linux: Add fallback for 64-bit time_t SO_{RCV,SND}TIMEO

The constant values will be changed for __TIMESIZE=64, so binaries built
with 64-bit time support might fail to work properly on old kernels.
Both {get,set}sockopt will retry the syscall with the old constant
values and the timeout value adjusted when kernel returns ENOTPROTOPT.

It also adds an internal only SO_{RCV,SND}TIMEO where
COMPAT_SO_{RCV,SND}TIMEO_OLD indicates pre 32-bit time support and
COMPAT_SO_{RCV,SND}TIMEO_NEW indicates time64 support.  It allows to
refer to constant independently of the time_t ABI and kernel version
used.

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, 63 insertions, 7 deletions

diff --git a/sysdeps/unix/sysv/linux/getsockopt.c b/sysdeps/unix/sysv/linux/getsockopt.c
index 76ee8a94d6..688a7de087 100644
--- a/sysdeps/unix/sysv/linux/getsockopt.c
+++ b/sysdeps/unix/sysv/linux/getsockopt.c
@@ -15,16 +15,15 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
-#include <errno.h>
-#include <signal.h>
 #include <sys/socket.h>
-
+#include <time.h>
+#include <sysdep.h>
 #include <socketcall.h>
-#include <kernel-features.h>
-#include <sys/syscall.h>
+#include <socket-constants-time64.h>
 
-int
-__getsockopt (int fd, int level, int optname, void *optval, socklen_t *len)
+static int
+getsockopt_syscall (int fd, int level, int optname, void *optval,
+		    socklen_t *len)
 {
 #ifdef __ASSUME_GETSOCKOPT_SYSCALL
   return INLINE_SYSCALL (getsockopt, 5, fd, level, optname, optval, len);
@@ -32,4 +31,61 @@ __getsockopt (int fd, int level, int optname, void *optval, socklen_t *len)
   return SOCKETCALL (getsockopt, fd, level, optname, optval, len);
 #endif
 }
+
+#ifndef __ASSUME_TIME64_SYSCALLS
+static int
+getsockopt32 (int fd, int level, int optname, void *optval,
+	      socklen_t *len)
+{
+  int r = -1;
+
+  if (level != SOL_SOCKET)
+    return r;
+
+  switch (optname)
+    {
+    case COMPAT_SO_RCVTIMEO_NEW:
+    case COMPAT_SO_SNDTIMEO_NEW:
+      {
+	if (optname == COMPAT_SO_RCVTIMEO_NEW)
+	  optname = COMPAT_SO_RCVTIMEO_OLD;
+	if (optname == COMPAT_SO_SNDTIMEO_NEW)
+	  optname = COMPAT_SO_SNDTIMEO_OLD;
+
+	struct __timeval32 tv32;
+	r = getsockopt_syscall (fd, level, optname, &tv32,
+				(socklen_t[]) { sizeof tv32 });
+	if (r < 0)
+	  break;
+
+	/* POSIX states that if the size of the option value is greater than
+	   then option length, the option value argument shall be silently
+	   truncated.  */
+	if (*len >= sizeof (struct __timeval64))
+	  {
+	    struct __timeval64 *tv64 = (struct __timeval64 *) optval;
+	    *tv64 = valid_timeval32_to_timeval64 (tv32);
+	    *len = sizeof (*tv64);
+	  }
+	else
+	  memcpy (optval, &tv32, sizeof tv32);
+      }
+    }
+
+  return r;
+}
+#endif
+
+int
+__getsockopt (int fd, int level, int optname, void *optval, socklen_t *len)
+{
+  int r = getsockopt_syscall (fd, level, optname, optval, len);
+
+#ifndef __ASSUME_TIME64_SYSCALLS
+  if (r == -1 && errno == ENOPROTOOPT)
+    r = getsockopt32 (fd, level, optname, optval, len);
+#endif
+
+ return r;
+}
 weak_alias (__getsockopt, getsockopt)