On Fri, Jun 22, 2018 at 04:17:32PM +0200, Arnd Bergmann wrote: > 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. > > The same behavior is used in Darwin and presumaby all versions of MacOS X, > as seen in the to_hfs_time() function in [2]. It is unclear whether this > is a bug in the file system code, or intentional but undocumented behavior. But the to_bsd_time() function considers wrapped timestamps as invalid, doesn't it? So it seems they simply don't care about the post-2040 (or pre-1970) case? > > This changes Linux over to the traditional MacOS (pre MacOS X) > behavior. This means all files that are created on MacOS X or Linux > with future timestamps between 2040 and 2106 will now show up as past > dates. Timestamps between 2038 and 2040 will still be represented > incorrectly on 32-bit architectures as times between 1902 and 1904, > but that will be fixed once we have user space with 64-bit time_t. > > Cc: stable@xxxxxxxxxxxxxxx > Link: [1] https://developer.apple.com/library/archive/technotes/tn/tn1150.html > Link: [2] https://opensource.apple.com/source/xnu/xnu-344/bsd/hfs/MacOSStubs.c > Suggested-by: Viacheslav Dubeyko <slava@xxxxxxxxxxx> > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> > --- > Note: This is the patch that Viacheslav asked for, but given how > MacOS X behaves, I'm increasingly thinking this is a bad idea. I agree that it made more sense before. > --- > fs/hfs/hfs_fs.h | 2 +- > fs/hfsplus/hfsplus_fs.h | 5 +++-- > 2 files changed, 4 insertions(+), 3 deletions(-) > > diff --git a/fs/hfs/hfs_fs.h b/fs/hfs/hfs_fs.h > index 6d0783e2e276..39c1f3a43ed8 100644 > --- a/fs/hfs/hfs_fs.h > +++ b/fs/hfs/hfs_fs.h > @@ -247,7 +247,7 @@ extern void hfs_mark_mdb_dirty(struct super_block *sb); > * > */ > #define __hfs_u_to_mtime(sec) cpu_to_be32(sec + 2082844800U - sys_tz.tz_minuteswest * 60) > -#define __hfs_m_to_utime(sec) (be32_to_cpu(sec) - 2082844800U + sys_tz.tz_minuteswest * 60) > +#define __hfs_m_to_utime(sec) ((time64_t)be32_to_cpu(sec) - 2082844800U + sys_tz.tz_minuteswest * 60) > > #define HFS_I(inode) (container_of(inode, struct hfs_inode_info, vfs_inode)) > #define HFS_SB(sb) ((struct hfs_sb_info *)(sb)->s_fs_info) > diff --git a/fs/hfsplus/hfsplus_fs.h b/fs/hfsplus/hfsplus_fs.h > index d9255abafb81..57838ef4dcdc 100644 > --- a/fs/hfsplus/hfsplus_fs.h > +++ b/fs/hfsplus/hfsplus_fs.h > @@ -530,8 +530,9 @@ int hfsplus_submit_bio(struct super_block *sb, sector_t sector, void *buf, > void **data, int op, int op_flags); > int hfsplus_read_wrapper(struct super_block *sb); > > -/* time macros */ > -#define __hfsp_mt2ut(t) (be32_to_cpu(t) - 2082844800U) > +/* time macros: convert between 1904-2040 and 1970-2106 range, > + * pre-1970 timestamps are interpreted as post-2038 times after wrap-around */ This comment seems to be from the original series, maybe you forgot to change it? > +#define __hfsp_mt2ut(t) ((time64_t)be32_to_cpu(t) - 2082844800U) > #define __hfsp_ut2mt(t) (cpu_to_be32(t + 2082844800U)) > > /* compatibility */ > -- > 2.9.0 >
