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

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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>
This commit is contained in:
Adhemerval Zanella
2020-06-30 14:08:22 -03:00
parent 7929d77985
commit ffd178c651
15 changed files with 336 additions and 55 deletions
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37
sysdeps/unix/sysv/linux/bits/types/struct_shmid64_ds.h Normal file
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@ -0,0 +1,37 @@
/* Generic implementation of the shared memory struct shmid_ds.
Copyright (C) 2020 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#ifndef _SYS_SHM_H
# error "Never include <bits/types/struct_shmid_ds.h> directly; use <sys/shm.h> instead."
#endif
#if __TIMESIZE == 64
# define __shmid64_ds shmid_ds
#else
struct __shmid64_ds
{
struct ipc_perm shm_perm; /* operation permission struct */
size_t shm_segsz; /* size of segment in bytes */
__time64_t shm_atime; /* time of last shmat() */
__time64_t shm_dtime; /* time of last shmdt() */
__time64_t shm_ctime; /* time of last change by shmctl() */
__pid_t shm_cpid; /* pid of creator */
__pid_t shm_lpid; /* pid of last shmop */
shmatt_t shm_nattch; /* number of current attaches */
};
#endif

6
sysdeps/unix/sysv/linux/bits/types/struct_shmid_ds.h
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@ -27,11 +27,11 @@ struct shmid_ds
size_t shm_segsz; /* size of segment in bytes */
#if __TIMESIZE == 32
__time_t shm_atime; /* time of last shmat() */
unsigned long int __glibc_reserved1;
unsigned long int __shm_atime_high;
__time_t shm_dtime; /* time of last shmdt() */
unsigned long int __glibc_reserved2;
unsigned long int __shm_dtime_high;
__time_t shm_ctime; /* time of last change by shmctl() */
unsigned long int __glibc_reserved3;
unsigned long int __shm_ctime_high;
#else
__time_t shm_atime; /* time of last shmat() */
__time_t shm_dtime; /* time of last shmdt() */