python: Make gdb.execute("show commands") work (PR 23669)

Since commit

  56bcdbea2bed ("Let gdb.execute handle multi-line commands")

trying to use a command like gdb.execute("show commands") in Python
fails.  GDB ends up trying to run the "commands" command.

The reason is that GDB gets confused with the special "commands"
command.  In process_next_line, the lookup_cmd_1 function returns the
cmd_list_element representing the "commands" sub-command of "show".
Lower, we check the cmd_list_element to see if it matches various
control commands by name, including the "commands" command.  This is
where we wrongfully conclude that the executed command must be
"commands", when in reality it was "show commands".

The fix proposed in this patch removes the comparisons by name, instead
comparing the cmd_list_element object by pointer with the objects
created at initialization time.

Tested on the buildbot, though on a single builder (Fedora-x86_64-m64).

gdb/ChangeLog:

	PR python/23669
	* breakpoint.c (commands_cmd_element): New.
	(_initialize_breakpoint): Assign commands_cmd_element.
	* breakpoint.h (commands_cmd_element): New.
	* cli/cli-script.c (while_cmd_element, if_command,
	define_cmd_element): New.
	(command_name_equals): Remove.
	(process_next_line): Compare commands by pointer, not by name.
	(_initialize_cli_script): Assign the various cmd_list_element
	variables.
	* compile/compile.c (compile_cmd_element): New.
	(_initialize_compile): Assign compile_cmd_element.
	* compile/compile.h (compile_cmd_element): New.
	* guile/guile.c (guile_cmd_element): New.
	(install_gdb_commands): Assign guile_cmd_element.
	* guile/guile.h (guile_cmd_element): New.
	* python/python.c (python_cmd_element): New.
	(_initialize_python): Assign python_cmd_element.
	* python/python.h (python_cmd_element): New.
	* tracepoint.c (while_stepping_cmd_element): New.
	(_initialize_tracepoint): Assign while_stepping_cmd_element.
	* tracepoint.h (while_stepping_cmd_element): New.

gdb/testsuite/ChangeLog:

	PR python/23669
	* gdb.python/python.exp: Test gdb.execute("show commands").

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 351dc2dab19eed58d59dba5b11c15b0d248177ef..7fb64d639e6f9024eb4da545b17002b5316513ef 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,28 @@
+2018-09-17  Simon Marchi  <simon.marchi@polymtl.ca>
+
+       PR python/23669
+       * breakpoint.c (commands_cmd_element): New.
+       (_initialize_breakpoint): Assign commands_cmd_element.
+       * breakpoint.h (commands_cmd_element): New.
+       * cli/cli-script.c (while_cmd_element, if_command,
+       define_cmd_element): New.
+       (command_name_equals): Remove.
+       (process_next_line): Compare commands by pointer, not by name.
+       (_initialize_cli_script): Assign the various cmd_list_element
+       variables.
+       * compile/compile.c (compile_cmd_element): New.
+       (_initialize_compile): Assign compile_cmd_element.
+       * compile/compile.h (compile_cmd_element): New.
+       * guile/guile.c (guile_cmd_element): New.
+       (install_gdb_commands): Assign guile_cmd_element.
+       * guile/guile.h (guile_cmd_element): New.
+       * python/python.c (python_cmd_element): New.
+       (_initialize_python): Assign python_cmd_element.
+       * python/python.h (python_cmd_element): New.
+       * tracepoint.c (while_stepping_cmd_element): New.
+       (_initialize_tracepoint): Assign while_stepping_cmd_element.
+       * tracepoint.h (while_stepping_cmd_element): New.
+
 2018-09-17  Tom Tromey  <tom@tromey.com>
 
        * infrun.c (save_infcall_suspend_state): Return

diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index 85cb7d7afcd53a94c4b7fc020b1711d844cf6882..7591648f5eb4dea4ec075e4b014bb71e141847ce 100644 (file)
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -15506,6 +15506,10 @@ initialize_breakpoint_ops (void)
 
 static struct cmd_list_element *enablebreaklist = NULL;
 
+/* See breakpoint.h.  */
+
+cmd_list_element *commands_cmd_element = nullptr;
+
 void
 _initialize_breakpoint (void)
 {
@@ -15531,7 +15535,8 @@ _initialize_breakpoint (void)
 Set ignore-count of breakpoint number N to COUNT.\n\
 Usage is `ignore N COUNT'."));
 
-  add_com ("commands", class_breakpoint, commands_command, _("\
+  commands_cmd_element = add_com ("commands", class_breakpoint,
+                                 commands_command, _("\
 Set commands to be executed when the given breakpoints are hit.\n\
 Give a space-separated breakpoint list as argument after \"commands\".\n\
 A list element can be a breakpoint number (e.g. `5') or a range of numbers\n\

diff --git a/gdb/breakpoint.h b/gdb/breakpoint.h
index 63cb5370c16aa6bb5b2e7f382c0d139fcda472f5..66375b68c27b607c47823fe34b7d3fae8dfa4d8e 100644 (file)
--- a/gdb/breakpoint.h
+++ b/gdb/breakpoint.h
@@ -1679,4 +1679,7 @@ extern void maybe_print_thread_hit_breakpoint (struct ui_out *uiout);
 /* Print the specified breakpoint.  */
 extern void print_breakpoint (breakpoint *bp);
 
+/* Command element for the 'commands' command.  */
+extern cmd_list_element *commands_cmd_element;
+
 #endif /* !defined (BREAKPOINT_H) */

diff --git a/gdb/cli/cli-script.c b/gdb/cli/cli-script.c
index 8496fb85e6f5ea4439e76214582906e63646c087..e5b0f40cf40ee3497cd2aa57c8a52881a0d39bc2 100644 (file)
--- a/gdb/cli/cli-script.c
+++ b/gdb/cli/cli-script.c
@@ -25,6 +25,7 @@
 #include "ui-out.h"
 #include "top.h"
 #include "breakpoint.h"
+#include "tracepoint.h"
 #include "cli/cli-cmds.h"
 #include "cli/cli-decode.h"
 #include "cli/cli-script.h"
@@ -33,6 +34,8 @@
 #include "interps.h"
 #include "compile/compile.h"
 #include "common/gdb_string_view.h"
+#include "python/python.h"
+#include "guile/guile.h"
 
 #include <vector>
 
@@ -58,6 +61,15 @@ static int command_nest_depth = 1;
 /* This is to prevent certain commands being printed twice.  */
 static int suppress_next_print_command_trace = 0;
 
+/* Command element for the 'while' command.  */
+static cmd_list_element *while_cmd_element = nullptr;
+
+/* Command element for the 'if' command.  */
+static cmd_list_element *if_cmd_element = nullptr;
+
+/* Command element for the 'define' command.  */
+static cmd_list_element *define_cmd_element = nullptr;
+
 /* Structure for arguments to user defined functions.  */
 
 class user_args
@@ -906,16 +918,6 @@ read_next_line (void)
   return command_line_input (prompt_ptr, "commands");
 }
 
-/* Return true if CMD's name is NAME.  */
-
-static bool
-command_name_equals (struct cmd_list_element *cmd, const char *name)
-{
-  return (cmd != NULL
-         && cmd != CMD_LIST_AMBIGUOUS
-         && strcmp (cmd->name, name) == 0);
-}
-
 /* Given an input line P, skip the command and return a pointer to the
    first argument.  */
 
@@ -990,7 +992,7 @@ process_next_line (const char *p, struct command_line **command,
 
       /* Check for while, if, break, continue, etc and build a new
         command line structure for them.  */
-      if (command_name_equals (cmd, "while-stepping"))
+      if (cmd == while_stepping_cmd_element)
        {
          /* Because validate_actionline and encode_action lookup
             command's line as command, we need the line to
@@ -1005,34 +1007,28 @@ process_next_line (const char *p, struct command_line **command,
             not.  */
          *command = build_command_line (while_stepping_control, p);
        }
-      else if (command_name_equals (cmd, "while"))
-       {
-         *command = build_command_line (while_control, line_first_arg (p));
-       }
-      else if (command_name_equals (cmd, "if"))
-       {
-         *command = build_command_line (if_control, line_first_arg (p));
-       }
-      else if (command_name_equals (cmd, "commands"))
-       {
-         *command = build_command_line (commands_control, line_first_arg (p));
-       }
-      else if (command_name_equals (cmd, "define"))
+      else if (cmd == while_cmd_element)
+       *command = build_command_line (while_control, line_first_arg (p));
+      else if (cmd == if_cmd_element)
+       *command = build_command_line (if_control, line_first_arg (p));
+      else if (cmd == commands_cmd_element)
+       *command = build_command_line (commands_control, line_first_arg (p));
+      else if (cmd == define_cmd_element)
        *command = build_command_line (define_control, line_first_arg (p));
-      else if (command_name_equals (cmd, "python") && !inline_cmd)
+      else if (cmd == python_cmd_element && !inline_cmd)
        {
          /* Note that we ignore the inline "python command" form
             here.  */
          *command = build_command_line (python_control, "");
        }
-      else if (command_name_equals (cmd, "compile") && !inline_cmd)
+      else if (cmd == compile_cmd_element && !inline_cmd)
        {
          /* Note that we ignore the inline "compile command" form
             here.  */
          *command = build_command_line (compile_control, "");
          (*command)->control_u.compile.scope = COMPILE_I_INVALID_SCOPE;
        }
-      else if (command_name_equals (cmd, "guile") && !inline_cmd)
+      else if (cmd == guile_cmd_element && !inline_cmd)
        {
          /* Note that we ignore the inline "guile command" form here.  */
          *command = build_command_line (guile_control, "");
@@ -1597,7 +1593,7 @@ _initialize_cli_script (void)
 Document a user-defined command.\n\
 Give command name as argument.  Give documentation on following lines.\n\
 End with a line of just \"end\"."));
-  add_com ("define", class_support, define_command, _("\
+  define_cmd_element = add_com ("define", class_support, define_command, _("\
 Define a new command name.  Command name is argument.\n\
 Definition appears on following lines, one command per line.\n\
 End with a line of just \"end\".\n\
@@ -1606,13 +1602,13 @@ Commands defined in this way may accept an unlimited number of arguments\n\
 accessed via $arg0 .. $argN.  $argc tells how many arguments have\n\
 been passed."));
 
-  add_com ("while", class_support, while_command, _("\
+  while_cmd_element = add_com ("while", class_support, while_command, _("\
 Execute nested commands WHILE the conditional expression is non zero.\n\
 The conditional expression must follow the word `while' and must in turn be\n\
 followed by a new line.  The nested commands must be entered one per line,\n\
 and should be terminated by the word `end'."));
 
-  add_com ("if", class_support, if_command, _("\
+  if_cmd_element = add_com ("if", class_support, if_command, _("\
 Execute nested commands once IF the conditional expression is non zero.\n\
 The conditional expression must follow the word `if' and must in turn be\n\
 followed by a new line.  The nested commands must be entered one per line,\n\

diff --git a/gdb/compile/compile.c b/gdb/compile/compile.c
index f4d20913c3ec7f8488246e58980edc5e6f570ea6..02c162cf73c7eb21ce29a53e8d2315991d164a9f 100644 (file)
--- a/gdb/compile/compile.c
+++ b/gdb/compile/compile.c
@@ -908,14 +908,16 @@ compile_instance::compile (const char *filename, int verbose_level)
 
 #undef FORWARD
 
+/* See compile.h.  */
+cmd_list_element *compile_cmd_element = nullptr;
 
 void
 _initialize_compile (void)
 {
   struct cmd_list_element *c = NULL;
 
-  add_prefix_cmd ("compile", class_obscure, compile_command,
-                 _("\
+  compile_cmd_element = add_prefix_cmd ("compile", class_obscure,
+                                       compile_command, _("\
 Command to compile source code and inject it into the inferior."),
                  &compile_command_list, "compile ", 1, &cmdlist);
   add_com_alias ("expression", "compile", class_obscure, 0);

diff --git a/gdb/compile/compile.h b/gdb/compile/compile.h
index 89cc00fdd2d0f2f05122ec87f6484d48c95c196e..955f8836ca1bc2e5de3896d35d35f5eaa8d9402f 100644 (file)
--- a/gdb/compile/compile.h
+++ b/gdb/compile/compile.h
@@ -103,4 +103,7 @@ extern void compile_dwarf_bounds_to_c (string_file *stream,
 
 extern void compile_print_value (struct value *val, void *data_voidp);
 
+/* Command element for the 'compile' command.  */
+extern cmd_list_element *compile_cmd_element;
+
 #endif /* GDB_COMPILE_H */

diff --git a/gdb/guile/guile.c b/gdb/guile/guile.c
index 95b36febed040d1cc51acfeb8c5621309580c0c6..9384e84bde0b0f0f27d94c0354ded2a9d753a658 100644 (file)
--- a/gdb/guile/guile.c
+++ b/gdb/guile/guile.c
@@ -700,6 +700,9 @@ gdbscm_set_backtrace (int enable)
 
 #endif /* HAVE_GUILE */
 
+/* See guile.h.  */
+cmd_list_element *guile_cmd_element = nullptr;
+
 /* Install the various gdb commands used by Guile.  */
 
 static void
@@ -725,7 +728,7 @@ This command is only a placeholder.")
 
   /* Since "help guile" is easy to type, and intuitive, we add general help
      in using GDB+Guile to this command.  */
-  add_com ("guile", class_obscure, guile_command,
+  guile_cmd_element = add_com ("guile", class_obscure, guile_command,
 #ifdef HAVE_GUILE
           _("\
 Evaluate one or more Guile expressions.\n\

diff --git a/gdb/guile/guile.h b/gdb/guile/guile.h
index aaa005816e626faef62dba93b699eb8223bcdf4c..2faa23da814c81ead027a22ce24c37e63fc5c9bd 100644 (file)
--- a/gdb/guile/guile.h
+++ b/gdb/guile/guile.h
@@ -25,4 +25,7 @@
 /* This is all that guile exports to gdb.  */
 extern const struct extension_language_defn extension_language_guile;
 
+/* Command element for the 'guile' command.  */
+extern cmd_list_element *guile_cmd_element;
+
 #endif /* GDB_GUILE_H */

diff --git a/gdb/python/python.c b/gdb/python/python.c
index 1a0562a22751e05b9591382f7c24b6744bf3b8bf..c16305b900fe12274e4a5d8b70e86496f32cf7f8 100644 (file)
--- a/gdb/python/python.c
+++ b/gdb/python/python.c
@@ -1745,6 +1745,9 @@ do_start_initialization ()
 
 #endif /* HAVE_PYTHON */
 
+/* See python.h.  */
+cmd_list_element *python_cmd_element = nullptr;
+
 void
 _initialize_python (void)
 {
@@ -1774,7 +1777,7 @@ This command is only a placeholder.")
           );
   add_com_alias ("pi", "python-interactive", class_obscure, 1);
 
-  add_com ("python", class_obscure, python_command,
+  python_cmd_element = add_com ("python", class_obscure, python_command,
 #ifdef HAVE_PYTHON
           _("\
 Evaluate a Python command.\n\

diff --git a/gdb/python/python.h b/gdb/python/python.h
index de58fd81df83f196258950cf512733df015fe121..4b36f8385313fe9f7aa4c8dac14fd3870936baf9 100644 (file)
--- a/gdb/python/python.h
+++ b/gdb/python/python.h
@@ -25,4 +25,7 @@
 /* This is all that python exports to gdb.  */
 extern const struct extension_language_defn extension_language_python;
 
+/* Command element for the 'python' command.  */
+extern cmd_list_element *python_cmd_element;
+
 #endif /* GDB_PYTHON_H */

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 02aeb04a5d133ab22ede1d4e1ba7f765c9a805d9..ad74bfdbf74a0f94014c4d403f8a366d271bfd6e 100644 (file)
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2018-09-17  Simon Marchi  <simon.marchi@polymtl.ca>
+
+       PR python/23669
+       * gdb.python/python.exp: Test gdb.execute("show commands").
+
 2018-09-16  Tom Tromey  <tom@tromey.com>
 
        * gdb.base/new-ui.exp (do_execution_tests): Update.

diff --git a/gdb/testsuite/gdb.python/python.exp b/gdb/testsuite/gdb.python/python.exp
index 1d7ea5b6b4b2e2cd175ef1d6cd1267bf33889b6c..a37113c17c7b13f0fdfc00911afb8ed06fe80881 100644 (file)
--- a/gdb/testsuite/gdb.python/python.exp
+++ b/gdb/testsuite/gdb.python/python.exp
@@ -497,3 +497,7 @@ gdb_test "python print(gdb.convenience_variable('cvar3'))" "None" \
     "print reset convenience variable from python"
 gdb_test "print \$cvar3" "= void" \
     "print reset convenience variable from CLI"
+
+# Test PR 23669, the following would invoke the "commands" command instead of
+# "show commands".
+gdb_test "python gdb.execute(\"show commands\")" "$decimal  print \\\$cvar3.*"

diff --git a/gdb/tracepoint.c b/gdb/tracepoint.c
index bb5a8507739f8c9481b94bd22bdfae3a04fe6c76..6d964c154bf069fb5dcceb20e3f74fbd757985a9 100644 (file)
--- a/gdb/tracepoint.c
+++ b/gdb/tracepoint.c
@@ -3977,6 +3977,9 @@ static const struct internalvar_funcs sdata_funcs =
   NULL
 };
 
+/* See tracepoint.h.  */
+cmd_list_element *while_stepping_cmd_element = nullptr;
+
 /* module initialization */
 void
 _initialize_tracepoint (void)
@@ -4088,7 +4091,8 @@ Entering \"end\" on a line by itself is the normal way to terminate\n\
 such a list.\n\n\
 Note: the \"end\" command cannot be used at the gdb prompt."));
 
-  add_com ("while-stepping", class_trace, while_stepping_pseudocommand, _("\
+  while_stepping_cmd_element = add_com ("while-stepping", class_trace,
+                                       while_stepping_pseudocommand, _("\
 Specify single-stepping behavior at a tracepoint.\n\
 Argument is number of instructions to trace in single-step mode\n\
 following the tracepoint.  This command is normally followed by\n\

diff --git a/gdb/tracepoint.h b/gdb/tracepoint.h
index c185672cc1b8d0f61e40a9fbe114c854218029d2..b43fbd7606863297ffbda95b913add51518b3c7a 100644 (file)
--- a/gdb/tracepoint.h
+++ b/gdb/tracepoint.h
@@ -436,4 +436,7 @@ extern struct traceframe_info *get_traceframe_info (void);
 
 extern struct bp_location *get_traceframe_location (int *stepping_frame_p);
 
+/* Command element for the 'while-stepping' command.  */
+extern cmd_list_element *while_stepping_cmd_element;
+
 #endif /* TRACEPOINT_H */