gdb/python/py-cmd.c

   1 /* gdb commands implemented in Python
   2
   3    Copyright (C) 2008-2020 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20
  21 #include "defs.h"
  22 #include "arch-utils.h"
  23 #include "value.h"
  24 #include "python-internal.h"
  25 #include "charset.h"
  26 #include "gdbcmd.h"
  27 #include "cli/cli-decode.h"
  28 #include "completer.h"
  29 #include "language.h"
  30
  31 /* Struct representing built-in completion types.  */
  32 struct cmdpy_completer
  33 {
  34   /* Python symbol name.  */
  35   const char *name;
  36   /* Completion function.  */
  37   completer_ftype *completer;
  38 };
  39
  40 static const struct cmdpy_completer completers[] =
  41 {
  42   { "COMPLETE_NONE", noop_completer },
  43   { "COMPLETE_FILENAME", filename_completer },
  44   { "COMPLETE_LOCATION", location_completer },
  45   { "COMPLETE_COMMAND", command_completer },
  46   { "COMPLETE_SYMBOL", symbol_completer },
  47   { "COMPLETE_EXPRESSION", expression_completer },
  48 };
  49
  50 #define N_COMPLETERS (sizeof (completers) / sizeof (completers[0]))
  51
  52 /* A gdb command.  For the time being only ordinary commands (not
  53    set/show commands) are allowed.  */
  54 struct cmdpy_object
  55 {
  56   PyObject_HEAD
  57
  58   /* The corresponding gdb command object, or NULL if the command is
  59      no longer installed.  */
  60   struct cmd_list_element *command;
  61
  62   /* A prefix command requires storage for a list of its sub-commands.
  63      A pointer to this is passed to add_prefix_command, and to add_cmd
  64      for sub-commands of that prefix.  If this Command is not a prefix
  65      command, then this field is unused.  */
  66   struct cmd_list_element *sub_list;
  67 };
  68
  69 typedef struct cmdpy_object cmdpy_object;
  70
  71 extern PyTypeObject cmdpy_object_type
  72     CPYCHECKER_TYPE_OBJECT_FOR_TYPEDEF ("cmdpy_object");
  73
  74 /* Constants used by this module.  */
  75 static PyObject *invoke_cst;
  76 static PyObject *complete_cst;
  77
  78 \f
  79
  80 /* Python function which wraps dont_repeat.  */
  81 static PyObject *
  82 cmdpy_dont_repeat (PyObject *self, PyObject *args)
  83 {
  84   dont_repeat ();
  85   Py_RETURN_NONE;
  86 }
  87
  88 \f
  89
  90 /* Called if the gdb cmd_list_element is destroyed.  */
  91
  92 static void
  93 cmdpy_destroyer (struct cmd_list_element *self, void *context)
  94 {
  95   gdbpy_enter enter_py (get_current_arch (), current_language);
  96
  97   /* Release our hold on the command object.  */
  98   gdbpy_ref<cmdpy_object> cmd ((cmdpy_object *) context);
  99   cmd->command = NULL;
 100
 101   /* We may have allocated the prefix name.  */
 102   xfree ((char *) self->prefixname);
 103 }
 104
 105 /* Called by gdb to invoke the command.  */
 106
 107 static void
 108 cmdpy_function (struct cmd_list_element *command,
 109                 const char *args, int from_tty)
 110 {
 111   cmdpy_object *obj = (cmdpy_object *) get_cmd_context (command);
 112
 113   gdbpy_enter enter_py (get_current_arch (), current_language);
 114
 115   if (! obj)
 116     error (_("Invalid invocation of Python command object."));
 117   if (! PyObject_HasAttr ((PyObject *) obj, invoke_cst))
 118     {
 119       if (obj->command->prefixname)
 120         {
 121           /* A prefix command does not need an invoke method.  */
 122           return;
 123         }
 124       error (_("Python command object missing 'invoke' method."));
 125     }
 126
 127   if (! args)
 128     args = "";
 129   gdbpy_ref<> argobj (PyUnicode_Decode (args, strlen (args), host_charset (),
 130                                         NULL));
 131   if (argobj == NULL)
 132     {
 133       gdbpy_print_stack ();
 134       error (_("Could not convert arguments to Python string."));
 135     }
 136
 137   gdbpy_ref<> ttyobj
 138     = gdbpy_ref<>::new_reference (from_tty ? Py_True : Py_False);
 139   gdbpy_ref<> result (PyObject_CallMethodObjArgs ((PyObject *) obj, invoke_cst,
 140                                                   argobj.get (), ttyobj.get (),
 141                                                   NULL));
 142
 143   if (result == NULL)
 144     gdbpy_handle_exception ();
 145 }
 146
 147 /* Helper function for the Python command completers (both "pure"
 148    completer and brkchar handler).  This function takes COMMAND, TEXT
 149    and WORD and tries to call the Python method for completion with
 150    these arguments.
 151
 152    This function is usually called twice: once when we are figuring out
 153    the break characters to be used, and another to perform the real
 154    completion itself.  The reason for this two step dance is that we
 155    need to know the set of "brkchars" to use early on, before we
 156    actually try to perform the completion.  But if a Python command
 157    supplies a "complete" method then we have to call that method
 158    first: it may return as its result the kind of completion to
 159    perform and that will in turn specify which brkchars to use.  IOW,
 160    we need the result of the "complete" method before we actually
 161    perform the completion.  The only situation when this function is
 162    not called twice is when the user uses the "complete" command: in
 163    this scenario, there is no call to determine the "brkchars".
 164
 165    Ideally, it would be nice to cache the result of the first call (to
 166    determine the "brkchars") and return this value directly in the
 167    second call (to perform the actual completion).  However, due to
 168    the peculiarity of the "complete" command mentioned above, it is
 169    possible to put GDB in a bad state if you perform a TAB-completion
 170    and then a "complete"-completion sequentially.  Therefore, we just
 171    recalculate everything twice for TAB-completions.
 172
 173    This function returns a reference to the PyObject representing the
 174    Python method call.  */
 175
 176 static gdbpy_ref<>
 177 cmdpy_completer_helper (struct cmd_list_element *command,
 178                         const char *text, const char *word)
 179 {
 180   cmdpy_object *obj = (cmdpy_object *) get_cmd_context (command);
 181
 182   if (obj == NULL)
 183     error (_("Invalid invocation of Python command object."));
 184   if (!PyObject_HasAttr ((PyObject *) obj, complete_cst))
 185     {
 186       /* If there is no complete method, don't error.  */
 187       return NULL;
 188     }
 189
 190   gdbpy_ref<> textobj (PyUnicode_Decode (text, strlen (text), host_charset (),
 191                                          NULL));
 192   if (textobj == NULL)
 193     error (_("Could not convert argument to Python string."));
 194
 195   gdbpy_ref<> wordobj;
 196   if (word == NULL)
 197     {
 198       /* "brkchars" phase.  */
 199       wordobj = gdbpy_ref<>::new_reference (Py_None);
 200     }
 201   else
 202     {
 203       wordobj.reset (PyUnicode_Decode (word, strlen (word), host_charset (),
 204                                        NULL));
 205       if (wordobj == NULL)
 206         error (_("Could not convert argument to Python string."));
 207     }
 208
 209   gdbpy_ref<> resultobj (PyObject_CallMethodObjArgs ((PyObject *) obj,
 210                                                      complete_cst,
 211                                                      textobj.get (),
 212                                                      wordobj.get (), NULL));
 213   if (resultobj == NULL)
 214     {
 215       /* Just swallow errors here.  */
 216       PyErr_Clear ();
 217     }
 218
 219   return resultobj;
 220 }
 221
 222 /* Python function called to determine the break characters of a
 223    certain completer.  We are only interested in knowing if the
 224    completer registered by the user will return one of the integer
 225    codes (see COMPLETER_* symbols).  */
 226
 227 static void
 228 cmdpy_completer_handle_brkchars (struct cmd_list_element *command,
 229                                  completion_tracker &tracker,
 230                                  const char *text, const char *word)
 231 {
 232   gdbpy_enter enter_py (get_current_arch (), current_language);
 233
 234   /* Calling our helper to obtain a reference to the PyObject of the Python
 235      function.  */
 236   gdbpy_ref<> resultobj = cmdpy_completer_helper (command, text, word);
 237
 238   /* Check if there was an error.  */
 239   if (resultobj == NULL)
 240     return;
 241
 242   if (PyInt_Check (resultobj.get ()))
 243     {
 244       /* User code may also return one of the completion constants,
 245          thus requesting that sort of completion.  We are only
 246          interested in this kind of return.  */
 247       long value;
 248
 249       if (!gdb_py_int_as_long (resultobj.get (), &value))
 250         {
 251           /* Ignore.  */
 252           PyErr_Clear ();
 253         }
 254       else if (value >= 0 && value < (long) N_COMPLETERS)
 255         {
 256           completer_handle_brkchars_ftype *brkchars_fn;
 257
 258           /* This is the core of this function.  Depending on which
 259              completer type the Python function returns, we have to
 260              adjust the break characters accordingly.  */
 261           brkchars_fn = (completer_handle_brkchars_func_for_completer
 262                          (completers[value].completer));
 263           brkchars_fn (command, tracker, text, word);
 264         }
 265     }
 266 }
 267
 268 /* Called by gdb for command completion.  */
 269
 270 static void
 271 cmdpy_completer (struct cmd_list_element *command,
 272                  completion_tracker &tracker,
 273                  const char *text, const char *word)
 274 {
 275   gdbpy_enter enter_py (get_current_arch (), current_language);
 276
 277   /* Calling our helper to obtain a reference to the PyObject of the Python
 278      function.  */
 279   gdbpy_ref<> resultobj = cmdpy_completer_helper (command, text, word);
 280
 281   /* If the result object of calling the Python function is NULL, it
 282      means that there was an error.  In this case, just give up.  */
 283   if (resultobj == NULL)
 284     return;
 285
 286   if (PyInt_Check (resultobj.get ()))
 287     {
 288       /* User code may also return one of the completion constants,
 289          thus requesting that sort of completion.  */
 290       long value;
 291
 292       if (! gdb_py_int_as_long (resultobj.get (), &value))
 293         {
 294           /* Ignore.  */
 295           PyErr_Clear ();
 296         }
 297       else if (value >= 0 && value < (long) N_COMPLETERS)
 298         completers[value].completer (command, tracker, text, word);
 299     }
 300   else
 301     {
 302       gdbpy_ref<> iter (PyObject_GetIter (resultobj.get ()));
 303
 304       if (iter == NULL)
 305         return;
 306
 307       bool got_matches = false;
 308       while (true)
 309         {
 310           gdbpy_ref<> elt (PyIter_Next (iter.get ()));
 311           if (elt == NULL)
 312             break;
 313
 314           if (! gdbpy_is_string (elt.get ()))
 315             {
 316               /* Skip problem elements.  */
 317               continue;
 318             }
 319           gdb::unique_xmalloc_ptr<char>
 320             item (python_string_to_host_string (elt.get ()));
 321           if (item == NULL)
 322             {
 323               /* Skip problem elements.  */
 324               PyErr_Clear ();
 325               continue;
 326             }
 327           tracker.add_completion (std::move (item));
 328           got_matches = true;
 329         }
 330
 331       /* If we got some results, ignore problems.  Otherwise, report
 332          the problem.  */
 333       if (got_matches && PyErr_Occurred ())
 334         PyErr_Clear ();
 335     }
 336 }
 337
 338 /* Helper for cmdpy_init which locates the command list to use and
 339    pulls out the command name.
 340
 341    NAME is the command name list.  The final word in the list is the
 342    name of the new command.  All earlier words must be existing prefix
 343    commands.
 344
 345    *BASE_LIST is set to the final prefix command's list of
 346    *sub-commands.
 347
 348    START_LIST is the list in which the search starts.
 349
 350    This function returns the xmalloc()d name of the new command.  On
 351    error sets the Python error and returns NULL.  */
 352
 353 char *
 354 gdbpy_parse_command_name (const char *name,
 355                           struct cmd_list_element ***base_list,
 356                           struct cmd_list_element **start_list)
 357 {
 358   struct cmd_list_element *elt;
 359   int len = strlen (name);
 360   int i, lastchar;
 361   const char *prefix_text2;
 362   char *result;
 363
 364   /* Skip trailing whitespace.  */
 365   for (i = len - 1; i >= 0 && (name[i] == ' ' || name[i] == '\t'); --i)
 366     ;
 367   if (i < 0)
 368     {
 369       PyErr_SetString (PyExc_RuntimeError, _("No command name found."));
 370       return NULL;
 371     }
 372   lastchar = i;
 373
 374   /* Find first character of the final word.  */
 375   for (; i > 0 && valid_cmd_char_p (name[i - 1]); --i)
 376     ;
 377   result = (char *) xmalloc (lastchar - i + 2);
 378   memcpy (result, &name[i], lastchar - i + 1);
 379   result[lastchar - i + 1] = '\0';
 380
 381   /* Skip whitespace again.  */
 382   for (--i; i >= 0 && (name[i] == ' ' || name[i] == '\t'); --i)
 383     ;
 384   if (i < 0)
 385     {
 386       *base_list = start_list;
 387       return result;
 388     }
 389
 390   std::string prefix_text (name, i + 1);
 391
 392   prefix_text2 = prefix_text.c_str ();
 393   elt = lookup_cmd_1 (&prefix_text2, *start_list, NULL, 1);
 394   if (elt == NULL || elt == CMD_LIST_AMBIGUOUS)
 395     {
 396       PyErr_Format (PyExc_RuntimeError, _("Could not find command prefix %s."),
 397                     prefix_text.c_str ());
 398       xfree (result);
 399       return NULL;
 400     }
 401
 402   if (elt->prefixlist)
 403     {
 404       *base_list = elt->prefixlist;
 405       return result;
 406     }
 407
 408   PyErr_Format (PyExc_RuntimeError, _("'%s' is not a prefix command."),
 409                 prefix_text.c_str ());
 410   xfree (result);
 411   return NULL;
 412 }
 413
 414 /* Object initializer; sets up gdb-side structures for command.
 415
 416    Use: __init__(NAME, COMMAND_CLASS [, COMPLETER_CLASS][, PREFIX]]).
 417
 418    NAME is the name of the command.  It may consist of multiple words,
 419    in which case the final word is the name of the new command, and
 420    earlier words must be prefix commands.
 421
 422    COMMAND_CLASS is the kind of command.  It should be one of the COMMAND_*
 423    constants defined in the gdb module.
 424
 425    COMPLETER_CLASS is the kind of completer.  If not given, the
 426    "complete" method will be used.  Otherwise, it should be one of the
 427    COMPLETE_* constants defined in the gdb module.
 428
 429    If PREFIX is True, then this command is a prefix command.
 430
 431    The documentation for the command is taken from the doc string for
 432    the python class.  */
 433
 434 static int
 435 cmdpy_init (PyObject *self, PyObject *args, PyObject *kw)
 436 {
 437   cmdpy_object *obj = (cmdpy_object *) self;
 438   const char *name;
 439   int cmdtype;
 440   int completetype = -1;
 441   char *docstring = NULL;
 442   struct cmd_list_element **cmd_list;
 443   char *cmd_name, *pfx_name;
 444   static const char *keywords[] = { "name", "command_class", "completer_class",
 445                                     "prefix", NULL };
 446   PyObject *is_prefix = NULL;
 447   int cmp;
 448
 449   if (obj->command)
 450     {
 451       /* Note: this is apparently not documented in Python.  We return
 452          0 for success, -1 for failure.  */
 453       PyErr_Format (PyExc_RuntimeError,
 454                     _("Command object already initialized."));
 455       return -1;
 456     }
 457
 458   if (!gdb_PyArg_ParseTupleAndKeywords (args, kw, "si|iO",
 459                                         keywords, &name, &cmdtype,
 460                                         &completetype, &is_prefix))
 461     return -1;
 462
 463   if (cmdtype != no_class && cmdtype != class_run
 464       && cmdtype != class_vars && cmdtype != class_stack
 465       && cmdtype != class_files && cmdtype != class_support
 466       && cmdtype != class_info && cmdtype != class_breakpoint
 467       && cmdtype != class_trace && cmdtype != class_obscure
 468       && cmdtype != class_maintenance && cmdtype != class_user)
 469     {
 470       PyErr_Format (PyExc_RuntimeError, _("Invalid command class argument."));
 471       return -1;
 472     }
 473
 474   if (completetype < -1 || completetype >= (int) N_COMPLETERS)
 475     {
 476       PyErr_Format (PyExc_RuntimeError,
 477                     _("Invalid completion type argument."));
 478       return -1;
 479     }
 480
 481   cmd_name = gdbpy_parse_command_name (name, &cmd_list, &cmdlist);
 482   if (! cmd_name)
 483     return -1;
 484
 485   pfx_name = NULL;
 486   if (is_prefix != NULL)
 487     {
 488       cmp = PyObject_IsTrue (is_prefix);
 489       if (cmp == 1)
 490         {
 491           int i, out;
 492
 493           /* Make a normalized form of the command name.  */
 494           pfx_name = (char *) xmalloc (strlen (name) + 2);
 495
 496           i = 0;
 497           out = 0;
 498           while (name[i])
 499             {
 500               /* Skip whitespace.  */
 501               while (name[i] == ' ' || name[i] == '\t')
 502                 ++i;
 503               /* Copy non-whitespace characters.  */
 504               while (name[i] && name[i] != ' ' && name[i] != '\t')
 505                 pfx_name[out++] = name[i++];
 506               /* Add a single space after each word -- including the final
 507                  word.  */
 508               pfx_name[out++] = ' ';
 509             }
 510           pfx_name[out] = '\0';
 511         }
 512       else if (cmp < 0)
 513         {
 514           xfree (cmd_name);
 515           return -1;
 516         }
 517     }
 518   if (PyObject_HasAttr (self, gdbpy_doc_cst))
 519     {
 520       gdbpy_ref<> ds_obj (PyObject_GetAttr (self, gdbpy_doc_cst));
 521
 522       if (ds_obj != NULL && gdbpy_is_string (ds_obj.get ()))
 523         {
 524           docstring = python_string_to_host_string (ds_obj.get ()).release ();
 525           if (docstring == NULL)
 526             {
 527               xfree (cmd_name);
 528               xfree (pfx_name);
 529               return -1;
 530             }
 531         }
 532     }
 533   if (! docstring)
 534     docstring = xstrdup (_("This command is not documented."));
 535
 536   gdbpy_ref<> self_ref = gdbpy_ref<>::new_reference (self);
 537
 538   try
 539     {
 540       struct cmd_list_element *cmd;
 541
 542       if (pfx_name)
 543         {
 544           int allow_unknown;
 545
 546           /* If we have our own "invoke" method, then allow unknown
 547              sub-commands.  */
 548           allow_unknown = PyObject_HasAttr (self, invoke_cst);
 549           cmd = add_prefix_cmd (cmd_name, (enum command_class) cmdtype,
 550                                 NULL, docstring, &obj->sub_list,
 551                                 pfx_name, allow_unknown, cmd_list);
 552         }
 553       else
 554         cmd = add_cmd (cmd_name, (enum command_class) cmdtype,
 555                        docstring, cmd_list);
 556
 557       /* There appears to be no API to set this.  */
 558       cmd->func = cmdpy_function;
 559       cmd->destroyer = cmdpy_destroyer;
 560       cmd->doc_allocated = 1;
 561       cmd->name_allocated = 1;
 562
 563       obj->command = cmd;
 564       set_cmd_context (cmd, self_ref.release ());
 565       set_cmd_completer (cmd, ((completetype == -1) ? cmdpy_completer
 566                                : completers[completetype].completer));
 567       if (completetype == -1)
 568         set_cmd_completer_handle_brkchars (cmd,
 569                                            cmdpy_completer_handle_brkchars);
 570     }
 571   catch (const gdb_exception &except)
 572     {
 573       xfree (cmd_name);
 574       xfree (docstring);
 575       xfree (pfx_name);
 576       gdbpy_convert_exception (except);
 577       return -1;
 578     }
 579
 580   return 0;
 581 }
 582
 583 \f
 584
 585 /* Initialize the 'commands' code.  */
 586
 587 int
 588 gdbpy_initialize_commands (void)
 589 {
 590   int i;
 591
 592   cmdpy_object_type.tp_new = PyType_GenericNew;
 593   if (PyType_Ready (&cmdpy_object_type) < 0)
 594     return -1;
 595
 596   /* Note: alias and user are special; pseudo appears to be unused,
 597      and there is no reason to expose tui, I think.  */
 598   if (PyModule_AddIntConstant (gdb_module, "COMMAND_NONE", no_class) < 0
 599       || PyModule_AddIntConstant (gdb_module, "COMMAND_RUNNING", class_run) < 0
 600       || PyModule_AddIntConstant (gdb_module, "COMMAND_DATA", class_vars) < 0
 601       || PyModule_AddIntConstant (gdb_module, "COMMAND_STACK", class_stack) < 0
 602       || PyModule_AddIntConstant (gdb_module, "COMMAND_FILES", class_files) < 0
 603       || PyModule_AddIntConstant (gdb_module, "COMMAND_SUPPORT",
 604                                   class_support) < 0
 605       || PyModule_AddIntConstant (gdb_module, "COMMAND_STATUS", class_info) < 0
 606       || PyModule_AddIntConstant (gdb_module, "COMMAND_BREAKPOINTS",
 607                                   class_breakpoint) < 0
 608       || PyModule_AddIntConstant (gdb_module, "COMMAND_TRACEPOINTS",
 609                                   class_trace) < 0
 610       || PyModule_AddIntConstant (gdb_module, "COMMAND_OBSCURE",
 611                                   class_obscure) < 0
 612       || PyModule_AddIntConstant (gdb_module, "COMMAND_MAINTENANCE",
 613                                   class_maintenance) < 0
 614       || PyModule_AddIntConstant (gdb_module, "COMMAND_USER", class_user) < 0)
 615     return -1;
 616
 617   for (i = 0; i < N_COMPLETERS; ++i)
 618     {
 619       if (PyModule_AddIntConstant (gdb_module, completers[i].name, i) < 0)
 620         return -1;
 621     }
 622
 623   if (gdb_pymodule_addobject (gdb_module, "Command",
 624                               (PyObject *) &cmdpy_object_type) < 0)
 625     return -1;
 626
 627   invoke_cst = PyString_FromString ("invoke");
 628   if (invoke_cst == NULL)
 629     return -1;
 630   complete_cst = PyString_FromString ("complete");
 631   if (complete_cst == NULL)
 632     return -1;
 633
 634   return 0;
 635 }
 636
 637 \f
 638
 639 static PyMethodDef cmdpy_object_methods[] =
 640 {
 641   { "dont_repeat", cmdpy_dont_repeat, METH_NOARGS,
 642     "Prevent command repetition when user enters empty line." },
 643
 644   { 0 }
 645 };
 646
 647 PyTypeObject cmdpy_object_type =
 648 {
 649   PyVarObject_HEAD_INIT (NULL, 0)
 650   "gdb.Command",                  /*tp_name*/
 651   sizeof (cmdpy_object),          /*tp_basicsize*/
 652   0,                              /*tp_itemsize*/
 653   0,                              /*tp_dealloc*/
 654   0,                              /*tp_print*/
 655   0,                              /*tp_getattr*/
 656   0,                              /*tp_setattr*/
 657   0,                              /*tp_compare*/
 658   0,                              /*tp_repr*/
 659   0,                              /*tp_as_number*/
 660   0,                              /*tp_as_sequence*/
 661   0,                              /*tp_as_mapping*/
 662   0,                              /*tp_hash */
 663   0,                              /*tp_call*/
 664   0,                              /*tp_str*/
 665   0,                              /*tp_getattro*/
 666   0,                              /*tp_setattro*/
 667   0,                              /*tp_as_buffer*/
 668   Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /*tp_flags*/
 669   "GDB command object",           /* tp_doc */
 670   0,                              /* tp_traverse */
 671   0,                              /* tp_clear */
 672   0,                              /* tp_richcompare */
 673   0,                              /* tp_weaklistoffset */
 674   0,                              /* tp_iter */
 675   0,                              /* tp_iternext */
 676   cmdpy_object_methods,           /* tp_methods */
 677   0,                              /* tp_members */
 678   0,                              /* tp_getset */
 679   0,                              /* tp_base */
 680   0,                              /* tp_dict */
 681   0,                              /* tp_descr_get */
 682   0,                              /* tp_descr_set */
 683   0,                              /* tp_dictoffset */
 684   cmdpy_init,                     /* tp_init */
 685   0,                              /* tp_alloc */
 686 };
 687
 688 \f
 689
 690 /* Utility to build a buildargv-like result from ARGS.
 691    This intentionally parses arguments the way libiberty/argv.c:buildargv
 692    does.  It splits up arguments in a reasonable way, and we want a standard
 693    way of parsing arguments.  Several gdb commands use buildargv to parse their
 694    arguments.  Plus we want to be able to write compatible python
 695    implementations of gdb commands.  */
 696
 697 PyObject *
 698 gdbpy_string_to_argv (PyObject *self, PyObject *args)
 699 {
 700   const char *input;
 701
 702   if (!PyArg_ParseTuple (args, "s", &input))
 703     return NULL;
 704
 705   gdbpy_ref<> py_argv (PyList_New (0));
 706   if (py_argv == NULL)
 707     return NULL;
 708
 709   /* buildargv uses NULL to represent an empty argument list, but we can't use
 710      that in Python.  Instead, if ARGS is "" then return an empty list.
 711      This undoes the NULL -> "" conversion that cmdpy_function does.  */
 712
 713   if (*input != '\0')
 714     {
 715       gdb_argv c_argv (input);
 716
 717       for (char *arg : c_argv)
 718         {
 719           gdbpy_ref<> argp (PyString_FromString (arg));
 720
 721           if (argp == NULL
 722               || PyList_Append (py_argv.get (), argp.get ()) < 0)
 723             return NULL;
 724         }
 725     }
 726
 727   return py_argv.release ();
 728 }