides the automatic setting for 'set check range'. As a
consequence a user is free to override this setting if they want. */
virtual bool range_checking_on_by_default () const
{ return false; }
/* Is this language case sensitive? The return value from this function
provides the automatic setting for 'set case-sensitive', as a
consequence, a user is free to override this setting if they want. */
virtual enum case_sensitivity case_sensitivity () const
{ return case_sensitive_on; }
/* Multi-dimensional array ordering. */
virtual enum array_ordering array_ordering () const
{ return array_row_major; }
/* Style of macro expansion, if any, supported by this language. The
default is no macro expansion. */
virtual enum macro_expansion macro_expansion () const
{ return macro_expansion_no; }
/* Return a structure containing various operations on varobj specific
for this language. */
virtual const struct lang_varobj_ops *varobj_ops () const;
protected:
/* This is the overridable part of the GET_SYMBOL_NAME_MATCHER method.
See that method for a description of the arguments. */
virtual symbol_name_matcher_ftype *get_symbol_name_matcher_inner
(const lookup_name_info &lookup_name) const;
};
/* Pointer to the language_defn for our current language. This pointer
always points to *some* valid struct; it can be used without checking
it for validity.
The current language affects expression parsing and evaluation
(FIXME: it might be cleaner to make the evaluation-related stuff
separate exp_opcodes for each different set of semantics. We
should at least think this through more clearly with respect to
what happens if the language is changed between parsing and
evaluation) and printing of things like types and arrays. It does
*not* affect symbol-reading-- each source file in a symbol-file has
its own language and we should keep track of that regardless of the
language when symbols are read. If we want some manual setting for
the language of symbol files (e.g. detecting when ".c" files are
C++), it should be a separate setting from the current_language. */
extern const struct language_defn *current_language;
/* Pointer to the language_defn expected by the user, e.g. the language
of main(), or the language we last mentioned in a message, or C. */
extern const struct language_defn *expected_language;
/* Warning issued when current_language and the language of the current
frame do not match. */
extern const char lang_frame_mismatch_warn[];
/* language_mode ==
language_mode_auto: current_language automatically set upon selection
of scope (e.g. stack frame)
language_mode_manual: current_language set only by user. */
extern enum language_mode
{
language_mode_auto, language_mode_manual
}
language_mode;
/* Return the type that should be used for booleans for language L in
GDBARCH. */
struct type *language_bool_type (const struct language_defn *l,
struct gdbarch *gdbarch);
/* Return the type that should be used for characters within a string for
language L in GDBARCH. */
struct type *language_string_char_type (const struct language_defn *l,
struct gdbarch *gdbarch);
/* Look up a type from the set of OS/ABI specific types defined in
GDBARCH for language L. NAME is used for selecting the matching
type, and is passed through to the corresponding
lookup_primitive_type member function inside the language_arch_info
class. */
struct type *language_lookup_primitive_type (const struct language_defn *l,
struct gdbarch *gdbarch,
const char *name);
/* Look up a type from the set of OS/ABI specific types defined in
GDBARCH for language L. FILTER is used for selecting the matching
type, and is passed through to the corresponding
lookup_primitive_type member function inside the language_arch_info
class. */
struct type *language_lookup_primitive_type
(const struct language_defn *la,
struct gdbarch *gdbarch,
gdb::function_view<bool (struct type *)> filter);
/* Wrapper around language_lookup_primitive_type to return the
corresponding symbol. */
struct symbol *
language_lookup_primitive_type_as_symbol (const struct language_defn *l,
struct gdbarch *gdbarch,
const char *name);
/* These macros define the behaviour of the expression
evaluator. */
/* Should we range check values against the domain of their type? */
#define RANGE_CHECK (range_check != range_check_off)
/* "cast" really means conversion. */
/* FIXME -- should be a setting in language_defn. */
#define CAST_IS_CONVERSION(LANG) ((LANG)->la_language == language_c || \
(LANG)->la_language == language_cplus || \
(LANG)->la_language == language_objc)
/* Print out the current language settings: language, range and
type checking. */
extern void language_info ();
/* Set the current language to LANG. */
extern void set_language (enum language lang);
/* Test a character to decide whether it can be printed in literal form
or needs to be printed in another representation. For example,
in C the literal form of the character with octal value 141 is 'a'
and the "other representation" is '\141'. The "other representation"
is program language dependent. */
#define PRINT_LITERAL_FORM(c) \
((c) >= 0x20 \
&& ((c) < 0x7F || (c) >= 0xA0) \
&& (!sevenbit_strings || (c) < 0x80))
/* Error messages */
extern void range_error (const char *, ...) ATTRIBUTE_PRINTF (1, 2);
/* Misc: The string representing a particular enum language. */
extern enum language language_enum (const char *str);
extern const struct language_defn *language_def (enum language);
extern const char *language_str (enum language);
/* Check for a language-specific trampoline. */
extern CORE_ADDR skip_language_trampoline (const frame_info_ptr &, CORE_ADDR pc);
/* Return information about whether TYPE should be passed
(and returned) by reference at the language level. */
struct language_pass_by_ref_info language_pass_by_reference (struct type *type);
void c_get_string (struct value *value,
gdb::unique_xmalloc_ptr<gdb_byte> *buffer,
int *length, struct type **char_type,
const char **charset);
/* Get LANG's symbol_name_matcher method for LOOKUP_NAME. Returns
default_symbol_name_matcher if not set. LANG is used as a hint;
the function may ignore it depending on the current language and
LOOKUP_NAME. Specifically, if the current language is Ada, this
may return an Ada matcher regardless of LANG. */
symbol_name_matcher_ftype *get_symbol_name_matcher
(const language_defn *lang, const lookup_name_info &lookup_name);
/* Save the current language and restore it upon destruction. */
class scoped_restore_current_language
{
public:
explicit scoped_restore_current_language ()
: m_lang (current_language->la_language)
{
}
~scoped_restore_current_language ()
{
set_language (m_lang);
}
scoped_restore_current_language (const scoped_restore_current_language &)
= delete;
scoped_restore_current_language &operator=
(const scoped_restore_current_language &) = delete;
private:
enum language m_lang;
};
/* If language_mode is language_mode_auto,
then switch current language to the language of SYM
and restore current language upon destruction.
Else do nothing. */
class scoped_switch_to_sym_language_if_auto
{
public:
explicit scoped_switch_to_sym_language_if_auto (const struct symbol *sym)
{
if (language_mode == language_mode_auto)
{
m_lang = current_language->la_language;
m_switched = true;
set_language (sym->language ());
}
else
{
m_switched = false;
/* Assign to m_lang to silence a GCC warning. See
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80635. */
m_lang = language_unknown;
}
}
~scoped_switch_to_sym_language_if_auto ()
{
if (m_switched)
set_language (m_lang);
}
DISABLE_COPY_AND_ASSIGN (scoped_switch_to_sym_language_if_auto);
private:
bool m_switched;
enum language m_lang;
};
#endif /* defined (LANGUAGE_H) */
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