ovsdb-error: New function ovsdb_error_to_string_free().

This allows slight code simplifications across the tree.

Signed-off-by: Ben Pfaff <blp@ovn.org>
Tested-by: Yifeng Sun <pkusunyifeng@gmail.com>
Reviewed-by: Yifeng Sun <pkusunyifeng@gmail.com>

4 files changed, 30 insertions, 16 deletions

diff --git a/lib/ovsdb-data.c b/lib/ovsdb-data.c
index 5d560fd98..3ddf5f5bd 100644
--- a/lib/ovsdb-data.c
+++ b/lib/ovsdb-data.c
@@ -1,4 +1,4 @@
-/* Copyright (c) 2009, 2010, 2011, 2012, 2014, 2016 Nicira, Inc.
+/* Copyright (c) 2009, 2010, 2011, 2012, 2014, 2016, 2017 Nicira, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -664,8 +664,7 @@ ovsdb_atom_from_string(union ovsdb_atom *atom,
             free(*range_end_atom);
             *range_end_atom = NULL;
         }
-        msg = ovsdb_error_to_string(error);
-        ovsdb_error_destroy(error);
+        msg = ovsdb_error_to_string_free(error);
     }
     return msg;
 }
diff --git a/lib/ovsdb-error.c b/lib/ovsdb-error.c
index d8161e6d7..9b1af68c6 100644
--- a/lib/ovsdb-error.c
+++ b/lib/ovsdb-error.c
@@ -1,4 +1,4 @@
-/* Copyright (c) 2009, 2010, 2011, 2012, 2016 Nicira, Inc.
+/* Copyright (c) 2009, 2010, 2011, 2012, 2016, 2017 Nicira, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -153,11 +153,9 @@ ovsdb_internal_error(struct ovsdb_error *inner_error,
     ds_put_format(&ds, " (%s %s)", program_name, VERSION);
 
     if (inner_error) {
-        char *s = ovsdb_error_to_string(inner_error);
+        char *s = ovsdb_error_to_string_free(inner_error);
         ds_put_format(&ds, " (generated from: %s)", s);
         free(s);
-
-        ovsdb_error_destroy(inner_error);
     }
 
     error = ovsdb_error("internal error", "%s", ds_cstr(&ds));
@@ -223,6 +221,8 @@ ovsdb_error_to_json(const struct ovsdb_error *error)
     return json;
 }
 
+/* Returns 'error' converted to a string suitable for use as an error message.
+ * The caller must free the returned string (with free()). */
 char *
 ovsdb_error_to_string(const struct ovsdb_error *error)
 {
@@ -240,6 +240,24 @@ ovsdb_error_to_string(const struct ovsdb_error *error)
     return ds_steal_cstr(&ds);
 }
 
+/* Returns 'error' converted to a string suitable for use as an error message.
+ * The caller must free the returned string (with free()).
+ *
+ * If 'error' is NULL, returns NULL.
+ *
+ * Also, frees 'error'. */
+char *
+ovsdb_error_to_string_free(struct ovsdb_error *error)
+{
+    if (error) {
+        char *s = ovsdb_error_to_string(error);
+        ovsdb_error_destroy(error);
+        return s;
+    } else {
+        return NULL;
+    }
+}
+
 const char *
 ovsdb_error_get_tag(const struct ovsdb_error *error)
 {
@@ -254,9 +272,8 @@ ovsdb_error_assert(struct ovsdb_error *error)
 {
     if (error) {
         static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 1);
-        char *s = ovsdb_error_to_string(error);
+        char *s = ovsdb_error_to_string_free(error);
         VLOG_ERR_RL(&rl, "unexpected ovsdb error: %s", s);
         free(s);
-        ovsdb_error_destroy(error);
     }
 }
diff --git a/lib/ovsdb-error.h b/lib/ovsdb-error.h
index da91b7499..ff9b889a8 100644
--- a/lib/ovsdb-error.h
+++ b/lib/ovsdb-error.h
@@ -1,4 +1,4 @@
-/* Copyright (c) 2009, 2010, 2011 Nicira, Inc.
+/* Copyright (c) 2009, 2010, 2011, 2016, 2017 Nicira, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -64,6 +64,7 @@ struct ovsdb_error *ovsdb_error_clone(const struct ovsdb_error *)
     OVS_WARN_UNUSED_RESULT;
 
 char *ovsdb_error_to_string(const struct ovsdb_error *);
+char *ovsdb_error_to_string_free(struct ovsdb_error *);
 struct json *ovsdb_error_to_json(const struct ovsdb_error *);
 
 const char *ovsdb_error_get_tag(const struct ovsdb_error *);
diff --git a/lib/ovsdb-idl.c b/lib/ovsdb-idl.c
index 2a3405b6f..96e5c1f58 100644
--- a/lib/ovsdb-idl.c
+++ b/lib/ovsdb-idl.c
@@ -1455,10 +1455,9 @@ ovsdb_idl_send_schema_request(struct ovsdb_idl *idl)
 static void
 log_error(struct ovsdb_error *error)
 {
-    char *s = ovsdb_error_to_string(error);
+    char *s = ovsdb_error_to_string_free(error);
     VLOG_WARN("error parsing database schema: %s", s);
     free(s);
-    ovsdb_error_destroy(error);
 }
 
 /* Frees 'schema', which is in the format returned by parse_schema(). */
@@ -1976,12 +1975,11 @@ ovsdb_idl_row_change__(struct ovsdb_idl_row *row, const struct json *row_json,
 
             ovsdb_datum_destroy(&datum, &column->type);
         } else {
-            char *s = ovsdb_error_to_string(error);
+            char *s = ovsdb_error_to_string_free(error);
             VLOG_WARN_RL(&syntax_rl, "error parsing column %s in row "UUID_FMT
                          " in table %s: %s", column_name,
                          UUID_ARGS(&row->uuid), table->class_->name, s);
             free(s);
-            ovsdb_error_destroy(error);
         }
     }
     return changed;
@@ -4186,11 +4184,10 @@ ovsdb_idl_txn_process_insert_reply(struct ovsdb_idl_txn_insert *insert,
 
     error = ovsdb_atom_from_json(&uuid, &uuid_type, json_uuid, NULL);
     if (error) {
-        char *s = ovsdb_error_to_string(error);
+        char *s = ovsdb_error_to_string_free(error);
         VLOG_WARN_RL(&syntax_rl, "\"insert\" reply \"uuid\" is not a JSON "
                      "UUID: %s", s);
         free(s);
-        ovsdb_error_destroy(error);
         return false;
     }