llvm/lldb/scripts/Python/modules/readline/readline.cpp

// NOTE: Since Python may define some pre-processor definitions which affect the
// standard headers on some systems, you must include Python.h before any
// standard headers are included.
#include "Python.h"

#include <stdio.h>

#ifndef LLDB_DISABLE_LIBEDIT
#include <editline/readline.h>
#endif

// Simple implementation of the Python readline module using libedit.
// In the event that libedit is excluded from the build, this turns
// back into a null implementation that blocks the module from pulling
// in the GNU readline shared lib, which causes linkage confusion when
// both readline and libedit's readline compatibility symbols collide.
//
// Currently it only installs a PyOS_ReadlineFunctionPointer, without
// implementing any of the readline module methods. This is meant to
// work around LLVM pr18841 to avoid seg faults in the stock Python
// readline.so linked against GNU readline.

#ifndef LLDB_DISABLE_LIBEDIT
PyDoc_STRVAR(moduleDocumentation,
             "Simple readline module implementation based on libedit.");
#else
PyDoc_STRVAR(moduleDocumentation,
             "Stub module meant to avoid linking GNU readline.");
#endif

#if PY_MAJOR_VERSION >= 3
static struct PyModuleDef readline_module = {
    PyModuleDef_HEAD_INIT, // m_base
    "readline",            // m_name
    moduleDocumentation,   // m_doc
    -1,                    // m_size
    nullptr,               // m_methods
    nullptr,               // m_reload
    nullptr,               // m_traverse
    nullptr,               // m_clear
    nullptr,               // m_free
};
#else
static struct PyMethodDef moduleMethods[] = {{nullptr, nullptr, 0, nullptr}};
#endif

#ifndef LLDB_DISABLE_LIBEDIT
static char *
#if PY_MAJOR_VERSION >= 3
simple_readline(FILE *stdin, FILE *stdout, const char *prompt)
#else
simple_readline(FILE *stdin, FILE *stdout, char *prompt)
#endif
{
  rl_instream = stdin;
  rl_outstream = stdout;
  char *line = readline(prompt);
  if (!line) {
    char *ret = (char *)PyMem_Malloc(1);
    if (ret != NULL)
      *ret = '\0';
    return ret;
  }
  if (*line)
    add_history(line);
  int n = strlen(line);
  char *ret = (char *)PyMem_Malloc(n + 2);
  strncpy(ret, line, n);
  free(line);
  ret[n] = '\n';
  ret[n + 1] = '\0';
  return ret;
}
#endif

PyMODINIT_FUNC initreadline(void) {
#ifndef LLDB_DISABLE_LIBEDIT
  PyOS_ReadlineFunctionPointer = simple_readline;
#endif

#if PY_MAJOR_VERSION >= 3
  return PyModule_Create(&readline_module);
#else
  Py_InitModule4("readline", moduleMethods, moduleDocumentation,
                 static_cast<PyObject *>(NULL), PYTHON_API_VERSION);
#endif
}