From 8416ed2cdae579c1a1ef6c3357fe838472c6d618 Mon Sep 17 00:00:00 2001
From: Panu Matilainen <pmatilai@redhat.com>
Date: Apr 23 2020 14:26:58 +0000
Subject: Monkey-patch .decode() method to our strings as a temporary compat crutch


As a temporary crutch to support faster deployment of the sane
string behavior on python3, monkey-patch a decode method into all
strings we return. This seems to be enough to fix practically all
API users who have already adapted to the long-standing broken API
on Python 3. API users compatible with both Python 2 and 3 never needed
this anyway. Issue a warning with pointer to the relevant bug when the
fake decode() method is used to alert users to the issue.

This is certainly an evil thing to do and will be removed as soon as
the critical users have been fixed to work with the new, corrected
behavior.

---

diff --git a/python/rpm/__init__.py b/python/rpm/__init__.py
index 54728bb..6d69eda 100644
--- a/python/rpm/__init__.py
+++ b/python/rpm/__init__.py
@@ -61,6 +61,9 @@ except ImportError:
 # backwards compatibility + give the same class both ways
 ts = TransactionSet
 
+def _fakedecode(self, encoding='utf-8', errors='strict'):
+    warnings.warn("decode() called on unicode string, see https://bugzilla.redhat.com/show_bug.cgi?id=1693751", UnicodeWarning, stacklevel=2)
+    return self
 
 def headerLoad(*args, **kwds):
     """DEPRECATED! Use rpm.hdr() instead."""
diff --git a/python/rpmmodule.c b/python/rpmmodule.c
index f822c2c..b43d7af 100644
--- a/python/rpmmodule.c
+++ b/python/rpmmodule.c
@@ -28,6 +28,7 @@
  */
 
 PyObject * pyrpmError;
+PyObject * fakedecode = NULL;
 
 static PyObject * archScore(PyObject * self, PyObject * arg)
 {
diff --git a/python/rpmsystem-py.h b/python/rpmsystem-py.h
index ae9418b..4011ba4 100644
--- a/python/rpmsystem-py.h
+++ b/python/rpmsystem-py.h
@@ -52,12 +52,29 @@ typedef Py_ssize_t (*lenfunc)(PyObject *);
 #define PyInt_AsSsize_t PyLong_AsSsize_t
 #endif
 
+PyObject * fakedecode;
+
 static inline PyObject * utf8FromString(const char *s)
 {
 /* In Python 3, we return all strings as surrogate-escaped utf-8 */
 #if PY_MAJOR_VERSION >= 3
-    if (s != NULL)
-	return PyUnicode_DecodeUTF8(s, strlen(s), "surrogateescape");
+    if (s != NULL) {
+	PyObject *o = PyUnicode_DecodeUTF8(s, strlen(s), "surrogateescape");
+	/* fish the fake decode function from python side if not done yet */
+	if (fakedecode == NULL) {
+	    PyObject *n = PyUnicode_FromString("rpm");
+	    PyObject *m = PyImport_Import(n);
+	    PyObject *md = PyModule_GetDict(m);
+	    fakedecode = PyDict_GetItemString(md, "_fakedecode");
+	    Py_DECREF(m);
+	    Py_DECREF(n);
+	}
+	if (fakedecode && o) {
+	    /* monkey-patch it into the string object as "decode" */
+	    PyDict_SetItemString(Py_TYPE(o)->tp_dict, "decode", fakedecode);
+	}
+	return o;
+    }
 #else
     if (s != NULL)
 	return PyBytes_FromString(s);