On Nov 9, 2019, at 12:32 AM, Arnd Bergmann arnd@arndb.de 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.... 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
v3: revert back to 1970-2106 time range fix bugs found in review merge both patches into one drop cc:stable tag v2: treat pre-1970 dates as invalid following MacOS X behavior, reword and expand changelog text
fs/hfs/hfs_fs.h | 26 ++++++++++++++++++++------ fs/hfs/inode.c | 4 ++-- fs/hfsplus/hfsplus_fs.h | 26 +++++++++++++++++++++----- fs/hfsplus/inode.c | 12 ++++++------ 4 files changed, 49 insertions(+), 19 deletions(-)
diff --git a/fs/hfs/hfs_fs.h b/fs/hfs/hfs_fs.h index 6d0783e2e276..26733051ee50 100644 --- a/fs/hfs/hfs_fs.h +++ b/fs/hfs/hfs_fs.h @@ -242,19 +242,33 @@ extern void hfs_mark_mdb_dirty(struct super_block *sb); /*
- There are two time systems. Both are based on seconds since
- a particular time/date.
- Unix: unsigned lil-endian since 00:00 GMT, Jan. 1, 1970
- Unix: signed little-endian since 00:00 GMT, Jan. 1, 1970
- mac: unsigned big-endian since 00:00 GMT, Jan. 1, 1904
- HFS implementations are highly inconsistent, this one matches the
- traditional behavior of 64-bit Linux, giving the most useful
- time range between 1970 and 2106, by treating any on-disk timestamp
- under 2082844800U (Jan 1 1970) as a time between 2040 and 2106.
*/ -#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)
I believe it makes sense to introduce some constant instead of hardcoded value (2082844800U and 60). It will be easier to understand the code without necessity to take a look into the comments. What do you think?
+static inline time64_t __hfs_m_to_utime(__be32 mt) +{
- time64_t ut = (u32)(be32_to_cpu(mt) - 2082844800U);
Ditto.
- return ut + sys_tz.tz_minuteswest * 60;
+}
+static inline __be32 __hfs_u_to_mtime(time64_t ut) +{
- ut -= sys_tz.tz_minuteswest * 60;
- return cpu_to_be32(lower_32_bits(ut) + 2082844800U);
Ditto.
+} #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)
-#define hfs_m_to_utime(time) (struct timespec){ .tv_sec = __hfs_m_to_utime(time) } -#define hfs_u_to_mtime(time) __hfs_u_to_mtime((time).tv_sec) -#define hfs_mtime() __hfs_u_to_mtime(get_seconds()) +#define hfs_m_to_utime(time) (struct timespec64){ .tv_sec = __hfs_m_to_utime(time) } +#define hfs_u_to_mtime(time) __hfs_u_to_mtime((time).tv_sec) +#define hfs_mtime() __hfs_u_to_mtime(ktime_get_real_seconds())
static inline const char *hfs_mdb_name(struct super_block *sb) { diff --git a/fs/hfs/inode.c b/fs/hfs/inode.c index da243c84e93b..2f224b98ee94 100644 --- a/fs/hfs/inode.c +++ b/fs/hfs/inode.c @@ -351,7 +351,7 @@ static int hfs_read_inode(struct inode *inode, void *data) inode->i_mode &= ~hsb->s_file_umask; inode->i_mode |= S_IFREG; inode->i_ctime = inode->i_atime = inode->i_mtime =
timespec_to_timespec64(hfs_m_to_utime(rec->file.MdDat));
hfs_m_to_utime(rec->file.MdDat);@@ -362,7 +362,7 @@ static int hfs_read_inode(struct inode *inode, void *data) HFS_I(inode)->fs_blocks = 0; inode->i_mode = S_IFDIR | (S_IRWXUGO & ~hsb->s_dir_umask); inode->i_ctime = inode->i_atime = inode->i_mtime =
timespec_to_timespec64(hfs_m_to_utime(rec->dir.MdDat));
hfs_m_to_utime(rec->dir.MdDat);diff --git a/fs/hfsplus/hfsplus_fs.h b/fs/hfsplus/hfsplus_fs.h index b8471bf05def..22d0a22c41a3 100644 --- a/fs/hfsplus/hfsplus_fs.h +++ b/fs/hfsplus/hfsplus_fs.h @@ -533,13 +533,29 @@ 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) -#define __hfsp_ut2mt(t) (cpu_to_be32(t + 2082844800U))
Ditto.
+/*
- time helpers: convert between 1904-base and 1970-base timestamps
- HFS+ implementations are highly inconsistent, this one matches the
- traditional behavior of 64-bit Linux, giving the most useful
- time range between 1970 and 2106, by treating any on-disk timestamp
- under 2082844800U (Jan 1 1970) as a time between 2040 and 2106.
- */
+static inline time64_t __hfsp_mt2ut(__be32 mt) +{
- time64_t ut = (u32)(be32_to_cpu(mt) - 2082844800U);
Ditto.
- return ut;
+}
+static inline __be32 __hfsp_ut2mt(time64_t ut) +{
- return cpu_to_be32(lower_32_bits(ut) + 2082844800U);
Ditto.
+}
/* compatibility */ -#define hfsp_mt2ut(t) (struct timespec){ .tv_sec = __hfsp_mt2ut(t) } +#define hfsp_mt2ut(t) (struct timespec64){ .tv_sec = __hfsp_mt2ut(t) } #define hfsp_ut2mt(t) __hfsp_ut2mt((t).tv_sec) -#define hfsp_now2mt() __hfsp_ut2mt(get_seconds()) +#define hfsp_now2mt() __hfsp_ut2mt(ktime_get_real_seconds())
#endif diff --git a/fs/hfsplus/inode.c b/fs/hfsplus/inode.c index d131c8ea7eb6..94bd83b36644 100644 --- a/fs/hfsplus/inode.c +++ b/fs/hfsplus/inode.c @@ -504,9 +504,9 @@ int hfsplus_cat_read_inode(struct inode *inode, struct hfs_find_data *fd) hfsplus_get_perms(inode, &folder->permissions, 1); set_nlink(inode, 1); inode->i_size = 2 + be32_to_cpu(folder->valence);
inode->i_atime = timespec_to_timespec64(hfsp_mt2ut(folder->access_date));inode->i_mtime = timespec_to_timespec64(hfsp_mt2ut(folder->content_mod_date));inode->i_ctime = timespec_to_timespec64(hfsp_mt2ut(folder->attribute_mod_date));
inode->i_atime = hfsp_mt2ut(folder->access_date);inode->i_mtime = hfsp_mt2ut(folder->content_mod_date);inode->i_ctime = hfsp_mt2ut(folder->attribute_mod_date);@@ -542,9 +542,9 @@ int hfsplus_cat_read_inode(struct inode *inode, struct hfs_find_data *fd) init_special_inode(inode, inode->i_mode, be32_to_cpu(file->permissions.dev)); }
inode->i_atime = timespec_to_timespec64(hfsp_mt2ut(file->access_date));inode->i_mtime = timespec_to_timespec64(hfsp_mt2ut(file->content_mod_date));inode->i_ctime = timespec_to_timespec64(hfsp_mt2ut(file->attribute_mod_date));
inode->i_atime = hfsp_mt2ut(file->access_date);inode->i_mtime = hfsp_mt2ut(file->content_mod_date);inode->i_ctime = hfsp_mt2ut(file->attribute_mod_date);— 2.20.0
The patch looks pretty clean and good.
Thanks, Viacheslav Dubeyko.