sysv: linux: Add 64-bit time_t variant for shmctl

To provide a y2038 safe interface a new symbol __shmctl64 is added
and __shmctl is change to call it instead (it adds some extra buffer
copying for the 32 bit time_t implementation).

Two new structures are added:

  1. kernel_shmid64_ds: used internally only on 32-bit architectures
     to issue the syscall.  A handful of architectures (hppa, i386,
     mips, powerpc32, and sparc32) require specific implementations
     due to their kernel ABI.

  2. shmid_ds64: this is only for __TIMESIZE != 64 to use along with
     the 64-bit shmctl.  It is different than the kernel struct because
     the exported 64-bit time_t might require different alignment
     depending on the architecture ABI.

So the resulting implementation does:

  1. For 64-bit architectures it assumes shmid_ds already contains
     64-bit time_t fields and will result in just the __shmctl symbol
     using the __shmctl64 code.  The shmid_ds argument is passed as-is
     to the syscall.

  2. For 32-bit architectures with default 64-bit time_t (newer ABIs
     such riscv32 or arc), it will also result in only one exported
     symbol but with the required high/low time handling.

  3. Finally for 32-bit architecture with both 32-bit and 64-bit time_t
     support we follow the already set way to provide one symbol with
     64-bit time_t support and implement the 32-bit time_t support
     using of the 64-bit one.

     The default 32-bit symbol will allocate and copy the shmid_ds
     over multiple buffers, but this should be deprecated in favor
     of the __shmctl64 anyway.

Checked on i686-linux-gnu and x86_64-linux-gnu.  I also did some sniff
tests on powerpc, powerpc64, mips, mips64, armhf, sparcv9, and
sparc64.

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Tested-by: Alistair Francis <alistair.francis@wdc.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/sysdeps/unix/sysv/linux/mips/bits/types/struct_shmid_ds.h b/sysdeps/unix/sysv/linux/mips/bits/types/struct_shmid_ds.h
index 8e13928980..58090e2fcb 100644
--- a/sysdeps/unix/sysv/linux/mips/bits/types/struct_shmid_ds.h
+++ b/sysdeps/unix/sysv/linux/mips/bits/types/struct_shmid_ds.h
@@ -38,9 +38,9 @@ struct shmid_ds
     __pid_t shm_lpid;			/* pid of last shmop */
     shmatt_t shm_nattch;		/* number of current attaches */
 #if __TIMESIZE == 32
-    unsigned short int __glibc_reserved1;
-    unsigned short int __glibc_reserved2;
-    unsigned short int __glibc_reserved3;
+    unsigned short int __shm_atime_high;
+    unsigned short int __shm_dtime_high;
+    unsigned short int __shm_ctime_high;
     unsigned short int __glibc_reserved4;
 #else
     __syscall_ulong_t __glibc_reserved5;