From: Roy Marples <roy@marples.name>
Date: Fri, 2 Sep 2016 10:42:09 +0000 (+0000)
Subject: Provide better commentary.
X-Git-Tag: v6.11.4~60
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ec07c16ec3715f7b4c1a36a261e22b4c58074eff;p=thirdparty%2Fdhcpcd.git

Provide better commentary.
---

diff --git a/common.c b/common.c
index 5ba3deeb..9b803226 100644
--- a/common.c
+++ b/common.c
@@ -397,7 +397,7 @@ recvmsg_realloc(int fd, struct msghdr *msg, int flags)
 	iov = &msg->msg_iov[msg->msg_iovlen - 1];
 
 	for (;;) {
-		msg->msg_flags = 0;
+		/* Passing MSG_TRUNC should return the actual size needed. */
 		slen = recvmsg(fd, msg, flags | MSG_PEEK | MSG_TRUNC);
 		if (slen == -1)
 			return -1;
@@ -406,9 +406,9 @@ recvmsg_realloc(int fd, struct msghdr *msg, int flags)
 
 		len = (size_t)slen;
 
-		/* Some kernels return the truncated size, but others
-		 * can return the actual size needed because
-		 * we passed MSG_TRUNC above. */
+		/* Some kernels return the size of the receive buffer
+		 * on truncation, not the actual size needed.
+		 * So grow the buffer and try again. */
 		if (iov->iov_len == len)
 			len = roundup(len + 1, IOVEC_BUFSIZ);
 		else if (iov->iov_len > len)
@@ -419,7 +419,6 @@ recvmsg_realloc(int fd, struct msghdr *msg, int flags)
 		iov->iov_len = len;
 	}
 
-	msg->msg_flags = 0;
 	slen = recvmsg(fd, msg, flags);
 	if (msg->msg_flags & MSG_TRUNC) {
 		/* This should not be possible ... */