Explicitly return None for value-returning functions

get_clevis_config_from_protected_header() and get_distfile() return
values in some exit paths. In the default case, explicitly return `None`
to point out that the caller expects a return value.

Invert the conditions to move the error/default cases into the "then"
blocks, and the "main case" on the top level.

Spotted by CodeQL "Explicit returns mixed with implicit (fall through)
returns" notes.

pkg/storaged/luksmeta-monitor-hack.py

@@ -24,23 +24,25 @@ def get_clevis_config_from_protected_header(protected_header):
     header = b64_decode(protected_header).decode("utf-8")
     header_object = json.loads(header)
     clevis = header_object.get("clevis", None)
-    if clevis:
-        pin = clevis.get("pin", None)
-        if pin == "tang":
-            return clevis
-        elif pin == "sss":
-            subpins = {}
-            jwes = clevis["sss"]["jwe"]
-            for jwe in jwes:
-                subconf = get_clevis_config_from_jwe(jwe)
-                subpin = subconf["pin"]
-                if subpin not in subpins:
-                    subpins[subpin] = [subconf[subpin]]
-                else:
-                    subpins[subpin].append(subconf[subpin])
-            return {"pin": "sss", "sss": {"t": clevis["sss"]["t"], "pins": subpins}}
-        else:
-            return {"pin": pin, pin: {}}
+    if clevis is None:
+        return None
+
+    pin = clevis.get("pin", None)
+    if pin == "tang":
+        return clevis
+    elif pin == "sss":
+        subpins = {}
+        jwes = clevis["sss"]["jwe"]
+        for jwe in jwes:
+            subconf = get_clevis_config_from_jwe(jwe)
+            subpin = subconf["pin"]
+            if subpin not in subpins:
+                subpins[subpin] = [subconf[subpin]]
+            else:
+                subpins[subpin].append(subconf[subpin])
+        return {"pin": "sss", "sss": {"t": clevis["sss"]["t"], "pins": subpins}}
+    else:
+        return {"pin": pin, pin: {}}
 
 
 def get_clevis_config_from_jwe(jwe):

test/common/lcov.py

@@ -157,19 +157,22 @@ def get_dist_map(package):
 
 def get_distfile(url, dist_map, webpack_name):
     parts = url.split("/")
-    if len(parts) > 2 and "cockpit" in parts:
-        base = parts[-2]
-        file = parts[-1]
-        if file == "manifests.js":
-            return None
-        if base in dist_map:
-            path = dist_map[base] + "/" + file
-        else:
-            path = f"{BASE_DIR}/dist/" + base + "/" + file
-        if os.path.exists(path) and os.path.exists(path + ".map"):
-            return DistFile(path, webpack_name)
-        else:
-            sys.stderr.write(f"SKIP {url} -> {path}\n")
+    if len(parts) < 3 or "cockpit" not in parts:
+        return None
+
+    base = parts[-2]
+    file = parts[-1]
+    if file == "manifests.js":
+        return None
+    if base in dist_map:
+        path = dist_map[base] + "/" + file
+    else:
+        path = f"{BASE_DIR}/dist/" + base + "/" + file
+    if os.path.exists(path) and os.path.exists(path + ".map"):
+        return DistFile(path, webpack_name)
+    else:
+        sys.stderr.write(f"SKIP {url} -> {path}\n")
+        return None
 
 
 def grow_array(arr, size, val):