linux-user: fix accept(2) with NULL peer

Based on scratchbox2 patch by Mika Westerberg

Signed-off-by: Riku Voipio <riku.voipio@iki.fi>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6478 c046a42c-6fe2-441c-8c8c-71466251a162

linux-user/syscall.c

@@ -1267,6 +1267,9 @@ static abi_long do_getsockname(int fd, abi_ulong target_addr,
     void *addr;
     abi_long ret;
 
+    if (target_addr == 0)
+       return get_errno(accept(fd, NULL, NULL));
+
     if (get_user_u32(addrlen, target_addrlen_addr))
         return -TARGET_EFAULT;