On 02/01/2020 22:34, Assaf Gordon wrote:
Hello,
On 2020-01-02 2:01 p.m., Pádraig Brady wrote:
On 02/01/2020 20:29, Assaf Gordon wrote:
Regarding "fall back to mtime", I'm seeing the following results
on some systems - not necessarily a bug, but perhaps it's worth
knowing what to expect:
* Debian 10/x86_64, Linux Kernel 4.19.0, glibc 2.28-10,
with ext2 file system (not supporting birthtime):
$ ./src/ls -l --time=birth /tmp/dummy-ext2/2
-rw-r--r-- 1 root root 0 Dec 31 1969 /tmp/dummy-ext2/2
Hmm. That suggests that STATX_BTIME is set in the
returned statx mask, but populated with 0 in the structure
({-1,-1} would have printed as '?').
Indeed, the returned "btime" is zero:
$ strace -v -e trace=statx ./src/ls -l --time=birth /tmp/dummy-ext2/2
statx(AT_FDCWD, "/tmp/dummy-ext2/2",
AT_STATX_SYNC_AS_STAT|AT_SYMLINK_NOFOLLOW,
STATX_MODE|STATX_NLINK|STATX_UID|STATX_GID|STATX_SIZE|STATX_BTIME,
{stx_mask=STATX_BASIC_STATS, stx_blksize=1024, stx_attributes=0,
stx_nlink=1, stx_uid=0, stx_gid=0, stx_mode=S_IFREG|0644, stx_ino=12,
stx_size=0, stx_blocks=0,
stx_attributes_mask=STATX_ATTR_COMPRESSED|STATX_ATTR_IMMUTABLE|STATX_ATTR_APPEND|STATX_ATTR_NODUMP|STATX_ATTR_ENCRYPTED,
stx_atime={tv_sec=1577995860, tv_nsec=0} /* 2020-01-02T13:11:00-0700 */,
stx_btime={tv_sec=0, tv_nsec=0}, stx_ctime={tv_sec=1577995860,
Looking closer at the new ls.c code (** are added for emphasis):
** if (mask & STATX_BTIME)
st->st_mtim = statx_timestamp_to_timespec (stx.stx_btime);
** else if (want_btime)
st->st_mtim.tv_sec = st->st_mtim.tv_nsec = -1;
Wouldn't "mask & STATX_BTIME" always be the same as "want_btime",
resulting in the "else if" part never to be executed?
IIUC, "mask" is the requested bitmask.
Right of course.
Fixed that up locally to:
if (stx.stx_mask & STATX_BTIME)
st->st_mtim = statx_timestamp_to_timespec (stx.stx_btime);
else if (want_btime)
st->st_mtim.tv_sec = st->st_mtim.tv_nsec = -1;
thanks!
Pádraig
