1 files changed, 133 insertions, 0 deletions
diff --git a/src/circbuffer.c b/src/circbuffer.c
new file mode 100644
index 0000000..aabd9dc
--- /dev/null
+++ b/src/circbuffer.c
@@ -0,0 +1,133 @@
+/*
+ * Dropbear SSH
+ * 
+ * Copyright (c) 2002-2004 Matt Johnston
+ * All rights reserved.
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE. */
+
+#include "includes.h"
+#include "dbutil.h"
+#include "circbuffer.h"
+
+#define MAX_CBUF_SIZE 100000000
+
+circbuffer * cbuf_new(unsigned int size) {
+
+	circbuffer *cbuf = NULL;
+
+	if (size > MAX_CBUF_SIZE) {
+		dropbear_exit("Bad cbuf size");
+	}
+
+	cbuf = (circbuffer*)m_malloc(sizeof(circbuffer));
+	/* data is malloced on first write */
+	cbuf->data = NULL;
+	cbuf->used = 0;
+	cbuf->readpos = 0;
+	cbuf->writepos = 0;
+	cbuf->size = size;
+
+	return cbuf;
+}
+
+void cbuf_free(circbuffer * cbuf) {
+
+	if (cbuf->data) {
+		m_burn(cbuf->data, cbuf->size);
+		m_free(cbuf->data);
+	}
+	m_free(cbuf);
+}
+
+unsigned int cbuf_getused(const circbuffer * cbuf) {
+
+	return cbuf->used;
+
+}
+
+unsigned int cbuf_getavail(const circbuffer * cbuf) {
+
+	return cbuf->size - cbuf->used;
+
+}
+
+unsigned int cbuf_writelen(const circbuffer *cbuf) {
+
+	dropbear_assert(cbuf->used <= cbuf->size);
+	dropbear_assert(((2*cbuf->size)+cbuf->writepos-cbuf->readpos)%cbuf->size == cbuf->used%cbuf->size);
+	dropbear_assert(((2*cbuf->size)+cbuf->readpos-cbuf->writepos)%cbuf->size == (cbuf->size-cbuf->used)%cbuf->size);
+
+	if (cbuf->used == cbuf->size) {
+		TRACE(("cbuf_writelen: full buffer"))
+		return 0; /* full */
+	}
+	
+	if (cbuf->writepos < cbuf->readpos) {
+		return cbuf->readpos - cbuf->writepos;
+	}
+
+	return cbuf->size - cbuf->writepos;
+}
+
+void cbuf_readptrs(const circbuffer *cbuf,
+	unsigned char **p1, unsigned int *len1, 
+	unsigned char **p2, unsigned int *len2) {
+	*p1 = &cbuf->data[cbuf->readpos];
+	*len1 = MIN(cbuf->used, cbuf->size - cbuf->readpos);
+
+	if (*len1 < cbuf->used) {
+		*p2 = cbuf->data;
+		*len2 = cbuf->used - *len1;
+	} else {
+		*p2 = NULL;
+		*len2 = 0;
+	}
+}
+
+unsigned char* cbuf_writeptr(circbuffer *cbuf, unsigned int len) {
+
+	if (len > cbuf_writelen(cbuf)) {
+		dropbear_exit("Bad cbuf write");
+	}
+
+	if (!cbuf->data) {
+		/* lazy allocation */
+		cbuf->data = (unsigned char*)m_malloc(cbuf->size);
+	}
+
+	return &cbuf->data[cbuf->writepos];
+}
+
+void cbuf_incrwrite(circbuffer *cbuf, unsigned int len) {
+	if (len > cbuf_writelen(cbuf)) {
+		dropbear_exit("Bad cbuf write");
+	}
+
+	cbuf->used += len;
+	dropbear_assert(cbuf->used <= cbuf->size);
+	cbuf->writepos = (cbuf->writepos + len) % cbuf->size;
+}
+
+
+void cbuf_incrread(circbuffer *cbuf, unsigned int len) {
+	dropbear_assert(cbuf->used >= len);
+	cbuf->used -= len;
+	cbuf->readpos = (cbuf->readpos + len) % cbuf->size;
+}