gdb/python/py-cmd.c

   1 /* gdb commands implemented in Python
   2
   3    Copyright (C) 2008-2012 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 "exceptions.h"
  25 #include "python-internal.h"
  26 #include "charset.h"
  27 #include "gdbcmd.h"
  28 #include "cli/cli-decode.h"
  29 #include "completer.h"
  30 #include "language.h"
  31
  32 /* Struct representing built-in completion types.  */
  33 struct cmdpy_completer
  34 {
  35   /* Python symbol name.  */
  36   char *name;
  37   /* Completion function.  */
  38   completer_ftype *completer;
  39 };
  40
  41 static struct cmdpy_completer completers[] =
  42 {
  43   { "COMPLETE_NONE", noop_completer },
  44   { "COMPLETE_FILENAME", filename_completer },
  45   { "COMPLETE_LOCATION", location_completer },
  46   { "COMPLETE_COMMAND", command_completer },
  47   { "COMPLETE_SYMBOL", make_symbol_completion_list_fn },
  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 static PyTypeObject cmdpy_object_type;
  72
  73 /* Constants used by this module.  */
  74 static PyObject *invoke_cst;
  75 static PyObject *complete_cst;
  76
  77 \f
  78
  79 /* Python function which wraps dont_repeat.  */
  80 static PyObject *
  81 cmdpy_dont_repeat (PyObject *self, PyObject *args)
  82 {
  83   dont_repeat ();
  84   Py_RETURN_NONE;
  85 }
  86
  87 \f
  88
  89 /* Called if the gdb cmd_list_element is destroyed.  */
  90
  91 static void
  92 cmdpy_destroyer (struct cmd_list_element *self, void *context)
  93 {
  94   cmdpy_object *cmd;
  95   struct cleanup *cleanup;
  96
  97   cleanup = ensure_python_env (get_current_arch (), current_language);
  98
  99   /* Release our hold on the command object.  */
 100   cmd = (cmdpy_object *) context;
 101   cmd->command = NULL;
 102   Py_DECREF (cmd);
 103
 104   /* We allocated the name, doc string, and perhaps the prefix
 105      name.  */
 106   xfree (self->name);
 107   xfree (self->doc);
 108   xfree (self->prefixname);
 109
 110   do_cleanups (cleanup);
 111 }
 112
 113 /* Called by gdb to invoke the command.  */
 114
 115 static void
 116 cmdpy_function (struct cmd_list_element *command, char *args, int from_tty)
 117 {
 118   cmdpy_object *obj = (cmdpy_object *) get_cmd_context (command);
 119   PyObject *argobj, *ttyobj, *result;
 120   struct cleanup *cleanup;
 121
 122   cleanup = ensure_python_env (get_current_arch (), current_language);
 123
 124   if (! obj)
 125     error (_("Invalid invocation of Python command object."));
 126   if (! PyObject_HasAttr ((PyObject *) obj, invoke_cst))
 127     {
 128       if (obj->command->prefixname)
 129         {
 130           /* A prefix command does not need an invoke method.  */
 131           do_cleanups (cleanup);
 132           return;
 133         }
 134       error (_("Python command object missing 'invoke' method."));
 135     }
 136
 137   if (! args)
 138     args = "";
 139   argobj = PyUnicode_Decode (args, strlen (args), host_charset (), NULL);
 140   if (! argobj)
 141     {
 142       gdbpy_print_stack ();
 143       error (_("Could not convert arguments to Python string."));
 144     }
 145
 146   ttyobj = from_tty ? Py_True : Py_False;
 147   Py_INCREF (ttyobj);
 148   result = PyObject_CallMethodObjArgs ((PyObject *) obj, invoke_cst, argobj,
 149                                        ttyobj, NULL);
 150   Py_DECREF (argobj);
 151   Py_DECREF (ttyobj);
 152
 153   if (! result)
 154     {
 155       PyObject *ptype, *pvalue, *ptraceback;
 156       char *msg;
 157
 158       PyErr_Fetch (&ptype, &pvalue, &ptraceback);
 159
 160       /* Try to fetch an error message contained within ptype, pvalue.
 161          When fetching the error message we need to make our own copy,
 162          we no longer own ptype, pvalue after the call to PyErr_Restore.  */
 163
 164       msg = gdbpy_exception_to_string (ptype, pvalue);
 165       make_cleanup (xfree, msg);
 166
 167       if (msg == NULL)
 168         {
 169           /* An error occurred computing the string representation of the
 170              error message.  This is rare, but we should inform the user.  */
 171           printf_filtered (_("An error occurred in a Python command\n"
 172                              "and then another occurred computing the "
 173                              "error message.\n"));
 174           gdbpy_print_stack ();
 175         }
 176
 177       /* Don't print the stack for gdb.GdbError exceptions.
 178          It is generally used to flag user errors.
 179
 180          We also don't want to print "Error occurred in Python command"
 181          for user errors.  However, a missing message for gdb.GdbError
 182          exceptions is arguably a bug, so we flag it as such.  */
 183
 184       if (! PyErr_GivenExceptionMatches (ptype, gdbpy_gdberror_exc)
 185           || msg == NULL || *msg == '\0')
 186         {
 187           PyErr_Restore (ptype, pvalue, ptraceback);
 188           gdbpy_print_stack ();
 189           if (msg != NULL && *msg != '\0')
 190             error (_("Error occurred in Python command: %s"), msg);
 191           else
 192             error (_("Error occurred in Python command."));
 193         }
 194       else
 195         {
 196           Py_XDECREF (ptype);
 197           Py_XDECREF (pvalue);
 198           Py_XDECREF (ptraceback);
 199           error ("%s", msg);
 200         }
 201     }
 202
 203   Py_DECREF (result);
 204   do_cleanups (cleanup);
 205 }
 206
 207 /* Called by gdb for command completion.  */
 208
 209 static VEC (char_ptr) *
 210 cmdpy_completer (struct cmd_list_element *command, char *text, char *word)
 211 {
 212   cmdpy_object *obj = (cmdpy_object *) get_cmd_context (command);
 213   PyObject *textobj, *wordobj, *resultobj = NULL;
 214   VEC (char_ptr) *result = NULL;
 215   struct cleanup *cleanup;
 216
 217   cleanup = ensure_python_env (get_current_arch (), current_language);
 218
 219   if (! obj)
 220     error (_("Invalid invocation of Python command object."));
 221   if (! PyObject_HasAttr ((PyObject *) obj, complete_cst))
 222     {
 223       /* If there is no complete method, don't error -- instead, just
 224          say that there are no completions.  */
 225       goto done;
 226     }
 227
 228   textobj = PyUnicode_Decode (text, strlen (text), host_charset (), NULL);
 229   if (! textobj)
 230     error (_("Could not convert argument to Python string."));
 231   wordobj = PyUnicode_Decode (word, strlen (word), host_charset (), NULL);
 232   if (! wordobj)
 233     error (_("Could not convert argument to Python string."));
 234
 235   resultobj = PyObject_CallMethodObjArgs ((PyObject *) obj, complete_cst,
 236                                           textobj, wordobj, NULL);
 237   Py_DECREF (textobj);
 238   Py_DECREF (wordobj);
 239   if (! resultobj)
 240     {
 241       /* Just swallow errors here.  */
 242       PyErr_Clear ();
 243       goto done;
 244     }
 245   make_cleanup_py_decref (resultobj);
 246
 247   result = NULL;
 248   if (PySequence_Check (resultobj))
 249     {
 250       Py_ssize_t i, len = PySequence_Size (resultobj);
 251       Py_ssize_t out;
 252
 253       if (len < 0)
 254         goto done;
 255
 256       for (i = out = 0; i < len; ++i)
 257         {
 258           PyObject *elt = PySequence_GetItem (resultobj, i);
 259           char *item;
 260
 261           if (elt == NULL || ! gdbpy_is_string (elt))
 262             {
 263               /* Skip problem elements.  */
 264               PyErr_Clear ();
 265               continue;
 266             }
 267           item = python_string_to_host_string (elt);
 268           if (item == NULL)
 269             {
 270               /* Skip problem elements.  */
 271               PyErr_Clear ();
 272               continue;
 273             }
 274           VEC_safe_push (char_ptr, result, item);
 275         }
 276     }
 277   else if (PyInt_Check (resultobj))
 278     {
 279       /* User code may also return one of the completion constants,
 280          thus requesting that sort of completion.  */
 281       long value;
 282
 283       if (! gdb_py_int_as_long (resultobj, &value))
 284         {
 285           /* Ignore.  */
 286           PyErr_Clear ();
 287         }
 288       else if (value >= 0 && value < (long) N_COMPLETERS)
 289         result = completers[value].completer (command, text, word);
 290     }
 291
 292  done:
 293
 294   do_cleanups (cleanup);
 295
 296   return result;
 297 }
 298
 299 /* Helper for cmdpy_init which locates the command list to use and
 300    pulls out the command name.
 301
 302    NAME is the command name list.  The final word in the list is the
 303    name of the new command.  All earlier words must be existing prefix
 304    commands.
 305
 306    *BASE_LIST is set to the final prefix command's list of
 307    *sub-commands.
 308
 309    START_LIST is the list in which the search starts.
 310
 311    This function returns the xmalloc()d name of the new command.  On
 312    error sets the Python error and returns NULL.  */
 313
 314 char *
 315 gdbpy_parse_command_name (const char *name,
 316                           struct cmd_list_element ***base_list,
 317                           struct cmd_list_element **start_list)
 318 {
 319   struct cmd_list_element *elt;
 320   int len = strlen (name);
 321   int i, lastchar;
 322   char *prefix_text, *prefix_text2;
 323   char *result;
 324
 325   /* Skip trailing whitespace.  */
 326   for (i = len - 1; i >= 0 && (name[i] == ' ' || name[i] == '\t'); --i)
 327     ;
 328   if (i < 0)
 329     {
 330       PyErr_SetString (PyExc_RuntimeError, _("No command name found."));
 331       return NULL;
 332     }
 333   lastchar = i;
 334
 335   /* Find first character of the final word.  */
 336   for (; i > 0 && (isalnum (name[i - 1])
 337                    || name[i - 1] == '-'
 338                    || name[i - 1] == '_');
 339        --i)
 340     ;
 341   result = xmalloc (lastchar - i + 2);
 342   memcpy (result, &name[i], lastchar - i + 1);
 343   result[lastchar - i + 1] = '\0';
 344
 345   /* Skip whitespace again.  */
 346   for (--i; i >= 0 && (name[i] == ' ' || name[i] == '\t'); --i)
 347     ;
 348   if (i < 0)
 349     {
 350       *base_list = start_list;
 351       return result;
 352     }
 353
 354   prefix_text = xmalloc (i + 2);
 355   memcpy (prefix_text, name, i + 1);
 356   prefix_text[i + 1] = '\0';
 357
 358   prefix_text2 = prefix_text;
 359   elt = lookup_cmd_1 (&prefix_text2, *start_list, NULL, 1);
 360   if (!elt || elt == (struct cmd_list_element *) -1)
 361     {
 362       PyErr_Format (PyExc_RuntimeError, _("Could not find command prefix %s."),
 363                     prefix_text);
 364       xfree (prefix_text);
 365       xfree (result);
 366       return NULL;
 367     }
 368
 369   if (elt->prefixlist)
 370     {
 371       xfree (prefix_text);
 372       *base_list = elt->prefixlist;
 373       return result;
 374     }
 375
 376   PyErr_Format (PyExc_RuntimeError, _("'%s' is not a prefix command."),
 377                 prefix_text);
 378   xfree (prefix_text);
 379   xfree (result);
 380   return NULL;
 381 }
 382
 383 /* Object initializer; sets up gdb-side structures for command.
 384
 385    Use: __init__(NAME, COMMAND_CLASS [, COMPLETER_CLASS][, PREFIX]]).
 386
 387    NAME is the name of the command.  It may consist of multiple words,
 388    in which case the final word is the name of the new command, and
 389    earlier words must be prefix commands.
 390
 391    COMMAND_CLASS is the kind of command.  It should be one of the COMMAND_*
 392    constants defined in the gdb module.
 393
 394    COMPLETER_CLASS is the kind of completer.  If not given, the
 395    "complete" method will be used.  Otherwise, it should be one of the
 396    COMPLETE_* constants defined in the gdb module.
 397
 398    If PREFIX is True, then this command is a prefix command.
 399
 400    The documentation for the command is taken from the doc string for
 401    the python class.  */
 402
 403 static int
 404 cmdpy_init (PyObject *self, PyObject *args, PyObject *kw)
 405 {
 406   cmdpy_object *obj = (cmdpy_object *) self;
 407   const char *name;
 408   int cmdtype;
 409   int completetype = -1;
 410   char *docstring = NULL;
 411   volatile struct gdb_exception except;
 412   struct cmd_list_element **cmd_list;
 413   char *cmd_name, *pfx_name;
 414   static char *keywords[] = { "name", "command_class", "completer_class",
 415                               "prefix", NULL };
 416   PyObject *is_prefix = NULL;
 417   int cmp;
 418
 419   if (obj->command)
 420     {
 421       /* Note: this is apparently not documented in Python.  We return
 422          0 for success, -1 for failure.  */
 423       PyErr_Format (PyExc_RuntimeError,
 424                     _("Command object already initialized."));
 425       return -1;
 426     }
 427
 428   if (! PyArg_ParseTupleAndKeywords (args, kw, "si|iO",
 429                                      keywords, &name, &cmdtype,
 430                           &completetype, &is_prefix))
 431     return -1;
 432
 433   if (cmdtype != no_class && cmdtype != class_run
 434       && cmdtype != class_vars && cmdtype != class_stack
 435       && cmdtype != class_files && cmdtype != class_support
 436       && cmdtype != class_info && cmdtype != class_breakpoint
 437       && cmdtype != class_trace && cmdtype != class_obscure
 438       && cmdtype != class_maintenance && cmdtype != class_user)
 439     {
 440       PyErr_Format (PyExc_RuntimeError, _("Invalid command class argument."));
 441       return -1;
 442     }
 443
 444   if (completetype < -1 || completetype >= (int) N_COMPLETERS)
 445     {
 446       PyErr_Format (PyExc_RuntimeError,
 447                     _("Invalid completion type argument."));
 448       return -1;
 449     }
 450
 451   cmd_name = gdbpy_parse_command_name (name, &cmd_list, &cmdlist);
 452   if (! cmd_name)
 453     return -1;
 454
 455   pfx_name = NULL;
 456   if (is_prefix != NULL)
 457     {
 458       cmp = PyObject_IsTrue (is_prefix);
 459       if (cmp == 1)
 460         {
 461           int i, out;
 462
 463           /* Make a normalized form of the command name.  */
 464           pfx_name = xmalloc (strlen (name) + 2);
 465
 466           i = 0;
 467           out = 0;
 468           while (name[i])
 469             {
 470               /* Skip whitespace.  */
 471               while (name[i] == ' ' || name[i] == '\t')
 472                 ++i;
 473               /* Copy non-whitespace characters.  */
 474               while (name[i] && name[i] != ' ' && name[i] != '\t')
 475                 pfx_name[out++] = name[i++];
 476               /* Add a single space after each word -- including the final
 477                  word.  */
 478               pfx_name[out++] = ' ';
 479             }
 480           pfx_name[out] = '\0';
 481         }
 482       else if (cmp < 0)
 483         {
 484           xfree (cmd_name);
 485           return -1;
 486         }
 487     }
 488   if (PyObject_HasAttr (self, gdbpy_doc_cst))
 489     {
 490       PyObject *ds_obj = PyObject_GetAttr (self, gdbpy_doc_cst);
 491
 492       if (ds_obj && gdbpy_is_string (ds_obj))
 493         {
 494           docstring = python_string_to_host_string (ds_obj);
 495           if (docstring == NULL)
 496             {
 497               xfree (cmd_name);
 498               xfree (pfx_name);
 499               return -1;
 500             }
 501         }
 502     }
 503   if (! docstring)
 504     docstring = xstrdup (_("This command is not documented."));
 505
 506   Py_INCREF (self);
 507
 508   TRY_CATCH (except, RETURN_MASK_ALL)
 509     {
 510       struct cmd_list_element *cmd;
 511
 512       if (pfx_name)
 513         {
 514           int allow_unknown;
 515
 516           /* If we have our own "invoke" method, then allow unknown
 517              sub-commands.  */
 518           allow_unknown = PyObject_HasAttr (self, invoke_cst);
 519           cmd = add_prefix_cmd (cmd_name, (enum command_class) cmdtype,
 520                                 NULL, docstring, &obj->sub_list,
 521                                 pfx_name, allow_unknown, cmd_list);
 522         }
 523       else
 524         cmd = add_cmd (cmd_name, (enum command_class) cmdtype, NULL,
 525                        docstring, cmd_list);
 526
 527       /* There appears to be no API to set this.  */
 528       cmd->func = cmdpy_function;
 529       cmd->destroyer = cmdpy_destroyer;
 530
 531       obj->command = cmd;
 532       set_cmd_context (cmd, self);
 533       set_cmd_completer (cmd, ((completetype == -1) ? cmdpy_completer
 534                                : completers[completetype].completer));
 535     }
 536   if (except.reason < 0)
 537     {
 538       xfree (cmd_name);
 539       xfree (docstring);
 540       xfree (pfx_name);
 541       Py_DECREF (self);
 542       PyErr_Format (except.reason == RETURN_QUIT
 543                     ? PyExc_KeyboardInterrupt : PyExc_RuntimeError,
 544                     "%s", except.message);
 545       return -1;
 546     }
 547   return 0;
 548 }
 549
 550 \f
 551
 552 /* Initialize the 'commands' code.  */
 553
 554 void
 555 gdbpy_initialize_commands (void)
 556 {
 557   int i;
 558
 559   cmdpy_object_type.tp_new = PyType_GenericNew;
 560   if (PyType_Ready (&cmdpy_object_type) < 0)
 561     return;
 562
 563   /* Note: alias and user are special; pseudo appears to be unused,
 564      and there is no reason to expose tui or xdb, I think.  */
 565   if (PyModule_AddIntConstant (gdb_module, "COMMAND_NONE", no_class) < 0
 566       || PyModule_AddIntConstant (gdb_module, "COMMAND_RUNNING", class_run) < 0
 567       || PyModule_AddIntConstant (gdb_module, "COMMAND_DATA", class_vars) < 0
 568       || PyModule_AddIntConstant (gdb_module, "COMMAND_STACK", class_stack) < 0
 569       || PyModule_AddIntConstant (gdb_module, "COMMAND_FILES", class_files) < 0
 570       || PyModule_AddIntConstant (gdb_module, "COMMAND_SUPPORT",
 571                                   class_support) < 0
 572       || PyModule_AddIntConstant (gdb_module, "COMMAND_STATUS", class_info) < 0
 573       || PyModule_AddIntConstant (gdb_module, "COMMAND_BREAKPOINTS",
 574                                   class_breakpoint) < 0
 575       || PyModule_AddIntConstant (gdb_module, "COMMAND_TRACEPOINTS",
 576                                   class_trace) < 0
 577       || PyModule_AddIntConstant (gdb_module, "COMMAND_OBSCURE",
 578                                   class_obscure) < 0
 579       || PyModule_AddIntConstant (gdb_module, "COMMAND_MAINTENANCE",
 580                                   class_maintenance) < 0
 581       || PyModule_AddIntConstant (gdb_module, "COMMAND_USER", class_user) < 0)
 582     return;
 583
 584   for (i = 0; i < N_COMPLETERS; ++i)
 585     {
 586       if (PyModule_AddIntConstant (gdb_module, completers[i].name, i) < 0)
 587         return;
 588     }
 589
 590   Py_INCREF (&cmdpy_object_type);
 591   PyModule_AddObject (gdb_module, "Command",
 592                       (PyObject *) &cmdpy_object_type);
 593
 594   invoke_cst = PyString_FromString ("invoke");
 595   complete_cst = PyString_FromString ("complete");
 596 }
 597
 598 \f
 599
 600 static PyMethodDef cmdpy_object_methods[] =
 601 {
 602   { "dont_repeat", cmdpy_dont_repeat, METH_NOARGS,
 603     "Prevent command repetition when user enters empty line." },
 604
 605   { 0 }
 606 };
 607
 608 static PyTypeObject cmdpy_object_type =
 609 {
 610   PyObject_HEAD_INIT (NULL)
 611   0,                              /*ob_size*/
 612   "gdb.Command",                  /*tp_name*/
 613   sizeof (cmdpy_object),          /*tp_basicsize*/
 614   0,                              /*tp_itemsize*/
 615   0,                              /*tp_dealloc*/
 616   0,                              /*tp_print*/
 617   0,                              /*tp_getattr*/
 618   0,                              /*tp_setattr*/
 619   0,                              /*tp_compare*/
 620   0,                              /*tp_repr*/
 621   0,                              /*tp_as_number*/
 622   0,                              /*tp_as_sequence*/
 623   0,                              /*tp_as_mapping*/
 624   0,                              /*tp_hash */
 625   0,                              /*tp_call*/
 626   0,                              /*tp_str*/
 627   0,                              /*tp_getattro*/
 628   0,                              /*tp_setattro*/
 629   0,                              /*tp_as_buffer*/
 630   Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /*tp_flags*/
 631   "GDB command object",           /* tp_doc */
 632   0,                              /* tp_traverse */
 633   0,                              /* tp_clear */
 634   0,                              /* tp_richcompare */
 635   0,                              /* tp_weaklistoffset */
 636   0,                              /* tp_iter */
 637   0,                              /* tp_iternext */
 638   cmdpy_object_methods,           /* tp_methods */
 639   0,                              /* tp_members */
 640   0,                              /* tp_getset */
 641   0,                              /* tp_base */
 642   0,                              /* tp_dict */
 643   0,                              /* tp_descr_get */
 644   0,                              /* tp_descr_set */
 645   0,                              /* tp_dictoffset */
 646   cmdpy_init,                     /* tp_init */
 647   0,                              /* tp_alloc */
 648 };
 649
 650 \f
 651
 652 /* Utility to build a buildargv-like result from ARGS.
 653    This intentionally parses arguments the way libiberty/argv.c:buildargv
 654    does.  It splits up arguments in a reasonable way, and we want a standard
 655    way of parsing arguments.  Several gdb commands use buildargv to parse their
 656    arguments.  Plus we want to be able to write compatible python
 657    implementations of gdb commands.  */
 658
 659 PyObject *
 660 gdbpy_string_to_argv (PyObject *self, PyObject *args)
 661 {
 662   PyObject *py_argv;
 663   const char *input;
 664
 665   if (!PyArg_ParseTuple (args, "s", &input))
 666     return NULL;
 667
 668   py_argv = PyList_New (0);
 669
 670   /* buildargv uses NULL to represent an empty argument list, but we can't use
 671      that in Python.  Instead, if ARGS is "" then return an empty list.
 672      This undoes the NULL -> "" conversion that cmdpy_function does.  */
 673
 674   if (*input != '\0')
 675     {
 676       char **c_argv = gdb_buildargv (input);
 677       int i;
 678
 679       for (i = 0; c_argv[i] != NULL; ++i)
 680         {
 681           PyObject *argp = PyString_FromString (c_argv[i]);
 682
 683           if (argp == NULL
 684               || PyList_Append (py_argv, argp) < 0)
 685             {
 686               Py_XDECREF (argp);
 687               Py_DECREF (py_argv);
 688               freeargv (c_argv);
 689               return NULL;
 690             }
 691           Py_DECREF (argp);
 692         }
 693
 694       freeargv (c_argv);
 695     }
 696
 697   return py_argv;
 698 }