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Re: [coreutils] stat: reverting recent %X %Y %Z change
|
From: |
Jim Meyering |
|
Subject: |
Re: [coreutils] stat: reverting recent %X %Y %Z change |
|
Date: |
Tue, 26 Oct 2010 19:59:48 +0200 |
Jim Meyering wrote:
> Jim Meyering wrote:
>
>> Pádraig Brady wrote:
>>> On 22/10/10 18:43, Jim Meyering wrote:
>>>> Part of reverting this change:
>>>>
>>>> stat now outputs the full sub-second resolution for the atime,
>>>> mtime, and ctime values since the Epoch, when using the %X, %Y, and
>>>> %Z directives of the --format option. This matches the fact that
>>>> %x, %y, and %z were already doing so for the human-readable variant.
>>>>
>>>> means considering whether to do the same sort of thing with the
>>>> newly-added %W (birth time/crtime). Note that %W currently expands to "-"
>>>> on systems with no support (e.g., linux).
>>>>
>>>> I don't particularly like the idea of making stat do this:
>>>>
>>>> $ src/stat -c %W.%:W .
>>>> -.-
>>>>
>>>> Rather, I have a slight preference to make it do this:
>>>>
>>>> $ src/stat -c %W.%:W .
>>>> 0.000000000
>>>
>>> I prefer that as it would mean less special
>>> cases in code that uses the output.
>>
>> Exactly.
>>
>>>> In any case, I think %w should still expand to "-".
>>>>
>>>> The alternative is to leave %W separate, with no %:W variant.
>>>> I.e., %W would continue to print floating point seconds.
>>>> In that case, it would be inconsistent with %X, %Y and %Z.
>>>
>>> I don't like that.
>>
>> Thanks for the feedback!
>
> Here's a mostly-ready proposed change.
>
> I've just realized it doesn't mention the nanosecond field width issue:
> the default is 9, and it's always zero-padded, but only to a width of 9,
> which is surprising if you ever specify a larger field width:
>
> $ src/stat -c %12:W .
> 000000000
>
> I dislike such surprises...
I've adjusted things so that it's not so bad.
Setup:
$ touch -d '2010-10-21 18:43:33.000000789' k
With the incremental patch below, you get "09" modifiers only
when you specify no other modifier:
$ stat -c ns_%12:X_ k
ns_ 789_
$ stat -c ns_%:X_ k
ns_000000789_
$ stat -c ns_%9:X_ k
ns_ 789_
diff --git a/src/stat.c b/src/stat.c
index 9a6bb8f..9d3db1b 100644
--- a/src/stat.c
+++ b/src/stat.c
@@ -471,14 +471,19 @@ epoch_sec (struct timespec t)
return timetostr (t.tv_sec, str);
}
-/* Return a string representation (in static storage)
- of nanoseconds part of T. */
-static char * ATTRIBUTE_WARN_UNUSED_RESULT
-epoch_ns (struct timespec t)
+/* Output the number of nanoseconds, ARG.tv_nsec. */
+static void
+out_ns (char *pformat, size_t prefix_len, struct timespec arg)
{
- static char str[10];
- sprintf (str, "%09ld", t.tv_nsec);
- return str;
+ /* If no format modifier is specified, i.e., nothing between the
+ "%" and ":" of "%:X", then use the default of zero-padding and
+ a width of 9. Otherwise, use the specified modifier(s).
+ This is to avoid the mistake of omitting the zero padding on
+ a number with fewer digits than the field width: when printing
+ nanoseconds after a decimal place, the resulting floating point
+ fraction would off by a factor of 10 or more. */
+ strcpy (pformat + prefix_len, prefix_len == 1 ? "09ld" : "ld");
+ printf (pformat, arg.tv_nsec);
}
static void
@@ -829,8 +834,7 @@ print_stat (char *pformat, size_t prefix_len, unsigned int
m,
epoch_sec (neg_to_zero (get_stat_birthtime (statbuf))));
break;
case 'W' + 256:
- out_string (pformat, prefix_len,
- epoch_ns (neg_to_zero (get_stat_birthtime (statbuf))));
+ out_ns (pformat, prefix_len, neg_to_zero (get_stat_birthtime (statbuf)));
break;
case 'x':
out_string (pformat, prefix_len, human_time (get_stat_atime (statbuf)));
@@ -839,7 +843,7 @@ print_stat (char *pformat, size_t prefix_len, unsigned int
m,
out_string (pformat, prefix_len, epoch_sec (get_stat_atime (statbuf)));
break;
case 'X' + 256:
- out_string (pformat, prefix_len, epoch_ns (get_stat_atime (statbuf)));
+ out_ns (pformat, prefix_len, get_stat_atime (statbuf));
break;
case 'y':
out_string (pformat, prefix_len, human_time (get_stat_mtime (statbuf)));
@@ -848,7 +852,7 @@ print_stat (char *pformat, size_t prefix_len, unsigned int
m,
out_string (pformat, prefix_len, epoch_sec (get_stat_mtime (statbuf)));
break;
case 'Y' + 256:
- out_string (pformat, prefix_len, epoch_ns (get_stat_mtime (statbuf)));
+ out_ns (pformat, prefix_len, get_stat_mtime (statbuf));
break;
case 'z':
out_string (pformat, prefix_len, human_time (get_stat_ctime (statbuf)));
@@ -857,7 +861,7 @@ print_stat (char *pformat, size_t prefix_len, unsigned int
m,
out_string (pformat, prefix_len, epoch_sec (get_stat_ctime (statbuf)));
break;
case 'Z' + 256:
- out_string (pformat, prefix_len, epoch_ns (get_stat_ctime (statbuf)));
+ out_ns (pformat, prefix_len, get_stat_ctime (statbuf));
break;
case 'C':
fail |= out_file_context (pformat, prefix_len, filename);
diff --git a/doc/coreutils.texi b/doc/coreutils.texi
index 94e8ebf..58a700b 100644
--- a/doc/coreutils.texi
+++ b/doc/coreutils.texi
@@ -10699,18 +10699,23 @@ stat invocation
@item %U - User name of owner
@item %w - Time of file birth, or @samp{-} if unknown
@item %W - Time of file birth as seconds since Epoch, or @samp{0}
-@item %:W - Time of file birth: 0-padded nanoseconds remainder, or @samp{0}
+@item %:W - Time of file birth: nanoseconds remainder, or @samp{0}
@item %x - Time of last access
@item %X - Time of last access as seconds since Epoch
-@item %:X - Time of last access: 0-padded nanoseconds remainder
+@item %:X - Time of last access: nanoseconds remainder
@item %y - Time of last modification
@item %Y - Time of last modification as seconds since Epoch
-@item %:Y - Time of last modification: 0-padded nanoseconds remainder
+@item %:Y - Time of last modification: nanoseconds remainder
@item %z - Time of last change
@item %Z - Time of last change as seconds since Epoch
-@item %:Z - Time of last change: 0-padded nanoseconds remainder
+@item %:Z - Time of last change: nanoseconds remainder
@end itemize
+Note that each of @samp{%:W}, @samp{%:X}, @samp{%:Y} and @samp{%:Z}
+prints its zero-padded number of nanoseconds on a field of width 9.
+However, if you specify anything between the @samp{%} and @samp{:},
+e.g., @samp{%10:X}, your modifier replaces the default of @samp{09}.
+
The mount point printed by @samp{%m} is similar to that output
by @command{df}, except that:
@itemize @bullet
Here's the combined patch:
>From eba6292f45c9b46fb8a64f8a017bf2e9437cc60e Mon Sep 17 00:00:00 2001
From: Jim Meyering <address@hidden>
Date: Thu, 21 Oct 2010 18:41:24 +0200
Subject: [PATCH] stat: revert %X-%Y-%Z change; use e.g., %:X to print
fractional seconds
This reverts part of the recent commit 9069af45,
"stat: print timestamps to full resolution", which made %X, %Y, %Z
print floating point numbers. We prefer to retain portability of
%X, %Y and %Z uses, while still providing access to full-resolution
time stamps via modified format strings. Also make the new
%W consistent.
* src/stat.c (print_it): Accept a new %...:[XYZ] format directive,
e.g., %:X, to print the nanoseconds portion of the corresponding time.
For example, %3.3:Y prints the zero-padded, truncated, milliseconds
part of the time of last modification.
(print_it): Update print_func signature to match.
(neg_to_zero): New helper function.
(epoch_time): Remove function; replace with...
(epoch_sec): New function; use timetostr.
(out_ns): New function. Use "09" only when no other modifier
is specified.
(print_statfs): Change type of "m" to unsigned int,
now that it must accommodate values larger than 255.
(print_stat): Likewise.
Map :X to a code of 'X' + 256. Likewise for Y, Z and W.
(usage): Update.
* tests/touch/60-seconds: Use %Y.%:Y in place of %Y.
* NEWS (Changes in behavior): Mention this.
Thanks to Andreas Schwab for raising the issue.
---
NEWS | 15 ++++++
doc/coreutils.texi | 11 ++++-
src/stat.c | 118 ++++++++++++++++++++++++++++++++----------------
tests/touch/60-seconds | 2 +-
4 files changed, 105 insertions(+), 41 deletions(-)
diff --git a/NEWS b/NEWS
index 7dbbf1f..2a21109 100644
--- a/NEWS
+++ b/NEWS
@@ -7,6 +7,21 @@ GNU coreutils NEWS -*-
outline -*-
tail -F once again notices changes in a currently unavailable
remote directory [bug introduced in coreutils-7.5]
+** Changes in behavior
+
+ stat's %X, %Y, and %Z directives once again print only the integer
+ part of seconds since the epoch. This reverts a change, introduced
+ in coreutils-8.6, that was deemed unnecessarily disruptive. To obtain
+ the nanoseconds portion corresponding to %X, you may now use %:X.
+ I.e., to print the floating point number of seconds using maximum
+ precision, use this format string: %X.%:X. Likewise for %Y, %Z and %W.
+
+ stat's new %W format directive would print floating point seconds.
+ However, with the above change to %X, %Y and %Z, we've made %W work
+ the same way: %W now expands to seconds since the epoch (or 0 when
+ not supported), and %:W expands to the nanoseconds portion, or to
+ 0 if not supported.
+
* Noteworthy changes in release 8.6 (2010-10-15) [stable]
diff --git a/doc/coreutils.texi b/doc/coreutils.texi
index 4d17ed1..58a700b 100644
--- a/doc/coreutils.texi
+++ b/doc/coreutils.texi
@@ -10698,15 +10698,24 @@ stat invocation
@item %u - User ID of owner
@item %U - User name of owner
@item %w - Time of file birth, or @samp{-} if unknown
-@item %W - Time of file birth as seconds since Epoch, or @samp{-}
+@item %W - Time of file birth as seconds since Epoch, or @samp{0}
+@item %:W - Time of file birth: nanoseconds remainder, or @samp{0}
@item %x - Time of last access
@item %X - Time of last access as seconds since Epoch
+@item %:X - Time of last access: nanoseconds remainder
@item %y - Time of last modification
@item %Y - Time of last modification as seconds since Epoch
+@item %:Y - Time of last modification: nanoseconds remainder
@item %z - Time of last change
@item %Z - Time of last change as seconds since Epoch
+@item %:Z - Time of last change: nanoseconds remainder
@end itemize
+Note that each of @samp{%:W}, @samp{%:X}, @samp{%:Y} and @samp{%:Z}
+prints its zero-padded number of nanoseconds on a field of width 9.
+However, if you specify anything between the @samp{%} and @samp{:},
+e.g., @samp{%10:X}, your modifier replaces the default of @samp{09}.
+
The mount point printed by @samp{%m} is similar to that output
by @command{df}, except that:
@itemize @bullet
diff --git a/src/stat.c b/src/stat.c
index fabbc17..9d3db1b 100644
--- a/src/stat.c
+++ b/src/stat.c
@@ -462,24 +462,28 @@ human_time (struct timespec t)
return str;
}
+/* Return a string representation (in static storage)
+ of the number of seconds in T since the epoch. */
static char * ATTRIBUTE_WARN_UNUSED_RESULT
-epoch_time (struct timespec t)
+epoch_sec (struct timespec t)
{
- static char str[INT_STRLEN_BOUND (time_t) + sizeof ".NNNNNNNNN"];
- /* Note that time_t can technically be a floating point value, such
- that casting to [u]intmax_t could lose a fractional value or
- suffer from overflow. However, most porting targets have an
- integral time_t; also, we know of no file systems that store
- valid time values outside the bounds of intmax_t even if that
- value were represented as a floating point. Besides, the cost of
- converting to struct tm just to use nstrftime (str, len, "%s.%N",
- tm, 0, t.tv_nsec) is pointless, since nstrftime would have to
- convert back to seconds as time_t. */
- if (TYPE_SIGNED (time_t))
- sprintf (str, "%" PRIdMAX ".%09ld", (intmax_t) t.tv_sec, t.tv_nsec);
- else
- sprintf (str, "%" PRIuMAX ".%09ld", (uintmax_t) t.tv_sec, t.tv_nsec);
- return str;
+ static char str[INT_BUFSIZE_BOUND (time_t)];
+ return timetostr (t.tv_sec, str);
+}
+
+/* Output the number of nanoseconds, ARG.tv_nsec. */
+static void
+out_ns (char *pformat, size_t prefix_len, struct timespec arg)
+{
+ /* If no format modifier is specified, i.e., nothing between the
+ "%" and ":" of "%:X", then use the default of zero-padding and
+ a width of 9. Otherwise, use the specified modifier(s).
+ This is to avoid the mistake of omitting the zero padding on
+ a number with fewer digits than the field width: when printing
+ nanoseconds after a decimal place, the resulting floating point
+ fraction would off by a factor of 10 or more. */
+ strcpy (pformat + prefix_len, prefix_len == 1 ? "09ld" : "ld");
+ printf (pformat, arg.tv_nsec);
}
static void
@@ -539,7 +543,8 @@ out_file_context (char *pformat, size_t prefix_len, char
const *filename)
/* Print statfs info. Return zero upon success, nonzero upon failure. */
static bool ATTRIBUTE_WARN_UNUSED_RESULT
-print_statfs (char *pformat, size_t prefix_len, char m, char const *filename,
+print_statfs (char *pformat, size_t prefix_len, unsigned int m,
+ char const *filename,
void const *data)
{
STRUCT_STATVFS const *statfsbuf = data;
@@ -711,9 +716,19 @@ print_mount_point:
return fail;
}
+/* Map a TS with negative TS.tv_nsec to {0,0}. */
+static inline struct
+timespec neg_to_zero (struct timespec ts)
+{
+ if (0 <= ts.tv_nsec)
+ return ts;
+ struct timespec z = {0, 0};
+ return z;
+}
+
/* Print stat info. Return zero upon success, nonzero upon failure. */
static bool
-print_stat (char *pformat, size_t prefix_len, char m,
+print_stat (char *pformat, size_t prefix_len, unsigned int m,
char const *filename, void const *data)
{
struct stat *statbuf = (struct stat *) data;
@@ -815,31 +830,38 @@ print_stat (char *pformat, size_t prefix_len, char m,
}
break;
case 'W':
- {
- struct timespec t = get_stat_birthtime (statbuf);
- if (t.tv_nsec < 0)
- out_string (pformat, prefix_len, "-");
- else
- out_string (pformat, prefix_len, epoch_time (t));
- }
+ out_string (pformat, prefix_len,
+ epoch_sec (neg_to_zero (get_stat_birthtime (statbuf))));
+ break;
+ case 'W' + 256:
+ out_ns (pformat, prefix_len, neg_to_zero (get_stat_birthtime (statbuf)));
break;
case 'x':
out_string (pformat, prefix_len, human_time (get_stat_atime (statbuf)));
break;
case 'X':
- out_string (pformat, prefix_len, epoch_time (get_stat_atime (statbuf)));
+ out_string (pformat, prefix_len, epoch_sec (get_stat_atime (statbuf)));
+ break;
+ case 'X' + 256:
+ out_ns (pformat, prefix_len, get_stat_atime (statbuf));
break;
case 'y':
out_string (pformat, prefix_len, human_time (get_stat_mtime (statbuf)));
break;
case 'Y':
- out_string (pformat, prefix_len, epoch_time (get_stat_mtime (statbuf)));
+ out_string (pformat, prefix_len, epoch_sec (get_stat_mtime (statbuf)));
+ break;
+ case 'Y' + 256:
+ out_ns (pformat, prefix_len, get_stat_mtime (statbuf));
break;
case 'z':
out_string (pformat, prefix_len, human_time (get_stat_ctime (statbuf)));
break;
case 'Z':
- out_string (pformat, prefix_len, epoch_time (get_stat_ctime (statbuf)));
+ out_string (pformat, prefix_len, epoch_sec (get_stat_ctime (statbuf)));
+ break;
+ case 'Z' + 256:
+ out_ns (pformat, prefix_len, get_stat_ctime (statbuf));
break;
case 'C':
fail |= out_file_context (pformat, prefix_len, filename);
@@ -897,7 +919,8 @@ print_esc_char (char c)
Return zero upon success, nonzero upon failure. */
static bool ATTRIBUTE_WARN_UNUSED_RESULT
print_it (char const *format, char const *filename,
- bool (*print_func) (char *, size_t, char, char const *, void const
*),
+ bool (*print_func) (char *, size_t, unsigned int,
+ char const *, void const *),
void const *data)
{
bool fail = false;
@@ -922,10 +945,23 @@ print_it (char const *format, char const *filename,
{
size_t len = strspn (b + 1, "#-+.I 0123456789");
char const *fmt_char = b + len + 1;
+ unsigned int fmt_code;
memcpy (dest, b, len + 1);
+ /* The ":" modifier just before the letter in %W, %X, %Y, %Z
+ tells stat to print the nanoseconds portion of the date. */
+ if (*fmt_char == ':' && strchr ("WXYZ", fmt_char[1]))
+ {
+ fmt_code = fmt_char[1] + 256;
+ ++fmt_char;
+ }
+ else
+ {
+ fmt_code = fmt_char[0];
+ }
+
b = fmt_char;
- switch (*fmt_char)
+ switch (fmt_code)
{
case '\0':
--b;
@@ -941,7 +977,7 @@ print_it (char const *format, char const *filename,
putchar ('%');
break;
default:
- fail |= print_func (dest, len + 1, *fmt_char, filename, data);
+ fail |= print_func (dest, len + 1, fmt_code, filename, data);
break;
}
break;
@@ -1215,14 +1251,18 @@ The valid format sequences for files (without
--file-system):\n\
fputs (_("\
%u User ID of owner\n\
%U User name of owner\n\
- %w Time of file birth, or - if unknown\n\
- %W Time of file birth as seconds since Epoch, or - if unknown\n\
- %x Time of last access\n\
- %X Time of last access as seconds since Epoch\n\
- %y Time of last modification\n\
- %Y Time of last modification as seconds since Epoch\n\
- %z Time of last change\n\
- %Z Time of last change as seconds since Epoch\n\
+ %w Time of file birth, human-readable; - if unknown\n\
+ %W Time of file birth, seconds since Epoch; 0 if unknown\n\
+ %:W Time of file birth, nanoseconds remainder; 0 if unknown\n\
+ %x Time of last access, human-readable\n\
+ %X Time of last access, seconds since Epoch\n\
+ %:X Time of last access, nanoseconds remainder\n\
+ %y Time of last modification, human-readable\n\
+ %Y Time of last modification, seconds since Epoch\n\
+ %:Y Time of last modification, nanoseconds remainder\n\
+ %z Time of last change, human-readable\n\
+ %Z Time of last change, seconds since Epoch\n\
+ %:Z Time of last change, nanoseconds remainder\n\
\n\
"), stdout);
diff --git a/tests/touch/60-seconds b/tests/touch/60-seconds
index f98f0c5..d008296 100755
--- a/tests/touch/60-seconds
+++ b/tests/touch/60-seconds
@@ -30,7 +30,7 @@ echo 60.000000000 > exp || framework_failure
# an `invalid date format'. Specifying 60 seconds *is* valid.
TZ=UTC0 touch -t 197001010000.60 f || fail=1
-stat --p='%Y\n' f > out || fail=1
+stat --p='%Y.%:Y\n' f > out || fail=1
compare out exp || fail=1
--
1.7.3.1.216.g329be
- [coreutils] stat: reverting recent %X %Y %Z change, Jim Meyering, 2010/10/22
- Re: [coreutils] stat: reverting recent %X %Y %Z change, Pádraig Brady, 2010/10/22
- Re: [coreutils] stat: reverting recent %X %Y %Z change, Jim Meyering, 2010/10/23
- Re: [coreutils] stat: reverting recent %X %Y %Z change, Jim Meyering, 2010/10/24
- Re: [coreutils] stat: reverting recent %X %Y %Z change,
Jim Meyering <=
- Re: [coreutils] stat: reverting recent %X %Y %Z change, Pádraig Brady, 2010/10/26
- Re: [coreutils] stat: reverting recent %X %Y %Z change, Jim Meyering, 2010/10/27
- Re: [coreutils] stat: reverting recent %X %Y %Z change, Jim Meyering, 2010/10/28
- Re: [coreutils] stat: reverting recent %X %Y %Z change, Pádraig Brady, 2010/10/29