bpo-34672: Try to pass the C library's own timezone strings back to it.benjamin-musl-z-workaround

2 files changed, 21 insertions, 4 deletions

diff --git a/Misc/NEWS.d/next/Library/2018-09-13-21-04-23.bpo-34672.BYuKKS.rst b/Misc/NEWS.d/next/Library/2018-09-13-21-04-23.bpo-34672.BYuKKS.rst
new file mode 100644
index 0000000000..59d106b600
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2018-09-13-21-04-23.bpo-34672.BYuKKS.rst
@@ -0,0 +1,2 @@
+Add a workaround, so the ``'Z'`` :func:`time.strftime` specifier on the musl
+C library can work in some cases.
diff --git a/Modules/timemodule.c b/Modules/timemodule.c
index dbe2fbaf07..9170505712 100644
--- a/Modules/timemodule.c
+++ b/Modules/timemodule.c
@@ -565,11 +565,26 @@ gettmarg(PyObject *args, struct tm *p, const char *format)
     if (Py_TYPE(args) == &StructTimeType) {
         PyObject *item;
         item = PyTuple_GET_ITEM(args, 9);
-        p->tm_zone = item == Py_None ? NULL : (char*)PyUnicode_AsUTF8(item);
+        if (item != Py_None) {
+            p->tm_zone = PyUnicode_AsUTF8(item);
+            if (p->tm_zone == NULL) {
+                return 0;
+            }
+            // Make an attempt to return the C library's own timezone strings to
+            // it. musl refuses to process a tm_zone field unless it produced
+            // it. See issue #34672.
+            if (tzname[0] && strcmp(p->tm_zone, tzname[0]) == 0) {
+                p->tm_zone = tzname[0];
+            } else if (tzname[1] && strcmp(p->tm_zone, tzname[1]) == 0) {
+                p->tm_zone = tzname[1];
+            }
+        }
         item = PyTuple_GET_ITEM(args, 10);
-        p->tm_gmtoff = item == Py_None ? 0 : PyLong_AsLong(item);
-        if (PyErr_Occurred())
-            return 0;
+        if (item != Py_None) {
+            p->tm_gmtoff = PyLong_AsLong(item);
+            if (PyErr_Occurred())
+                return 0;
+        }
     }
 #endif /* HAVE_STRUCT_TM_TM_ZONE */
     return 1;