xref: /freebsd/contrib/llvm-project/lldb/source/Plugins/ScriptInterpreter/Python/PythonReadline.cpp (revision b3e7694832e81d7a904a10f525f8797b753bf0d3)
1 #include "PythonReadline.h"
2 
3 #ifdef LLDB_USE_LIBEDIT_READLINE_COMPAT_MODULE
4 
5 #include <cstdio>
6 
7 #include <editline/readline.h>
8 
9 // Simple implementation of the Python readline module using libedit.
10 // In the event that libedit is excluded from the build, this turns
11 // back into a null implementation that blocks the module from pulling
12 // in the GNU readline shared lib, which causes linkage confusion when
13 // both readline and libedit's readline compatibility symbols collide.
14 //
15 // Currently it only installs a PyOS_ReadlineFunctionPointer, without
16 // implementing any of the readline module methods. This is meant to
17 // work around LLVM pr18841 to avoid seg faults in the stock Python
18 // readline.so linked against GNU readline.
19 //
20 // Bug on the cpython side: https://bugs.python.org/issue38634
21 
22 PyDoc_STRVAR(moduleDocumentation,
23              "Simple readline module implementation based on libedit.");
24 
25 static struct PyModuleDef readline_module = {
26     PyModuleDef_HEAD_INIT, // m_base
27     "lldb_editline",       // m_name
28     moduleDocumentation,   // m_doc
29     -1,                    // m_size
30     nullptr,               // m_methods
31     nullptr,               // m_reload
32     nullptr,               // m_traverse
33     nullptr,               // m_clear
34     nullptr,               // m_free
35 };
36 
37 static char *simple_readline(FILE *stdin, FILE *stdout, const char *prompt) {
38   rl_instream = stdin;
39   rl_outstream = stdout;
40   char *line = readline(prompt);
41   if (!line) {
42     char *ret = (char *)PyMem_RawMalloc(1);
43     if (ret != nullptr)
44       *ret = '\0';
45     return ret;
46   }
47   if (*line)
48     add_history(line);
49   int n = strlen(line);
50   char *ret = (char *)PyMem_RawMalloc(n + 2);
51   if (ret) {
52     memcpy(ret, line, n);
53     free(line);
54     ret[n] = '\n';
55     ret[n + 1] = '\0';
56   }
57   return ret;
58 }
59 
60 PyMODINIT_FUNC initlldb_readline(void) {
61   PyOS_ReadlineFunctionPointer = simple_readline;
62 
63   return PyModule_Create(&readline_module);
64 }
65 #endif
66