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linux: Add fallback for 64-bit time_t SO_TIMESTAMP{NS}

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The recvmsg handling is more complicated because it requires check the
returned kernel control message and make some convertions.  For
!__ASSUME_TIME64_SYSCALLS it converts the first 32-bit time SO_TIMESTAMP
or SO_TIMESTAMPNS and appends it to the control buffer if has extra
space or returns MSG_CTRUNC otherwise.  The 32-bit time field is kept
as-is.

Calls with __TIMESIZE=32 will see the converted 64-bit time control
messages as spurious control message of unknown type.  Calls with
__TIMESIZE=64 running on pre-time64 kernels will see the original
message as a spurious control ones of unknown typ while running on
kernel with native 64-bit time support will only see the time64 version
of the control message.

Checked on x86_64-linux-gnu and i686-linux-gnu (on 5.4 and on 4.15
kernel).

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
This commit is contained in:
Adhemerval Zanella
2020-09-07 17:08:46 -03:00
parent 8dfb169c80
commit 13c51549e2
11 changed files with 167 additions and 7 deletions
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23
sysdeps/unix/sysv/linux/recvmsg.c
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@ -19,16 +19,27 @@
#include <sys/socket.h>
#include <sysdep-cancel.h>
#include <socketcall.h>
#include <shlib-compat.h>
ssize_t
__libc_recvmsg (int fd, struct msghdr *msg, int flags)
{
# ifdef __ASSUME_RECVMSG_SYSCALL
return SYSCALL_CANCEL (recvmsg, fd, msg, flags);
# else
return SOCKETCALL_CANCEL (recvmsg, fd, msg, flags);
# endif
ssize_t r;
#ifndef __ASSUME_TIME64_SYSCALLS
socklen_t orig_controllen = msg->msg_controllen;
#endif
#ifdef __ASSUME_RECVMSG_SYSCALL
r = SYSCALL_CANCEL (recvmsg, fd, msg, flags);
#else
r = SOCKETCALL_CANCEL (recvmsg, fd, msg, flags);
#endif
#ifndef __ASSUME_TIME64_SYSCALLS
if (r >= 0)
__convert_scm_timestamps (msg, orig_controllen);
#endif
return r;
}
weak_alias (__libc_recvmsg, recvmsg)
weak_alias (__libc_recvmsg, __recvmsg)