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