Allocate array in nc_sendv_compat on the heap if it is large to reduce stack
frame size, as stated in the BiteSizedTasks wiki page.
Signed-off-by: Nikos Filippakis <aesm...@gmail.com>
---
net/net.c | 32 +++++++++++++++++++++++++-------
1 file changed, 25 insertions(+), 7 deletions(-)
diff --git a/net/net.c b/net/net.c
index b0c832e..a9be287 100644
--- a/net/net.c
+++ b/net/net.c
@@ -709,23 +709,41 @@ ssize_t qemu_send_packet_raw(NetClientState *nc, const
uint8_t *buf, int size)
static ssize_t nc_sendv_compat(NetClientState *nc, const struct iovec *iov,
int iovcnt, unsigned flags)
{
- uint8_t buf[NET_BUFSIZE];
- uint8_t *buffer;
- size_t offset;
+ const size_t STACKBUF_SIZE = 2048;
+
+ uint8_t *buffer, *dynbuf = NULL;
+ uint8_t stackbuf[STACKBUF_SIZE];
+ size_t offset, iov_len;
+ ssize_t ret;
if (iovcnt == 1) {
buffer = iov[0].iov_base;
offset = iov[0].iov_len;
} else {
- buffer = buf;
- offset = iov_to_buf(iov, iovcnt, 0, buf, sizeof(buf));
+ iov_len = iov_size(iov, iovcnt);
+
+ if (iov_len <= STACKBUF_SIZE) {
+ buffer = stackbuf;
+ } else if (iov_len <= NET_BUFSIZE) {
+ buffer = dynbuf = g_new(uint8_t, iov_len);
+ } else {
+ errno = EINVAL;
+ return 0;
+ }
+
+ offset = iov_to_buf(iov, iovcnt, 0, buffer,
+ NET_BUFSIZE * sizeof(uint8_t));
}
if (flags & QEMU_NET_PACKET_FLAG_RAW && nc->info->receive_raw) {
- return nc->info->receive_raw(nc, buffer, offset);
+ ret = nc->info->receive_raw(nc, buffer, offset);
} else {
- return nc->info->receive(nc, buffer, offset);
+ ret = nc->info->receive(nc, buffer, offset);
}
+
+ g_free(dynbuf);
+
+ return ret;
}
ssize_t qemu_deliver_packet_iov(NetClientState *sender,
--
1.9.1
