add a replacement API for PyCObject, PyCapsule #5630

All stdlib modules with C-APIs now use this.

Patch by Larry Hastings

1 files changed, 324 insertions, 0 deletions

diff --git a/Objects/capsule.c b/Objects/capsule.c
new file mode 100644
index 0000000..5304ce1
--- /dev/null
+++ b/Objects/capsule.c
@@ -0,0 +1,324 @@
+/* Wrap void * pointers to be passed between C modules */
+
+#include "Python.h"
+
+/* Internal structure of PyCapsule */
+typedef struct {
+    PyObject_HEAD
+    void *pointer;
+    const char *name;
+    void *context;
+    PyCapsule_Destructor destructor;
+} PyCapsule;
+
+
+
+static int
+_is_legal_capsule(PyCapsule *capsule, const char *invalid_capsule)
+{
+    if (!capsule || !PyCapsule_CheckExact(capsule) || capsule->pointer == NULL) {
+        PyErr_SetString(PyExc_ValueError, invalid_capsule);
+        return 0;
+    }
+    return 1;
+}
+
+#define is_legal_capsule(capsule, name) \
+    (_is_legal_capsule(capsule, \
+     name " called with invalid PyCapsule object"))
+
+
+static int
+name_matches(const char *name1, const char *name2) {
+    /* if either is NULL, */
+    if (!name1 || !name2) {
+        /* they're only the same if they're both NULL. */
+        return name2 == name2;
+    }
+    return !strcmp(name1, name2);
+}
+
+
+
+PyObject *
+PyCapsule_New(void *pointer, const char *name, PyCapsule_Destructor destructor)
+{
+    PyCapsule *capsule;
+
+    if (!pointer) {
+        PyErr_SetString(PyExc_ValueError, "PyCapsule_New called with null pointer");
+        return NULL;
+    }
+
+    capsule = PyObject_NEW(PyCapsule, &PyCapsule_Type);
+    if (capsule == NULL) {
+        return NULL;
+    }
+
+    capsule->pointer = pointer;
+    capsule->name = name;
+    capsule->context = NULL;
+    capsule->destructor = destructor;
+
+    return (PyObject *)capsule;
+}
+
+
+int
+PyCapsule_IsValid(PyObject *o, const char *name)
+{
+    PyCapsule *capsule = (PyCapsule *)o;
+
+    return (capsule != NULL &&
+            PyCapsule_CheckExact(capsule) &&
+            capsule->pointer != NULL &&
+            name_matches(capsule->name, name));
+}
+
+
+void *
+PyCapsule_GetPointer(PyObject *o, const char *name)
+{
+    PyCapsule *capsule = (PyCapsule *)o;
+
+    if (!is_legal_capsule(capsule, "PyCapsule_GetPointer")) {
+        return NULL;
+    }
+
+    if (!name_matches(name, capsule->name)) {
+        PyErr_SetString(PyExc_ValueError, "PyCapsule_GetPointer called with incorrect name");
+        return NULL;
+    }
+
+    return capsule->pointer;
+}
+
+
+const char *
+PyCapsule_GetName(PyObject *o)
+{
+    PyCapsule *capsule = (PyCapsule *)o;
+
+    if (!is_legal_capsule(capsule, "PyCapsule_GetName")) {
+        return NULL;
+    }
+    return capsule->name;
+}
+
+
+PyCapsule_Destructor
+PyCapsule_GetDestructor(PyObject *o)
+{
+    PyCapsule *capsule = (PyCapsule *)o;
+
+    if (!is_legal_capsule(capsule, "PyCapsule_GetDestructor")) {
+        return NULL;
+    }
+    return capsule->destructor;
+}
+
+
+void *
+PyCapsule_GetContext(PyObject *o)
+{
+    PyCapsule *capsule = (PyCapsule *)o;
+
+    if (!is_legal_capsule(capsule, "PyCapsule_GetContext")) {
+        return NULL;
+    }
+    return capsule->context;
+}
+
+
+int
+PyCapsule_SetPointer(PyObject *o, void *pointer)
+{
+    PyCapsule *capsule = (PyCapsule *)o;
+
+    if (!pointer) {
+        PyErr_SetString(PyExc_ValueError, "PyCapsule_SetPointer called with null pointer");
+        return -1;
+    }
+
+    if (!is_legal_capsule(capsule, "PyCapsule_SetPointer")) {
+        return -1;
+    }
+
+    capsule->pointer = pointer;
+    return 0;
+}
+
+
+int
+PyCapsule_SetName(PyObject *o, const char *name)
+{
+    PyCapsule *capsule = (PyCapsule *)o;
+
+    if (!is_legal_capsule(capsule, "PyCapsule_SetName")) {
+        return -1;
+    }
+
+    capsule->name = name;
+    return 0;
+}
+
+
+int
+PyCapsule_SetDestructor(PyObject *o, PyCapsule_Destructor destructor)
+{
+    PyCapsule *capsule = (PyCapsule *)o;
+
+    if (!is_legal_capsule(capsule, "PyCapsule_SetDestructor")) {
+        return -1;
+    }
+
+    capsule->destructor = destructor;
+    return 0;
+}
+
+
+int
+PyCapsule_SetContext(PyObject *o, void *context)
+{
+    PyCapsule *capsule = (PyCapsule *)o;
+
+    if (!is_legal_capsule(capsule, "PyCapsule_SetContext")) {
+        return -1;
+    }
+
+    capsule->context = context;
+    return 0;
+}
+
+
+void *
+PyCapsule_Import(const char *name, int no_block)
+{
+    PyObject *object = NULL;
+    void *return_value = NULL;
+    char *trace;
+    int name_length = (strlen(name) + 1) * sizeof(char);
+    char *name_dup = (char *)PyMem_MALLOC(name_length);
+
+    if (!name_dup) {
+        return NULL;
+    }
+
+    memcpy(name_dup, name, name_length);
+
+    trace = name_dup;
+    while (trace) {
+        char *dot = strchr(trace, '.');
+        if (dot) {
+            *dot++ = '\0';
+        }
+
+        if (object == NULL) {
+            if (no_block) {
+                object = PyImport_ImportModuleNoBlock(trace);
+            } else {
+                object = PyImport_ImportModule(trace);
+                if (!object) {
+                    PyErr_Format(PyExc_ImportError, "PyCapsule_Import could not import module \"%s\"", trace);
+                }
+            }
+        } else {
+            PyObject *object2 = PyObject_GetAttrString(object, trace);
+            Py_DECREF(object);
+            object = object2;
+        }
+        if (!object) {
+            goto EXIT;
+        }
+
+        trace = dot;
+    }
+
+    /* compare attribute name to module.name by hand */
+    if (PyCapsule_IsValid(object, name)) {
+        PyCapsule *capsule = (PyCapsule *)object;
+        return_value = capsule->pointer;
+    } else {
+        PyErr_Format(PyExc_AttributeError,
+            "PyCapsule_Import \"%s\" is not valid",
+            name);
+    }
+
+EXIT:
+    Py_XDECREF(object);
+    if (name_dup) {
+        PyMem_FREE(name_dup);
+    }
+    return return_value;
+}
+
+
+static void
+capsule_dealloc(PyObject *o)
+{
+    PyCapsule *capsule = (PyCapsule *)o;
+    if (capsule->destructor) {
+        capsule->destructor(o);
+    }
+    PyObject_DEL(o);
+}
+
+
+static PyObject *
+capsule_repr(PyObject *o)
+{
+    PyCapsule *capsule = (PyCapsule *)o;
+    const char *name;
+    const char *quote;
+
+    if (capsule->name) {
+        quote = "\"";
+        name = capsule->name;
+    } else {
+        quote = "";
+        name = "NULL";
+    }
+
+    return PyUnicode_FromFormat("<capsule object %s%s%s at %p>",
+        quote, name, quote, capsule);
+}
+
+
+
+PyDoc_STRVAR(PyCapsule_Type__doc__,
+"Capsule objects let you wrap a C \"void *\" pointer in a Python\n\
+object.  They're a way of passing data through the Python interpreter\n\
+without creating your own custom type.\n\
+\n\
+Capsules are used for communication between extension modules.\n\
+They provide a way for an extension module to export a C interface\n\
+to other extension modules, so that extension modules can use the\n\
+Python import mechanism to link to one another.\n\
+");
+
+PyTypeObject PyCapsule_Type = {
+    PyVarObject_HEAD_INIT(&PyType_Type, 0)
+    "PyCapsule",		/*tp_name*/
+    sizeof(PyCapsule),		/*tp_basicsize*/
+    0,				/*tp_itemsize*/
+    /* methods */
+    capsule_dealloc, /*tp_dealloc*/
+    0,				/*tp_print*/
+    0,				/*tp_getattr*/
+    0,				/*tp_setattr*/
+    0,				/*tp_reserved*/
+    capsule_repr, /*tp_repr*/
+    0,				/*tp_as_number*/
+    0,				/*tp_as_sequence*/
+    0,				/*tp_as_mapping*/
+    0,				/*tp_hash*/
+    0,				/*tp_call*/
+    0,				/*tp_str*/
+    0,				/*tp_getattro*/
+    0,				/*tp_setattro*/
+    0,				/*tp_as_buffer*/
+    0,				/*tp_flags*/
+    PyCapsule_Type__doc__	/*tp_doc*/
+};
+
+