lxml.c

// Copyright (c) 2017 Ryan Leckey
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#include "common.h"
#include "lxml.h"
#include "exception.h"

#include <etree_defs.h>
#include <etree_api.h>

#include <libxml/xmlmemory.h>
#include <libxml/parser.h>
#include <libxml/dict.h>

#define XMLSEC_EXTRACT_VERSION(x, y) ((x / (y)) % 100)

#define XMLSEC_EXTRACT_MAJOR(x) XMLSEC_EXTRACT_VERSION(x, 100 * 100)
#define XMLSEC_EXTRACT_MINOR(x) XMLSEC_EXTRACT_VERSION(x, 100)
#define XMLSEC_EXTRACT_PATCH(x) XMLSEC_EXTRACT_VERSION(x, 1)

static long PyXmlSec_GetLibXmlVersionLong() {
    return PyOS_strtol(xmlParserVersion, NULL, 10);
}
long PyXmlSec_GetLibXmlVersionMajor() {
    return XMLSEC_EXTRACT_MAJOR(PyXmlSec_GetLibXmlVersionLong());
}
long PyXmlSec_GetLibXmlVersionMinor() {
    return XMLSEC_EXTRACT_MINOR(PyXmlSec_GetLibXmlVersionLong());
}
long PyXmlSec_GetLibXmlVersionPatch() {
    return XMLSEC_EXTRACT_PATCH(PyXmlSec_GetLibXmlVersionLong());
}

long PyXmlSec_GetLibXmlCompiledVersionMajor() {
    return XMLSEC_EXTRACT_MAJOR(LIBXML_VERSION);
}
long PyXmlSec_GetLibXmlCompiledVersionMinor() {
    return XMLSEC_EXTRACT_MINOR(LIBXML_VERSION);
}
long PyXmlSec_GetLibXmlCompiledVersionPatch() {
    return XMLSEC_EXTRACT_PATCH(LIBXML_VERSION);
}

static int PyXmlSec_CheckLxmlLibraryVersion(void) {
    // Make sure that the version of libxml2 lxml is using is the same as the one we are using. Because
    // we pass trees between the two libraries, we need to make sure that they are using the same version
    // of libxml2, or we could run into difficult to debug segfaults.
    // See: https://github.com/xmlsec/python-xmlsec/issues/283

    PyObject* lxml = NULL;
    PyObject* version = NULL;

    // Default to failure
    int result = -1;

    lxml = PyImport_ImportModule("lxml.etree");
    if (lxml == NULL) {
        goto FINALIZE;
    }
    version = PyObject_GetAttrString(lxml, "LIBXML_VERSION");
    if (version == NULL) {
        goto FINALIZE;
    }
    if (!PyTuple_Check(version) || PyTuple_Size(version) < 2) {
        goto FINALIZE;
    }

    PyObject* major = PyTuple_GetItem(version, 0);
    PyObject* minor = PyTuple_GetItem(version, 1);

    if (PyErr_Occurred()) {
        goto FINALIZE;
    }

    if (!PyLong_Check(major) || !PyLong_Check(minor)) {
        goto FINALIZE;
    }

    long lxml_major = PyLong_AsLong(major);
    long lxml_minor = PyLong_AsLong(minor);
    long xmlsec_major = PyXmlSec_GetLibXmlVersionMajor();
    long xmlsec_minor = PyXmlSec_GetLibXmlVersionMinor();

    if (PyErr_Occurred()) {
        goto FINALIZE;
    }

    if (lxml_major != xmlsec_major || lxml_minor != xmlsec_minor) {
        goto FINALIZE;
    }

    result = 0;

FINALIZE:
    // Cleanup our references, and return the result
    Py_XDECREF(lxml);
    Py_XDECREF(version);

    // Clear any errors that may have occurred
    PyErr_Clear();

    return result;
}

int PyXmlSec_InitLxmlModule(void) {
    if (PyXmlSec_CheckLxmlLibraryVersion() < 0) {
        PyXmlSec_SetLastError("lxml & xmlsec libxml2 library version mismatch");
        return -1;
    }

    return import_lxml__etree();
}

int PyXmlSec_IsElement(xmlNodePtr xnode) {
    return _isElement(xnode);
}

PyXmlSec_LxmlElementPtr PyXmlSec_elementFactory(PyXmlSec_LxmlDocumentPtr doc, xmlNodePtr xnode) {
    return elementFactory(doc, xnode);
}


int PyXmlSec_LxmlElementConverter(PyObject* o, PyXmlSec_LxmlElementPtr* p) {
    PyXmlSec_LxmlElementPtr node = rootNodeOrRaise(o);
    if (node == NULL) {
        return 0;
    }
    *p = node;
    // rootNodeOrRaise - increments ref-count, so need to compensate this.
    Py_DECREF(node);
    return 1;
}