workaround broken msghdr struct on 64bit linux

POSIX clearly specifies the type of msg_iovlen and msg_controllen, and
Linux ignores it and makes them both size_t instead. to work around
this we add padding (instead of just using the wrong types like glibc
does), but we also need to patch-up the struct before passing it to
the kernel in case the caller did not zero-fill it.

if i could trust the kernel to just ignore the upper 32 bits, this
would not be necessary, but i don't think it will ignore them...

diff --git a/arch/x86_64/bits/socket.h b/arch/x86_64/bits/socket.h
index b32306254fe016a4239a3e7af3575f2734218066..0e5ee1aa26a65da7e5b5eebf0674a8aa67237fcf 100644 (file)
--- a/arch/x86_64/bits/socket.h
+++ b/arch/x86_64/bits/socket.h
@@ -3,9 +3,9 @@ struct msghdr
        void *msg_name;
        socklen_t msg_namelen;
        struct iovec *msg_iov;
-       int msg_iovlen;
+       int msg_iovlen, __pad1;
        void *msg_control;
-       socklen_t msg_controllen;
+       socklen_t msg_controllen, __pad2;
        int msg_flags;
 };
 

diff --git a/src/network/recvmsg.c b/src/network/recvmsg.c
index edc5f2417d34ac13167d54ca9ca18bee2b81d18f..65094fc8be4b9e08b95a5671f30bdaed6eca4cea 100644 (file)
--- a/src/network/recvmsg.c
+++ b/src/network/recvmsg.c
@@ -1,12 +1,24 @@
 #include <sys/socket.h>
+#include <limits.h>
 #include "syscall.h"
 #include "libc.h"
 
 ssize_t recvmsg(int fd, struct msghdr *msg, int flags)
 {
        ssize_t r;
+#if LONG_MAX > INT_MAX
+       struct msghdr h, *orig = msg;
+       if (msg) {
+               h = *msg;
+               h.__pad1 = h.__pad2 = 0;
+               msg = &h;
+       }
+#endif
        CANCELPT_BEGIN;
        r = socketcall(recvmsg, fd, msg, flags, 0, 0, 0);
        CANCELPT_END;
+#if LONG_MAX > INT_MAX
+       if (orig) *orig = h;
+#endif
        return r;
 }

diff --git a/src/network/sendmsg.c b/src/network/sendmsg.c
index 5d1123f0fff8a5fd463b389e9e124eac9fc64b9b..047c0effa7cd25b9b37c29aa0bb3906212f5ffce 100644 (file)
--- a/src/network/sendmsg.c
+++ b/src/network/sendmsg.c
@@ -1,10 +1,19 @@
 #include <sys/socket.h>
+#include <limits.h>
 #include "syscall.h"
 #include "libc.h"
 
 ssize_t sendmsg(int fd, const struct msghdr *msg, int flags)
 {
        ssize_t r;
+#if LONG_MAX > INT_MAX
+       struct msghdr h;
+       if (msg) {
+               h = *msg;
+               h.__pad1 = h.__pad2 = 0;
+               msg = &h;
+       }
+#endif
        CANCELPT_BEGIN;
        r = socketcall(sendmsg, fd, msg, flags, 0, 0, 0);
        CANCELPT_END;