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workaround broken msghdr struct on 64bit linux

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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...
This commit is contained in:
Rich Felker 2011-04-08 09:24:19 -04:00
parent 5b8d81f706
commit 7168790763
3 changed files with 23 additions and 2 deletions
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4
arch/x86_64/bits/socket.h
View File

@ -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;
};

12
src/network/recvmsg.c
View File

@ -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;
}

9
src/network/sendmsg.c
View File

@ -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;