Add simple buffer management code.

[meshlink] / src / buffer.c

diff --git a/src/buffer.c b/src/buffer.c
new file mode 100644 (file)
index 0000000..fc4fac0
--- /dev/null
+++ b/src/buffer.c
@@ -0,0 +1,99 @@
+/*
+    buffer.c -- buffer management
+    Copyright (C) 2011 Guus Sliepen <guus@tinc-vpn.org>,
+
+    This program 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 of the License, or
+    (at your option) any later version.
+
+    This program 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 this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "system.h"
+
+#include "buffer.h"
+#include "xalloc.h"
+
+// Make sure we can add size bytes to the buffer, and return a pointer to the start of those bytes.
+
+char *buffer_prepare(buffer_t *buffer, int size) {
+       if(!buffer->data) {
+               buffer->maxlen = size;
+               buffer->data = xmalloc(size);
+       } else {
+               if(buffer->offset && buffer->len + size > buffer->maxlen) {
+                       memmove(buffer->data, buffer->data + buffer->offset, buffer->len - buffer->offset);
+                       buffer->len -= buffer->offset;
+                       buffer->offset = 0;
+               }
+
+               if(buffer->len + size > buffer->maxlen) {
+                       buffer->maxlen = buffer->len + size;
+                       buffer->data = xrealloc(buffer->data, buffer->maxlen);
+               }
+       }
+
+       buffer->len += size;
+       return buffer->data + buffer->offset;
+}
+
+// Copy data into the buffer.
+                       
+char *buffer_add(buffer_t *buffer, const char *data, int size) {
+       memcpy(buffer_prepare(buffer, size), data, size);
+}
+
+// Remove given number of bytes from the buffer, return a pointer to the start of them.
+
+static char *buffer_consume(buffer_t *buffer, int size) {
+       char *start = buffer->data + buffer->offset;
+
+       buffer->offset += size;
+
+       if(buffer->offset >= buffer->len) {
+               buffer->offset = 0;
+               buffer->len = 0;
+       } else {
+               buffer->offset += size;
+       }
+
+       return start;
+}
+
+// Check if there is a complete line in the buffer, and if so, return it NULL-terminated.
+
+char *buffer_readline(buffer_t *buffer) {
+       char *newline = memchr(buffer->data + buffer->offset, '\n', buffer->len - buffer->offset);
+
+       if(!newline)
+               return NULL;
+
+       int len = newline + 1 - buffer->data + buffer->offset;
+       *newline = 0;
+       return buffer_consume(buffer, len);
+}
+
+// Check if we have enough bytes in the buffer, and if so, return a pointer to the start of them.
+
+char *buffer_read(buffer_t *buffer, int size) {
+       if(buffer->len - buffer->offset < size)
+               return NULL;
+
+       return buffer_consume(buffer, size);
+}
+
+void buffer_clear(buffer_t *buffer) {
+       free(buffer->data);
+       buffer->data = 0;
+       buffer->maxlen = 0;
+       buffer->len = 0;
+       buffer->offset = 0;
+}