pass socket address in our or out. This makes Linux programs using IPv6
working under emulation. This addresses kern/13279 by Jun-ichiro itojun Hagino.
Change sendmsg()/recvmsg() to expect the control information
to be passed the standard way (not 4.3BSD one, imlied by compat_43 code
or MSG_COMPAT). Linux uses different (arguably broken) CMSG_ALIGN() on some
architectures unfortunately, that would need to be handled eventually.
Also provide some other trivial stubs (like linux_sys_send()) to avoid
unneeded dependance on uipc_syscalls_43.c.
trap/interrupt/syscall entry from userspace.
Remove special-case "by hand" validation of fs/gs register values as
well as special handling of them in various signal handling paths.
Now, like %ds and %es, they are validated by the hardware on return to
userland.
This paves the way for the use of %fs for per-cpu data on
multiprocessor systems, and fixes an otherwise difficult-to-fix
interaction between threads/clone(2) and USER_LDT.
Discussed in advance with Frank van der Linden.
Async I/O OS specifities should now handled in OS specific code. Linux
has been done, but other emulation should be handled. See case LINUX_F_SETFL
in sys/compat/linux/common/linux_file.c:linux_sys_fcntl() for more details.
The data that has been collected yet:
Net Free Open Linux SunOS AIX OSF1 Darwin
send SIGIO to write end of pipe Y N N N N N Y Y
send SIGIO to read end of pipe Y Y N N N ? Y ?
send SIGIO to write end of socket Y Y Y N N Y Y Y
send SIGIO to read end of socket Y Y Y Y Y ? Y ?
neither it does send any SIGIO for pipes. If async I/O
was requested, we keep the SS_ASYNC in struct socket flag
set, but we clear SB_ASYNC flags on the sending buffer
(for socket), and on the sending and the receiving buffer
(for pipes).
Because we do not alter to SS_ASYNC in struct socket,
the Linux process keeps a consistent view of async I/O
status if it attemps to read the async flag (SS_ASYNC)
This async I/O problem does matters, since some Linux
a programs such as the JDK request async I/O on pipes,
but they fail if they happen to get a SIGIO to the write
end of the pipe.
between creation of a file descriptor and close(2) when using kernel
assisted threads. What we do is stick descriptors in the table, but
mark them as "larval". This causes essentially everything to treat
it as a non-existent descriptor, except for fdalloc(), which sees a
filled slot so that it won't (incorrectly) allocate it again. When
a descriptor is fully constructed, the code that has constructed it
marks it as "mature" (which actually clears the "larval" flag), and
things continue to work as normal.
While here, gather all the code that gets a descriptor from the table
into a fd_getfile() function, and call it, rather than having the
same (sometimes incorrect) code copied all over the place.
