sr_init/sr_exit: Improve docs, add error checks.

diff --git a/backend.c b/backend.c
index dd38f66e287a4fb5c53332ac84aacb7a0f672922..eba03aafb5388197cb743f9cd09240ba4a28f851 100644 (file)
--- a/backend.c
+++ b/backend.c
@@ -25,13 +25,27 @@
 /**
  * Initialize libsigrok.
  *
- * @return SR_OK upon success, a (negative) error code otherwise.
+ * This function must be called before any other libsigrok function.
+ *
+ * @param ctx Pointer to a libsigrok context struct pointer. Must not be NULL.
+ *            This will be a pointer to a newly allocated libsigrok context
+ *            object upon success, and is undefined upon errors.
+ *
+ * @return SR_OK upon success, a (negative) error code otherwise. Upon errors
+ *         the 'ctx' pointer is undefined and should not be used. Upon success,
+ *         the context will be free'd by sr_exit() as part of the libsigrok
+ *         shutdown.
  */
 SR_API int sr_init(struct sr_context **ctx)
 {
        int ret = SR_ERR;
        struct sr_context *context;
 
+       if (!ctx) {
+               sr_err("%s(): libsigrok context was NULL.", __func__);
+               return SR_ERR;
+       }
+
        /* + 1 to handle when struct sr_context has no members. */
        context = g_try_malloc0(sizeof(struct sr_context) + 1);
 
@@ -42,8 +56,8 @@ SR_API int sr_init(struct sr_context **ctx)
 
 #ifdef HAVE_LIBUSB_1_0
        ret = libusb_init(&context->libusb_ctx);
-       if (LIBUSB_SUCCESS != ret) {
-               sr_err("libusb_init() returned %s\n", libusb_error_name(ret));
+       if (LIBUSB_SUCCESS == ret) {
+               sr_err("libusb_init() returned %s.\n", libusb_error_name(ret));
                goto done;
        }
 #endif
@@ -58,10 +72,17 @@ done:
 /**
  * Shutdown libsigrok.
  *
+ * @param ctx Pointer to a libsigrok context struct. Must not be NULL.
+ *
  * @return SR_OK upon success, a (negative) error code otherwise.
  */
 SR_API int sr_exit(struct sr_context *ctx)
 {
+       if (!ctx) {
+               sr_err("%s(): libsigrok context was NULL.", __func__);
+               return SR_ERR;
+       }
+
        sr_hw_cleanup_all();
 
 #ifdef HAVE_LIBUSB_1_0