From 94811042d73239d35b9d4bf7592c62ccc65ce633 Mon Sep 17 00:00:00 2001 From: "Albert ARIBAUD (3ADEV)" Date: Sun, 10 Jun 2018 10:47:12 +0200 Subject: Y2038: provide kernel support indication Introduce __ASSUME_KERNEL_Y2038_SUPPORT which means that the underlying kernel *always* implements 64-bit-time Y2038-proof syscalls. If __ASSUME_KERNEL_Y2038_SUPPORT is not defined, glibc must check dynamically whether the underlying kernel provides these syscalls or not, and must fallback to 32-bit-time syscalls if not. Introduce function __y2038_get_kernel_support(), which returns true if the underlying kernel supports 64-bit-time syscalls. Also introduce function __y2038_set_kernel_support(), which allows an implementation to notify glibc of the absence of 64-bit-time syscalls (ENOSYS) so that they are not needlessly tried again. * misc/Makefile: Add module y2038-support. * misc/Versions: (__y2038_get_kernel_support): Add to GLIBC_PRIVATE. * misc/Versions: (__y2038_set_kernel_support): Likewise. * misc/y2038-support.c: New file. * misc/y2038-support.h: Likewise. * sysdeps/unix/sysv/linux/kernel-features.h (__ASSUME_KERNEL_Y2038_SUPPORT): Add. * sysdeps/unix/sysv/linux/y2038-support.c: New file. * sysdeps/unix/sysv/linux/y2038-support.h: New file. --- misc/Makefile | 2 +- misc/Versions | 4 +++ misc/y2038-support.c | 40 +++++++++++++++++++++++++++ misc/y2038-support.h | 33 ++++++++++++++++++++++ sysdeps/unix/sysv/linux/kernel-features.h | 14 ++++++++++ sysdeps/unix/sysv/linux/y2038-support.c | 46 +++++++++++++++++++++++++++++++ sysdeps/unix/sysv/linux/y2038-support.h | 34 +++++++++++++++++++++++ 7 files changed, 172 insertions(+), 1 deletion(-) create mode 100644 misc/y2038-support.c create mode 100644 misc/y2038-support.h create mode 100644 sysdeps/unix/sysv/linux/y2038-support.c create mode 100644 sysdeps/unix/sysv/linux/y2038-support.h diff --git a/misc/Makefile b/misc/Makefile index 30e0673..7ced1ea 100644 --- a/misc/Makefile +++ b/misc/Makefile @@ -71,7 +71,7 @@ routines := brk sbrk sstk ioctl \ fgetxattr flistxattr fremovexattr fsetxattr getxattr \ listxattr lgetxattr llistxattr lremovexattr lsetxattr \ removexattr setxattr getauxval ifunc-impl-list makedev \ - allocate_once + allocate_once y2038-support generated += tst-error1.mtrace tst-error1-mem.out \ tst-allocate_once.mtrace tst-allocate_once-mem.out diff --git a/misc/Versions b/misc/Versions index 900e4ff..48285d8 100644 --- a/misc/Versions +++ b/misc/Versions @@ -158,6 +158,8 @@ libc { GLIBC_2.26 { preadv2; preadv64v2; pwritev2; pwritev64v2; } + GLIBC_2.29 { + } GLIBC_PRIVATE { __madvise; __mktemp; @@ -166,5 +168,7 @@ libc { __mmap; __munmap; __mprotect; __sched_get_priority_min; __sched_get_priority_max; __libc_allocate_once_slow; + __y2038_get_kernel_support; + __y2038_set_kernel_support; } } diff --git a/misc/y2038-support.c b/misc/y2038-support.c new file mode 100644 index 0000000..64f8036 --- /dev/null +++ b/misc/y2038-support.c @@ -0,0 +1,40 @@ +/* y2038 general kernel support indication. + Copyright (C) 2018 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 + . */ + +#include + +#ifndef __ASSUME_KERNEL_Y2038_SUPPORT + +/* By default glibc assumes the underlying kernel does not support Y2038. */ +bool +__default_y2038_get_kernel_support (void) +{ + return false; +} +weak_alias (__default_y2038_get_kernel_support, __y2038_get_kernel_support) + +/* By default glibc just ignores Y2038 support indication setting. */ +void +__default_y2038_set_kernel_support (bool support __attribute__ ((unused))) +{ + /* Do nothing. */ +} +weak_alias (__default_y2038_set_kernel_support, __y2038_set_kernel_support) + +#endif diff --git a/misc/y2038-support.h b/misc/y2038-support.h new file mode 100644 index 0000000..aad387b --- /dev/null +++ b/misc/y2038-support.h @@ -0,0 +1,33 @@ +/* y2038 general kernel support indication. + Copyright (C) 2018 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 + . */ + +#include + +/* If we do not assume that the kernel provides 64-bit-time syscalls, + * then we need a dynamic way to remember whether it does or not. */ + +#ifndef __ASSUME_KERNEL_Y2038_SUPPORT + +/* Dynamically check whether actual kernel supports Y2038 or not. */ +extern bool __y2038_get_kernel_support (void); + +/* Dynamically set whether actual kernel supports Y2038 or not. */ +extern void __y2038_set_kernel_support (bool support); + +#endif diff --git a/sysdeps/unix/sysv/linux/kernel-features.h b/sysdeps/unix/sysv/linux/kernel-features.h index 5543d92..b47755b 100644 --- a/sysdeps/unix/sysv/linux/kernel-features.h +++ b/sysdeps/unix/sysv/linux/kernel-features.h @@ -154,3 +154,17 @@ */ #define __ASSUME_CLONE_DEFAULT 1 + +/* Support for Y2038-proof times. + + If defined, the underlying kernel always provides a set of syscalls + (__NR_* names and numbers) which can handle times beyond Y2038. + + If undefined, whether the underlying kernel provides this set or not + must be checked dynamically. + + Definition is commented out until Y2038 syscalls are merged in the + kernel. + */ + +/* #define __ASSUME_KERNEL_Y2038_SUPPORT 1 */ diff --git a/sysdeps/unix/sysv/linux/y2038-support.c b/sysdeps/unix/sysv/linux/y2038-support.c new file mode 100644 index 0000000..adbcd8f --- /dev/null +++ b/sysdeps/unix/sysv/linux/y2038-support.c @@ -0,0 +1,46 @@ +/* y2038 Linux kernel support indication. + Copyright (C) 2018 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 + . */ + +#ifndef __ASSUME_KERNEL_Y2038_SUPPORT + +#include + +/* By default the underlying Linux kernel is assumed not to support Y2038. + * Any Linux architecture may (test and) claim Y2038 kernel support by + * setting __y2038_linux_support. + */ +bool __y2038_linux_support = false; + +/* For Linux, Y2038 kernel support is determined by __y2038_linux_support. */ + +bool +__linux_y2038_get_kernel_support (void) +{ + return __y2038_linux_support; +} +strong_alias (__linux_y2038_get_kernel_support, __y2038_get_kernel_support) + +void +__linux_y2038_set_kernel_support (bool support) +{ + __y2038_linux_support = support; +} +strong_alias (__linux_y2038_set_kernel_support, __y2038_set_kernel_support) + +#endif diff --git a/sysdeps/unix/sysv/linux/y2038-support.h b/sysdeps/unix/sysv/linux/y2038-support.h new file mode 100644 index 0000000..b8b6b8e --- /dev/null +++ b/sysdeps/unix/sysv/linux/y2038-support.h @@ -0,0 +1,34 @@ +/* y2038 Linux kernel support indication. + Copyright (C) 2018 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 + . */ + +#ifndef __ASSUME_KERNEL_Y2038_SUPPORT + +#include + +/* Indicates Y2038 support. + * Can be read directly from within libc linux-related files. + * Can be written non-zero to indicate support or lack thereof. + * Other libraries (e.g. librt) cannot access this variable and must + * call __y2038_get_kernel_support() and __y2038_set_kernel_support(). */ +extern bool __y2038_linux_support; + +#endif + +/* As a fallback, provide generic Y2038 support indication. */ +#include -- cgit v1.1