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using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;
namespace Python.Runtime
{
/// <summary>
/// Implements the "import hook" used to integrate Python with the CLR.
/// </summary>
internal static class ImportHook
{
private static IntPtr py_import;
private static CLRModule root;
private static MethodWrapper hook;
private static IntPtr py_clr_module;
private static IntPtr module_def = IntPtr.Zero;
internal static void InitializeModuleDef()
{
if (module_def == IntPtr.Zero)
{
module_def = ModuleDefOffset.AllocModuleDef("clr");
}
}
internal static void ReleaseModuleDef()
{
if (module_def == IntPtr.Zero)
{
return;
}
ModuleDefOffset.FreeModuleDef(module_def);
module_def = IntPtr.Zero;
}
/// <summary>
/// Initialize just the __import__ hook itself.
/// </summary>
static void InitImport()
{
// We replace the built-in Python __import__ with our own: first
// look in CLR modules, then if we don't find any call the default
// Python __import__.
IntPtr builtins = Runtime.GetBuiltins();
py_import = Runtime.PyObject_GetAttr(builtins, PyIdentifier.__import__);
PythonException.ThrowIfIsNull(py_import);
hook = new MethodWrapper(typeof(ImportHook), "__import__", "TernaryFunc");
int res = Runtime.PyObject_SetAttr(builtins, PyIdentifier.__import__, hook.ptr);
PythonException.ThrowIfIsNotZero(res);
Runtime.XDecref(builtins);
}
/// <summary>
/// Restore the __import__ hook.
/// </summary>
static void RestoreImport()
{
IntPtr builtins = Runtime.GetBuiltins();
int res = Runtime.PyObject_SetAttr(builtins, PyIdentifier.__import__, py_import);
PythonException.ThrowIfIsNotZero(res);
Runtime.XDecref(py_import);
py_import = IntPtr.Zero;
hook.Release();
hook = null;
Runtime.XDecref(builtins);
}
/// <summary>
/// Initialization performed on startup of the Python runtime.
/// </summary>
internal static void Initialize()
{
InitImport();
// Initialize the clr module and tell Python about it.
root = new CLRModule();
// create a python module with the same methods as the clr module-like object
InitializeModuleDef();
py_clr_module = Runtime.PyModule_Create2(module_def, 3);
// both dicts are borrowed references
IntPtr mod_dict = Runtime.PyModule_GetDict(py_clr_module);
IntPtr clr_dict = Runtime._PyObject_GetDictPtr(root.pyHandle); // PyObject**
clr_dict = (IntPtr)Marshal.PtrToStructure(clr_dict, typeof(IntPtr));
Runtime.PyDict_Update(mod_dict, clr_dict);
IntPtr dict = Runtime.PyImport_GetModuleDict();
Runtime.PyDict_SetItemString(dict, "CLR", py_clr_module);
Runtime.PyDict_SetItemString(dict, "clr", py_clr_module);
}
/// <summary>
/// Cleanup resources upon shutdown of the Python runtime.
/// </summary>
internal static void Shutdown()
{
if (Runtime.Py_IsInitialized() == 0)
{
return;
}
RestoreImport();
bool shouldFreeDef = Runtime.Refcount(py_clr_module) == 1;
Runtime.XDecref(py_clr_module);
py_clr_module = IntPtr.Zero;
if (shouldFreeDef)
{
ReleaseModuleDef();
}
Runtime.XDecref(root.pyHandle);
root = null;
CLRModule.Reset();
}
internal static void SaveRuntimeData(RuntimeDataStorage storage)
{
// Increment the reference counts here so that the objects don't
// get freed in Shutdown.
Runtime.XIncref(py_clr_module);
Runtime.XIncref(root.pyHandle);
storage.AddValue("py_clr_module", py_clr_module);
storage.AddValue("root", root.pyHandle);
}
internal static void RestoreRuntimeData(RuntimeDataStorage storage)
{
InitImport();
storage.GetValue("py_clr_module", out py_clr_module);
var rootHandle = storage.GetValue<IntPtr>("root");
root = (CLRModule)ManagedType.GetManagedObject(rootHandle);
}
/// <summary>
/// Return the clr python module (new reference)
/// </summary>
public static IntPtr GetCLRModule(IntPtr? fromList = null)
{
root.InitializePreload();
// update the module dictionary with the contents of the root dictionary
root.LoadNames();
IntPtr py_mod_dict = Runtime.PyModule_GetDict(py_clr_module);
IntPtr clr_dict = Runtime._PyObject_GetDictPtr(root.pyHandle); // PyObject**
clr_dict = (IntPtr)Marshal.PtrToStructure(clr_dict, typeof(IntPtr));
Runtime.PyDict_Update(py_mod_dict, clr_dict);
// find any items from the from list and get them from the root if they're not
// already in the module dictionary
if (fromList != null && fromList != IntPtr.Zero)
{
if (Runtime.PyTuple_Check(fromList.GetValueOrDefault()))
{
Runtime.XIncref(py_mod_dict);
using (var mod_dict = new PyDict(py_mod_dict))
{
Runtime.XIncref(fromList.GetValueOrDefault());
using (var from = new PyTuple(fromList.GetValueOrDefault()))
{
foreach (PyObject item in from)
{
if (mod_dict.HasKey(item))
{
continue;
}
var s = item.AsManagedObject(typeof(string)) as string;
if (s == null)
{
continue;
}
ManagedType attr = root.GetAttribute(s, true);
if (attr == null)
{
continue;
}
Runtime.XIncref(attr.pyHandle);
using (var obj = new PyObject(attr.pyHandle))
{
mod_dict.SetItem(s, obj);
}
}
}
}
}
}
Runtime.XIncref(py_clr_module);
return py_clr_module;
}
/// <summary>
/// The actual import hook that ties Python to the managed world.
/// </summary>
public static IntPtr __import__(IntPtr self, IntPtr args, IntPtr kw)
{
// Replacement for the builtin __import__. The original import
// hook is saved as this.py_import. This version handles CLR
// import and defers to the normal builtin for everything else.
var num_args = Runtime.PyTuple_Size(args);
if (num_args < 1)
{
return Exceptions.RaiseTypeError("__import__() takes at least 1 argument (0 given)");
}
// borrowed reference
IntPtr py_mod_name = Runtime.PyTuple_GetItem(args, 0);
if (py_mod_name == IntPtr.Zero ||
!Runtime.IsStringType(py_mod_name))
{
return Exceptions.RaiseTypeError("string expected");
}
// Check whether the import is of the form 'from x import y'.
// This determines whether we return the head or tail module.
IntPtr fromList = IntPtr.Zero;
var fromlist = false;
if (num_args >= 4)
{
fromList = Runtime.PyTuple_GetItem(args, 3);
if (fromList != IntPtr.Zero &&
Runtime.PyObject_IsTrue(fromList) == 1)
{
fromlist = true;
}
}
string mod_name = Runtime.GetManagedString(py_mod_name);
// Check these BEFORE the built-in import runs; may as well
// do the Incref()ed return here, since we've already found
// the module.
if (mod_name == "clr" || mod_name == "CLR")
{
if (mod_name == "CLR")
{
Exceptions.deprecation("The CLR module is deprecated. Please use 'clr'.");
}
IntPtr clr_module = GetCLRModule(fromList);
if (clr_module != IntPtr.Zero)
{
IntPtr sys_modules = Runtime.PyImport_GetModuleDict();
if (sys_modules != IntPtr.Zero)
{
Runtime.PyDict_SetItemString(sys_modules, "clr", clr_module);
}
}
return clr_module;
}
string realname = mod_name;
string clr_prefix = null;
if (mod_name.StartsWith("CLR."))
{
clr_prefix = "CLR."; // prepend when adding the module to sys.modules
realname = mod_name.Substring(4);
string msg = $"Importing from the CLR.* namespace is deprecated. Please import '{realname}' directly.";
Exceptions.deprecation(msg);
}
else
{
// 2010-08-15: Always seemed smart to let python try first...
// This shaves off a few tenths of a second on test_module.py
// and works around a quirk where 'sys' is found by the
// LoadImplicit() deprecation logic.
// Turns out that the AssemblyManager.ResolveHandler() checks to see if any
// Assembly's FullName.ToLower().StartsWith(name.ToLower()), which makes very
// little sense to me.
IntPtr res = Runtime.PyObject_Call(py_import, args, kw);
if (res != IntPtr.Zero)
{
// There was no error.
if (fromlist && IsLoadAll(fromList))
{
var mod = ManagedType.GetManagedObject(res) as ModuleObject;
mod?.LoadNames();
}
return res;
}
// There was an error
if (!Exceptions.ExceptionMatches(Exceptions.ImportError))
{
// and it was NOT an ImportError; bail out here.
return IntPtr.Zero;
}
if (mod_name == string.Empty)
{
// Most likely a missing relative import.
// For example site-packages\bs4\builder\__init__.py uses it to check if a package exists:
// from . import _html5lib
// We don't support them anyway
return IntPtr.Zero;
}
// Otherwise, just clear the it.
Exceptions.Clear();
}
string[] names = realname.Split('.');
// Now we need to decide if the name refers to a CLR module,
// and may have to do an implicit load (for b/w compatibility)
// using the AssemblyManager. The assembly manager tries
// really hard not to use Python objects or APIs, because
// parts of it can run recursively and on strange threads.
//
// It does need an opportunity from time to time to check to
// see if sys.path has changed, in a context that is safe. Here
// we know we have the GIL, so we'll let it update if needed.
AssemblyManager.UpdatePath();
if (!AssemblyManager.IsValidNamespace(realname))
{
var loadExceptions = new List<Exception>();
if (!AssemblyManager.LoadImplicit(realname, assemblyLoadErrorHandler: loadExceptions.Add))
{
// May be called when a module being imported imports a module.
// In particular, I've seen decimal import copy import org.python.core
IntPtr importResult = Runtime.PyObject_Call(py_import, args, kw);
// TODO: use ModuleNotFoundError in Python 3.6+
if (importResult == IntPtr.Zero && loadExceptions.Count > 0
&& Exceptions.ExceptionMatches(Exceptions.ImportError))
{
loadExceptions.Add(new PythonException());
var importError = new PyObject(new BorrowedReference(Exceptions.ImportError));
importError.SetAttr("__cause__", new AggregateException(loadExceptions).ToPython());
Runtime.PyErr_SetObject(new BorrowedReference(Exceptions.ImportError), importError.Reference);
}
return importResult;
}
}
// See if sys.modules for this interpreter already has the
// requested module. If so, just return the existing module.
IntPtr modules = Runtime.PyImport_GetModuleDict();
IntPtr module = Runtime.PyDict_GetItem(modules, py_mod_name);
if (module != IntPtr.Zero)
{
if (fromlist)
{
if (IsLoadAll(fromList))
{
var mod = ManagedType.GetManagedObject(module) as ModuleObject;
mod?.LoadNames();
}
Runtime.XIncref(module);
return module;
}
if (clr_prefix != null)
{
return GetCLRModule(fromList);
}
module = Runtime.PyDict_GetItemString(modules, names[0]);
Runtime.XIncref(module);
return module;
}
Exceptions.Clear();
// Traverse the qualified module name to get the named module
// and place references in sys.modules as we go. Note that if
// we are running in interactive mode we pre-load the names in
// each module, which is often useful for introspection. If we
// are not interactive, we stick to just-in-time creation of
// objects at lookup time, which is much more efficient.
// NEW: The clr got a new module variable preload. You can
// enable preloading in a non-interactive python processing by
// setting clr.preload = True
ModuleObject head = mod_name == realname ? null : root;
ModuleObject tail = root;
root.InitializePreload();
foreach (string name in names)
{
ManagedType mt = tail.GetAttribute(name, true);
if (!(mt is ModuleObject))
{
Exceptions.SetError(Exceptions.ImportError, $"No module named {name}");
return IntPtr.Zero;
}
if (head == null)
{
head = (ModuleObject)mt;
}
tail = (ModuleObject)mt;
if (CLRModule.preload)
{
tail.LoadNames();
}
// Add the module to sys.modules
Runtime.PyDict_SetItemString(modules, tail.moduleName, tail.pyHandle);
// If imported from CLR add CLR.<modulename> to sys.modules as well
if (clr_prefix != null)
{
Runtime.PyDict_SetItemString(modules, clr_prefix + tail.moduleName, tail.pyHandle);
}
}
{
var mod = fromlist ? tail : head;
if (fromlist && IsLoadAll(fromList))
{
mod.LoadNames();
}
Runtime.XIncref(mod.pyHandle);
return mod.pyHandle;
}
}
private static bool IsLoadAll(IntPtr fromList)
{
if (CLRModule.preload)
{
return false;
}
if (Runtime.PySequence_Size(fromList) != 1)
{
return false;
}
IntPtr fp = Runtime.PySequence_GetItem(fromList, 0);
bool res = Runtime.GetManagedString(fp) == "*";
Runtime.XDecref(fp);
return res;
}
}
}