gdb/python/py-gdb-readline.c

   1 /* Readline support for Python.
   2
   3    Copyright (C) 2012-2014 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 #include "defs.h"
  21 #include "python-internal.h"
  22 #include "exceptions.h"
  23 #include "top.h"
  24 #include "cli/cli-utils.h"
  25 /* Readline function suitable for PyOS_ReadlineFunctionPointer, which
  26    is used for Python's interactive parser and raw_input.  In both
  27    cases, sys_stdin and sys_stdout are always stdin and stdout
  28    respectively, as far as I can tell; they are ignored and
  29    command_line_input is used instead.  */
  30
  31 static char *
  32 gdbpy_readline_wrapper (FILE *sys_stdin, FILE *sys_stdout,
  33                         char *prompt)
  34 {
  35   int n;
  36   char *p = NULL, *q;
  37   volatile struct gdb_exception except;
  38
  39   TRY_CATCH (except, RETURN_MASK_ALL)
  40     p = command_line_input (prompt, 0, "python");
  41
  42   /* Detect user interrupt (Ctrl-C).  */
  43   if (except.reason == RETURN_QUIT)
  44     return NULL;
  45
  46   /* Handle errors by raising Python exceptions.  */
  47   if (except.reason < 0)
  48     {
  49       /* The thread state is nulled during gdbpy_readline_wrapper,
  50          with the original value saved in the following undocumented
  51          variable (see Python's Parser/myreadline.c and
  52          Modules/readline.c).  */
  53       PyEval_RestoreThread (_PyOS_ReadlineTState);
  54       gdbpy_convert_exception (except);
  55       PyEval_SaveThread ();
  56       return NULL;
  57     }
  58
  59   /* Detect EOF (Ctrl-D).  */
  60   if (p == NULL)
  61     {
  62       q = PyMem_Malloc (1);
  63       if (q != NULL)
  64         q[0] = '\0';
  65       return q;
  66     }
  67
  68   n = strlen (p);
  69
  70   /* Copy the line to Python and return.  */
  71   q = PyMem_Malloc (n + 2);
  72   if (q != NULL)
  73     {
  74       strncpy (q, p, n);
  75       q[n] = '\n';
  76       q[n + 1] = '\0';
  77     }
  78   return q;
  79 }
  80
  81 /* Initialize Python readline support.  */
  82
  83 void
  84 gdbpy_initialize_gdb_readline (void)
  85 {
  86   /* Python's readline module conflicts with GDB's use of readline
  87      since readline is not reentrant.  Ideally, a reentrant wrapper to
  88      GDB's readline should be implemented to replace Python's readline
  89      and prevent conflicts.  For now, this file implements a
  90      sys.meta_path finder that simply fails to import the readline
  91      module.  */
  92   if (PyRun_SimpleString ("\
  93 import sys\n\
  94 \n\
  95 class GdbRemoveReadlineFinder:\n\
  96   def find_module(self, fullname, path=None):\n\
  97     if fullname == 'readline' and path is None:\n\
  98       return self\n\
  99     return None\n\
 100 \n\
 101   def load_module(self, fullname):\n\
 102     raise ImportError('readline module disabled under GDB')\n\
 103 \n\
 104 sys.meta_path.append(GdbRemoveReadlineFinder())\n\
 105 ") == 0)
 106     PyOS_ReadlineFunctionPointer = gdbpy_readline_wrapper;
 107 }
 108