DLT daemon improvement - dlt_init()-check

DLT daemon improvement - parameter value range check

Adapt unit tests to check for enum return values

Changed C version to gnu99 and C++ version to gnu++0c

Signed-off-by: Alexander Wenzel <Alexander.AW.Wenzel@bmw.de>

6 files changed, 310 insertions, 274 deletions

diff --git a/include/dlt/dlt_client.h b/include/dlt/dlt_client.h
index 6f62a67..a7ff7d4 100644
--- a/include/dlt/dlt_client.h
+++ b/include/dlt/dlt_client.h
@@ -98,31 +98,31 @@ void dlt_client_register_message_callback(int (*registerd_callback) (DltMessage
  * Initialising dlt client structure
  * @param client pointer to dlt client structure
  * @param verbose if set to true verbose information is printed out.
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_client_init(DltClient *client, int verbose);
+DltReturnValue dlt_client_init(DltClient *client, int verbose);
 /**
  * Connect to dlt daemon using the information from the dlt client structure
  * @param client pointer to dlt client structure
  * @param verbose if set to true verbose information is printed out.
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_client_connect(DltClient *client, int verbose);
+DltReturnValue dlt_client_connect(DltClient *client, int verbose);
 /**
  * Cleanup dlt client structure
  * @param client pointer to dlt client structure
  * @param verbose if set to true verbose information is printed out.
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_client_cleanup(DltClient *client, int verbose);
+DltReturnValue dlt_client_cleanup(DltClient *client, int verbose);
 /**
  * Main Loop of dlt client application
  * @param client pointer to dlt client structure
  * @param data pointer to data to be provided to the main loop
  * @param verbose if set to true verbose information is printed out.
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_client_main_loop(DltClient *client, void *data, int verbose);
+DltReturnValue dlt_client_main_loop(DltClient *client, void *data, int verbose);
 /**
  * Send ancontrol message to the dlt daemon
  * @param client pointer to dlt client structure
@@ -130,9 +130,9 @@ int dlt_client_main_loop(DltClient *client, void *data, int verbose);
  * @param ctid context id
  * @param payload Buffer filled with control message data
  * @param size Size of control message data
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_client_send_ctrl_msg(DltClient *client, char *apid, char *ctid, uint8_t *payload, uint32_t size);
+DltReturnValue dlt_client_send_ctrl_msg(DltClient *client, char *apid, char *ctid, uint8_t *payload, uint32_t size);
 /**
  * Send an injection message to the dlt daemon
  * @param client pointer to dlt client structure
@@ -141,68 +141,68 @@ int dlt_client_send_ctrl_msg(DltClient *client, char *apid, char *ctid, uint8_t
  * @param serviceID service id
  * @param buffer Buffer filled with injection message data
  * @param size Size of injection data within buffer
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_client_send_inject_msg(DltClient *client, char *apid, char *ctid, uint32_t serviceID, uint8_t *buffer, uint32_t size);
+DltReturnValue dlt_client_send_inject_msg(DltClient *client, char *apid, char *ctid, uint32_t serviceID, uint8_t *buffer, uint32_t size);
 /**
  * Send an set  log level message to the dlt daemon
  * @param client pointer to dlt client structure
  * @param apid application id
  * @param ctid context id
  * @param SendLogLevel Log Level
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_client_send_log_level(DltClient *client, char *apid, char *ctid, uint8_t logLevel);
+DltReturnValue dlt_client_send_log_level(DltClient *client, char *apid, char *ctid, uint8_t logLevel);
 /**
  * Send a set trace status message to the dlt daemon
  * @param client pointer to dlt client structure
  * @param apid application id
  * @param ctid context id
  * @param defaultTraceStatus Default Trace Status
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_client_send_trace_status(DltClient *client, char *apid, char *ctid, uint8_t traceStatus);
+DltReturnValue dlt_client_send_trace_status(DltClient *client, char *apid, char *ctid, uint8_t traceStatus);
 /**
  * Send the default log level to the dlt daemon
  * @param client pointer to dlt client structure
  * @param defaultLogLevel Default Log Level
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_client_send_default_log_level(DltClient *client, uint8_t defaultLogLevel);
+DltReturnValue dlt_client_send_default_log_level(DltClient *client, uint8_t defaultLogLevel);
 /**
  * Send the default trace status to the dlt daemon
  * @param client pointer to dlt client structure
  * @param defaultTraceStatus Default Trace Status
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_client_send_default_trace_status(DltClient *client, uint8_t defaultTraceStatus);
+DltReturnValue dlt_client_send_default_trace_status(DltClient *client, uint8_t defaultTraceStatus);
 /**
  * Send the timing pakets status to the dlt daemon
  * @param client pointer to dlt client structure
  * @param timingPakets Timing pakets enabled
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_client_send_timing_pakets(DltClient *client, uint8_t timingPakets);
+DltReturnValue dlt_client_send_timing_pakets(DltClient *client, uint8_t timingPakets);
 /**
  * Send the store config command to the dlt daemon
  * @param client pointer to dlt client structure
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_client_send_store_config(DltClient *client);
+DltReturnValue dlt_client_send_store_config(DltClient *client);
 /**
  * Send the reset to factory default command to the dlt daemon
  * @param client pointer to dlt client structure
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_client_send_reset_to_factory_default(DltClient *client);
+DltReturnValue dlt_client_send_reset_to_factory_default(DltClient *client);
 
 /**
  * Set baudrate within dlt client structure
  * @param client pointer to dlt client structure
  * @param baudrate Baudrate
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_client_setbaudrate(DltClient *client, int baudrate);
+DltReturnValue dlt_client_setbaudrate(DltClient *client, int baudrate);
 
 #ifdef __cplusplus
 }
diff --git a/include/dlt/dlt_common.h b/include/dlt/dlt_common.h
index da9835c..4b7f45f 100644
--- a/include/dlt/dlt_common.h
+++ b/include/dlt/dlt_common.h
@@ -667,7 +667,7 @@ extern "C"
      * @param size number of bytes to be printed.
      * @return negative value if there was an error
      */
-    int dlt_print_hex_string(char *text,int textlength,uint8_t *ptr,int size);
+    DltReturnValue dlt_print_hex_string(char *text,int textlength,uint8_t *ptr,int size);
     /**
      * Helper function to print a byte array in hex and ascii into a string.
      * @param text pointer to a ASCII string, in which the text is written
@@ -677,7 +677,7 @@ extern "C"
      * @param html output is html? 0 - false, 1 - true
      * @return negative value if there was an error
      */
-    int dlt_print_mixed_string(char *text,int textlength,uint8_t *ptr,int size,int html);
+    DltReturnValue dlt_print_mixed_string(char *text,int textlength,uint8_t *ptr,int size,int html);
     /**
      * Helper function to print a byte array in ascii into a string.
      * @param text pointer to a ASCII string, in which the text is written
@@ -686,7 +686,7 @@ extern "C"
      * @param size number of bytes to be printed.
      * @return negative value if there was an error
      */
-    int dlt_print_char_string(char **text,int textlength,uint8_t *ptr,int size);
+    DltReturnValue dlt_print_char_string(char **text,int textlength,uint8_t *ptr,int size);
 
     /**
      * Helper function to print an id.
@@ -716,14 +716,14 @@ extern "C"
      * @param verbose if set to true verbose information is printed out.
      * @return negative value if there was an error
      */
-    int dlt_filter_init(DltFilter *filter,int verbose);
+    DltReturnValue dlt_filter_init(DltFilter *filter,int verbose);
     /**
      * Free the used memory by the organising structure of filter.
      * @param filter pointer to structure of organising DLT filter
      * @param verbose if set to true verbose information is printed out.
      * @return negative value if there was an error
      */
-    int dlt_filter_free(DltFilter *filter,int verbose);
+    DltReturnValue dlt_filter_free(DltFilter *filter,int verbose);
     /**
      * Load filter list from file.
      * @param filter pointer to structure of organising DLT filter
@@ -731,7 +731,7 @@ extern "C"
      * @param verbose if set to true verbose information is printed out.
      * @return negative value if there was an error
      */
-    int dlt_filter_load(DltFilter *filter,const char *filename,int verbose);
+    DltReturnValue dlt_filter_load(DltFilter *filter,const char *filename,int verbose);
     /**
      * Save filter list to file.
      * @param filter pointer to structure of organising DLT filter
@@ -739,7 +739,7 @@ extern "C"
      * @param verbose if set to true verbose information is printed out.
      * @return negative value if there was an error
      */
-    int dlt_filter_save(DltFilter *filter,const char *filename,int verbose);
+    DltReturnValue dlt_filter_save(DltFilter *filter,const char *filename,int verbose);
     /**
      * Find index of filter in filter list
      * @param filter pointer to structure of organising DLT filter
@@ -757,7 +757,7 @@ extern "C"
      * @param verbose if set to true verbose information is printed out.
      * @return negative value if there was an error
      */
-    int dlt_filter_add(DltFilter *filter,const char *apid,const char *ctid,int verbose);
+    DltReturnValue dlt_filter_add(DltFilter *filter,const char *apid,const char *ctid,int verbose);
     /**
      * Delete filter from filter list
      * @param filter pointer to structure of organising DLT filter
@@ -766,7 +766,7 @@ extern "C"
      * @param verbose if set to true verbose information is printed out.
      * @return negative value if there was an error
      */
-    int dlt_filter_delete(DltFilter *filter,const char *apid,const char *ctid,int verbose);
+    DltReturnValue dlt_filter_delete(DltFilter *filter,const char *apid,const char *ctid,int verbose);
 
     /**
      * Initialise the structure used to access a DLT message.
@@ -775,14 +775,14 @@ extern "C"
      * @param verbose if set to true verbose information is printed out.
      * @return negative value if there was an error
      */
-    int dlt_message_init(DltMessage *msg,int verbose);
+    DltReturnValue dlt_message_init(DltMessage *msg,int verbose);
     /**
      * Free the used memory by the organising structure of file.
      * @param msg pointer to structure of organising access to DLT messages
      * @param verbose if set to true verbose information is printed out.
      * @return negative value if there was an error
      */
-    int dlt_message_free(DltMessage *msg,int verbose);
+    DltReturnValue dlt_message_free(DltMessage *msg,int verbose);
     /**
      * Print Header into an ASCII string.
      * This function calls dlt_message_header_flags() with flags=DLT_HEADER_SHOW_ALL
@@ -792,7 +792,7 @@ extern "C"
      * @param verbose if set to true verbose information is printed out.
      * @return negative value if there was an error
      */
-    int dlt_message_header(DltMessage *msg,char *text,int textlength,int verbose);
+    DltReturnValue dlt_message_header(DltMessage *msg,char *text,int textlength,int verbose);
     /**
      * Print Header into an ASCII string, selective.
      * @param msg pointer to structure of organising access to DLT messages
@@ -802,7 +802,7 @@ extern "C"
      * @param verbose if set to true verbose information is printed out.
      * @return negative value if there was an error
      */
-    int dlt_message_header_flags(DltMessage *msg,char *text,int textlength,int flags, int verbose);
+    DltReturnValue dlt_message_header_flags(DltMessage *msg,char *text,int textlength,int flags, int verbose);
     /**
      * Print Payload into an ASCII string.
      * @param msg pointer to structure of organising access to DLT messages
@@ -812,7 +812,7 @@ extern "C"
      * @param verbose if set to true verbose information is printed out.
      * @return negative value if there was an error
      */
-    int dlt_message_payload(DltMessage *msg,char *text,int textlength,int type,int verbose);
+    DltReturnValue dlt_message_payload(DltMessage *msg,char *text,int textlength,int type,int verbose);
     /**
      * Check if message is filtered or not. All filters are applied (logical OR).
      * @param msg pointer to structure of organising access to DLT messages
@@ -820,7 +820,7 @@ extern "C"
      * @param verbose if set to true verbose information is printed out.
      * @return 1 = filter matches, 0 = filter does not match, negative value if there was an error
      */
-    int dlt_message_filter_check(DltMessage *msg,DltFilter *filter,int verbose);
+    DltReturnValue dlt_message_filter_check(DltMessage *msg,DltFilter *filter,int verbose);
 
     /**
      * Read message from memory buffer.
@@ -840,7 +840,7 @@ extern "C"
      * @param verbose if set to true verbose information is printed out.
      * @return negative value if there was an error
      */
-    int dlt_message_get_extraparameters(DltMessage *msg,int verbose);
+    DltReturnValue dlt_message_get_extraparameters(DltMessage *msg,int verbose);
 
     /**
      * Set standard header extra parameters
@@ -848,7 +848,7 @@ extern "C"
      * @param verbose if set to true verbose information is printed out.
      * @return negative value if there was an error
      */
-    int dlt_message_set_extraparameters(DltMessage *msg,int verbose);
+    DltReturnValue dlt_message_set_extraparameters(DltMessage *msg,int verbose);
 
     /**
      * Initialise the structure used to access a DLT file.
@@ -857,7 +857,7 @@ extern "C"
      * @param verbose if set to true verbose information is printed out.
      * @return negative value if there was an error
      */
-    int dlt_file_init(DltFile *file,int verbose);
+    DltReturnValue dlt_file_init(DltFile *file,int verbose);
     /**
      * Set a list to filters.
      * This function should be called before loading a DLT file, if filters should be used.
@@ -868,7 +868,7 @@ extern "C"
      * @param verbose if set to true verbose information is printed out.
      * @return negative value if there was an error
      */
-    int dlt_file_set_filter(DltFile *file,DltFilter *filter,int verbose);
+    DltReturnValue dlt_file_set_filter(DltFile *file,DltFilter *filter,int verbose);
     /**
      * Initialising loading a DLT file.
      * @param file pointer to structure of organising access to DLT file
@@ -876,7 +876,7 @@ extern "C"
      * @param verbose if set to true verbose information is printed out.
      * @return negative value if there was an error
      */
-    int dlt_file_open(DltFile *file,const char *filename,int verbose);
+    DltReturnValue dlt_file_open(DltFile *file,const char *filename,int verbose);
     /**
      * Find next message in the DLT file and parse them.
      * This function finds the next message in the DLT file.
@@ -885,7 +885,7 @@ extern "C"
      * @param verbose if set to true verbose information is printed out.
      * @return 0 = message does not match filter, 1 = message was read, negative value if there was an error
      */
-    int dlt_file_read(DltFile *file,int verbose);
+    DltReturnValue dlt_file_read(DltFile *file,int verbose);
     /**
      * Find next message in the DLT file in RAW format (without storage header) and parse them.
      * This function finds the next message in the DLT file.
@@ -895,21 +895,21 @@ extern "C"
      * @param verbose if set to true verbose information is printed out.
      * @return 0 = message does not match filter, 1 = message was read, negative value if there was an error
      */
-    int dlt_file_read_raw(DltFile *file,int resync,int verbose);
+    DltReturnValue dlt_file_read_raw(DltFile *file,int resync,int verbose);
     /**
      * Closing loading a DLT file.
      * @param file pointer to structure of organising access to DLT file
      * @param verbose if set to true verbose information is printed out.
      * @return negative value if there was an error
      */
-    int dlt_file_close(DltFile *file,int verbose);
+    DltReturnValue dlt_file_close(DltFile *file,int verbose);
     /**
      * Load standard header of a message from file
      * @param file pointer to structure of organising access to DLT file
      * @param verbose if set to true verbose information is printed out.
      * @return negative value if there was an error
      */
-    int dlt_file_read_header(DltFile *file,int verbose);
+    DltReturnValue dlt_file_read_header(DltFile *file,int verbose);
     /**
      * Load standard header of a message from file in RAW format (without storage header)
      * @param file pointer to structure of organising access to DLT file
@@ -917,7 +917,7 @@ extern "C"
      * @param verbose if set to true verbose information is printed out.
      * @return negative value if there was an error
      */
-    int dlt_file_read_header_raw(DltFile *file,int resync,int verbose);
+    DltReturnValue dlt_file_read_header_raw(DltFile *file,int resync,int verbose);
     /**
      * Load, if available in message, extra standard header fields and
      * extended header of a message from file
@@ -926,7 +926,7 @@ extern "C"
      * @param verbose if set to true verbose information is printed out.
      * @return negative value if there was an error
      */
-    int dlt_file_read_header_extended(DltFile *file, int verbose);
+    DltReturnValue dlt_file_read_header_extended(DltFile *file, int verbose);
     /**
      * Load payload of a message from file
      * (dlt_file_read_header() must have been called before this call!)
@@ -934,7 +934,7 @@ extern "C"
      * @param verbose if set to true verbose information is printed out.
      * @return negative value if there was an error
      */
-    int dlt_file_read_data(DltFile *file, int verbose);
+    DltReturnValue dlt_file_read_data(DltFile *file, int verbose);
     /**
      * Load headers and payload of a message selected by the index.
      * If filters are set, index is based on the filtered list.
@@ -943,14 +943,14 @@ extern "C"
      * @param verbose if set to true verbose information is printed out.
      * @return number of messages loaded, negative value if there was an error
      */
-    int dlt_file_message(DltFile *file,int index,int verbose);
+    DltReturnValue dlt_file_message(DltFile *file,int index,int verbose);
     /**
      * Free the used memory by the organising structure of file.
      * @param file pointer to structure of organising access to DLT file
      * @param verbose if set to true verbose information is printed out.
      * @return negative value if there was an error
      */
-    int dlt_file_free(DltFile *file,int verbose);
+    DltReturnValue dlt_file_free(DltFile *file,int verbose);
 
     /**
      * Set internal logging filename if mode 2
@@ -973,7 +973,22 @@ extern "C"
      * @param s Pointer to ASCII string with null-termination
      * @return negative value if there was an error
      */
-    int dlt_log(int prio, char *s);
+    DltReturnValue dlt_log(int prio, char *s);
+    /**
+     * Log with variable arguments to (external) logging facility (like printf)
+     * @param prio priority (see syslog() call)
+     * @param format format string for log message
+     * @return negative value if there was an error
+     */
+    DltReturnValue dlt_vlog(int prio, const char *format, ...);
+    /**
+     * Log size bytes with variable arguments to (external) logging facility (similar to snprintf)
+     * @param prio priority (see syslog() call)
+     * @param size number of bytes to log
+     * @param format format string for log message
+     * @return negative value if there was an error
+     */
+    DltReturnValue dlt_vnlog(int prio, size_t size, const char *format, ...);
     /**
      * De-Initialize (external) logging facility
      */
@@ -986,23 +1001,23 @@ extern "C"
      * @param _buffersize size of data buffer for storing the received data
      * @return negative value if there was an error
      */
-    int dlt_receiver_init(DltReceiver *receiver,int _fd, int _buffersize);
+    DltReturnValue dlt_receiver_init(DltReceiver *receiver,int _fd, int _buffersize);
     /**
      * De-Initialize a dlt receiver structure
      * @param receiver pointer to dlt receiver structure
      * @return negative value if there was an error
      */
-    int dlt_receiver_free(DltReceiver *receiver);
+    DltReturnValue dlt_receiver_free(DltReceiver *receiver);
     /**
      * Receive data from socket using the dlt receiver structure
      * @param receiver pointer to dlt receiver structure
-     * @return negative value if there was an error
+     * @return number of received bytes or negative value if there was an error
      */
     int dlt_receiver_receive_socket(DltReceiver *receiver);
     /**
      * Receive data from file/fifo using the dlt receiver structure
      * @param receiver pointer to dlt receiver structure
-     * @return negative value if there was an error
+     * @return number of received bytes or negative value if there was an error
      */
     int dlt_receiver_receive_fd(DltReceiver *receiver);
     /**
@@ -1011,13 +1026,13 @@ extern "C"
      * @param size amount of bytes to be removed
      * @return negative value if there was an error
      */
-    int dlt_receiver_remove(DltReceiver *receiver,int size);
+    DltReturnValue dlt_receiver_remove(DltReceiver *receiver,int size);
     /**
      * Move data from last receive call to front of receive buffer
      * @param receiver pointer to dlt receiver structure
      * @return negative value if there was an error
      */
-    int dlt_receiver_move_to_begin(DltReceiver *receiver);
+    DltReturnValue dlt_receiver_move_to_begin(DltReceiver *receiver);
 
     /**
      * Fill out storage header of a dlt message
@@ -1025,13 +1040,13 @@ extern "C"
      * @param ecu name of ecu to be set in storage header
      * @return negative value if there was an error
      */
-    int dlt_set_storageheader(DltStorageHeader *storageheader, const char *ecu);
+    DltReturnValue dlt_set_storageheader(DltStorageHeader *storageheader, const char *ecu);
     /**
      * Check if a storage header contains its marker
      * @param storageheader pointer to storage header of a dlt message
      * @return 0 no, 1 yes, negative value if there was an error
      */
-    int dlt_check_storageheader(DltStorageHeader *storageheader);
+    DltReturnValue dlt_check_storageheader(DltStorageHeader *storageheader);
 
 
     /**
@@ -1043,7 +1058,7 @@ extern "C"
      * @param size Maximum size of buffer in bytes
      * @return negative value if there was an error
      */
-    int dlt_buffer_init_static_server(DltBuffer *buf, const unsigned char *ptr, uint32_t size);
+    DltReturnValue dlt_buffer_init_static_server(DltBuffer *buf, const unsigned char *ptr, uint32_t size);
 
     /**
      * Initialize static ringbuffer with a size of size.
@@ -1054,7 +1069,7 @@ extern "C"
      * @param size Maximum size of buffer in bytes
      * @return negative value if there was an error
      */
-    int dlt_buffer_init_static_client(DltBuffer *buf, const unsigned char *ptr, uint32_t size);
+    DltReturnValue dlt_buffer_init_static_client(DltBuffer *buf, const unsigned char *ptr, uint32_t size);
 
     /**
      * Initialize dynamic ringbuffer with a size of size.
@@ -1068,21 +1083,21 @@ extern "C"
      * @param step_size size of which ringbuffer is increased
      * @return negative value if there was an error
      */
-    int dlt_buffer_init_dynamic(DltBuffer *buf, uint32_t min_size, uint32_t max_size,uint32_t step_size);
+    DltReturnValue dlt_buffer_init_dynamic(DltBuffer *buf, uint32_t min_size, uint32_t max_size,uint32_t step_size);
 
     /**
      * Deinitilaise usage of static ringbuffer
      * @param buf Pointer to ringbuffer structure
      * @return negative value if there was an error
      */
-    int dlt_buffer_free_static(DltBuffer *buf);
+    DltReturnValue dlt_buffer_free_static(DltBuffer *buf);
 
     /**
      * Release and free memory used by dynamic ringbuffer
      * @param buf Pointer to ringbuffer structure
      * @return negative value if there was an error
      */
-    int dlt_buffer_free_dynamic(DltBuffer *buf);
+    DltReturnValue dlt_buffer_free_dynamic(DltBuffer *buf);
 
     /**
      * Write one entry to ringbuffer
@@ -1091,7 +1106,7 @@ extern "C"
      * @param size Size of data in bytes to be written to ringbuffer
      * @return negative value if there was an error
      */
-    int dlt_buffer_push(DltBuffer *buf,const unsigned char *data,unsigned int size);
+    DltReturnValue dlt_buffer_push(DltBuffer *buf,const unsigned char *data,unsigned int size);
 
     /**
      * Write up to three entries to ringbuffer.
@@ -1105,7 +1120,7 @@ extern "C"
      * @param size3 Size of data in bytes to be written to ringbuffer
      * @return negative value if there was an error
      */
-    int dlt_buffer_push3(DltBuffer *buf,const unsigned char *data1,unsigned int size1,const unsigned char *data2,unsigned int size2,const unsigned char *data3,unsigned int size3);
+    DltReturnValue dlt_buffer_push3(DltBuffer *buf,const unsigned char *data1,unsigned int size1,const unsigned char *data2,unsigned int size2,const unsigned char *data3,unsigned int size3);
 
     /**
      * Read one entry from ringbuffer.
@@ -1152,7 +1167,7 @@ extern "C"
      * @param buf Pointer to ringbuffer structure
      * @return total size of buffer
      */
-    int dlt_buffer_get_total_size(DltBuffer *buf);
+    uint32_t dlt_buffer_get_total_size(DltBuffer *buf);
 
     /**
      * Get used size in bytes of ringbuffer.
@@ -1176,7 +1191,7 @@ extern "C"
      * @param speed Serial line speed, as defined in termios.h
      * @return negative value if there was an error
      */
-    int dlt_setup_serial(int fd, speed_t speed);
+    DltReturnValue dlt_setup_serial(int fd, speed_t speed);
 
     /**
      * Helper function: Convert serial line baudrate (as number) to line speed (as defined in termios.h)
@@ -1215,7 +1230,7 @@ extern "C"
      * Common part of initialisation
      * @return negative value if there was an error
      */
-    int dlt_init_common(void);
+    DltReturnValue dlt_init_common(void);
 
     /**
      * Return the uptime of the system in 0.1 ms resolution
@@ -1231,7 +1246,7 @@ extern "C"
      * @param verbose if set to true verbose information is printed out.
      * @return negative value if there was an error
      */
-    int dlt_message_print_header(DltMessage *message, char *text, uint32_t size, int verbose);
+    DltReturnValue dlt_message_print_header(DltMessage *message, char *text, uint32_t size, int verbose);
 
     /**
      * Print payload of a DLT message as Hex-Output
@@ -1241,7 +1256,7 @@ extern "C"
      * @param verbose if set to true verbose information is printed out.
      * @return negative value if there was an error
      */
-    int dlt_message_print_hex(DltMessage *message, char *text, uint32_t size, int verbose);
+    DltReturnValue dlt_message_print_hex(DltMessage *message, char *text, uint32_t size, int verbose);
 
     /**
      * Print payload of a DLT message as ASCII-Output
@@ -1251,7 +1266,7 @@ extern "C"
      * @param verbose if set to true verbose information is printed out.
      * @return negative value if there was an error
      */
-    int dlt_message_print_ascii(DltMessage *message, char *text, uint32_t size, int verbose);
+    DltReturnValue dlt_message_print_ascii(DltMessage *message, char *text, uint32_t size, int verbose);
 
     /**
      * Print payload of a DLT message as Mixed-Ouput (Hex and ASCII), for plain text output
@@ -1261,7 +1276,7 @@ extern "C"
      * @param verbose if set to true verbose information is printed out.
      * @return negative value if there was an error
      */
-    int dlt_message_print_mixed_plain(DltMessage *message, char *text, uint32_t size, int verbose);
+    DltReturnValue dlt_message_print_mixed_plain(DltMessage *message, char *text, uint32_t size, int verbose);
 
     /**
      * Print payload of a DLT message as Mixed-Ouput (Hex and ASCII), for HTML text output
@@ -1271,7 +1286,7 @@ extern "C"
      * @param verbose if set to true verbose information is printed out.
      * @return negative value if there was an error
      */
-    int dlt_message_print_mixed_html(DltMessage *message, char *text, uint32_t size, int verbose);
+    DltReturnValue dlt_message_print_mixed_html(DltMessage *message, char *text, uint32_t size, int verbose);
 
     /**
      * Decode and print a argument of a DLT message
@@ -1285,7 +1300,7 @@ extern "C"
      * @param verbose if set to true verbose information is printed out.
      * @return negative value if there was an error
      */
-    int dlt_message_argument_print(DltMessage *msg,uint32_t type_info,uint8_t **ptr,int32_t *datalength,char *text,int textlength,int byteLength,int verbose);
+    DltReturnValue dlt_message_argument_print(DltMessage *msg,uint32_t type_info,uint8_t **ptr,int32_t *datalength,char *text,int textlength,int byteLength,int verbose);
 
     /**
      * Check environment variables.
diff --git a/include/dlt/dlt_offline_trace.h b/include/dlt/dlt_offline_trace.h
index 64a6afe..90cfa96 100644
--- a/include/dlt/dlt_offline_trace.h
+++ b/include/dlt/dlt_offline_trace.h
@@ -59,6 +59,8 @@
 
 #include <limits.h>
 
+#include "dlt_types.h"
+
 typedef struct
 {
     char directory[NAME_MAX + 1];/**< (String) Store DLT messages to local directory */
@@ -80,7 +82,7 @@ typedef struct
  * @param maxSize maximum size of complete offline trace in bytes.
  * @return negative value if there was an error
  */
-extern int dlt_offline_trace_init(DltOfflineTrace *trace,const char *directory,int fileSize,int maxSize);
+extern DltReturnValue dlt_offline_trace_init(DltOfflineTrace *trace,const char *directory,int fileSize,int maxSize);
 
 /**
  * Uninitialise the offline trace
@@ -89,7 +91,7 @@ extern int dlt_offline_trace_init(DltOfflineTrace *trace,const char *directory,i
  * @param trace pointer to offline trace structure
  * @return negative value if there was an error
  */
-extern int dlt_offline_trace_free(DltOfflineTrace *buf);
+extern DltReturnValue dlt_offline_trace_free(DltOfflineTrace *buf);
 
 /**
  * Write data into offline trace
@@ -105,7 +107,7 @@ extern int dlt_offline_trace_free(DltOfflineTrace *buf);
  * @param size3 size in bytes of third data block to be written, 0 if not used
  * @return negative value if there was an error
  */
-extern int dlt_offline_trace_write(DltOfflineTrace *trace,unsigned char *data1,int size1,unsigned char *data2,int size2,unsigned char *data3,int size3);
+extern DltReturnValue dlt_offline_trace_write(DltOfflineTrace *trace,unsigned char *data1,int size1,unsigned char *data2,int size2,unsigned char *data3,int size3);
 
 /**
  * Get size of currently used offline trace buffer
diff --git a/include/dlt/dlt_shm.h b/include/dlt/dlt_shm.h
index 52e8e1a..20f9110 100644
--- a/include/dlt/dlt_shm.h
+++ b/include/dlt/dlt_shm.h
@@ -99,7 +99,7 @@ typedef struct
  * @param key the identifier of the shm, must be the same for server and client
  * @return negative value if there was an error
  */
-extern int dlt_shm_init_client(DltShm *buf,int key);
+extern DltReturnValue dlt_shm_init_client(DltShm *buf,int key);
 
 /**
  * Initialise the shared memory on the server side.
@@ -109,7 +109,7 @@ extern int dlt_shm_init_client(DltShm *buf,int key);
  * @param size the requested size of the shm
  * @return negative value if there was an error
  */
-extern int dlt_shm_init_server(DltShm *buf,int key,int size);
+extern DltReturnValue dlt_shm_init_server(DltShm *buf,int key,int size);
 
 /**
  * Push data from client onto the shm.
@@ -172,7 +172,7 @@ extern void dlt_shm_status(DltShm *buf);
  * @param buf pointer to shm structure
  * @return negative value if there was an error
  */
-extern int dlt_shm_free_client(DltShm *buf);
+extern DltReturnValue dlt_shm_free_client(DltShm *buf);
 
 /**
  * Returns the total size of the shm.
diff --git a/include/dlt/dlt_types.h b/include/dlt/dlt_types.h
index 1e7c8e6..a0400ad 100644
--- a/include/dlt/dlt_types.h
+++ b/include/dlt/dlt_types.h
@@ -80,6 +80,99 @@ typedef unsigned int speed_t;
 #include <stdint.h>
 #endif
 
+/**
+ * Definitions of DLT return values
+ */
+typedef enum
+{
+    DLT_RETURN_WRONG_PARAMETER    = -5,
+    DLT_RETURN_BUFFER_FULL      = -4,
+    DLT_RETURN_PIPE_FULL        = -3,
+    DLT_RETURN_PIPE_ERROR       = -2,
+    DLT_RETURN_ERROR            = -1,
+    DLT_RETURN_OK               =  0,
+    DLT_RETURN_TRUE             =  1
+} DltReturnValue;
+
+/**
+ * Definitions of DLT log level
+ */
+typedef enum
+{
+    DLT_LOG_DEFAULT =             -1,   /**< Default log level */
+    DLT_LOG_OFF     =           0x00,   /**< Log level off */
+    DLT_LOG_FATAL   =           0x01,   /**< fatal system error */
+    DLT_LOG_ERROR   =           0x02,   /**< error with impact to correct functionality */
+    DLT_LOG_WARN    =           0x03,   /**< warning, correct behaviour could not be ensured */
+    DLT_LOG_INFO    =           0x04,   /**< informational */
+    DLT_LOG_DEBUG   =           0x05,   /**< debug  */
+    DLT_LOG_VERBOSE =           0x06,   /**< highest grade of information */
+    DLT_LOG_MAX                         /**< maximum value, used for range check */
+} DltLogLevelType;
+
+/**
+ * Definitions of DLT Format
+ */
+typedef enum
+{
+    DLT_FORMAT_DEFAULT  =       0x00,   /**< no sepecial format */
+    DLT_FORMAT_HEX8     =       0x01,   /**< Hex 8 */
+    DLT_FORMAT_HEX16    =       0x02,   /**< Hex 16 */
+    DLT_FORMAT_HEX32    =       0x03,   /**< Hex 32 */
+    DLT_FORMAT_HEX64    =       0x04,   /**< Hex 64 */
+    DLT_FORMAT_BIN8     =       0x05,   /**< Binary 8 */
+    DLT_FORMAT_BIN16    =       0x06,   /**< Binary 16  */
+    DLT_FORMAT_MAX                      /**< maximum value, used for range check */
+} DltFormatType;
+
+/**
+ * Definitions of DLT trace status
+ */
+typedef enum
+{
+    DLT_TRACE_STATUS_DEFAULT    =   -1,    /**< Default trace status */
+    DLT_TRACE_STATUS_OFF        =   0x00,  /**< Trace status: Off */
+    DLT_TRACE_STATUS_ON         =   0x01,  /**< Trace status: On */
+    DLT_TRACE_STATUS_MAX                   /**< maximum value, used for range check */
+} DltTraceStatusType;
+
+/**
+ * Definitions for  dlt_user_trace_network/DLT_TRACE_NETWORK()
+ * as defined in the DLT protocol
+ */
+typedef enum
+{
+    DLT_NW_TRACE_IPC            =   0x01,   /**< Interprocess communication */
+    DLT_NW_TRACE_CAN            =   0x02,   /**< Controller Area Network Bus */
+    DLT_NW_TRACE_FLEXRAY        =   0x03,   /**< Flexray Bus */
+    DLT_NW_TRACE_MOST           =   0x04,   /**< Media Oriented System Transport Bus */
+    DLT_NW_TRACE_RESERVED0      =   0x05,
+    DLT_NW_TRACE_RESERVED1      =   0x06,
+    DLT_NW_TRACE_RESERVED2      =   0x07,
+    DLT_NW_TRACE_USER_DEFINED0  =   0x08,
+    DLT_NW_TRACE_USER_DEFINED1  =   0x09,
+    DLT_NW_TRACE_USER_DEFINED2  =   0x0A,
+    DLT_NW_TRACE_USER_DEFINED3  =   0x0B,
+    DLT_NW_TRACE_USER_DEFINED4  =   0x0C,
+    DLT_NW_TRACE_USER_DEFINED5  =   0x0D,
+    DLT_NW_TRACE_USER_DEFINED6  =   0x0E,
+    DLT_NW_TRACE_USER_DEFINED7  =   0x0F,
+    DLT_NW_TRACE_MAX                        /**< maximum value, used for range check */
+} DltNetworkTraceType;
+
+/**
+ * This are the log modes.
+ */
+typedef enum
+{
+    DLT_USER_MODE_UNDEFINED =   -1,
+    DLT_USER_MODE_OFF       =   0,
+    DLT_USER_MODE_EXTERNAL       ,
+    DLT_USER_MODE_INTERNAL       ,
+    DLT_USER_MODE_BOTH           ,
+    DLT_USER_MODE_MAX                       /**< maximum value, used for range check */
+} DltUserLogMode;
+
 typedef float  float32_t;
 typedef double float64_t;
 
diff --git a/include/dlt/dlt_user.h b/include/dlt/dlt_user.h
index df41259..d5d8ed7 100644
--- a/include/dlt/dlt_user.h
+++ b/include/dlt/dlt_user.h
@@ -75,94 +75,20 @@
   \addtogroup userapi
   \{
 */
-#include "dlt_types.h"
-#include "dlt_common.h"
-#include "dlt_user_macros.h"
-#include "dlt_shm.h"
 #include <mqueue.h>
 
 #if !defined (__WIN32__)
 #include <semaphore.h>
 #endif
 
+#include "dlt_types.h"
+#include "dlt_user_macros.h"
+#include "dlt_shm.h"
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-/**
- * Definitions of DLT log level
- */
-typedef enum
-{
-    DLT_LOG_DEFAULT =             -1,   /**< Default log level */
-    DLT_LOG_OFF     =           0x00,   /**< Log level off */
-    DLT_LOG_FATAL   =           0x01,   /**< fatal system error */
-    DLT_LOG_ERROR   =           0x02,   /**< error with impact to correct functionality */
-    DLT_LOG_WARN    =           0x03,   /**< warning, correct behaviour could not be ensured */
-    DLT_LOG_INFO    =           0x04,   /**< informational */
-    DLT_LOG_DEBUG   =           0x05,   /**< debug  */
-    DLT_LOG_VERBOSE =           0x06    /**< highest grade of information */
-} DltLogLevelType;
-
-/**
- * Definitions of DLT Format
- */
-typedef enum
-{
-    DLT_FORMAT_DEFAULT   =          0x00,   /**< no sepecial format */
-    DLT_FORMAT_HEX8  =          0x01,   /**< Hex 8 */
-    DLT_FORMAT_HEX16 =          0x02,   /**< Hex 16 */
-    DLT_FORMAT_HEX32 =          0x03,   /**< Hex 32 */
-    DLT_FORMAT_HEX64 =          0x04,   /**< Hex 64 */
-    DLT_FORMAT_BIN8  =          0x05,   /**< Binary 8 */
-    DLT_FORMAT_BIN16 =          0x06    /**< Binary 16  */
-} DltFormatType;
-
-/**
- * Definitions of DLT trace status
- */
-typedef enum
-{
-    DLT_TRACE_STATUS_DEFAULT =   -1,    /**< Default trace status */
-    DLT_TRACE_STATUS_OFF     = 0x00,    /**< Trace status: Off */
-    DLT_TRACE_STATUS_ON      = 0x01     /**< Trace status: On */
-} DltTraceStatusType;
-
-/**
- * Definitions for  dlt_user_trace_network/DLT_TRACE_NETWORK()
- * as defined in the DLT protocol
- */
-typedef enum
-{
-    DLT_NW_TRACE_IPC     = 0x01,    /**< Interprocess communication */
-    DLT_NW_TRACE_CAN     = 0x02,    /**< Controller Area Network Bus */
-    DLT_NW_TRACE_FLEXRAY = 0x03,    /**< Flexray Bus */
-    DLT_NW_TRACE_MOST    = 0x04,    /**< Media Oriented System Transport Bus */
-    DLT_NW_TRACE_RESERVED0 = 0x05,
-    DLT_NW_TRACE_RESERVED1 = 0x06,
-    DLT_NW_TRACE_RESERVED2 = 0x07,
-    DLT_NW_TRACE_USER_DEFINED0 = 0x08,
-    DLT_NW_TRACE_USER_DEFINED1 = 0x09,
-    DLT_NW_TRACE_USER_DEFINED2 = 0x0A,
-    DLT_NW_TRACE_USER_DEFINED3 = 0x0B,
-    DLT_NW_TRACE_USER_DEFINED4 = 0x0C,
-    DLT_NW_TRACE_USER_DEFINED5 = 0x0D,
-    DLT_NW_TRACE_USER_DEFINED6 = 0x0E,
-    DLT_NW_TRACE_USER_DEFINED7 = 0x0F
-} DltNetworkTraceType;
-
-/**
- * This are the log modes.
- */
-typedef enum
-{
-    DLT_USER_MODE_UNDEFINED   =  -1,
-    DLT_USER_MODE_OFF         =  0,
-    DLT_USER_MODE_EXTERNAL        ,
-    DLT_USER_MODE_INTERNAL        ,
-    DLT_USER_MODE_BOTH
-} DltUserLogMode;
-
 #define DLT_USER_BUF_MAX_SIZE 2048               /**< maximum size of each user buffer, also used for injection buffer */
 
 #define DLT_USER_RESENDBUF_MAX_SIZE (DLT_USER_BUF_MAX_SIZE + 100)       /**< Size of resend buffer; Max DLT message size is 2K plus some extra header space  */
@@ -325,9 +251,9 @@ typedef struct
  * @param handle pointer to an object containing information about one special logging context
  * @param log pointer to an object containing information about logging context data
  * @param loglevel this is the current log level of the log message to be sent
- * @return negative value if there was an error, zero if log level is below current log level, one if log level is matching
+ * @return Value from DltReturnValue enum, DLT_RETURN_TRUE if log level is matching
  */
-int dlt_user_log_write_start(DltContext *handle, DltContextData *log, DltLogLevelType loglevel);
+DltReturnValue dlt_user_log_write_start(DltContext *handle, DltContextData *log, DltLogLevelType loglevel);
 
 /**
  * Initialize the generation of a DLT log message (intended for usage in verbose mode)
@@ -338,17 +264,17 @@ int dlt_user_log_write_start(DltContext *handle, DltContextData *log, DltLogLeve
  * @param log pointer to an object containing information about logging context data
  * @param loglevel this is the current log level of the log message to be sent
  * @param messageid message id of message
- * @return negative value if there was an error, zero if log level is below current log level, one if log level is matching
+ * @return Value from DltReturnValue enum, DLT_RETURN_TRUE if log level is matching
  */
-int dlt_user_log_write_start_id(DltContext *handle, DltContextData *log, DltLogLevelType loglevel, uint32_t messageid);
+DltReturnValue dlt_user_log_write_start_id(DltContext *handle, DltContextData *log, DltLogLevelType loglevel, uint32_t messageid);
 
 /**
  * Finishing the generation of a DLT log message and sending it to the DLT daemon.
  * This function has to be called after writing all the log attributes of a log message.
  * @param log pointer to an object containing information about logging context data
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_user_log_write_finish(DltContextData *log);
+DltReturnValue dlt_user_log_write_finish(DltContextData *log);
 
 /**
  * Write a boolean parameter into a DLT log message.
@@ -356,9 +282,9 @@ int dlt_user_log_write_finish(DltContextData *log);
  * Finish sending log message by calling dlt_user_log_write_finish.
  * @param log pointer to an object containing information about logging context data
  * @param data boolean parameter written into log message (mapped to uint8)
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_user_log_write_bool(DltContextData *log, uint8_t data);
+DltReturnValue dlt_user_log_write_bool(DltContextData *log, uint8_t data);
 
 /**
  * Write a float parameter into a DLT log message.
@@ -366,9 +292,9 @@ int dlt_user_log_write_bool(DltContextData *log, uint8_t data);
  * Finish sending log message by calling dlt_user_log_write_finish.
  * @param log pointer to an object containing information about logging context data
  * @param data float32_t parameter written into log message.
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_user_log_write_float32(DltContextData *log, float32_t data);
+DltReturnValue dlt_user_log_write_float32(DltContextData *log, float32_t data);
 
 /**
  * Write a double parameter into a DLT log message.
@@ -376,9 +302,9 @@ int dlt_user_log_write_float32(DltContextData *log, float32_t data);
  * Finish sending log message by calling dlt_user_log_write_finish.
  * @param log pointer to an object containing information about logging context data
  * @param data float64_t parameter written into log message.
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_user_log_write_float64(DltContextData *log, double data);
+DltReturnValue dlt_user_log_write_float64(DltContextData *log, double data);
 
 /**
  * Write a uint parameter into a DLT log message.
@@ -386,13 +312,13 @@ int dlt_user_log_write_float64(DltContextData *log, double data);
  * Finish sending log message by calling dlt_user_log_write_finish.
  * @param log pointer to an object containing information about logging context data
  * @param data unsigned int parameter written into log message.
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_user_log_write_uint(DltContextData *log, unsigned int data);
-int dlt_user_log_write_uint8(DltContextData *log, uint8_t data);
-int dlt_user_log_write_uint16(DltContextData *log, uint16_t data);
-int dlt_user_log_write_uint32(DltContextData *log, uint32_t data);
-int dlt_user_log_write_uint64(DltContextData *log, uint64_t data);
+DltReturnValue dlt_user_log_write_uint(DltContextData *log, unsigned int data);
+DltReturnValue dlt_user_log_write_uint8(DltContextData *log, uint8_t data);
+DltReturnValue dlt_user_log_write_uint16(DltContextData *log, uint16_t data);
+DltReturnValue dlt_user_log_write_uint32(DltContextData *log, uint32_t data);
+DltReturnValue dlt_user_log_write_uint64(DltContextData *log, uint64_t data);
 
 /**
  * Write a uint parameter into a DLT log message. The output will be formatted as given by the parameter type.
@@ -401,12 +327,12 @@ int dlt_user_log_write_uint64(DltContextData *log, uint64_t data);
  * @param log pointer to an object containing information about logging context data
  * @param data unsigned int parameter written into log message.
  * @param type The formatting type of the string output.
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_user_log_write_uint8_formatted(DltContextData *log, uint8_t data, DltFormatType type);
-int dlt_user_log_write_uint16_formatted(DltContextData *log, uint16_t data, DltFormatType type);
-int dlt_user_log_write_uint32_formatted(DltContextData *log, uint32_t data, DltFormatType type);
-int dlt_user_log_write_uint64_formatted(DltContextData *log, uint64_t data, DltFormatType type);
+DltReturnValue dlt_user_log_write_uint8_formatted(DltContextData *log, uint8_t data, DltFormatType type);
+DltReturnValue dlt_user_log_write_uint16_formatted(DltContextData *log, uint16_t data, DltFormatType type);
+DltReturnValue dlt_user_log_write_uint32_formatted(DltContextData *log, uint32_t data, DltFormatType type);
+DltReturnValue dlt_user_log_write_uint64_formatted(DltContextData *log, uint64_t data, DltFormatType type);
 
 /**
  * Write a int parameter into a DLT log message.
@@ -414,22 +340,22 @@ int dlt_user_log_write_uint64_formatted(DltContextData *log, uint64_t data, DltF
  * Finish sending log message by calling dlt_user_log_write_finish.
  * @param log pointer to an object containing information about logging context data
  * @param data int parameter written into log message.
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_user_log_write_int(DltContextData *log, int data);
-int dlt_user_log_write_int8(DltContextData *log, int8_t data);
-int dlt_user_log_write_int16(DltContextData *log, int16_t data);
-int dlt_user_log_write_int32(DltContextData *log, int32_t data);
-int dlt_user_log_write_int64(DltContextData *log, int64_t data);
+DltReturnValue dlt_user_log_write_int(DltContextData *log, int data);
+DltReturnValue dlt_user_log_write_int8(DltContextData *log, int8_t data);
+DltReturnValue dlt_user_log_write_int16(DltContextData *log, int16_t data);
+DltReturnValue dlt_user_log_write_int32(DltContextData *log, int32_t data);
+DltReturnValue dlt_user_log_write_int64(DltContextData *log, int64_t data);
 /**
  * Write a null terminated ASCII string into a DLT log message.
  * dlt_user_log_write_start has to be called before adding any attributes to the log message.
  * Finish sending log message by calling dlt_user_log_write_finish.
  * @param log pointer to an object containing information about logging context data
  * @param text pointer to the parameter written into log message containing null termination.
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_user_log_write_string( DltContextData *log, const char *text);
+DltReturnValue dlt_user_log_write_string( DltContextData *log, const char *text);
 
 /**
  * Write a constant null terminated ASCII string into a DLT log message.
@@ -438,9 +364,9 @@ int dlt_user_log_write_string( DltContextData *log, const char *text);
  * Finish sending log message by calling dlt_user_log_write_finish.
  * @param log pointer to an object containing information about logging context data
  * @param text pointer to the parameter written into log message containing null termination.
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_user_log_write_constant_string( DltContextData *log, const char *text);
+DltReturnValue dlt_user_log_write_constant_string( DltContextData *log, const char *text);
 
 /**
  * Write a null terminated UTF8 string into a DLT log message.
@@ -448,9 +374,9 @@ int dlt_user_log_write_constant_string( DltContextData *log, const char *text);
  * Finish sending log message by calling dlt_user_log_write_finish.
  * @param log pointer to an object containing information about logging context data
  * @param text pointer to the parameter written into log message containing null termination.
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_user_log_write_utf8_string(DltContextData *log, const char *text);
+DltReturnValue dlt_user_log_write_utf8_string(DltContextData *log, const char *text);
 
 /**
  * Write a binary memory block into a DLT log message.
@@ -459,9 +385,9 @@ int dlt_user_log_write_utf8_string(DltContextData *log, const char *text);
  * @param log pointer to an object containing information about logging context data
  * @param data pointer to the parameter written into log message.
  * @param length length in bytes of the parameter written into log message.
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_user_log_write_raw(DltContextData *log,void *data,uint16_t length);
+DltReturnValue dlt_user_log_write_raw(DltContextData *log,void *data,uint16_t length);
 
 /**
  * Write a binary memory block into a DLT log message.
@@ -471,9 +397,9 @@ int dlt_user_log_write_raw(DltContextData *log,void *data,uint16_t length);
  * @param data pointer to the parameter written into log message.
  * @param length length in bytes of the parameter written into log message.
  * @param type the format information.
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_user_log_write_raw_formatted(DltContextData *log,void *data,uint16_t length,DltFormatType type);
+DltReturnValue dlt_user_log_write_raw_formatted(DltContextData *log,void *data,uint16_t length,DltFormatType type);
 
 /**
  * Trace network message
@@ -483,9 +409,9 @@ int dlt_user_log_write_raw_formatted(DltContextData *log,void *data,uint16_t len
  * @param header pointer to network message header
  * @param payload_len length of network message payload
  * @param payload pointer to network message payload
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_user_trace_network(DltContext *handle, DltNetworkTraceType nw_trace_type, uint16_t header_len, void *header, uint16_t payload_len, void *payload);
+DltReturnValue dlt_user_trace_network(DltContext *handle, DltNetworkTraceType nw_trace_type, uint16_t header_len, void *header, uint16_t payload_len, void *payload);
 
 /**
  * Trace network message, truncated if necessary.
@@ -496,9 +422,9 @@ int dlt_user_trace_network(DltContext *handle, DltNetworkTraceType nw_trace_type
  * @param payload_len length of network message payload
  * @param payload pointer to network message payload
  * @param allow_truncate Set to > 0 to allow truncating of the message if it is too large.
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_user_trace_network_truncated(DltContext *handle, DltNetworkTraceType nw_trace_type, uint16_t header_len, void *header, uint16_t payload_len, void *payload, int allow_truncate);
+DltReturnValue dlt_user_trace_network_truncated(DltContext *handle, DltNetworkTraceType nw_trace_type, uint16_t header_len, void *header, uint16_t payload_len, void *payload, int allow_truncate);
 
 /**
  * Trace network message in segmented asynchronous mode.
@@ -511,9 +437,9 @@ int dlt_user_trace_network_truncated(DltContext *handle, DltNetworkTraceType nw_
  * @param header pointer to network message header
  * @param payload_len length of network message payload
  * @param payload pointer to network message payload
- * @return 0 on success, -1 on failure
+ * @return Value from DltReturnValue enum
  */
-int dlt_user_trace_network_segmented(DltContext *handle, DltNetworkTraceType nw_trace_type, uint16_t header_len, void *header, uint16_t payload_len, void *payload);
+DltReturnValue dlt_user_trace_network_segmented(DltContext *handle, DltNetworkTraceType nw_trace_type, uint16_t header_len, void *header, uint16_t payload_len, void *payload);
 
 /**************************************************************************************************
  * The following API functions define a high level function interface for DLT
@@ -522,47 +448,47 @@ int dlt_user_trace_network_segmented(DltContext *handle, DltNetworkTraceType nw_
 /**
  * Initialize the user lib communication with daemon.
  * This function has to be called first, before using any DLT user lib functions.
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_init();
+DltReturnValue dlt_init();
 
 /**
  * Initialize the user lib writing only to file.
  * This function has to be called first, before using any DLT user lib functions.
  * @param name name of an optional log file
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_init_file(const char *name);
+DltReturnValue dlt_init_file(const char *name);
 
 /**
  * Terminate the user lib.
  * This function has to be called when finishing using the DLT user lib.
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_free();
+DltReturnValue dlt_free();
 
 /**
  * Check the library version of DLT library.
  * @param user_major_version the major version to be compared
  * @param user_minor_version the minor version to be compared
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum, DLT_RETURN_ERROR if there is a mismatch
  */
-int dlt_check_library_version(const char * user_major_version, const char * user_minor_version);
+DltReturnValue dlt_check_library_version(const char * user_major_version, const char * user_minor_version);
 
 /**
  * Register an application in the daemon.
  * @param appid four byte long character array with the application id
  * @param description long name of the application
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_register_app(const char *appid, const char * description);
+DltReturnValue dlt_register_app(const char *appid, const char * description);
 
 /**
  * Unregister an application in the daemon.
  * This function has to be called when finishing using an application.
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_unregister_app(void);
+DltReturnValue dlt_unregister_app(void);
 
 /**
  * Register a context in the daemon.
@@ -570,9 +496,9 @@ int dlt_unregister_app(void);
  * @param handle pointer to an object containing information about one special logging context
  * @param contextid four byte long character array with the context id
  * @param description long name of the context
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_register_context(DltContext *handle, const char *contextid, const char * description);
+DltReturnValue dlt_register_context(DltContext *handle, const char *contextid, const char * description);
 
 /**
  * Register a context in the daemon with pre-defined log level and pre-defined trace status.
@@ -584,17 +510,17 @@ int dlt_register_context(DltContext *handle, const char *contextid, const char *
           (DLT_LOG_DEFAULT is not allowed here)
  * @param tracestatus This is the trace status to be pre-set for this context
           (DLT_TRACE_STATUS_DEFAULT is not allowed here)
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_register_context_ll_ts(DltContext *handle, const char *contextid, const char * description, int loglevel, int tracestatus);
+DltReturnValue dlt_register_context_ll_ts(DltContext *handle, const char *contextid, const char * description, int loglevel, int tracestatus);
 
 /**
  * Unregister a context in the DLT daemon.
  * This function has to be called when finishing using a context.
  * @param handle pointer to an object containing information about one special logging context
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_unregister_context(DltContext *handle);
+DltReturnValue dlt_unregister_context(DltContext *handle);
 
 
 /**
@@ -608,9 +534,9 @@ int dlt_set_resend_timeout_atexit(uint32_t timeout_in_milliseconds);
  * The logging mode is stored persistantly by the daemon.
  * @see DltUserLogMode
  * @param mode the new logging mode used by the daemon: off, extern, internal, both.
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_set_log_mode(DltUserLogMode mode);
+DltReturnValue dlt_set_log_mode(DltUserLogMode mode);
 
 /**
  * Get the state of the connected client to the daemon.
@@ -627,80 +553,80 @@ int dlt_get_log_state();
  * @param handle pointer to an object containing information about one special logging context
  * @param service_id the service id to be waited for
  * @param (*dlt_injection_callback) function pointer to callback function
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_register_injection_callback(DltContext *handle, uint32_t service_id,
+DltReturnValue dlt_register_injection_callback(DltContext *handle, uint32_t service_id,
         int (*dlt_injection_callback)(uint32_t service_id, void *data, uint32_t length));
 
 /**
  * Register callback function called when log level of context was changed
  * @param handle pointer to an object containing information about one special logging context
  * @param (*dlt_log_level_changed_callback) function pointer to callback function
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_register_log_level_changed_callback(DltContext *handle,
+DltReturnValue dlt_register_log_level_changed_callback(DltContext *handle,
         void (*dlt_log_level_changed_callback)(char context_id[DLT_ID_SIZE],uint8_t log_level, uint8_t trace_status));
 
 /**
  * Switch to verbose mode
- *
+ * @return Value from DltReturnValue enum
  */
-int dlt_verbose_mode(void);
+DltReturnValue dlt_verbose_mode(void);
 
 /**
  * Check the version of dlt library with library version used of the application.
  * @param Major version number of application - see dlt_version.h
  * @param Minor version number of application - see dlt_version.h
- * @return negative value if there is a mismatch
+ *  @return Value from DltReturnValue enum, DLT_RETURN_ERROR if there is a mismatch
  */
-int dlt_user_check_library_version(const char *user_major_version,const char *user_minor_version);
+DltReturnValue dlt_user_check_library_version(const char *user_major_version,const char *user_minor_version);
 
 /**
  * Switch to non-verbose mode
  *
  */
-int dlt_nonverbose_mode(void);
+DltReturnValue dlt_nonverbose_mode(void);
 
 /**
  * Use extended header in non verbose mode.
  * Enabled by default.
  * @param use_extende_header_for_non_verbose Use extended header for non verbose mode if true
- * @return negative value if no success
+ * @return Value from DltReturnValue enum
  */
-int dlt_use_extended_header_for_non_verbose(int8_t use_extende_header_for_non_verbose);
+DltReturnValue dlt_use_extended_header_for_non_verbose(int8_t use_extende_header_for_non_verbose);
 
 /**
  * Send session id configuration.
  * Enabled by default.
  * @param with_session_id Send session id in each message if enabled
- * @return negative value if no success
+ * @return Value from DltReturnValue enum
  */
-int dlt_with_session_id(int8_t with_session_id);
+DltReturnValue dlt_with_session_id(int8_t with_session_id);
 
 /**
  * Send timestamp configuration.
  * Enabled by default.
  * @param with_timestamp Send timestamp id in each message if enabled
- * @return negative value if no success
+ * @return Value from DltReturnValue enum
  */
-int dlt_with_timestamp(int8_t with_timestamp);
+DltReturnValue dlt_with_timestamp(int8_t with_timestamp);
 
 /**
  * Send ecu id configuration.
  * Enabled by default.
  * @param with_ecu_id Send ecu id in each message if enabled
- * @return negative value if no success
+ * @return Value from DltReturnValue enum
  */
-int dlt_with_ecu_id(int8_t with_ecu_id);
+DltReturnValue dlt_with_ecu_id(int8_t with_ecu_id);
 
 /**
  * Set maximum logged log level and trace status of application
  *
  * @param loglevel This is the log level to be set for the whole application
  * @param tracestatus This is the trace status to be set for the whole application
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_set_application_ll_ts_limit(DltLogLevelType loglevel, DltTraceStatusType tracestatus);
+DltReturnValue dlt_set_application_ll_ts_limit(DltLogLevelType loglevel, DltTraceStatusType tracestatus);
 
 
 /**
@@ -738,24 +664,24 @@ void dlt_env_free_ll_set(dlt_env_ll_set * const ll_set);
 
 /**
  * Enable local printing of messages
- *
+ * @return Value from DltReturnValue enum
  */
-int dlt_enable_local_print(void);
+DltReturnValue dlt_enable_local_print(void);
 
 /**
  * Disable local printing of messages
- *
+ * @return Value from DltReturnValue enum
  */
-int dlt_disable_local_print(void);
+DltReturnValue dlt_disable_local_print(void);
 
 /**
  * Write a null terminated ASCII string into a DLT log message.
  * @param handle pointer to an object containing information about one special logging context
  * @param loglevel this is the current log level of the log message to be sent
  * @param text pointer to the ASCII string written into log message containing null termination.
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_log_string(DltContext *handle,DltLogLevelType loglevel, const char *text);
+DltReturnValue dlt_log_string(DltContext *handle,DltLogLevelType loglevel, const char *text);
 
 /**
  * Write a null terminated ASCII string and an integer value into a DLT log message.
@@ -763,9 +689,9 @@ int dlt_log_string(DltContext *handle,DltLogLevelType loglevel, const char *text
  * @param loglevel this is the current log level of the log message to be sent
  * @param text pointer to the ASCII string written into log message containing null termination.
  * @param data integer value written into the log message
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_log_string_int(DltContext *handle,DltLogLevelType loglevel, const char *text, int data);
+DltReturnValue dlt_log_string_int(DltContext *handle,DltLogLevelType loglevel, const char *text, int data);
 
 /**
  * Write a null terminated ASCII string and an unsigned integer value into a DLT log message.
@@ -773,27 +699,27 @@ int dlt_log_string_int(DltContext *handle,DltLogLevelType loglevel, const char *
  * @param loglevel this is the current log level of the log message to be sent
  * @param text pointer to the ASCII string written into log message containing null termination.
  * @param data unsigned integer value written into the log message
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_log_string_uint(DltContext *handle,DltLogLevelType loglevel, const char *text, unsigned int data);
+DltReturnValue dlt_log_string_uint(DltContext *handle,DltLogLevelType loglevel, const char *text, unsigned int data);
 
 /**
  * Write an integer value into a DLT log message.
  * @param handle pointer to an object containing information about one special logging context
  * @param loglevel this is the current log level of the log message to be sent
  * @param data integer value written into the log message
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_log_int(DltContext *handle,DltLogLevelType loglevel, int data);
+DltReturnValue dlt_log_int(DltContext *handle,DltLogLevelType loglevel, int data);
 
 /**
  * Write an unsigned integer value into a DLT log message.
  * @param handle pointer to an object containing information about one special logging context
  * @param loglevel this is the current log level of the log message to be sent
  * @param data unsigned integer value written into the log message
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_log_uint(DltContext *handle,DltLogLevelType loglevel, unsigned int data);
+DltReturnValue dlt_log_uint(DltContext *handle,DltLogLevelType loglevel, unsigned int data);
 
 /**
  * Write an unsigned integer value into a DLT log message.
@@ -801,23 +727,23 @@ int dlt_log_uint(DltContext *handle,DltLogLevelType loglevel, unsigned int data)
  * @param loglevel this is the current log level of the log message to be sent
  * @param data pointer to the parameter written into log message.
  * @param length length in bytes of the parameter written into log message.
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_log_raw(DltContext *handle,DltLogLevelType loglevel, void *data,uint16_t length);
+DltReturnValue dlt_log_raw(DltContext *handle,DltLogLevelType loglevel, void *data,uint16_t length);
 
 /**
  * Write marker message to DLT.
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_log_marker();
+DltReturnValue dlt_log_marker();
 
 /**
  * Forward a complete DLT message to the DLT daemon
  * @param msgdata Message data of DLT message
  * @param size Size of DLT message
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_forward_msg(void *msgdata,size_t size);
+DltReturnValue dlt_forward_msg(void *msgdata,size_t size);
 
 /**
  * Get the total size and available size of the shared memory buffer between daemon and applications.
@@ -825,9 +751,9 @@ int dlt_forward_msg(void *msgdata,size_t size);
  * For example only 50% of the buffer should be used for file transfer.
  * @param total_size total size of buffer in bytes
  * @param used_size used size of buffer in bytes
- * @return negative value if there was an error
+ * @return Value from DltReturnValue enum
  */
-int dlt_user_check_buffer(int *total_size, int *used_size);
+DltReturnValue dlt_user_check_buffer(int *total_size, int *used_size);
 
 /**
  * Try to resend log message in the user buffer. Stops if the dlt_uptime is bigger than
@@ -839,9 +765,9 @@ int dlt_user_atexit_blow_out_user_buffer(void);
 
 /**
  * Try to resend log message in the user buffer.
- * @return 0 on success, negative on failure.
+ * @return Value from DltReturnValue enum
  */
-int dlt_user_log_resend_buffer(void);
+DltReturnValue dlt_user_log_resend_buffer(void);
 
 #ifdef DLT_TEST_ENABLE
     void dlt_user_test_corrupt_user_header(int enable);