Libguestfs - Apr 2020 - [PATCH] python: Fix UnicodeError in inspect_list_applications2() (RHBZ#1684004)

The python3 bindings create unicode objects from application strings
on the guest (i.e. installed rpm, deb packages).
It is documented that rpm package fields such as description should be
utf8 encoded - however in some cases they are not a valid unicode
string, on SLES11 SP4 the following packages fail to be converted to
unicode using guestfs_int_py_fromstring() (which invokes
PyUnicode_FromString()):

 PackageKit
 aaa_base
 coreutils
 dejavu
 desktop-data-SLED
 gnome-utils
 hunspell
 hunspell-32bit
 hunspell-tools
 libblocxx6
 libexif
 libgphoto2
 libgtksourceview-2_0-0
 libmpfr1
 libopensc2
 libopensc2-32bit
 liborc-0_4-0
 libpackagekit-glib10
 libpixman-1-0
 libpixman-1-0-32bit
 libpoppler-glib4
 libpoppler5
 libsensors3
 libtelepathy-glib0
 m4
 opensc
 opensc-32bit
 permissions
 pinentry
 poppler-tools
 python-gtksourceview
 splashy
 syslog-ng
 tar
 tightvnc
 xorg-x11
 xorg-x11-xauth
 yast2-mouse

This is a surgical fix for inspect_list_applications2()'s description
field.

Signed-off-by: Sam Eiderman <sameid@google.com>
---
 generator/python.ml | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/generator/python.ml b/generator/python.ml
index f0d6b5d96..7394a943a 100644
--- a/generator/python.ml
+++ b/generator/python.ml
@@ -170,6 +170,14 @@ and generate_python_structs ()          function
         | name, FString ->
             pr "  value = guestfs_int_py_fromstring (%s->%s);\n"
typ name;
+            (match typ, name with
+            | "application", "app_description"
+            | "application2", "app2_description" ->
+                pr "  if (value == NULL) {\n";
+                pr "    value = guestfs_int_py_fromstring
(\"\");\n";
+                pr "    PyErr_Clear ();\n";
+                pr "  }\n";
+            | _ -> pr ""; );
             pr "  if (value == NULL)\n";
             pr "    goto err;\n";
             pr "  PyDict_SetItemString (dict, \"%s\",
value);\n" name;
-- 
2.26.1.301.g55bc3eb7cb9-goog