in_systemd: fix memory leak

Fix a memory leak in the systemd input plugin.
If option "lowercase" was on, the temporary buffer to
convert a key to the lower-case string was not freed.

Signed-off-by: Bodo Petermann <b.petermann@syseleven.de>

plugins/in_systemd/systemd.c

@@ -138,7 +138,7 @@ static int systemd_enumerate_data_store(struct flb_config *config,
     const char *sep;
     const char *key;
     const char *val;
-    char *buf = NULL;
+    char *buf;
     struct cfl_kvlist *kvlist = format_context;
     struct flb_systemd_config *ctx = plugin_context;
     struct cfl_variant *cfl_val = NULL;
@@ -155,31 +155,19 @@ static int systemd_enumerate_data_store(struct flb_config *config,
 
     len = (sep - key);
     key_len = len;
-
-    if (ctx->lowercase == FLB_TRUE) {
-        /*
-         * Ensure buf to have enough space for the key because the libsystemd
-         * might return larger data than the threshold.
-         */
-        if (buf == NULL) {
-            buf = flb_sds_create_len(NULL, ctx->threshold);
-        }
-        if (flb_sds_alloc(buf) < len) {
-            buf = flb_sds_increase(buf, len - flb_sds_alloc(buf));
-        }
-        for (i = 0; i < len; i++) {
-            buf[i] = tolower(key[i]);
-        }
-        list_key = flb_sds_create_len(buf, key_len);
-    }
-    else {
-        list_key = flb_sds_create_len(key, key_len);
-    }
+    list_key = flb_sds_create_len(key, key_len);
 
     if (!list_key) {
         return -1;
     }
 
+    if (ctx->lowercase == FLB_TRUE) {
+        buf = list_key;
+        for (i = 0; i < key_len; i++) {
+            buf[i] = tolower(buf[i]);
+        }
+    }
+
     /* Check existence */
     cfl_val = NULL;
     cfl_val = cfl_kvlist_fetch_s(kvlist, list_key, key_len);
@@ -274,7 +262,6 @@ static int in_systemd_collect(struct flb_input_instance *ins,
     uint64_t usec;
     size_t length;
     const char *key;
-    char *buf = NULL;
 #ifdef FLB_HAVE_SQLDB
     char *cursor = NULL;
 #endif
@@ -458,8 +445,6 @@ static int in_systemd_collect(struct flb_input_instance *ins,
         }
     }
 
-    flb_sds_destroy(buf);
-
 #ifdef FLB_HAVE_SQLDB
     /* Save cursor */
     if (ctx->db) {