[PATCH v3 3/3] y2038: linux: Provide __mq_timedreceive_time64 implementation

[Lukasz Majewski <lukma at denx dot de>]

This patch provides new __mq_timedreceive_time64 explicit 64 bit function for
receiving messages with absolute timeout.
Moreover, a 32 bit version - __mq_timedreceive has been refactored to
internally use __mq_timedreceive_time64.

The __mq_timedreceive is now supposed to be used on systems still supporting 32
bit time (__TIMESIZE != 64) - hence the necessary conversion to 64 bit struct
__timespec64 from struct timespec.

The new mq_timedsend_time64 syscall available from Linux 5.1+ has been used,
when applicable.

As this wrapper function is also used internally in the glibc, to e.g. provide
mq_receive implementation, an explicit check for abs_timeout being NULL has been
added due to conversions between struct timespec and struct __timespec64.
Before this change the Linux kernel handled this NULL pointer.

Build tests:
- ./src/scripts/build-many-glibcs.py glibcs

Run-time tests:
- Run specific tests on ARM/x86 32bit systems (qemu):
  https://github.com/lmajewski/meta-y2038 and run tests:
  https://github.com/lmajewski/y2038-tests/commits/master

Linux kernel, headers and minimal kernel version for glibc build test matrix:
- Linux v5.1 (with mq_timedreceive_time64) and glibc built with v5.1 as
  minimal kernel version (--enable-kernel="5.1.0")
  The __ASSUME_TIME64_SYSCALLS flag defined.

- Linux v5.1 and default minimal kernel version
  The __ASSUME_TIME64_SYSCALLS not defined, but kernel supports
  mq_timedreceive_time64 syscall.

- Linux v4.19 (no mq_timedreceive_time64 support) with default minimal kernel
  version for contemporary glibc (3.2.0)
  This kernel doesn't support mq_timedreceive_time64 syscall, so the fallback to
  mq_timedreceive is tested.

Above tests were performed with Y2038 redirection applied as well as without
(so the __TIMESIZE != 64 execution path is checked as well).

---
Changes for v2:
- Fix indentation in __mq_timedreceive function
---
 include/mqueue.h                          |  6 +++
 sysdeps/unix/sysv/linux/mq_timedreceive.c | 51 +++++++++++++++++++++--
 2 files changed, 53 insertions(+), 4 deletions(-)

diff --git a/include/mqueue.h b/include/mqueue.h
index 81d30dbdf7..1ef5d3e3af 100644
--- a/include/mqueue.h
+++ b/include/mqueue.h
@@ -12,11 +12,17 @@ hidden_proto (mq_setattr)
 # endif
 #if __TIMESIZE == 64
 # define __mq_timedsend_time64 __mq_timedsend
+# define __mq_timedreceive_time64 __mq_timedreceive
 #else
 # include <bits/types/struct___timespec64.h>
 extern int __mq_timedsend_time64 (mqd_t mqdes, const char *msg_ptr,
                                   size_t msg_len, unsigned int msg_prio,
                                   const struct __timespec64 *abs_timeout);
 librt_hidden_proto (__mq_timedsend_time64)
+extern ssize_t __mq_timedreceive_time64 (mqd_t mqdes, char *__restrict msg_ptr,
+                          size_t msg_len,
+                          unsigned int *__restrict msg_prio,
+                          const struct __timespec64 *__restrict abs_timeout);
+librt_hidden_proto (__mq_timedreceive_time64)
 #endif
 #endif
diff --git a/sysdeps/unix/sysv/linux/mq_timedreceive.c b/sysdeps/unix/sysv/linux/mq_timedreceive.c
index 73a1d63e41..6eb10595ac 100644
--- a/sysdeps/unix/sysv/linux/mq_timedreceive.c
+++ b/sysdeps/unix/sysv/linux/mq_timedreceive.c
@@ -22,13 +22,56 @@
 /* Receive the oldest from highest priority messages in message queue
    MQDES, stop waiting if ABS_TIMEOUT expires.  */
 ssize_t
-__mq_timedreceive (mqd_t mqdes, char *__restrict msg_ptr, size_t msg_len,
-		   unsigned int *__restrict msg_prio,
-		   const struct timespec *__restrict abs_timeout)
+__mq_timedreceive_time64 (mqd_t mqdes, char *__restrict msg_ptr, size_t msg_len,
+                          unsigned int *__restrict msg_prio,
+                          const struct __timespec64 *__restrict abs_timeout)
 {
+#ifdef __ASSUME_TIME64_SYSCALLS
+# ifndef __NR_mq_timedreceive_time64
+#  define __NR_mq_timedreceive_time64 __NR_mq_timedreceive
+# endif
+  return SYSCALL_CANCEL (mq_timedreceive_time64, mqdes, msg_ptr, msg_len,
+                         msg_prio, abs_timeout);
+#else
+  int ret = SYSCALL_CANCEL (mq_timedreceive_time64, mqdes, msg_ptr, msg_len,
+                            msg_prio, abs_timeout);
+  if (ret == 0 || errno != ENOSYS)
+    return ret;
+
+  struct timespec ts32;
+  if (abs_timeout)
+    {
+      if (! in_time_t_range (abs_timeout->tv_sec))
+        {
+          __set_errno (EOVERFLOW);
+          return -1;
+        }
+
+      ts32 = valid_timespec64_to_timespec (*abs_timeout);
+    }
+
   return SYSCALL_CANCEL (mq_timedreceive, mqdes, msg_ptr, msg_len, msg_prio,
-			 abs_timeout);
+                         abs_timeout ? &ts32 : NULL);
+#endif
+}
+
+#if __TIMESIZE != 64
+librt_hidden_def (__mq_timedreceive_time64)
+
+ssize_t
+__mq_timedreceive (mqd_t mqdes, char *__restrict msg_ptr, size_t msg_len,
+                   unsigned int *__restrict msg_prio,
+                   const struct timespec *__restrict abs_timeout)
+{
+  struct __timespec64 ts64;
+  if (abs_timeout)
+    ts64 = valid_timespec_to_timespec64 (*abs_timeout);
+
+  return __mq_timedreceive_time64 (mqdes, msg_ptr, msg_len, msg_prio,
+                                   abs_timeout ? &ts64 : NULL);
 }
+#endif
+
 hidden_def (__mq_timedreceive)
 weak_alias (__mq_timedreceive, mq_timedreceive)
 hidden_weak (mq_timedreceive)
-- 
2.20.1