From fce82f12ef0fde847d291b85057e9e0df07f011c Mon Sep 17 00:00:00 2001
From: compile_success <980965867@qq.com>
Date: Sat, 12 Nov 2022 14:19:30 +0000
Subject: [PATCH 20/20] modify readv and writev first buf is null

---
 src/lstack/api/lstack_wrap.c  |  7 ++++++-
 src/lstack/core/lstack_lwip.c | 10 +++++++++-
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/src/lstack/api/lstack_wrap.c b/src/lstack/api/lstack_wrap.c
index d48fee0..2eeda6b 100644
--- a/src/lstack/api/lstack_wrap.c
+++ b/src/lstack/api/lstack_wrap.c
@@ -352,7 +352,12 @@ static inline ssize_t do_readv(int32_t s, const struct iovec *iov, int iovcnt)
    msg.msg_control = NULL;
    msg.msg_controllen = 0;
    msg.msg_flags = 0;
-   return recvmsg_from_stack(s, &msg, 0);
+   ssize_t result = recvmsg_from_stack(s, &msg, 0);
+   if(result == -1 && errno == EAGAIN){
+        errno = 0;
+	return 0;
+   }
+   return result;
 }
 
 static inline ssize_t do_send(int32_t sockfd, const void *buf, size_t len, int32_t flags)
diff --git a/src/lstack/core/lstack_lwip.c b/src/lstack/core/lstack_lwip.c
index d9ae6c0..4fec74e 100644
--- a/src/lstack/core/lstack_lwip.c
+++ b/src/lstack/core/lstack_lwip.c
@@ -473,7 +473,7 @@ static int32_t check_msg_vaild(const struct msghdr *message)
     for (int32_t i = 0; i < message->msg_iovlen; i++) {
         if ((message->msg_iov[i].iov_base == NULL) || ((ssize_t)message->msg_iov[i].iov_len < 0) ||
             ((size_t)(ssize_t)message->msg_iov[i].iov_len != message->msg_iov[i].iov_len) ||
-            ((ssize_t)(buflen + (ssize_t)message->msg_iov[i].iov_len) <= 0)) {
+            ((ssize_t)(buflen + (ssize_t)message->msg_iov[i].iov_len) < 0)) {
             GAZELLE_RETURN(EINVAL);
         }
         buflen = (ssize_t)(buflen + (ssize_t)message->msg_iov[i].iov_len);
@@ -491,6 +491,10 @@ ssize_t recvmsg_from_stack(int32_t s, struct msghdr *message, int32_t flags)
     }
 
     for (int32_t i = 0; i < message->msg_iovlen; i++) {
+	if (message->msg_iov[i].iov_len == 0){
+	    continue;
+	}
+
         ssize_t recvd_local = read_stack_data(s, message->msg_iov[i].iov_base, message->msg_iov[i].iov_len, flags);
         if (recvd_local > 0) {
             buflen += recvd_local;
@@ -554,6 +558,10 @@ ssize_t sendmsg_to_stack(int32_t s, const struct msghdr *message, int32_t flags)
             continue;
         }
 
+	if (message->msg_iov[i].iov_len == 0){
+            continue;
+        }
+
         ret = write_stack_data(sock, message->msg_iov[i].iov_base, message->msg_iov[i].iov_len);
         if (ret <= 0) {
             buflen = (buflen == 0) ? ret : buflen;
-- 
2.23.0