[lib-result] owl_receive_position(): return a pointer

Return a pointer instead of using a result argument.

libowlps-resultreader-udp/libowlps-resultreader-udp.c

@@ -11,16 +11,14 @@
 
 
 /*
- * Receives a result from the socket of file descriptor 'sockfd' and
- * fills an owl_result structure 'result'.
+ * Receives a result from the socket of file descriptor 'sockfd', fills
+ * an owl_result structure with the received information, and returns a
+ * pointer to it (or NULL in case of error).
  *
- * Note that *result will be set by this function, and **result will
- * point on a valid owl_result structure if everything goes well.
- * You will have to free *result yourself with owl_free_result().
- *
- * In case of error, *result is set to NULL.
+ * Note that the new owl_result is allocated with malloc() and must be
+ * deleted using free().
  */
-void owl_receive_position(int sockfd, owl_result **result)
+owl_result* owl_receive_position(int sockfd)
 {
   ssize_t nread ; // recvfrom return value
   char csv[OWL_CSV_RESULT_STRLEN] ; // Read string
@@ -31,30 +29,35 @@ void owl_receive_position(int sockfd, owl_result **result)
   if (nread <= 0)
     {
       perror("No request received from listener") ;
-      *result = NULL ;
-      return ;
+      return NULL ;
     }
 
-  owl_fill_result(result, csv) ;
+  return owl_fill_result(csv) ;
 }
 
 
-/* Splits the 'csv' string received from OwlPS Positioning and stores
- * the fields in 'result' (which is allocated).
+/*
+ * Splits the 'csv' string received from OwlPS Positioning and stores
+ * the fields in a new owl_result, and returns a pointer to it (or NULL
+ * in case of error).
+ *
+ * Note that the new owl_result is allocated with malloc() and must be
+ * deleted using free().
  *
  * Handled CSV format:
  *  Mobile_MAC;Request_type;Request_timestamp;Algorithm;X;Y;Z;Error;Area
  * The Request_timestamp format is:
  *  seconds.nanoseconds
  */
-void owl_fill_result(owl_result **result, char *csv)
+owl_result* owl_fill_result(char *csv)
 {
   char *csv_field = NULL ;
+  owl_result *result = NULL ;
   int nb_algorithms = 0 ;
   owl_algorithm_result *current_algo = NULL ;
 
-  *result = malloc(sizeof(owl_result)) ;
-  (*result)->results = NULL ;
+  result = malloc(sizeof(owl_result)) ;
+  memset(result, 0, sizeof(*result)) ;
 
   /* Mobile MAC address */
   csv_field = strsep(&csv, CSV_DELIMITER) ;
@@ -65,7 +68,7 @@ void owl_fill_result(owl_result **result, char *csv)
               " string (empty string?)!\n") ;
       goto error ;
     }
-  (*result)->mobile_mac_addr =
+  result->mobile_mac_addr =
     strndup(csv_field, OWL_ETHER_ADDR_STRLEN) ;
 
   /* Request type */
@@ -76,7 +79,7 @@ void owl_fill_result(owl_result **result, char *csv)
               "Error reading the request type from the CSV string!\n") ;
       goto error ;
     }
-  (*result)->request_type = atoi(csv_field) ;
+  result->request_type = atoi(csv_field) ;
 
   /* Timestamp */
   // Seconds
@@ -88,7 +91,7 @@ void owl_fill_result(owl_result **result, char *csv)
               " string!\n") ;
       goto error ;
     }
-  (*result)->mobile_timestamp.tv_sec = atol(csv_field) ;
+  result->mobile_timestamp.tv_sec = atol(csv_field) ;
   // Nanoseconds
   csv_field = strsep(&csv, CSV_DELIMITER) ;
   if (! csv_field)
@@ -98,7 +101,7 @@ void owl_fill_result(owl_result **result, char *csv)
               " string!\n") ;
       goto error ;
     }
-  (*result)->mobile_timestamp.tv_nsec = atol(csv_field) ;
+  result->mobile_timestamp.tv_nsec = atol(csv_field) ;
 
   /* Algorithm results */
   csv_field = strsep(&csv, CSV_DELIMITER) ;
@@ -106,6 +109,7 @@ void owl_fill_result(owl_result **result, char *csv)
     {
       ++nb_algorithms ;
       current_algo = malloc(sizeof(owl_algorithm_result)) ;
+      memset(current_algo, 0, sizeof(*current_algo)) ;
 
       // Algorithm name
       if (! csv_field)
@@ -168,17 +172,17 @@ void owl_fill_result(owl_result **result, char *csv)
         current_algo->area = strndup(csv_field, OWL_AREA_STRLEN) ;
 
       // Insert the current algorithm at the begining of the list
-      current_algo->next = (*result)->results ;
-      (*result)->results = current_algo ;
+      current_algo->next = result->results ;
+      result->results = current_algo ;
     }
   while ((csv_field = strsep(&csv, CSV_DELIMITER))) ;
 
-  return ; // Success
+  return result ; // Success
 
  error:
-  owl_free_result(*result) ;
-  *result = NULL ;
-  free(current_algo) ;
+  owl_free_result(result) ;
+  owl_free_algorithm_result(current_algo) ;
+  return NULL ;
 }
 
 
@@ -296,7 +300,9 @@ void owl_fprint_algorithm_result(FILE *stream,
 
 
 /*
- * Frees the memory allocated by an owl_result.
+ * Frees the memory allocated by an owl_result. The 'results' and
+ * 'mobile_mac_addr' fields *must* be defined, either to NULL or to a
+ * valid memory block allocated with malloc().
  * Note that the pointer will not set to NULL.
  */
 void owl_free_result(owl_result *result)
@@ -316,7 +322,8 @@ void owl_free_result(owl_result *result)
 
 /*
  * Frees the memory allocated by a single owl_algorithm_result (*not*
- * recursively).
+ * recursively). The 'algorithm' and 'area' fields *must* be defined,
+ * either to NULL or to a valid memory block allocated with malloc().
  * Note that the pointer will not set to NULL.
  */
 void owl_free_algorithm_result(owl_algorithm_result *algo)

libowlps-resultreader-udp/owlps-resultreader-udp.c

@@ -20,8 +20,7 @@ int main(void)
 
   while (1)
     {
-      owl_receive_position(sockfd, &result) ;
-      if (result == NULL)
+      if (! (result = owl_receive_position(sockfd)))
         return 1 ;
       owl_print_result(result) ;
       owl_free_result(result) ;

libowlps-resultreader-udp/owlps-resultreader-udp.h

@@ -54,8 +54,8 @@ typedef struct _owl_result
 } owl_result ;
 
 
-void owl_receive_position(int sockfd, owl_result **result) ;
-void owl_fill_result(owl_result **result, char *csv) ;
+owl_result* owl_receive_position(int sockfd) ;
+owl_result* owl_fill_result(char *csv) ;
 
 void owl_result_to_csv(char dst[OWL_CSV_RESULT_STRLEN],
                        const owl_result *const src) ;