[Qemu-devel] [PATCH 1/5] net/dump: Add support for receive_iov function

[Thomas Huth <thuth@redhat.com>]

Adding a proper receive_iov function to the net dump module. This
will make it easier to support the dump feature for the -netdev
option in later patches.
Also make the receive functions available to the other parts of the
source code so we can later use them for dumping from net.c, too.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 net/clients.h |  3 +++
 net/dump.c    | 48 ++++++++++++++++++++++++++++++++++++++++--------
 2 files changed, 43 insertions(+), 8 deletions(-)

diff --git a/net/clients.h b/net/clients.h
index d47530e..5092f3d 100644
--- a/net/clients.h
+++ b/net/clients.h
@@ -29,6 +29,9 @@
 
 int net_init_dump(const NetClientOptions *opts, const char *name,
                   NetClientState *peer, Error **errp);
+ssize_t net_dump_receive(NetClientState *nc, const uint8_t *buf, size_t size);
+ssize_t net_dump_receive_iov(NetClientState *nc, const struct iovec *iov,
+                             int cnt);
 
 #ifdef CONFIG_SLIRP
 int net_init_slirp(const NetClientOptions *opts, const char *name,
diff --git a/net/dump.c b/net/dump.c
index 02c8064..383718a 100644
--- a/net/dump.c
+++ b/net/dump.c
@@ -57,27 +57,49 @@ struct pcap_sf_pkthdr {
     uint32_t len;
 };
 
-static ssize_t dump_receive(NetClientState *nc, const uint8_t *buf, size_t size)
+ssize_t net_dump_receive_iov(NetClientState *nc, const struct iovec *iov,
+                             int cnt)
 {
     DumpState *s = DO_UPCAST(DumpState, nc, nc);
     struct pcap_sf_pkthdr hdr;
     int64_t ts;
-    int caplen;
+    int caplen, i;
+    size_t size = 0;
+    struct iovec dumpiov[cnt + 1];
 
     /* Early return in case of previous error. */
     if (s->fd < 0) {
         return size;
     }
 
+    dumpiov[0].iov_base = &hdr;
+    dumpiov[0].iov_len = sizeof(hdr);
+    caplen = s->pcap_caplen;
+
+    /* Copy iov, limit maximum size to caplen, and count total input size */
+    for (i = 0; i < cnt; i++) {
+        dumpiov[i + 1].iov_base = iov[i].iov_base;
+        if (size + iov[i].iov_len <= caplen) {
+            dumpiov[i + 1].iov_len = iov[i].iov_len;
+        } else if (size < caplen) {
+            dumpiov[i + 1].iov_len = caplen - size;
+        } else {
+            dumpiov[i + 1].iov_len = 0;
+        }
+        size += iov[i].iov_len;
+    }
+
     ts = muldiv64(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL), 1000000, get_ticks_per_sec());
-    caplen = size > s->pcap_caplen ? s->pcap_caplen : size;
+    if (size < caplen) {
+        caplen = size;
+    }
 
     hdr.ts.tv_sec = ts / 1000000 + s->start_ts;
     hdr.ts.tv_usec = ts % 1000000;
     hdr.caplen = caplen;
     hdr.len = size;
-    if (write(s->fd, &hdr, sizeof(hdr)) != sizeof(hdr) ||
-        write(s->fd, buf, caplen) != caplen) {
+
+    if (writev(s->fd, dumpiov, cnt + 1) != sizeof(hdr) + caplen) {
         qemu_log("-net dump write error - stop dump\n");
         close(s->fd);
         s->fd = -1;
@@ -86,7 +108,16 @@ static ssize_t dump_receive(NetClientState *nc, const uint8_t *buf, size_t size)
     return size;
 }
 
-static void dump_cleanup(NetClientState *nc)
+ssize_t net_dump_receive(NetClientState *nc, const uint8_t *buf, size_t size)
+{
+    struct iovec iov = {
+        .iov_base = (void *)buf,
+        .iov_len = size
+    };
+    return net_dump_receive_iov(nc, &iov, 1);
+}
+
+static void net_dump_cleanup(NetClientState *nc)
 {
     DumpState *s = DO_UPCAST(DumpState, nc, nc);
 
@@ -96,8 +127,9 @@ static void dump_cleanup(NetClientState *nc)
 static NetClientInfo net_dump_info = {
     .type = NET_CLIENT_OPTIONS_KIND_DUMP,
     .size = sizeof(DumpState),
-    .receive = dump_receive,
-    .cleanup = dump_cleanup,
+    .receive = net_dump_receive,
+    .receive_iov = net_dump_receive_iov,
+    .cleanup = net_dump_cleanup,
 };
 
 static int net_dump_init(NetClientState *peer, const char *device,
-- 
1.8.3.1