common: add generic input-line interface, and an implementation of it for text files

common/include/ivy/line-source.h

@@ -1,21 +1,15 @@
 #ifndef IVY_COMMON_LINE_SOURCE_H_
 #define IVY_COMMON_LINE_SOURCE_H_
 
+#include <ivy/status.h>
 #include <stddef.h>
 
-enum ivy_line_source_status {
-	IVY_LS_OK = 0,
-	IVY_LS_EOF,
-	IVY_LS_ERR_IOERR,
-	IVY_LS_ERR_NOSYS,
-};
-
 struct ivy_line_source {
-	enum ivy_line_source_status (*s_readline)(
+	enum ivy_status (*s_readline)(
 		struct ivy_line_source *, char *, size_t, size_t *, const char *);
 };
 
-extern enum ivy_line_source_status ivy_line_source_readline(
+extern enum ivy_status ivy_line_source_readline(
 	struct ivy_line_source *src, char *buf, size_t count, size_t *nr_read,
 	const char *prompt);