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enabled the dl module in Python 2.7 with only a few symbols (qsort, m…
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…map, mprotect, munmap, memcpy), improved the Python 2.7 dl module: allowed pointer (int) as d.call function name; allowed long instead of int in arguments
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Peter Szabo committed Dec 15, 2019
1 parent e3d4df7 commit c02fce3
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Showing 4 changed files with 644 additions and 2 deletions.
2 changes: 1 addition & 1 deletion Modules.Setup.2.7.static
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Expand Up @@ -375,7 +375,7 @@ _curses _cursesmodule.c -lncurses
# it is a highly experimental and dangerous device for calling
# *arbitrary* C functions in *arbitrary* shared libraries:

#dl dlmodule.c
dl dlmodule.c


# Modules that provide persistent dictionary-like semantics. You will
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349 changes: 349 additions & 0 deletions Modules.dlmodule.2.7.c
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@@ -0,0 +1,349 @@

/* dl module */

#include "Python.h"

/* StaticPython */
/* --- fake -ldl */

#include <string.h>
#include <sys/mman.h>

/*#include <dlfcn.h>*/
#define dlopen fake_dlopen
#define dlclose fake_dlclose
#define dlerror fake_dlerror
#define dlsym fake_dlsym

/* Implements the slower insertion sort instead, but is compact. It makes no
* copies if the input is already sorted.
*/
void fake_qsort(void *base, size_t nmemb, size_t size, int (*compar)(const void *, const void *)) {
register char *cur;
char *savecur, *end;
char tmp[size]; /* Variable-length array. */
if (nmemb > 1) {
for (cur = (char*)base + size, end = (char*)base + (size * nmemb); cur != end; cur += size) {
if (compar(cur, cur - size) < 0) {
memcpy(tmp, cur, size);
savecur = cur;
do {
memcpy(cur, cur - size, size);
cur -= size;
} while (cur != (char*)base && compar(tmp, cur - size) < 0);
memcpy(cur, tmp, size);
cur = savecur;
}
}
}
}

void *dlopen(const char *filename, int flag) {
return (void*)1;
}
char *dlerror(void) {
return "symbol not emulated";
}
void *dlsym(void *handle, const char *symbol) {
(void)handle;
if (!strcmp(symbol, "qsort")) return fake_qsort;
if (!strcmp(symbol, "mmap")) return mmap;
if (!strcmp(symbol, "mprotect")) return mprotect;
if (!strcmp(symbol, "munmap")) return munmap;
if (!strcmp(symbol, "memcpy")) return memcpy;
return 0;
}
int dlclose(void *handle) {
(void)handle;
}

/* StaticPython */


#ifdef __VMS
#include <unistd.h>
#endif

#ifndef RTLD_LAZY
#define RTLD_LAZY 1
#endif

typedef void *PyUnivPtr;
typedef struct {
PyObject_HEAD
PyUnivPtr *dl_handle;
} dlobject;

static PyTypeObject Dltype;

static PyObject *Dlerror;

static PyObject *
newdlobject(PyUnivPtr *handle)
{
dlobject *xp;
xp = PyObject_New(dlobject, &Dltype);
if (xp == NULL)
return NULL;
xp->dl_handle = handle;
return (PyObject *)xp;
}

static void
dl_dealloc(dlobject *xp)
{
if (xp->dl_handle != NULL)
dlclose(xp->dl_handle);
PyObject_Del(xp);
}

static PyObject *
dl_close(dlobject *xp)
{
if (xp->dl_handle != NULL) {
dlclose(xp->dl_handle);
xp->dl_handle = NULL;
}
Py_INCREF(Py_None);
return Py_None;
}

static PyObject *
dl_sym(dlobject *xp, PyObject *args)
{
char *name;
PyUnivPtr *func;
if (PyString_Check(args)) {
name = PyString_AS_STRING(args);
} else {
PyErr_Format(PyExc_TypeError, "expected string, found %.200s",
Py_TYPE(args)->tp_name);
return NULL;
}
func = dlsym(xp->dl_handle, name);
if (func == NULL) {
Py_INCREF(Py_None);
return Py_None;
}
return PyInt_FromLong((long)func);
}

static PyObject *
dl_call(dlobject *xp, PyObject *args)
{
PyObject *name;
long (*func)(long, long, long, long, long,
long, long, long, long, long);
long alist[10];
long res;
Py_ssize_t i;
Py_ssize_t n = PyTuple_Size(args);
if (n < 1) {
PyErr_SetString(PyExc_TypeError, "at least a name is needed");
return NULL;
}
name = PyTuple_GetItem(args, 0);
if (PyInt_Check(name)) { /* StaticPython */
func = (long (*)(long, long, long, long, long,
long, long, long, long, long))
PyInt_AsLong(name);
} else if (PyString_Check(name)) {
func = (long (*)(long, long, long, long, long,
long, long, long, long, long))
dlsym(xp->dl_handle, PyString_AsString(name));
} else {
PyErr_SetString(PyExc_TypeError,
"function name must be a string");
return NULL;
}
if (func == NULL) {
PyErr_SetString(PyExc_ValueError, dlerror());
return NULL;
}
if (n-1 > 10) {
PyErr_SetString(PyExc_TypeError,
"too many arguments (max 10)");
return NULL;
}
for (i = 1; i < n; i++) {
PyObject *v = PyTuple_GetItem(args, i);
if (PyInt_Check(v))
alist[i-1] = PyInt_AS_LONG(v);
else if (PyLong_Check(v)) { /* StaticPython */
alist[i-1] = res = PyInt_AsLong(v);
if (res == -1 && PyErr_Occurred()) return 0;
}
/* !! StaticPython: Allow buffers as well. */
else if (PyString_Check(v))
alist[i-1] = (long)PyString_AsString(v);
else if (v == Py_None)
alist[i-1] = (long) ((char *)NULL);
else {
PyErr_SetString(PyExc_TypeError,
"arguments must be int, string or None");
return NULL;
}
}
for (; i <= 10; i++)
alist[i-1] = 0;
res = (*func)(alist[0], alist[1], alist[2], alist[3], alist[4],
alist[5], alist[6], alist[7], alist[8], alist[9]);
return PyInt_FromLong(res);
}

static PyMethodDef dlobject_methods[] = {
{"call", (PyCFunction)dl_call, METH_VARARGS},
{"sym", (PyCFunction)dl_sym, METH_O},
{"close", (PyCFunction)dl_close, METH_NOARGS},
{NULL, NULL} /* Sentinel */
};

static PyObject *
dl_getattr(dlobject *xp, char *name)
{
return Py_FindMethod(dlobject_methods, (PyObject *)xp, name);
}


static PyTypeObject Dltype = {
PyVarObject_HEAD_INIT(NULL, 0)
"dl.dl", /*tp_name*/
sizeof(dlobject), /*tp_basicsize*/
0, /*tp_itemsize*/
/* methods */
(destructor)dl_dealloc, /*tp_dealloc*/
0, /*tp_print*/
(getattrfunc)dl_getattr,/*tp_getattr*/
0, /*tp_setattr*/
0, /*tp_compare*/
0, /*tp_repr*/
0, /*tp_as_number*/
0, /*tp_as_sequence*/
0, /*tp_as_mapping*/
0, /*tp_hash*/
};

static PyObject *
dl_open(PyObject *self, PyObject *args)
{
char *name;
int mode;
PyUnivPtr *handle;
if (sizeof(int) != sizeof(long) ||
sizeof(long) != sizeof(char *)) {
PyErr_SetString(PyExc_SystemError,
"module dl requires sizeof(int) == sizeof(long) == sizeof(char*)");
return NULL;
}

if (PyArg_ParseTuple(args, "z:open", &name))
mode = RTLD_LAZY;
else {
PyErr_Clear();
if (!PyArg_ParseTuple(args, "zi:open", &name, &mode))
return NULL;
#ifndef RTLD_NOW
if (mode != RTLD_LAZY) {
PyErr_SetString(PyExc_ValueError, "mode must be 1");
return NULL;
}
#endif
}
handle = dlopen(name, mode);
if (handle == NULL) {
char *errmsg = dlerror();
if (!errmsg)
errmsg = "dlopen() error";
PyErr_SetString(Dlerror, errmsg);
return NULL;
}
#ifdef __VMS
/* Under OpenVMS dlopen doesn't do any check, just save the name
* for later use, so we have to check if the file is readable,
* the name can be a logical or a file from SYS$SHARE.
*/
if (access(name, R_OK)) {
char fname[strlen(name) + 20];
strcpy(fname, "SYS$SHARE:");
strcat(fname, name);
strcat(fname, ".EXE");
if (access(fname, R_OK)) {
dlclose(handle);
PyErr_SetString(Dlerror,
"File not found or protection violation");
return NULL;
}
}
#endif
return newdlobject(handle);
}

static PyMethodDef dl_methods[] = {
{"open", dl_open, METH_VARARGS},
{NULL, NULL} /* sentinel */
};

/* From socketmodule.c
* Convenience routine to export an integer value.
*
* Errors are silently ignored, for better or for worse...
*/
static void
insint(PyObject *d, char *name, int value)
{
PyObject *v = PyInt_FromLong((long) value);
if (!v || PyDict_SetItemString(d, name, v))
PyErr_Clear();

Py_XDECREF(v);
}

PyMODINIT_FUNC
initdl(void)
{
PyObject *m, *d, *x;

if (PyErr_WarnPy3k("the dl module has been removed in "
"Python 3.0; use the ctypes module instead", 2) < 0)
return;

/* Initialize object type */
Py_TYPE(&Dltype) = &PyType_Type;

/* Create the module and add the functions */
m = Py_InitModule("dl", dl_methods);
if (m == NULL)
return;

/* Add some symbolic constants to the module */
d = PyModule_GetDict(m);
Dlerror = x = PyErr_NewException("dl.error", NULL, NULL);
PyDict_SetItemString(d, "error", x);
x = PyInt_FromLong((long)RTLD_LAZY);
PyDict_SetItemString(d, "RTLD_LAZY", x);
#define INSINT(X) insint(d,#X,X)
#ifdef RTLD_NOW
INSINT(RTLD_NOW);
#endif
#ifdef RTLD_NOLOAD
INSINT(RTLD_NOLOAD);
#endif
#ifdef RTLD_GLOBAL
INSINT(RTLD_GLOBAL);
#endif
#ifdef RTLD_LOCAL
INSINT(RTLD_LOCAL);
#endif
#ifdef RTLD_PARENT
INSINT(RTLD_PARENT);
#endif
#ifdef RTLD_GROUP
INSINT(RTLD_GROUP);
#endif
#ifdef RTLD_WORLD
INSINT(RTLD_WORLD);
#endif
#ifdef RTLD_NODELETE
INSINT(RTLD_NODELETE);
#endif
}
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