Added generic line-buffering code (a la stdio)

src/tests/linebuf_test.c

@@ -0,0 +1,27 @@
+#include <stdint.h>
+#include <string.h>
+#include <vsprintf.h>
+#include <gpxe/linebuf.h>
+
+static const char data1[] = 
+"Hello world\r\n"
+"This is a particularly mean set of lines\n"
+"with a mixture of terminators\r\r\n"
+"There should be exactly one blank line above\n"
+"and this line should never appear at all since it has no terminator";
+
+void linebuf_test ( void ) {
+	struct line_buffer linebuf;
+	const char *data = data1;
+	size_t len = ( sizeof ( data1 ) - 1 /* be mean; strip the NUL */ );
+	size_t buffered;
+
+	memset ( &linebuf, 0, sizeof ( linebuf ) );
+	while ( ( buffered = line_buffer ( &linebuf, data, len ) ) != len ) {
+		printf ( "\"%s\"\n", buffered_line ( &linebuf ) );
+		data += buffered;
+		len -= buffered;
+	}
+
+	empty_line_buffer ( &linebuf );
+}