zdev: Improve handling of invalid udev rules

Add basic checking when reading udev rules and print a warning when an
invalid udev rule file is found. This addresses the current inconsistent
behavior:

  - CCW devices: invalid udev rules are considered valid
  - CCW group devices: invalid udev rules are silently ignored
  - zFCP LUNs: invalid rules cause chzdev/lszdev to silently terminate
    with non-zero exit code

Checks include a test for empty or truncated rule files that might be
the result of an interrupted chzdev operation, or a file system or I/O
error.

Note: The recommended way to correct invalid udev rules is to either
remove the offending rules file, or to repeat the associated persistent
configuration step.

Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Reported-by: Steffen Maier <maier@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

zdev/include/udev.h

@@ -40,6 +40,7 @@ struct udev_file {
 };
 
 exit_code_t udev_read_file(const char *, struct udev_file **);
+bool udev_file_is_empty(struct udev_file *file);
 void udev_free_file(struct udev_file *);
 void udev_file_print(struct udev_file *);
 

zdev/src/udev.c

@@ -346,6 +346,21 @@ exit_code_t udev_read_file(const char *path, struct udev_file **file_ptr)
 	return EXIT_OK;
 }
 
+/* Check if a udev file does not contain any statements. */
+bool udev_file_is_empty(struct udev_file *file)
+{
+	struct udev_line_node *l;
+
+	if (!file)
+		return true;
+	util_list_iterate(&file->lines, l) {
+		if (l->line[0])
+			return false;
+	}
+
+	return true;
+}
+
 static bool get_ids_cb(const char *filename, void *data)
 {
 	char *prefix = data;

zdev/src/udev_ccw.c

@@ -108,8 +108,13 @@ exit_code_t udev_ccw_read_device(struct device *dev, bool autoconf)
 	rc = udev_read_file(path, &file);
 	if (rc)
 		goto out;
-	udev_file_get_settings(file, st->dev_attribs, state->settings);
-	state->exists = 1;
+	if (udev_file_is_empty(file)) {
+		warn_once("Warning: Invalid udev rule: %s\n", path);
+		state->exists = 0;
+	} else {
+		udev_file_get_settings(file, st->dev_attribs, state->settings);
+		state->exists = 1;
+	}
 	udev_free_file(file);
 
 out:

zdev/src/udev_ccwgroup.c

@@ -163,9 +163,14 @@ exit_code_t udev_ccwgroup_read_device(struct device *dev, bool autoconf)
 	rc = udev_read_file(path, &file);
 	if (rc)
 		goto out;
-	udev_file_get_settings(file, st->dev_attribs, state->settings);
-	expand_id(dev, file);
-	state->exists = 1;
+	if (udev_file_is_empty(file)) {
+		warn_once("Warning: Invalid udev rule: %s\n", path);
+		state->exists = 0;
+	} else {
+		udev_file_get_settings(file, st->dev_attribs, state->settings);
+		expand_id(dev, file);
+		state->exists = 1;
+	}
 	udev_free_file(file);
 
 out:
@@ -344,6 +349,9 @@ static char *read_full_id(const char *path)
 out:
 	free(text);
 
+	if (!id)
+		warn_once("Warning: Invalid udev rule: %s\n", path);
+
 	return id;
 }
 

zdev/src/udev_zfcp_lun.c

@@ -393,6 +393,9 @@ static exit_code_t udev_read_zfcp_lun_rule(const char *filename,
 out:
 	udev_free_file(file);
 
+	if (!node)
+		warn_once("Warning: Invalid udev rule: %s\n", filename);
+
 	return rc;
 }
 
@@ -475,11 +478,17 @@ static void zfcp_lun_node_to_state(struct zfcp_lun_node *node,
 	struct attrib *a;
 	char *name;
 
-	state->exists = 1;
 	state->modified = 0;
 	state->deconfigured = 0;
 	state->definable = 0;
 
+	if (!node) {
+		state->exists = 0;
+		return;
+	}
+
+	state->exists = 1;
+
 	util_list_iterate(&node->fc_settings->list, s) {
 		a = attrib_find(attribs, s->name);
 		setting_list_add(state->settings,
@@ -519,10 +528,7 @@ exit_code_t udev_zfcp_lun_read_device(struct device *dev, bool autoconf)
 		goto out;
 
 	node = zfcp_lun_node_find(luns, dev->devid);
-	if (node)
-		zfcp_lun_node_to_state(node, st->dev_attribs, state);
-	else
-		rc = EXIT_DEVICE_NOT_FOUND;
+	zfcp_lun_node_to_state(node, st->dev_attribs, state);
 
 out:
 	zfcp_lun_node_list_free(luns);