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py-gdb-readline.c
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1/* Readline support for Python.
2
3 Copyright (C) 2012-2023 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
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
31static char *
32gdbpy_readline_wrapper (FILE *sys_stdin, FILE *sys_stdout,
33#if PY_MAJOR_VERSION == 3 && PY_MINOR_VERSION >= 4
34 const char *prompt)
35#else
36 char *prompt)
37#endif
38{
39 int n;
40 const char *p = NULL;
41 std::string buffer;
42 char *q;
43
44 try
45 {
46 p = command_line_input (buffer, prompt, "python");
47 }
48 /* Handle errors by raising Python exceptions. */
49 catch (const gdb_exception &except)
50 {
51 /* Detect user interrupt (Ctrl-C). */
52 if (except.reason == RETURN_QUIT)
53 return NULL;
54
55 /* The thread state is nulled during gdbpy_readline_wrapper,
56 with the original value saved in the following undocumented
57 variable (see Python's Parser/myreadline.c and
58 Modules/readline.c). */
59 PyEval_RestoreThread (_PyOS_ReadlineTState);
61 PyEval_SaveThread ();
62 return NULL;
63 }
64
65 /* Detect EOF (Ctrl-D). */
66 if (p == NULL)
67 {
68 q = (char *) PyMem_RawMalloc (1);
69 if (q != NULL)
70 q[0] = '\0';
71 return q;
72 }
73
74 n = strlen (p);
75
76 /* Copy the line to Python and return. */
77 q = (char *) PyMem_RawMalloc (n + 2);
78 if (q != NULL)
79 {
80 strcpy (q, p);
81 q[n] = '\n';
82 q[n + 1] = '\0';
83 }
84 return q;
85}
86
87/* Initialize Python readline support. */
88
89void
91{
92 /* Python's readline module conflicts with GDB's use of readline
93 since readline is not reentrant. Ideally, a reentrant wrapper to
94 GDB's readline should be implemented to replace Python's readline
95 and prevent conflicts. For now, this file implements a
96 sys.meta_path finder that simply fails to import the readline
97 module. */
98 if (PyRun_SimpleString ("\
99import sys\n\
100\n\
101class GdbRemoveReadlineFinder:\n\
102 def find_module(self, fullname, path=None):\n\
103 if fullname == 'readline' and path is None:\n\
104 return self\n\
105 return None\n\
106\n\
107 def load_module(self, fullname):\n\
108 raise ImportError('readline module disabled under GDB')\n\
109\n\
110sys.meta_path.append(GdbRemoveReadlineFinder())\n\
111") == 0)
112 PyOS_ReadlineFunctionPointer = gdbpy_readline_wrapper;
113}
114
const char * command_line_input(std::string &cmd_line_buffer, const char *, const char *)
Definition top.c:1339
void gdbpy_initialize_gdb_readline(void)
static char * gdbpy_readline_wrapper(FILE *sys_stdin, FILE *sys_stdout, char *prompt)
void gdbpy_convert_exception(const struct gdb_exception &exception)
Definition py-utils.c:216
#define PyMem_RawMalloc