allocate buffer and data in a single allocation

--HG--
branch : nocircbuffer

buffer.c

@@ -46,17 +46,15 @@ buffer* buf_new(unsigned int size) {
 		dropbear_exit("buf->size too big");
 	}
 
-	buf = (buffer*)m_malloc(sizeof(buffer));
+	buf = (buffer*)m_malloc(sizeof(buffer)+size);
 
 	if (size > 0) {
-		buf->data = (unsigned char*)m_malloc(size);
+		buf->data = (unsigned char*)buf + sizeof(buffer);
 	} else {
 		buf->data = NULL;
 	}
 
 	buf->size = size;
-	buf->pos = 0;
-	buf->len = 0;
 
 	return buf;
 
@@ -65,7 +63,6 @@ buffer* buf_new(unsigned int size) {
 /* free the buffer's data and the buffer itself */
 void buf_free(buffer* buf) {
 
-	m_free(buf->data)
 	m_free(buf);
 }
 
@@ -78,17 +75,18 @@ void buf_burn(buffer* buf) {
 
 /* resize a buffer, pos and len will be repositioned if required when
  * downsizing */
-void buf_resize(buffer *buf, unsigned int newsize) {
+buffer* buf_resize(buffer *buf, unsigned int newsize) {
 
 	if (newsize > BUF_MAX_SIZE) {
 		dropbear_exit("buf->size too big");
 	}
 
-	buf->data = m_realloc(buf->data, newsize);
+	buf = m_realloc(buf, sizeof(buffer)+newsize);
+	buf->data = (unsigned char*)buf + sizeof(buffer);
 	buf->size = newsize;
 	buf->len = MIN(newsize, buf->len);
 	buf->pos = MIN(newsize, buf->pos);
-
+	return buf;
 }
 
 /* Create a copy of buf, allocating required memory etc. */
@@ -227,15 +225,15 @@ unsigned char* buf_getstring(buffer* buf, unsigned int *retlen) {
 
 /* Return a string as a newly allocated buffer */
 buffer * buf_getstringbuf(buffer *buf) {
-	buffer *ret;
-	unsigned char* str;
-	unsigned int len;
-	str = buf_getstring(buf, &len);
-	ret = m_malloc(sizeof(*ret));
-	ret->data = str;
-	ret->len = len;
-	ret->size = len;
-	ret->pos = 0;
+	buffer *ret = NULL;
+	unsigned int len = buf_getint(buf);
+	if (len > MAX_STRING_LEN) {
+		dropbear_exit("String too long");
+	}
+	ret = buf_new(len);
+	memcpy(buf_getwriteptr(ret, len), buf_getptr(buf, len), len);
+	buf_incrpos(buf, len);
+	buf_incrlen(ret, len);
 	return ret;
 }