Fix: ust-comm recvmsg should handle partial receive

[lttng-ust.git] / liblttng-ust-comm / lttng-ust-comm.c

diff --git a/liblttng-ust-comm/lttng-ust-comm.c b/liblttng-ust-comm/lttng-ust-comm.c
index a31786ac52000994feec90a754b5f9ba9701c16c..751ad2e3cf2add1ffd805c9ca4df802034e793b1 100644 (file)
--- a/liblttng-ust-comm/lttng-ust-comm.c
+++ b/liblttng-ust-comm/lttng-ust-comm.c
@@ -265,7 +265,8 @@ ssize_t ustcomm_recv_unix_sock(int sock, void *buf, size_t len)
 {
        struct msghdr msg;
        struct iovec iov[1];
-       ssize_t ret;
+       ssize_t ret = -1;
+       size_t len_last;
 
        memset(&msg, 0, sizeof(msg));
 
@@ -275,8 +276,14 @@ ssize_t ustcomm_recv_unix_sock(int sock, void *buf, size_t len)
        msg.msg_iovlen = 1;
 
        do {
+               len_last = iov[0].iov_len;
                ret = recvmsg(sock, &msg, 0);
-       } while (ret < 0 && errno == EINTR);
+               if (ret > 0) {
+                       iov[0].iov_base += ret;
+                       iov[0].iov_len -= ret;
+                       assert(ret <= len_last);
+               }
+       } while ((ret > 0 && ret < len_last) || (ret < 0 && errno == EINTR));
 
        if (ret < 0) {
                int shutret;
@@ -290,7 +297,10 @@ ssize_t ustcomm_recv_unix_sock(int sock, void *buf, size_t len)
                shutret = shutdown(sock, SHUT_RDWR);
                if (shutret)
                        ERR("Socket shutdown error");
+       } else if (ret > 0) {
+               ret = len;
        }
+       /* ret = 0 means an orderly shutdown. */
 
        return ret;
 }