test_config: clarify some details about the CONF interface

trackrdrd/include/config_common.h

@@ -34,8 +34,11 @@
  * \brief Config handling interface
  * \details Common functions to get configuration data
  *
- * This header defines the functions the plugin uses to get its
- * configuration data.
+ * This header defines the functions used to get configuration data.
+ *
+ * If the conf_add() callback returns non-zero, CONF_ReadFile() prints
+ * an error message to `stderr` assuming that the return value is an
+ * errno value.
  */
 
 
@@ -44,7 +47,7 @@
  *
  * @param lval key
  * @param rval value
- * @return 0 on success, an error value on failure
+ * @return 0 on success, an errno value on failure
  */
 typedef int conf_add_f(const char *lval, const char *rval);
 

trackrdrd/src/test/test_config.c

@@ -183,7 +183,7 @@ static char
     TEST_catchStderrStart();
     err = CONF_ReadFile(confName, CONF_Add);
     TEST_catchStderrEnd();
-    VMASSERT(err == -1, "Wrong error code during reading config \"%s\": %i",
+    VMASSERT(err < 0, "Wrong error code during reading config \"%s\": %i",
              confName, err);
     err = TEST_stderrEquals(errmsg);
     VMASSERT(err == 0,

trackrdrd/src/trackrdrd.h

@@ -331,6 +331,13 @@ struct config {
 
 void CONF_Init(void);
 int CONF_Add(const char *lval, const char *rval);
+/**
+ * Reads the default config file `/etc/trackrdrd.conf`, if present
+ *
+ * @returns 0 if the file does not exist or was successfully read,
+ *          >0 (errno) if the file exists but cannot be read,
+ *          <0 if the file was read but the contents could not be processed
+ */
 int CONF_ReadDefault(void);
 void CONF_Dump(void);