dynamically allocate log_str buffer for hex dumps

the developer needs to make sure that [info,debug,warning,error]_hex() is used
wisely in the code as all log_str are now heap-allocated

lib/src/common/log_filter.cc

@@ -31,6 +31,9 @@
 
 namespace srslte{
 
+#define CHARS_FOR_HEX_DUMP(size)                                                                                       \
+  (3 * size + size / 16 * 20) // 3 chars per byte, plus 20 per line for position and newline)
+
 log_filter::log_filter() : log()
 {
   do_tti      = false;
@@ -75,9 +78,9 @@ void log_filter::all_log(
   if (logger_h) {
     logger::unique_log_str_t log_str = nullptr;
 
-    if (long_msg) {
+    if (long_msg || hex) {
       // For long messages, dynamically allocate a new log_str with enough size outside the pool.
-      uint32_t log_str_msg_len = sizeof(buffer_tti) + sizeof(buffer_time) + 20 + size;
+      uint32_t log_str_msg_len = sizeof(buffer_tti) + sizeof(buffer_time) + 20 + strlen(msg) + CHARS_FOR_HEX_DUMP(size);
       log_str = logger::unique_log_str_t(new logger::log_str(nullptr, log_str_msg_len), logger::log_str_deleter());
     } else {
       log_str = logger_h->allocate_unique_log_str();