Add a method to check if a backend is present.

Uses dlopen to check if a backend is present. This may be used by
consumers who need to check which backends are present on a system.

Issue #23

2 files changed, 10 insertions, 1 deletions

diff --git a/include/erasurecode/erasurecode.h b/include/erasurecode/erasurecode.h
index 793b829..f8621a4 100644
--- a/include/erasurecode/erasurecode.h
+++ b/include/erasurecode/erasurecode.h
@@ -93,6 +93,15 @@ struct ec_args {
 /* liberasurecode frontend API functions */
 
 /**
+ * Checks if a given backend is available.
+ *
+ * @param backend_id - one of the supported backends.
+ *
+ * @returns 1 if a backend is available; 0 otherwise
+ */
+int liberasurecode_backend_available(const ec_backend_id_t backend_id);
+
+/**
  * Create a liberasurecode instance and return a descriptor 
  * for use with EC operations (encode, decode, reconstruct)
  *
diff --git a/include/erasurecode/erasurecode_backend.h b/include/erasurecode/erasurecode_backend.h
index d62c6fb..4199344 100644
--- a/include/erasurecode/erasurecode_backend.h
+++ b/include/erasurecode/erasurecode_backend.h
@@ -142,7 +142,7 @@ int liberasurecode_backend_instance_unregister(ec_backend_t instance);
 
 
 /* Generic dlopen/dlclose routines */
-int liberasurecode_backend_open(ec_backend_t instance);
+void* liberasurecode_backend_open(ec_backend_t instance);
 int liberasurecode_backend_close(ec_backend_t instance);