cpython/Python/structmember.c

/* Map C struct members to Python object attributes */

#include "Python.h"

#include "structmember.h"

static PyObject *
listmembers(struct memberlist *mlist)
{
    int i, n;
    PyObject *v;
    for (n = 0; mlist[n].name != NULL; n++)
        ;
    v = PyList_New(n);
    if (v != NULL) {
        for (i = 0; i < n; i++)
            PyList_SetItem(v, i,
                           PyString_FromString(mlist[i].name));
        if (PyErr_Occurred()) {
            Py_DECREF(v);
            v = NULL;
        }
        else {
            PyList_Sort(v);
        }
    }
    return v;
}

PyObject *
PyMember_Get(const char *addr, struct memberlist *mlist, const char *name)
{
    struct memberlist *l;

    if (strcmp(name, "__members__") == 0)
        return listmembers(mlist);
    for (l = mlist; l->name != NULL; l++) {
        if (strcmp(l->name, name) == 0) {
            PyMemberDef copy;
            copy.name = l->name;
            copy.type = l->type;
            copy.offset = l->offset;
            copy.flags = l->flags;
            copy.doc = NULL;
            return PyMember_GetOne(addr, &copy);
        }
    }
    PyErr_SetString(PyExc_AttributeError, name);
    return NULL;
}

PyObject *
PyMember_GetOne(const char *addr, PyMemberDef *l)
{
    PyObject *v;
    if ((l->flags & READ_RESTRICTED) &&
        PyEval_GetRestricted()) {
        PyErr_SetString(PyExc_RuntimeError, "restricted attribute");
        return NULL;
    }
    addr += l->offset;
    switch (l->type) {
    case T_BOOL:
        v = PyBool_FromLong(*(char*)addr);
        break;
    case T_BYTE:
        v = PyInt_FromLong(*(char*)addr);
        break;
    case T_UBYTE:
        v = PyLong_FromUnsignedLong(*(unsigned char*)addr);
        break;
    case T_SHORT:
        v = PyInt_FromLong(*(short*)addr);
        break;
    case T_USHORT:
        v = PyLong_FromUnsignedLong(*(unsigned short*)addr);
        break;
    case T_INT:
        v = PyInt_FromLong(*(int*)addr);
        break;
    case T_UINT:
        v = PyLong_FromUnsignedLong(*(unsigned int*)addr);
        break;
    case T_LONG:
        v = PyInt_FromLong(*(long*)addr);
        break;
    case T_ULONG:
        v = PyLong_FromUnsignedLong(*(unsigned long*)addr);
        break;
    case T_PYSSIZET:
        v = PyInt_FromSsize_t(*(Py_ssize_t*)addr);
        break;
    case T_FLOAT:
        v = PyFloat_FromDouble((double)*(float*)addr);
        break;
    case T_DOUBLE:
        v = PyFloat_FromDouble(*(double*)addr);
        break;
    case T_STRING:
        if (*(char**)addr == NULL) {
            Py_INCREF(Py_None);
            v = Py_None;
        }
        else
            v = PyString_FromString(*(char**)addr);
        break;
    case T_STRING_INPLACE:
        v = PyString_FromString((char*)addr);
        break;
    case T_CHAR:
        v = PyString_FromStringAndSize((char*)addr, 1);
        break;
    case T_OBJECT:
        v = *(PyObject **)addr;
        if (v == NULL)
            v = Py_None;
        Py_INCREF(v);
        break;
    case T_OBJECT_EX:
        v = *(PyObject **)addr;
        if (v == NULL)
            PyErr_SetString(PyExc_AttributeError, l->name);
        Py_XINCREF(v);
        break;
#ifdef HAVE_LONG_LONG
    case T_LONGLONG:
        v = PyLong_FromLongLong(*(PY_LONG_LONG *)addr);
        break;
    case T_ULONGLONG:
        v = PyLong_FromUnsignedLongLong(*(unsigned PY_LONG_LONG *)addr);
        break;
#endif /* HAVE_LONG_LONG */
    default:
        PyErr_SetString(PyExc_SystemError, "bad memberdescr type");
        v = NULL;
    }
    return v;
}

int
PyMember_Set(char *addr, struct memberlist *mlist, const char *name, PyObject *v)
{
    struct memberlist *l;

    for (l = mlist; l->name != NULL; l++) {
        if (strcmp(l->name, name) == 0) {
            PyMemberDef copy;
            copy.name = l->name;
            copy.type = l->type;
            copy.offset = l->offset;
            copy.flags = l->flags;
            copy.doc = NULL;
            return PyMember_SetOne(addr, &copy, v);
        }
    }

    PyErr_SetString(PyExc_AttributeError, name);
    return -1;
}

#define WARN(msg)                                       \
    do {                                                \
    if (PyErr_Warn(PyExc_RuntimeWarning, msg) < 0)      \
        return -1;                                      \
    } while (0)

int
PyMember_SetOne(char *addr, PyMemberDef *l, PyObject *v)
{
    PyObject *oldv;

    addr += l->offset;

    if ((l->flags & READONLY))
    {
        PyErr_SetString(PyExc_TypeError, "readonly attribute");
        return -1;
    }
    if ((l->flags & PY_WRITE_RESTRICTED) && PyEval_GetRestricted()) {
        PyErr_SetString(PyExc_RuntimeError, "restricted attribute");
        return -1;
    }
    if (v == NULL) {
        if (l->type == T_OBJECT_EX) {
            /* Check if the attribute is set. */
            if (*(PyObject **)addr == NULL) {
                PyErr_SetString(PyExc_AttributeError, l->name);
                return -1;
            }
        }
        else if (l->type != T_OBJECT) {
            PyErr_SetString(PyExc_TypeError,
                            "can't delete numeric/char attribute");
            return -1;
        }
    }
    switch (l->type) {
    case T_BOOL:{
        if (!PyBool_Check(v)) {
            PyErr_SetString(PyExc_TypeError,
                            "attribute value type must be bool");
            return -1;
        }
        if (v == Py_True)
            *(char*)addr = (char) 1;
        else
            *(char*)addr = (char) 0;
        break;
        }
    case T_BYTE:{
        long long_val = PyInt_AsLong(v);
        if ((long_val == -1) && PyErr_Occurred())
            return -1;
        *(char*)addr = (char)long_val;
        /* XXX: For compatibility, only warn about truncations
           for now. */
        if ((long_val > CHAR_MAX) || (long_val < CHAR_MIN))
            WARN("Truncation of value to char");
        break;
        }
    case T_UBYTE:{
        long long_val = PyInt_AsLong(v);
        if ((long_val == -1) && PyErr_Occurred())
            return -1;
        *(unsigned char*)addr = (unsigned char)long_val;
        if ((long_val > UCHAR_MAX) || (long_val < 0))
            WARN("Truncation of value to unsigned char");
        break;
        }
    case T_SHORT:{
        long long_val = PyInt_AsLong(v);
        if ((long_val == -1) && PyErr_Occurred())
            return -1;
        *(short*)addr = (short)long_val;
        if ((long_val > SHRT_MAX) || (long_val < SHRT_MIN))
            WARN("Truncation of value to short");
        break;
        }
    case T_USHORT:{
        long long_val = PyInt_AsLong(v);
        if ((long_val == -1) && PyErr_Occurred())
            return -1;
        *(unsigned short*)addr = (unsigned short)long_val;
        if ((long_val > USHRT_MAX) || (long_val < 0))
            WARN("Truncation of value to unsigned short");
        break;
        }
    case T_INT:{
        long long_val = PyInt_AsLong(v);
        if ((long_val == -1) && PyErr_Occurred())
            return -1;
        *(int *)addr = (int)long_val;
        if ((long_val > INT_MAX) || (long_val < INT_MIN))
            WARN("Truncation of value to int");
        break;
        }
    case T_UINT:{
        unsigned long ulong_val = PyLong_AsUnsignedLong(v);
        if ((ulong_val == (unsigned long)-1) && PyErr_Occurred()) {
            /* XXX: For compatibility, accept negative int values
               as well. */
            PyErr_Clear();
            ulong_val = PyLong_AsLong(v);
            if ((ulong_val == (unsigned long)-1) &&
                PyErr_Occurred())
                return -1;
            *(unsigned int *)addr = (unsigned int)ulong_val;
            WARN("Writing negative value into unsigned field");
        } else
            *(unsigned int *)addr = (unsigned int)ulong_val;
        if (ulong_val > UINT_MAX)
            WARN("Truncation of value to unsigned int");
        break;
        }
    case T_LONG:{
        *(long*)addr = PyLong_AsLong(v);
        if ((*(long*)addr == -1) && PyErr_Occurred())
            return -1;
        break;
        }
    case T_ULONG:{
        *(unsigned long*)addr = PyLong_AsUnsignedLong(v);
        if ((*(unsigned long*)addr == (unsigned long)-1)
            && PyErr_Occurred()) {
            /* XXX: For compatibility, accept negative int values
               as well. */
            PyErr_Clear();
            *(unsigned long*)addr = PyLong_AsLong(v);
            if ((*(unsigned long*)addr == (unsigned long)-1)
                && PyErr_Occurred())
                return -1;
            WARN("Writing negative value into unsigned field");
        }
        break;
        }
    case T_PYSSIZET:{
        *(Py_ssize_t*)addr = PyInt_AsSsize_t(v);
        if ((*(Py_ssize_t*)addr == (Py_ssize_t)-1)
            && PyErr_Occurred())
                        return -1;
        break;
        }
    case T_FLOAT:{
        double double_val = PyFloat_AsDouble(v);
        if ((double_val == -1) && PyErr_Occurred())
            return -1;
        *(float*)addr = (float)double_val;
        break;
        }
    case T_DOUBLE:
        *(double*)addr = PyFloat_AsDouble(v);
        if ((*(double*)addr == -1) && PyErr_Occurred())
            return -1;
        break;
    case T_OBJECT:
    case T_OBJECT_EX:
        Py_XINCREF(v);
        oldv = *(PyObject **)addr;
        *(PyObject **)addr = v;
        Py_XDECREF(oldv);
        break;
    case T_CHAR:
        if (PyString_Check(v) && PyString_Size(v) == 1) {
            *(char*)addr = PyString_AsString(v)[0];
        }
        else {
            PyErr_BadArgument();
            return -1;
        }
        break;
    case T_STRING:
    case T_STRING_INPLACE:
        PyErr_SetString(PyExc_TypeError, "readonly attribute");
        return -1;
#ifdef HAVE_LONG_LONG
    case T_LONGLONG:{
        PY_LONG_LONG value;
        *(PY_LONG_LONG*)addr = value = PyLong_AsLongLong(v);
        if ((value == -1) && PyErr_Occurred())
            return -1;
        break;
        }
    case T_ULONGLONG:{
        unsigned PY_LONG_LONG value;
        /* ??? PyLong_AsLongLong accepts an int, but PyLong_AsUnsignedLongLong
            doesn't ??? */
        if (PyLong_Check(v))
            *(unsigned PY_LONG_LONG*)addr = value = PyLong_AsUnsignedLongLong(v);
        else
            *(unsigned PY_LONG_LONG*)addr = value = PyInt_AsLong(v);
        if ((value == (unsigned PY_LONG_LONG)-1) && PyErr_Occurred())
            return -1;
        break;
        }
#endif /* HAVE_LONG_LONG */
    default:
        PyErr_Format(PyExc_SystemError,
                     "bad memberdescr type for %s", l->name);
        return -1;
    }
    return 0;
}