gdb: add configure option to disable compile

GDB's compile subsystem is deeply tied to GDB's ability to understand
DWARF. A future patch will add the option to disable DWARF at configure
time, but for that to work, the compile subsystem will need to be
entirely disabled as well, so this patch adds that possibility.

I also think there is motive for a security conscious user to disable
compile for it's own sake. Considering that the code is quite
unmaintained, and depends on an equally unmaintained gcc plugin, there
is a case to be made that this is an unnecessary increase in the attack
surface if a user knows they won't use the subsystem. Additionally, this
can make compilation slightly faster and the final binary is around 3Mb
smaller. But these are all secondary to the main goal of being able to
disable dwarf at configure time.

To be able to achieve optional compilation, some of the code that
interfaces with compile had to be changed. All parts that directly
called compile things have been wrapped by ifdefs checking for compile
support.  The file compile/compile.c has been setup in a similar way to
how python's and guile's main file has been setup, still being compiled
but only for with placeholder command.

Finally, to avoid several new errors, a new TCL proc was introduced to
gdb.exp, allow_compile_tests, which checks if the "compile" command is
recognized before the inferior is started and otherwise skips the compile
tests. All tests in the gdb.compile subfolder have been updated to use
that, and the test gdb.base/filename-completion also uses this. The proc
skip_compile_feature_tests to recognize when the subsystem has been
disabled at compile time.

Reviewed-By: Eli Zaretskii <eliz@gnu.org>
Approved-By: Tom Tromey <tom@tromey.com>

gdb/Makefile.in

@@ -1912,8 +1912,7 @@ COMMON_OBS = $(DEPFILES) $(CONFIG_OBS) $(YYOBJ) \
 	$(patsubst %.c,%.o,$(COMMON_SFILES)) \
 	$(SUBDIR_CLI_OBS) \
 	$(SUBDIR_MI_OBS) \
-	$(SUBDIR_TARGET_OBS) \
+	$(SUBDIR_TARGET_OBS)
-	$(SUBDIR_GCC_COMPILE_OBS)
 
 SUBDIRS = doc @subdirs@ data-directory
 CLEANDIRS = $(SUBDIRS)

gdb/NEWS

@@ -108,6 +108,10 @@ qXfer:threads:read
 * Support for stabs debugging format and the a.out/dbx object format is
   deprecated, and will be removed in GDB 18.
 
+* A new configure option was added, allowing support for the compile
+  subsystem to be disabled at configure time, in the form of
+  --disable-gdb-compile.
+
 *** Changes in GDB 16
 
 * Support for Nios II targets has been removed as this architecture

gdb/README

@@ -442,6 +442,9 @@ more obscure GDB `configure' options are not listed here.
      Requires a curses library (ncurses and cursesX are also
      supported).
 
+`--disable-gdb-compile'
+    Build GDB without support for the 'compile' command.
+
 `--with-curses'
      Use the curses library instead of the termcap library, for
      text-mode terminal operations.

gdb/cli/cli-script.c

@@ -660,9 +660,13 @@ execute_control_command_1 (struct command_line *cmd, int from_tty)
       }
 
     case compile_control:
+#if defined(HAVE_COMPILE)
       eval_compile_command (cmd, NULL, cmd->control_u.compile.scope,
 			    cmd->control_u.compile.scope_data);
       ret = simple_control;
+#else
+      error (_("compile support has not been compiled into gdb"));
+#endif
       break;
 
     case define_control:

gdb/compile/compile.c

@@ -46,16 +46,17 @@
 #include "gdbsupport/scoped_ignore_signal.h"
 #include "gdbsupport/buildargv.h"
 
+/* Hold "compile" commands.  */
+
+static struct cmd_list_element *compile_command_list;
+
 
+#ifdef HAVE_COMPILE
 
 /* Initial filename for temporary files.  */
 
 #define TMP_PREFIX "/tmp/gdbobj-"
 
-/* Hold "compile" commands.  */
-
-static struct cmd_list_element *compile_command_list;
-
 /* Debug flag for "compile" commands.  */
 
 bool compile_debug;
@@ -852,6 +853,18 @@ compile_instance::compile (const char *filename, int verbose_level)
 
 #undef FORWARD
 
+#else /* HAVE_COMPILE */
+
+/* The "compile" prefix command, when support was disabled.  */
+
+static void
+compile_command (const char *args, int from_tty)
+{
+  error (_("This command is not supported."));
+}
+
+#endif /* HAVE_COMPILE */
+
 /* See compile.h.  */
 cmd_list_element *compile_cmd_element = nullptr;
 
@@ -859,14 +872,25 @@ void _initialize_compile ();
 void
 _initialize_compile ()
 {
-  struct cmd_list_element *c = NULL;
-
   compile_cmd_element = add_prefix_cmd ("compile", class_obscure,
-					compile_command, _("\
+					compile_command,
+#ifdef HAVE_COMPILE
+					_("\
 Command to compile source code and inject it into the inferior."),
+#else /* HAVE_COMPILE */
+					_("\
+Command to compile source code and inject it into the inferior.\n\
+\n\
+Code compilation and injection is not supported in this copy of GDB.\n\
+This command is only a placeholder."),
+#endif /* HAVE_COMPILE */
 		  &compile_command_list, 1, &cmdlist);
   add_com_alias ("expression", compile_cmd_element, class_obscure, 0);
 
+#ifdef HAVE_COMPILE
+
+  struct cmd_list_element *c = NULL;
+
   const auto compile_opts = make_compile_options_def_group (nullptr);
 
   static const std::string compile_code_help
@@ -973,4 +997,5 @@ It should be absolute filename of the gcc executable.\n\
 If empty the default target triplet will be searched in $PATH."),
 				     NULL, show_compile_gcc, &setlist,
 				     &showlist);
+#endif /* HAVE_COMPILE */
 }

gdb/config.in

@@ -104,6 +104,9 @@
    the CoreFoundation framework. */
 #undef HAVE_CFPREFERENCESCOPYAPPVALUE
 
+/* Define if compiling support to gdb compile. */
+#undef HAVE_COMPILE
+
 /* Define to 1 if you have the <cursesX.h> header file. */
 #undef HAVE_CURSESX_H
 

gdb/configure

@@ -956,6 +956,7 @@ with_libexpat_type
 with_python
 with_python_libdir
 with_guile
+enable_gdb_compile
 enable_source_highlight
 with_sysroot
 with_system_gdbinit
@@ -1650,6 +1651,8 @@ Optional Features:
   --enable-gdbtk          enable gdbtk graphical user interface (GUI)
   --enable-profiling      enable profiling of GDB
   --enable-codesign=CERT  sign gdb with 'codesign -s CERT'
+  --enable-gdb-compile    enable support for the compile subsystem, default
+                          'yes'
   --enable-source-highlight
                           enable source-highlight for source listings
   --enable-werror         treat compile warnings as errors
@@ -11500,7 +11503,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11503 "configure"
+#line 11506 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11606,7 +11609,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11609 "configure"
+#line 11612 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -28968,6 +28971,38 @@ else
 fi
 
 
+# ---------------------------- #
+# Check for compile support.   #
+# ---------------------------- #
+
+# Check whether --enable-gdb-compile was given.
+if test "${enable_gdb_compile+set}" = set; then :
+  enableval=$enable_gdb_compile;
+	   case $enableval in
+	     yes | no)
+	       ;;
+	     *)
+	       as_fn_error $? "bad value $enableval for --enable-gdb-compile" "$LINENO" 5
+	       ;;
+	   esac
+
+else
+  enable_gdb_compile=yes
+fi
+
+
+if test "${enable_gdb_compile}" == yes; then
+
+$as_echo "#define HAVE_COMPILE 1" >>confdefs.h
+
+    CONFIG_OBS="$CONFIG_OBS \$(SUBDIR_GCC_COMPILE_OBS)"
+else
+    # Even if compile support is not enabled, we need this file to define
+    # the "compile" command.
+    CONFIG_OBS="$CONFIG_OBS compile/compile.o"
+    CONFIG_SRCS="$CONFIG_SRCS compile/compile.c"
+fi
+
 # ---------------------------- #
 # Check for source highlight.  #
 # ---------------------------- #

gdb/configure.ac

@@ -1221,6 +1221,26 @@ AC_SUBST(GUILE_CPPFLAGS)
 AC_SUBST(GUILE_LIBS)
 AM_CONDITIONAL(HAVE_GUILE, test "${have_libguile}" != no)
 
+# ---------------------------- #
+# Check for compile support.   #
+# ---------------------------- #
+
+AC_ARG_ENABLE([gdb-compile],
+    AS_HELP_STRING([--enable-gdb-compile],
+	      [enable support for the compile subsystem, default 'yes']),
+	      [GDB_CHECK_YES_NO_VAL([$enableval], [--enable-gdb-compile])],
+	      [enable_gdb_compile=yes])
+
+if test "${enable_gdb_compile}" == yes; then
+    AC_DEFINE(HAVE_COMPILE, 1, [Define if compiling support to gdb compile.])
+    CONFIG_OBS="$CONFIG_OBS \$(SUBDIR_GCC_COMPILE_OBS)"
+else
+    # Even if compile support is not enabled, we need this file to define
+    # the "compile" command.
+    CONFIG_OBS="$CONFIG_OBS compile/compile.o"
+    CONFIG_SRCS="$CONFIG_SRCS compile/compile.c"
+fi
+
 # ---------------------------- #
 # Check for source highlight.  #
 # ---------------------------- #

gdb/dwarf2/loc.c

@@ -1784,6 +1784,7 @@ dwarf2_compile_property_to_c (string_file *stream,
 			      CORE_ADDR pc,
 			      struct symbol *sym)
 {
+#if defined (HAVE_COMPILE)
   const dwarf2_property_baton *baton = prop->baton ();
   const gdb_byte *data;
   size_t size;
@@ -1810,6 +1811,9 @@ dwarf2_compile_property_to_c (string_file *stream,
 			     gdbarch, registers_used,
 			     per_cu->addr_size (),
 			     data, data + size, per_cu, per_objfile);
+#else
+  gdb_assert_not_reached ("Compile support was disabled");
+#endif
 }
 
 /* Compute the correct symbol_needs_kind value for the location
@@ -3852,6 +3856,7 @@ locexpr_generate_c_location (struct symbol *sym, string_file *stream,
 			     std::vector<bool> &registers_used,
 			     CORE_ADDR pc, const char *result_name)
 {
+#if defined (HAVE_COMPILE)
   struct dwarf2_locexpr_baton *dlbaton
     = (struct dwarf2_locexpr_baton *) SYMBOL_LOCATION_BATON (sym);
   unsigned int addr_size = dlbaton->per_cu->addr_size ();
@@ -3863,6 +3868,9 @@ locexpr_generate_c_location (struct symbol *sym, string_file *stream,
 			   sym, pc, gdbarch, registers_used, addr_size,
 			   dlbaton->data, dlbaton->data + dlbaton->size,
 			   dlbaton->per_cu, dlbaton->per_objfile);
+#else
+  gdb_assert_not_reached ("Compile support was disabled");
+#endif
 }
 
 /* The set of location functions used with the DWARF-2 expression
@@ -4088,6 +4096,7 @@ loclist_generate_c_location (struct symbol *sym, string_file *stream,
 			     std::vector<bool> &registers_used,
 			     CORE_ADDR pc, const char *result_name)
 {
+#if defined (HAVE_COMPILE)
   struct dwarf2_loclist_baton *dlbaton
     = (struct dwarf2_loclist_baton *) SYMBOL_LOCATION_BATON (sym);
   unsigned int addr_size = dlbaton->per_cu->addr_size ();
@@ -4103,6 +4112,9 @@ loclist_generate_c_location (struct symbol *sym, string_file *stream,
 			   data, data + size,
 			   dlbaton->per_cu,
 			   dlbaton->per_objfile);
+#else
+  gdb_assert_not_reached ("Compile support was disabled");
+#endif
 }
 
 /* The set of location functions used with the DWARF-2 expression

gdb/testsuite/gdb.base/filename-completion.exp

@@ -381,11 +381,15 @@ proc run_mid_line_completion_tests { root cmd } {
 proc run_quoting_and_escaping_tests { root } {
     # Test all the commands which allow quoting of filenames, and
     # which require whitespace to be escaped in unquoted filenames.
-    foreach_with_prefix cmd { file exec-file symbol-file add-symbol-file \
+    set all_cmds { file exec-file symbol-file add-symbol-file \
-				  remove-symbol-file \
+		      remove-symbol-file \
-				  "target core" "target exec" "target tfile" \
+		      "target core" "target exec" "target tfile" \
-				  "maint print c-tdesc" "compile file" \
+		      "maint print c-tdesc" "save gdb-index"
-				  "save gdb-index" "save gdb-index -dwarf-5" } {
+		      "save gdb-index -dwarf-5" }
+    if { [allow_compile_tests] } {
+	lappend all_cmds "compile file"
+    }
+    foreach_with_prefix cmd $all_cmds {
 	# Try each test placing the filename as the first argument
 	# then again with a quoted string immediately after the
 	# command.  This works because the filename completer will

gdb/testsuite/gdb.compile/compile-cplus-anonymous.exp

@@ -23,6 +23,8 @@ require allow_cplus_tests
 
 require is_c_compiler_gcc
 
+require allow_compile_tests
+
 if {[prepare_for_testing $testfile $testfile $srcfile \
 	 {debug nowarnings c++}]} {
     return -1

gdb/testsuite/gdb.compile/compile-cplus-array-decay.exp

@@ -23,6 +23,8 @@ require allow_cplus_tests
 
 require is_c_compiler_gcc
 
+require allow_compile_tests
+
 if {[prepare_for_testing $testfile $testfile $srcfile \
 	 {debug nowarnings c++ additional_flags=-std=c++11}]} {
     return -1

gdb/testsuite/gdb.compile/compile-cplus-inherit.exp

@@ -23,6 +23,8 @@ require allow_cplus_tests
 
 require is_c_compiler_gcc
 
+require allow_compile_tests
+
 if {[prepare_for_testing $testfile $testfile $srcfile \
 	 {debug nowarnings c++}]} {
     return -1

gdb/testsuite/gdb.compile/compile-cplus-member.exp

@@ -23,6 +23,8 @@ require allow_cplus_tests
 
 require is_c_compiler_gcc
 
+require allow_compile_tests
+
 if {[prepare_for_testing $testfile $testfile $srcfile \
 	 {debug nowarnings c++}]} {
     return -1

gdb/testsuite/gdb.compile/compile-cplus-method.exp

@@ -23,6 +23,8 @@ require allow_cplus_tests
 
 require is_c_compiler_gcc
 
+require allow_compile_tests
+
 if {[prepare_for_testing $testfile $testfile $srcfile \
 	 {debug nowarnings c++}]} {
     return -1

gdb/testsuite/gdb.compile/compile-cplus-namespace.exp

@@ -23,6 +23,8 @@ require allow_cplus_tests
 
 require is_c_compiler_gcc
 
+require allow_compile_tests
+
 if {[prepare_for_testing $testfile $testfile $srcfile \
 	 {debug nowarnings c++}]} {
     return -1

gdb/testsuite/gdb.compile/compile-cplus-nested.exp

@@ -23,6 +23,8 @@ require allow_cplus_tests
 
 require is_c_compiler_gcc
 
+require allow_compile_tests
+
 if {[prepare_for_testing $testfile $testfile $srcfile \
 	 {debug nowarnings c++}]} {
     return -1

gdb/testsuite/gdb.compile/compile-cplus-print.exp

@@ -19,6 +19,8 @@ standard_testfile
 
 require is_c_compiler_gcc
 
+require allow_compile_tests
+
 set options {}
 if [test_compiler_info gcc*] {
     lappend options additional_flags=-g3

gdb/testsuite/gdb.compile/compile-cplus-virtual.exp

@@ -23,6 +23,8 @@ require allow_cplus_tests
 
 require is_c_compiler_gcc
 
+require allow_compile_tests
+
 if {[prepare_for_testing $testfile $testfile $srcfile \
 	 {debug nowarnings c++}]} {
     return -1

gdb/testsuite/gdb.compile/compile-cplus.exp

@@ -19,6 +19,8 @@ standard_testfile .c compile-shlib.c compile-constvar.S compile-nodebug.c
 
 require is_c_compiler_gcc
 
+require allow_compile_tests
+
 set options {}
 if { [test_compiler_info gcc*] || [test_compiler_info clang*] } {
     lappend options additional_flags=-g3

gdb/testsuite/gdb.compile/compile-ifunc.exp

@@ -17,6 +17,8 @@ load_lib compile-support.exp
 
 require allow_ifunc_tests
 
+require allow_compile_tests
+
 standard_testfile
 
 require is_c_compiler_gcc

gdb/testsuite/gdb.compile/compile-ops.exp

@@ -22,6 +22,8 @@ load_lib dwarf.exp
 # This test can only be run on targets which support DWARF-2 and use gas.
 require dwarf2_support
 
+require allow_compile_tests
+
 require is_c_compiler_gcc
 
 standard_testfile .c -dbg.S

gdb/testsuite/gdb.compile/compile-print.exp

@@ -19,6 +19,8 @@ standard_testfile
 
 require is_c_compiler_gcc
 
+require allow_compile_tests
+
 if { [prepare_for_testing "failed to prepare" "$testfile"] } {
     return -1
 }

gdb/testsuite/gdb.compile/compile-setjmp.exp

@@ -19,6 +19,8 @@ standard_testfile .c compile-setjmp-mod.c
 
 require is_c_compiler_gcc
 
+require allow_compile_tests
+
 if { [prepare_for_testing "failed to prepare" $testfile] } {
     return -1
 }

gdb/testsuite/gdb.compile/compile-tls.exp

@@ -19,6 +19,8 @@ standard_testfile .c
 
 require is_c_compiler_gcc
 
+require allow_compile_tests
+
 if {[gdb_compile_pthreads "${srcdir}/${subdir}/${srcfile}" "${binfile}" \
 	 executable {debug}] != "" } {
     return -1

gdb/testsuite/gdb.compile/compile.exp

@@ -15,6 +15,8 @@
 
 load_lib compile-support.exp
 
+require allow_compile_tests
+
 standard_testfile .c compile-shlib.c compile-constvar.S compile-nodebug.c
 
 require is_c_compiler_gcc

gdb/testsuite/lib/compile-support.exp

@@ -45,6 +45,9 @@ proc _do_check_compile {expr} {
 	    # This appears to be a bug in the compiler plugin.
 	    set result "apparent compiler plugin bug"
 	}
+	-re "This command is not supported." {
+	    set result "compiler disabled at configure time"
+	}
 	-re "\r\n$gdb_prompt $" {
 	}
     }

gdb/testsuite/lib/gdb.exp

@@ -2799,6 +2799,12 @@ gdb_caching_proc allow_python_tests {} {
     return [expr {[string first "--with-python" $output] != -1}]
 }
 
+# Return a 1 if GDB was configured to support compile commands.
+gdb_caching_proc allow_compile_tests {} {
+    set output [remote_exec host $::GDB "$::INTERNAL_GDBFLAGS -ex \"compile int x = 1\" -batch"]
+    return [expr {[string first "The program must be running" $output] != -1}]
+}
+
 # Return a 1 for configurations that use system readline rather than the
 # in-repo copy.