I suspect that any 32-bit systems running at that time will have been updated to have 64-bit time_t or otherwise have windowed the 32-bit time_t to have a new starting epoch.
So I'm willing to punt on decoding the 64-bit value correctly to libc and just assign our time to the system time_t.
Cheers, Andreas
> On Dec 7, 2013, at 13:02, David Turner <novalis@xxxxxxxxxxx> wrote:
>
> I went ahead and wrote some tests, and they seem to confirm that
> my patch to e2fsck works as expected (once I added crtime).
>
> However, as Andreas notes, "we want to verify .. that "debugfs -R
> 'stat testfile'" decodes the times correctly." Unfortunately, it
> does not, and it is not trivial to fix. debugfs uses an internal
> function time_to_string(__u32), which calls gmtime or localtime.
> These functions are defined on time_t, which is 32-bits on 32-bit
> Linux systems. In addition, because time_to_string takes
> an unsigned int, it returns bad results for pre-1970 dates.
>
> One fix for this would be to include our own gmtime/localtime
> defined on 64-bit integers. But this is likely to be
> complicated, given the dependence of localtime on timezone data.
>
> Instead, I decided to simply adjust time_to_string to take a
> time_t. This means that on 32-bit time_t systems, we will give
> wrong results for post-2038 dates, but correct results for
> pre-1970 dates. (see patch 2/2)
>
> For the tests, I am looking at the raw value of ctime and
> ctime_extra, which will work regardless of the size of time_t
>
> Is using time_t acceptable, or do you want me to copy over
> gmtime/localtime from glibc? Or is there a third approach
> that would be better?
>
> Also, while I was making this change, I happened to notice that
> there is no dtime_extra field into which to put the extra bits.
> This means that there is still a year 2038 problem with tools
> that deal with deleted files (including the corner case that the
> system is shut down cleanly at the exact second that the bottom
> 32 bits of the current time are zero, leading fsck to believe
> that there was an unclean shutdown).
>
> I want to make an additional change to correct this. Since I
> assume it is impossible to add an additional field, I propose to
> use ctime_extra to store the extra bits of dtime on deletion.
> This is a bit hackish, since it does destroy a bit of data, but
> it is significantly better than dtime being totally broken after
> 2038. What do people think?
> --
> Older kernels on 64-bit machines would incorrectly encode pre-1970
> ext4 dates as post-2311 dates. Detect and correct this (assuming the
> current date is before 2242).
>
> Includes tests for this, as well as changes to debugfs to correctly
> set crtimes.
>
> Signed-off-by: David Turner <novalis@xxxxxxxxxxx>
> ---
> debugfs/set_fields.c | 2 +-
> e2fsck/pass1.c | 43 ++++++++++++++++
> e2fsck/problem.c | 4 ++
> e2fsck/problem.h | 4 ++
> lib/extra_epoch.h | 2 +
> tests/f_pre_1970_date_encoding/expect | 45 ++++++++++++++++
> tests/f_pre_1970_date_encoding/name | 1 +
> tests/f_pre_1970_date_encoding/script | 96 +++++++++++++++++++++++++++++++++++
> 8 files changed, 196 insertions(+), 1 deletion(-)
> create mode 100644 lib/extra_epoch.h
> create mode 100644 tests/f_pre_1970_date_encoding/expect
> create mode 100644 tests/f_pre_1970_date_encoding/name
> create mode 100644 tests/f_pre_1970_date_encoding/script
>
> diff --git a/debugfs/set_fields.c b/debugfs/set_fields.c
> index aad1cd8..f7c55a7 100644
> --- a/debugfs/set_fields.c
> +++ b/debugfs/set_fields.c
> @@ -200,7 +200,7 @@ static struct field_set_info inode_fields[] = {
> 4, parse_uint },
> { "atime_extra", &set_inode.i_atime_extra, NULL,
> 4, parse_uint },
> - { "crtime", &set_inode.i_crtime, NULL, 4, parse_uint },
> + { "crtime", &set_inode.i_crtime, NULL, 4, parse_time },
> { "crtime_extra", &set_inode.i_crtime_extra, NULL,
> 4, parse_uint },
> { "bmap", NULL, NULL, 4, parse_bmap, FLAG_ARRAY },
> diff --git a/e2fsck/pass1.c b/e2fsck/pass1.c
> index ab23e42..ecbd79e 100644
> --- a/e2fsck/pass1.c
> +++ b/e2fsck/pass1.c
> @@ -50,6 +50,8 @@
>
> #include "problem.h"
>
> +#include "extra_epoch.h"
> +
> #ifdef NO_INLINE_FUNCS
> #define _INLINE_
> #else
> @@ -348,6 +350,21 @@ fix:
> EXT2_INODE_SIZE(sb), "pass1");
> }
>
> +static int check_inode_extra_negative_epoch(__u32 xtime, __u32 extra) {
> + return (xtime & (1 << 31)) != 0 &&
> + (extra & EXT4_EPOCH_MASK) == EXT4_EPOCH_MASK;
> +}
> +
> +#define CHECK_INODE_EXTRA_NEGATIVE_EPOCH(inode, xtime) \
> + check_inode_extra_negative_epoch(inode->i_##xtime, \
> + inode->i_##xtime##_extra)
> +
> +/* When today's date is earlier than 2242, we assume that atimes,
> + * ctimes, crtimes, and mtimes with years in the range 2310..2378 are
> + * actually pre-1970 dates mis-encoded.
> + */
> +#define EXT4_EXTRA_NEGATIVE_DATE_CUTOFF 2 * (1LL << 32)
> +
> static void check_inode_extra_space(e2fsck_t ctx, struct problem_context *pctx)
> {
> struct ext2_super_block *sb = ctx->fs->super;
> @@ -388,6 +405,32 @@ static void check_inode_extra_space(e2fsck_t ctx, struct problem_context *pctx)
> /* it seems inode has an extended attribute(s) in body */
> check_ea_in_inode(ctx, pctx);
> }
> +
> + /*
> + * If the inode's extended atime (ctime, crtime, mtime) is stored in
> + * the old, invalid format, repair it.
> + */
> + if (sizeof(time_t) > 4 && ctx->now < EXT4_EXTRA_NEGATIVE_DATE_CUTOFF &&
> + (CHECK_INODE_EXTRA_NEGATIVE_EPOCH(inode, atime) ||
> + CHECK_INODE_EXTRA_NEGATIVE_EPOCH(inode, ctime) ||
> + CHECK_INODE_EXTRA_NEGATIVE_EPOCH(inode, crtime) ||
> + CHECK_INODE_EXTRA_NEGATIVE_EPOCH(inode, mtime))) {
> +
> + if (!fix_problem(ctx, PR_1_EA_TIME_OUT_OF_RANGE, pctx))
> + return;
> +
> + if (CHECK_INODE_EXTRA_NEGATIVE_EPOCH(inode, atime))
> + inode->i_atime_extra &= ~EXT4_EPOCH_MASK;
> + if (CHECK_INODE_EXTRA_NEGATIVE_EPOCH(inode, ctime))
> + inode->i_ctime_extra &= ~EXT4_EPOCH_MASK;
> + if (CHECK_INODE_EXTRA_NEGATIVE_EPOCH(inode, crtime))
> + inode->i_crtime_extra &= ~EXT4_EPOCH_MASK;
> + if (CHECK_INODE_EXTRA_NEGATIVE_EPOCH(inode, mtime))
> + inode->i_mtime_extra &= ~EXT4_EPOCH_MASK;
> + e2fsck_write_inode_full(ctx, pctx->ino, pctx->inode,
> + EXT2_INODE_SIZE(sb), "pass1");
> + }
> +
> }
>
> /*
> diff --git a/e2fsck/problem.c b/e2fsck/problem.c
> index 897693a..b212d00 100644
> --- a/e2fsck/problem.c
> +++ b/e2fsck/problem.c
> @@ -1018,6 +1018,10 @@ static struct e2fsck_problem problem_table[] = {
> N_("@i %i, end of extent exceeds allowed value\n\t(logical @b %c, physical @b %b, len %N)\n"),
> PROMPT_CLEAR, 0 },
>
> + /* Timestamp(s) on inode beyond 2310-04-04 are likely pre-1970 dates. */
> + { PR_1_EA_TIME_OUT_OF_RANGE,
> + N_("Timestamp(s) on @i %i beyond 2310-04-04 are likely pre-1970 dates.\n"),
> + PROMPT_FIX | PR_PREEN_OK | PR_NO_OK, 0 },
>
> /* Pass 1b errors */
>
> diff --git a/e2fsck/problem.h b/e2fsck/problem.h
> index ae1ed26..3710638 100644
> --- a/e2fsck/problem.h
> +++ b/e2fsck/problem.h
> @@ -593,6 +593,10 @@ struct problem_context {
> #define PR_1_EXTENT_INDEX_START_INVALID 0x01006D
>
> #define PR_1_EXTENT_END_OUT_OF_BOUNDS 0x01006E
> +
> +/* Timestamp(s) on inode beyond 2310-04-04 are likely pre-1970 dates. */
> +#define PR_1_EA_TIME_OUT_OF_RANGE 0x01006F
> +
> /*
> * Pass 1b errors
> */
> diff --git a/lib/extra_epoch.h b/lib/extra_epoch.h
> new file mode 100644
> index 0000000..465c43f
> --- /dev/null
> +++ b/lib/extra_epoch.h
> @@ -0,0 +1,2 @@
> +#define EXT4_EPOCH_BITS 2
> +#define EXT4_EPOCH_MASK ((1 << EXT4_EPOCH_BITS) - 1)
> diff --git a/tests/f_pre_1970_date_encoding/expect b/tests/f_pre_1970_date_encoding/expect
> new file mode 100644
> index 0000000..1a71571
> --- /dev/null
> +++ b/tests/f_pre_1970_date_encoding/expect
> @@ -0,0 +1,45 @@
> +times for year-1909 =
> + ctime: 0x8e475440:00000003
> + atime: 0x8e475440:00000003
> + mtime: 0x8e475440:00000003
> +crtime: 0x8e475440:00000003
> +times for year-1979 =
> + ctime: 0x11db6940:00000000
> + atime: 0x11db6940:00000000
> + mtime: 0x11db6940:00000000
> +crtime: 0x11db6940:00000000
> +times for year-2039 =
> + ctime: 0x82a37b40:00000001
> + atime: 0x82a37b40:00000001
> + mtime: 0x82a37b40:00000001
> +crtime: 0x82a37b40:00000001
> +times for year-2139 =
> + ctime: 0x3e9b9940:00000001
> + atime: 0x3e9b9940:00000001
> + mtime: 0x3e9b9940:00000001
> +crtime: 0x3e9b9940:00000001
> +times for year-1909 =
> + ctime: 0x8e475440:00000000
> + atime: 0x8e475440:00000000
> + mtime: 0x8e475440:00000000
> +crtime: 0x8e475440:00000000
> +times for year-1979 =
> + ctime: 0x11db6940:00000000
> + atime: 0x11db6940:00000000
> + mtime: 0x11db6940:00000000
> +crtime: 0x11db6940:00000000
> +times for year-2039 =
> + ctime: 0x82a37b40:00000001
> + atime: 0x82a37b40:00000001
> + mtime: 0x82a37b40:00000001
> +crtime: 0x82a37b40:00000001
> +times for year-2139 =
> + ctime: 0x3e9b9940:00000001
> + atime: 0x3e9b9940:00000001
> + mtime: 0x3e9b9940:00000001
> +crtime: 0x3e9b9940:00000001
> +times for year-1909 =
> + ctime: 0x8e475440:00000003
> + atime: 0x8e475440:00000003
> + mtime: 0x8e475440:00000003
> +crtime: 0x8e475440:00000003
> diff --git a/tests/f_pre_1970_date_encoding/name b/tests/f_pre_1970_date_encoding/name
> new file mode 100644
> index 0000000..9805324
> --- /dev/null
> +++ b/tests/f_pre_1970_date_encoding/name
> @@ -0,0 +1 @@
> +correct mis-encoded pre-1970 dates
> diff --git a/tests/f_pre_1970_date_encoding/script b/tests/f_pre_1970_date_encoding/script
> new file mode 100644
> index 0000000..c3e12f5
> --- /dev/null
> +++ b/tests/f_pre_1970_date_encoding/script
> @@ -0,0 +1,96 @@
> +if test -x $DEBUGFS_EXE; then
> +
> +OUT=$test_name.log
> +TIMESTAMPS=$test_name.timestamps.log
> +EXP=$test_dir/expect
> +FSCK_OPT=-yf
> +
> +create_file_with_xtime_and_extra() {
> + name=$1
> + time=$2
> + extra=$3
> + $DEBUGFS -w -R "write /dev/null $name" $TMPFILE > $OUT 2>&1
> + for xtime in atime ctime mtime crtime
> + do
> + $DEBUGFS -w -R "set_inode_field $name $xtime @$time" $TMPFILE > $OUT 2>&1
> +
> + $DEBUGFS -w -R "set_inode_field $name ${xtime}_extra $extra" $TMPFILE > $OUT 2>&1
> + done
> +}
> +
> +get_file_xtime_and_extra() {
> + name=$1
> + echo "times for $name =" >> $TIMESTAMPS
> + $DEBUGFS -R "stat $name" $TMPFILE 2>&1 | egrep '^( a| c| m|cr)time: ' |sed 's/ --.*//' >> $TIMESTAMPS
> +}
> +
> +rm -f $OUT
> +rm -f $TIMESTAMPS
> +
> +#create an empty ext4 filesystem with 256-byte inodes for testing
> +dd status=none if=/dev/zero of=$TMPFILE bs=1024 count=5000
> +echo mkfs.ext4 -q -I 256 $TMPFILE >> $OUT
> +yes | mkfs.ext4 -q -I 256 $TMPFILE >> $OUT 2>&1
> +
> +# this is a pre-1970 file encoded with the old encoding.
> +# fsck should repair this
> +create_file_with_xtime_and_extra year-1909 -1907928000 3
> +
> +# these are all already encoded correctly
> +create_file_with_xtime_and_extra year-1979 299592000 0
> +create_file_with_xtime_and_extra year-2039 2191752000 1
> +create_file_with_xtime_and_extra year-2139 5345352000 1
> +
> +# confirm that the xtime is wrong on the pre-1970 file
> +get_file_xtime_and_extra year-1909
> +
> +# and confirm that it is right on the remaining files
> +get_file_xtime_and_extra year-1979
> +get_file_xtime_and_extra year-2039
> +get_file_xtime_and_extra year-2139
> +
> +# before we repair the filesystem, save off a copy so that
> +# we can use it later
> +
> +cp $TMPFILE $TMPFILE.backup
> +
> +# repair the filesystem
> +E2FSCK_TIME=1386393539 $FSCK $FSCK_OPT $TMPFILE >> $OUT 2>&1
> +
> +# check that the dates and xtime_extra on the file is now correct
> +get_file_xtime_and_extra year-1909
> +
> +# check that the remaining dates have not been altered
> +get_file_xtime_and_extra year-1979
> +get_file_xtime_and_extra year-2039
> +get_file_xtime_and_extra year-2139
> +
> +# now we need to check that after the year 2242, e2fsck does not
> +# modify dates with extra_xtime=3
> +
> +# restore the unrepaired filesystem
> +mv $TMPFILE.backup $TMPFILE
> +
> +#retry the repair
> +E2FSCK_TIME=9270393539 $FSCK $FSCK_OPT $TMPFILE >> $OUT 2>&1
> +
> +# check that the 1909 file is unaltered (i.e. it has a post-2378 date)
> +get_file_xtime_and_extra year-1909
> +
> +cmp -s $TIMESTAMPS $EXP
> +status=$?
> +
> +if [ "$status" = 0 ] ; then
> + echo "$test_name: $test_description: ok"
> + touch $test_name.ok
> +else
> + echo "$test_name: $test_description: failed"
> + diff $DIFF_OPTS $EXP $TIMESTAMPS > $test_name.failed
> +fi
> +
> +unset OUT TIMESTAMPS EXP FSCK_OPT
> +
> +else #if test -x $DEBUGFS_EXE; then
> + echo "$test_name: $test_description: skipped"
> +fi
> +
> --
> 1.8.1.2
>
>
>
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