import VTY code from zebra/quagga (from my cardshell project)
diff --git a/include/vty/buffer.h b/include/vty/buffer.h
new file mode 100644
index 0000000..87cb3fd
--- /dev/null
+++ b/include/vty/buffer.h
@@ -0,0 +1,100 @@
+/*
+ * Buffering to output and input.
+ * Copyright (C) 1998 Kunihiro Ishiguro
+ *
+ * This file is part of GNU Zebra.
+ *
+ * GNU Zebra is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published
+ * by the Free Software Foundation; either version 2, or (at your
+ * option) any later version.
+ *
+ * GNU Zebra is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GNU Zebra; see the file COPYING. If not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#ifndef _ZEBRA_BUFFER_H
+#define _ZEBRA_BUFFER_H
+
+/* Create a new buffer. Memory will be allocated in chunks of the given
+ size. If the argument is 0, the library will supply a reasonable
+ default size suitable for buffering socket I/O. */
+struct buffer *buffer_new(size_t);
+
+/* Free all data in the buffer. */
+void buffer_reset(struct buffer *);
+
+/* This function first calls buffer_reset to release all buffered data.
+ Then it frees the struct buffer itself. */
+void buffer_free(struct buffer *);
+
+/* Add the given data to the end of the buffer. */
+extern void buffer_put(struct buffer *, const void *, size_t);
+/* Add a single character to the end of the buffer. */
+extern void buffer_putc(struct buffer *, u_char);
+/* Add a NUL-terminated string to the end of the buffer. */
+extern void buffer_putstr(struct buffer *, const char *);
+
+/* Combine all accumulated (and unflushed) data inside the buffer into a
+ single NUL-terminated string allocated using XMALLOC(MTYPE_TMP). Note
+ that this function does not alter the state of the buffer, so the data
+ is still inside waiting to be flushed. */
+char *buffer_getstr(struct buffer *);
+
+/* Returns 1 if there is no pending data in the buffer. Otherwise returns 0. */
+int buffer_empty(struct buffer *);
+
+typedef enum {
+ /* An I/O error occurred. The buffer should be destroyed and the
+ file descriptor should be closed. */
+ BUFFER_ERROR = -1,
+
+ /* The data was written successfully, and the buffer is now empty
+ (there is no pending data waiting to be flushed). */
+ BUFFER_EMPTY = 0,
+
+ /* There is pending data in the buffer waiting to be flushed. Please
+ try flushing the buffer when select indicates that the file descriptor
+ is writeable. */
+ BUFFER_PENDING = 1
+} buffer_status_t;
+
+/* Try to write this data to the file descriptor. Any data that cannot
+ be written immediately is added to the buffer queue. */
+extern buffer_status_t buffer_write(struct buffer *, int fd,
+ const void *, size_t);
+
+/* This function attempts to flush some (but perhaps not all) of
+ the queued data to the given file descriptor. */
+extern buffer_status_t buffer_flush_available(struct buffer *, int fd);
+
+/* The following 2 functions (buffer_flush_all and buffer_flush_window)
+ are for use in lib/vty.c only. They should not be used elsewhere. */
+
+/* Call buffer_flush_available repeatedly until either all data has been
+ flushed, or an I/O error has been encountered, or the operation would
+ block. */
+extern buffer_status_t buffer_flush_all(struct buffer *, int fd);
+
+/* Attempt to write enough data to the given fd to fill a window of the
+ given width and height (and remove the data written from the buffer).
+
+ If !no_more, then a message saying " --More-- " is appended.
+ If erase is true, then first overwrite the previous " --More-- " message
+ with spaces.
+
+ Any write error (including EAGAIN or EINTR) will cause this function
+ to return -1 (because the logic for handling the erase and more features
+ is too complicated to retry the write later).
+*/
+extern buffer_status_t buffer_flush_window(struct buffer *, int fd, int width,
+ int height, int erase, int no_more);
+
+#endif /* _ZEBRA_BUFFER_H */