lib: fix a few bugs in ring buffers

* Fix rare failure caused when end pointer is at end of buffer memory
  and a call to ringbuf_get() is made that reads all of the data in the
  buffer; start pointer was advanced past end pointer, causing some
  special handling to be skipped
* Fix ringbuf_peek() moving start pointer
* Fix use after free
* Remove extraneous assignment
* Update relevant tests

Signed-off-by: Quentin Young <qlyoung@cumulusnetworks.com>

2 files changed, 6 insertions, 6 deletions

diff --git a/lib/ringbuf.c b/lib/ringbuf.c
index d4efbe05fb..11db502a94 100644
--- a/lib/ringbuf.c
+++ b/lib/ringbuf.c
@@ -58,7 +58,7 @@ size_t ringbuf_put(struct ringbuf *buf, const void *data, size_t size)
 	size_t space = ringbuf_space(buf);
 	size_t copysize = MIN(size, space);
 	size_t tocopy = copysize;
-	if (tocopy > buf->size - buf->end) {
+	if (tocopy >= buf->size - buf->end) {
 		size_t ts = buf->size - buf->end;
 		memcpy(buf->data + buf->end, dp, ts);
 		buf->end = 0;
@@ -102,7 +102,7 @@ size_t ringbuf_peek(struct ringbuf *buf, size_t offset, void *data, size_t size)
 	if (tocopy >= buf->size - cstart) {
 		size_t ts = buf->size - cstart;
 		memcpy(dp, buf->data + cstart, ts);
-		buf->start = cstart = 0;
+		cstart = 0;
 		tocopy -= ts;
 		dp += ts;
 	}
@@ -115,8 +115,9 @@ size_t ringbuf_copy(struct ringbuf *to, struct ringbuf *from, size_t size)
 	size_t tocopy = MIN(ringbuf_space(to), size);
 	uint8_t *cbuf = XCALLOC(MTYPE_TMP, tocopy);
 	tocopy = ringbuf_peek(from, 0, cbuf, tocopy);
+	size_t put = ringbuf_put(to, cbuf, tocopy);
 	XFREE(MTYPE_TMP, cbuf);
-	return ringbuf_put(to, cbuf, tocopy);
+	return put;
 }
 
 void ringbuf_reset(struct ringbuf *buf)
@@ -129,5 +130,4 @@ void ringbuf_wipe(struct ringbuf *buf)
 {
 	memset(buf->data, 0x00, buf->size);
 	ringbuf_reset(buf);
-	buf->empty = true;
 }
diff --git a/tests/lib/test_ringbuf.c b/tests/lib/test_ringbuf.c
index c2f4f76a6f..7ba5a29b62 100644
--- a/tests/lib/test_ringbuf.c
+++ b/tests/lib/test_ringbuf.c
@@ -65,7 +65,7 @@ int main(int argc, char **argv)
 
 	validate_state(soil, BUFSIZ, BUFSIZ);
 	assert(soil->start == 0);
-	assert(soil->end == BUFSIZ);
+	assert(soil->end == 0);
 
 	/* read 15 bytes of garbage */
 	printf("Validating read...\n");
@@ -73,7 +73,7 @@ int main(int argc, char **argv)
 
 	validate_state(soil, BUFSIZ, BUFSIZ - 15);
 	assert(soil->start == 15);
-	assert(soil->end == BUFSIZ);
+	assert(soil->end == 0);
 
 	/* put another 10 bytes and validate wraparound */
 	printf("Validating wraparound...\n");