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

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>

1 files changed, 12 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/getsockopt.c b/sysdeps/unix/sysv/linux/getsockopt.c
index 688a7de087..f86b06dec6 100644
--- a/sysdeps/unix/sysv/linux/getsockopt.c
+++ b/sysdeps/unix/sysv/linux/getsockopt.c
@@ -70,6 +70,18 @@ getsockopt32 (int fd, int level, int optname, void *optval,
 	else
 	  memcpy (optval, &tv32, sizeof tv32);
       }
+      break;
+
+    case COMPAT_SO_TIMESTAMP_NEW:
+    case COMPAT_SO_TIMESTAMPNS_NEW:
+      {
+	if (optname == COMPAT_SO_TIMESTAMP_NEW)
+	  optname = COMPAT_SO_TIMESTAMP_OLD;
+	if (optname == COMPAT_SO_TIMESTAMPNS_NEW)
+	  optname = COMPAT_SO_TIMESTAMPNS_OLD;
+	r = getsockopt_syscall (fd, level, optname, optval, len);
+      }
+      break;
     }
 
   return r;