From: Tom Gundersen <teg@jklm.no>
Date: Tue, 15 Apr 2014 10:01:39 +0000 (+0200)
Subject: sd-rtnl: message - make room for all pending messages, not just the first
X-Git-Tag: v213~382
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=commitdiff_plain;h=6fc518838cd717f2f8258f8a0cca37797c187a06

sd-rtnl: message - make room for all pending messages, not just the first

Also, don't actually read any of the message when peeking, just get its length.
---

diff --git a/src/libsystemd/sd-rtnl/rtnl-message.c b/src/libsystemd/sd-rtnl/rtnl-message.c
index 1afba8f0b..47dcd4a78 100644
--- a/src/libsystemd/sd-rtnl/rtnl-message.c
+++ b/src/libsystemd/sd-rtnl/rtnl-message.c
@@ -1080,26 +1080,23 @@ int socket_read_message(sd_rtnl *rtnl) {
 
         assert(rtnl);
         assert(rtnl->rbuffer);
+        assert(rtnl->rbuffer_allocated >= sizeof(struct nlmsghdr));
 
-        iov.iov_base = rtnl->rbuffer;
-        iov.iov_len = rtnl->rbuffer_allocated;
-
-        /* peek at the pending message header to get the message size */
-        r = recvmsg(rtnl->fd, &msg, MSG_PEEK);
+        /* read nothing, just get the pending message size */
+        r = recvmsg(rtnl->fd, &msg, MSG_PEEK | MSG_TRUNC);
         if (r < 0)
                 /* no data */
                 return (errno == EAGAIN) ? 0 : -errno;
         else if (r == 0)
                 /* connection was closed by the kernel */
                 return -ECONNRESET;
-        else if ((size_t)r < sizeof(struct nlmsghdr))
-                return -EIO;
+        else
+                len = (size_t)r;
 
         /* make room for the pending message */
         if (!greedy_realloc((void **)&rtnl->rbuffer,
                             &rtnl->rbuffer_allocated,
-                            rtnl->rbuffer->nlmsg_len,
-                            sizeof(uint8_t)))
+                            len, sizeof(uint8_t)))
                 return -ENOMEM;
 
         iov.iov_base = rtnl->rbuffer;