From: "Ernesto A. Fernández" <ernesto.mnd.fernandez@gmail.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: y2038@lists.linaro.org, linux-kernel@vger.kernel.org,
Viacheslav Dubeyko <slava@dubeyko.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 13/16] hfs/hfsplus: use 64-bit inode timestamps
Date: Wed, 13 Nov 2019 00:53:04 -0300 [thread overview]
Message-ID: <20191113035304.GA8753@eaf> (raw)
In-Reply-To: <20191108213257.3097633-14-arnd@arndb.de>
On Fri, Nov 08, 2019 at 10:32:51PM +0100, Arnd Bergmann wrote:
> The interpretation of on-disk timestamps in HFS and HFS+ differs
> between 32-bit and 64-bit kernels at the moment. Use 64-bit timestamps
> consistently so apply the current 64-bit behavior everyhere.
>
> According to the official documentation for HFS+ [1], inode timestamps
> are supposed to cover the time range from 1904 to 2040 as originally
> used in classic MacOS.
>
> The traditional Linux usage is to convert the timestamps into an unsigned
> 32-bit number based on the Unix epoch and from there to a time_t. On
> 32-bit systems, that wraps the time from 2038 to 1902, so the last
> two years of the valid time range become garbled. On 64-bit systems,
> all times before 1970 get turned into timestamps between 2038 and 2106,
> which is more convenient but also different from the documented behavior.
>
> Looking at the Darwin sources [2], it seems that MacOS is inconsistent in
> yet another way: all timestamps are wrapped around to a 32-bit unsigned
> number when written to the disk, but when read back, all numeric values
> lower than 2082844800U are assumed to be invalid, so we cannot represent
> the times before 1970 or the times after 2040.
>
> While all implementations seem to agree on the interpretation of values
> between 1970 and 2038, they often differ on the exact range they support
> when reading back values outside of the common range:
>
> MacOS (traditional): 1904-2040
> Apple Documentation: 1904-2040
> MacOS X source comments: 1970-2040
> MacOS X source code: 1970-2038
> 32-bit Linux: 1902-2038
> 64-bit Linux: 1970-2106
> hfsfuse: 1970-2040
> hfsutils (32 bit, old libc) 1902-2038
> hfsutils (32 bit, new libc) 1970-2106
> hfsutils (64 bit) 1904-2040
> hfsplus-utils 1904-2040
> hfsexplorer 1904-2040
> 7-zip 1904-2040
>
> Out of the above, the range from 1970 to 2106 seems to be the most useful,
> as it allows using HFS and HFS+ beyond year 2038, and this matches the
> behavior that most users would see today on Linux, as few people run
> 32-bit kernels any more.
>
> Link: [1] https://developer.apple.com/library/archive/technotes/tn/tn1150.html
> Link: [2] https://opensource.apple.com/source/hfs/hfs-407.30.1/core/MacOSStubs.c.auto.html
> Link: https://lore.kernel.org/lkml/20180711224625.airwna6gzyatoowe@eaf/
> Cc: Viacheslav Dubeyko <slava@dubeyko.com>
> Suggested-by: "Ernesto A. Fernández" <ernesto.mnd.fernandez@gmail.com>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
Reviewed-by: Ernesto A. Fernández <ernesto.mnd.fernandez@gmail.com>
next prev parent reply other threads:[~2019-11-13 3:53 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-08 21:32 [PATCH 00/16] drivers: y2038 updates Arnd Bergmann
2019-11-08 21:32 ` [PATCH 01/16] staging: exfat: use prandom_u32() for i_generation Arnd Bergmann
2019-11-08 21:53 ` Valdis Klētnieks
2019-11-08 21:32 ` [PATCH 02/16] fat: " Arnd Bergmann
2019-11-08 21:32 ` [PATCH 03/16] net: sock: use __kernel_old_timespec instead of timespec Arnd Bergmann
2019-11-09 19:09 ` Deepa Dinamani
2019-11-08 21:32 ` [PATCH 04/16] dlm: use SO_SNDTIMEO_NEW instead of SO_SNDTIMEO_OLD Arnd Bergmann
2019-11-09 19:14 ` Deepa Dinamani
2019-11-08 21:32 ` [PATCH 05/16] xtensa: ISS: avoid struct timeval Arnd Bergmann
2019-11-08 21:38 ` Max Filippov
2019-11-08 21:32 ` [PATCH 06/16] um: ubd: use 64-bit time_t where possible Arnd Bergmann
2019-11-08 21:32 ` [PATCH 07/16] acct: stop using get_seconds() Arnd Bergmann
2019-11-08 21:32 ` [PATCH 08/16] tsacct: add 64-bit btime field Arnd Bergmann
2019-11-08 21:32 ` [PATCH 09/16] netfilter: nft_meta: use 64-bit time arithmetic Arnd Bergmann
2019-11-09 11:20 ` Phil Sutter
2019-11-15 22:44 ` Pablo Neira Ayuso
2019-11-08 21:32 ` [PATCH 10/16] packet: clarify timestamp overflow Arnd Bergmann
2019-11-08 21:32 ` [PATCH 11/16] quota: avoid time_t in v1_disk_dqblk definition Arnd Bergmann
2019-11-08 21:32 ` [PATCH 12/16] hostfs: pass 64-bit timestamps to/from user space Arnd Bergmann
2019-11-20 20:30 ` [Y2038] " Ben Hutchings
2019-11-20 20:35 ` Ben Hutchings
2019-11-08 21:32 ` [PATCH 13/16] hfs/hfsplus: use 64-bit inode timestamps Arnd Bergmann
2019-11-13 3:53 ` Ernesto A. Fernández [this message]
2019-11-13 5:59 ` Viacheslav Dubeyko
2019-11-13 8:06 ` [Y2038] " Arnd Bergmann
2019-11-13 17:03 ` Viacheslav Dubeyko
2019-11-08 21:32 ` [PATCH 14/16] drm/msm: avoid using 'timespec' Arnd Bergmann
2019-11-12 16:55 ` Jordan Crouse
2019-11-08 21:32 ` [PATCH 15/16] drm/etnaviv: use ktime_t for timeouts Arnd Bergmann
2019-11-08 23:03 ` Lucas Stach
2019-11-09 12:12 ` Arnd Bergmann
2019-11-11 9:55 ` Lucas Stach
2019-11-11 16:24 ` Arnd Bergmann
2019-11-08 21:32 ` [PATCH 16/16] firewire: ohci: stop using get_seconds() for BUS_TIME Arnd Bergmann
2019-11-13 20:04 ` Stefan Richter
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