[<prev] [next>] [day] [month] [year] [list]
Message-ID: <20260318184510.41025-2-jeremymosas@gmail.com>
Date: Wed, 18 Mar 2026 19:45:11 +0100
From: statzitz <jeremy.primard01@...il.com>
To: musl@...ts.openwall.com
Cc: statzitz <jeremy.primard01@...il.com>
Subject: [PATCH v2] sys/socket.h: Fixed -Wsign-compare in musl CMSG_NXTHDR() macro
From: statzitz <jeremy.primard01@...il.com>
__CMSG_LEN(cmsg) is a size_t
sizeof(struct cmsghdr) is a size_t
So __CMSG_LEN(cmsg) + sizeof(struct cmsghdr) is also a size_t
__MHDR_END(mhdr) is an unsigned char pointer
(unsigned char *)(cmsg) is also an unsigned char pointer
so __MHDR_END(mhdr) - (unsigned char *)(cmsg) will not result in a
size_t, but in a ptrdiff_t (signed). The compiler think that there
is a world where the result can be negative, so we needs to
explicitely state that the result is a size_t (unsigned).
---
include/sys/socket.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/sys/socket.h b/include/sys/socket.h
index 6dc1e40a..0b39d835 100644
--- a/include/sys/socket.h
+++ b/include/sys/socket.h
@@ -355,7 +355,7 @@ struct linger {
#define CMSG_DATA(cmsg) ((unsigned char *) (((struct cmsghdr *)(cmsg)) + 1))
#define CMSG_NXTHDR(mhdr, cmsg) ((cmsg)->cmsg_len < sizeof (struct cmsghdr) || \
- __CMSG_LEN(cmsg) + sizeof(struct cmsghdr) >= __MHDR_END(mhdr) - (unsigned char *)(cmsg) \
+ __CMSG_LEN(cmsg) + sizeof(struct cmsghdr) >= (size_t)(__MHDR_END(mhdr) - (unsigned char *)(cmsg)) \
? 0 : (struct cmsghdr *)__CMSG_NEXT(cmsg))
#define CMSG_FIRSTHDR(mhdr) ((size_t) (mhdr)->msg_controllen >= sizeof (struct cmsghdr) ? (struct cmsghdr *) (mhdr)->msg_control : (struct cmsghdr *) 0)
--
2.53.0
Powered by blists - more mailing lists
Confused about mailing lists and their use?
Read about mailing lists on Wikipedia
and check out these
guidelines on proper formatting of your messages.
