(ls-lisp-time-to-seconds): New function.

(ls-lisp-format-time): Emulate GNU fileutils 4.1.1 ls, whose time stamps
always line up by default.  Also, it uses a slightly different window
to determine whether files are "recent".

1 files changed, 27 insertions, 13 deletions

diff --git a/lisp/ls-lisp.el b/lisp/ls-lisp.el
index aeada6ef886..dca1ebbd89c 100644
--- a/lisp/ls-lisp.el
+++ b/lisp/ls-lisp.el
@@ -515,26 +515,40 @@ Return nil if no time switch found."
         ((memq ?t switches) 5)          ; last modtime
         ((memq ?u switches) 4)))        ; last access
 
+(defun ls-lisp-time-to-seconds (time)
+  "Convert TIME to a floating point number."
+  (+ (* (car time) 65536.0)
+     (cadr time)
+     (/ (or (nth 2 time) 0) 1000000.0)))
+
 (defun ls-lisp-format-time (file-attr time-index now)
   "Format time for file with attributes FILE-ATTR according to TIME-INDEX.
 Use the same method as ls to decide whether to show time-of-day or year,
 depending on distance between file date and NOW.
 All ls time options, namely c, t and u, are handled."
   (let* ((time (nth (or time-index 5) file-attr)) ; default is last modtime
-         (diff16 (- (car time) (car now)))
-         (diff (+ (ash diff16 16) (- (car (cdr time)) (car (cdr now)))))
-         (past-cutoff (- (* 6 30 24 60 60)))    ; 6 30-day months
-         (future-cutoff (* 60 60)))             ; 1 hour
+         (diff (- (ls-lisp-time-to-seconds time)
+                  (ls-lisp-time-to-seconds now)))
+         ;; Consider a time to be recent if it is within the past six
+         ;; months.  A Gregorian year has 365.2425 * 24 * 60 * 60 ==
+         ;; 31556952 seconds on the average, and half of that is 15778476.
+         ;; Write the constant explicitly to avoid roundoff error.
+         (past-cutoff -15778476)) ; half a Gregorian year
     (condition-case nil
-        (format-time-string
-         (if (and
-              (<= past-cutoff diff) (<= diff future-cutoff)
-              ;; Sanity check in case `diff' computation overflowed.
-              (<= (1- (ash past-cutoff -16)) diff16)
-              (<= diff16 (1+ (ash future-cutoff -16))))
-             "%b %e %H:%M"
-           "%b %e  %Y")
-         time)
+        ;; Use traditional time format in the C or POSIX locale,
+        ;; ISO-style time format otherwise, so columns line up.
+        (let ((locale system-time-locale))
+          (if (not locale)
+              (let ((vars '("LC_ALL" "LC_TIME" "LANG")))
+                (while (and vars (not (setq locale (getenv (car vars)))))
+                  (setq vars (cdr vars)))))
+          (if (member locale '("C" "POSIX"))
+              (setq locale nil))
+          (format-time-string
+           (if (and (<= past-cutoff diff) (<= diff 0))
+               (if locale "%m-%d %H:%M" "%b %e %H:%M")
+             (if locale "%Y-%m-%d " "%b %e  %Y"))
+           time))
       (error "Unk  0  0000"))))
 
 (provide 'ls-lisp)