From 96cdb72eeaed9fbe6a3434eabcbf900fdfc1a6d5 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Sun, 6 Feb 2022 13:32:11 -0800
Subject: [PATCH 4/4] Use GNU ls algorithm for deciding timestamp format

Problem reported by Dan Jacobson (Bug#50694).
* gnulib.modules: Add gettime, timespec.
* src/copyin.c: Include timespec.h.
(current_time): Now struct timespec, not time_t.  All uses changed.
(long_format): When formatting a timestamp, use the same algorithm that
GNU ls does to decide whether a file is recent.
---
 gnulib.modules |  2 ++
 src/copyin.c   | 30 ++++++++++++++++++++++--------
 2 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/gnulib.modules b/gnulib.modules
index 15037a0..64cda0a 100644
--- a/gnulib.modules
+++ b/gnulib.modules
@@ -12,6 +12,7 @@ fnmatch-gnu
 full-write
 getline
 gettext-h
+gettime
 gitlog-to-changelog
 hash
 inttostr
@@ -24,6 +25,7 @@ stdbool
 stdint
 stpcpy
 strerror
+timespec
 unlocked-io
 utimens
 xalloc
diff --git a/src/copyin.c b/src/copyin.c
index 0af23a0..28d0c33 100644
--- a/src/copyin.c
+++ b/src/copyin.c
@@ -31,6 +31,7 @@
 #ifndef	FNM_PATHNAME
 # include <fnmatch.h>
 #endif
+#include <timespec.h>
 
 #ifndef HAVE_LCHOWN
 # define lchown(f,u,g) 0
@@ -719,7 +720,7 @@ copyin_file (struct cpio_file_stat *file_hdr, int in_file_des)
 
 
 /* Current time for verbose table.  */
-static time_t current_time;
+static struct timespec current_time;
 
 
 /* Print the file described by FILE_HDR in long format.
@@ -761,10 +762,25 @@ long_format (struct cpio_file_stat *file_hdr, char const *link_name)
      or a year outside the range 1000-9999, since 0 <= WHEN < 2**33.  */
   time_t when = file_hdr->c_mtime;
   char *tbuf = ctime (&when);
-  int six_months = 6 * 30 * 24 * 60 * 60;
-  bool recent = ((current_time < six_months
-		  || current_time - six_months <= when)
-		 && when <= current_time);
+
+  /* If the file appears to be in the future, update the current
+     time, in case the file happens to have been modified since
+     the last time we checked the clock.  */
+  struct timespec when_timespec = { .tv_sec = when };
+  if (timespec_cmp (current_time, when_timespec) < 0)
+    current_time = current_timespec ();
+
+  /* Consider a time to be recent if it is within the past six months.
+     Use the same algorithm that GNU 'ls' does, for consistency.
+     A Gregorian year has 365.2425 * 24 * 60 * 60 == 31556952 seconds
+     on the average.  Write this value as an integer constant to
+     avoid floating point hassles.  */
+  struct timespec six_months_ago = {
+    .tv_sec = current_time.tv_sec - 31556952 / 2,
+    .tv_nsec = current_time.tv_nsec
+  };
+  bool recent = (timespec_cmp (six_months_ago, when_timespec) < 0
+		 & timespec_cmp (when_timespec, current_time) < 0);
   if (!recent)
     {
       /* The file is older than 6 months, or in the future.
@@ -1264,9 +1280,7 @@ process_copy_in (void)
 
   /* Get date and time if needed for processing the table option.  */
   if (table_flag && verbose_flag)
-    {
-      time (&current_time);
-    }
+    current_time = current_timespec ();
 
   /* Check whether the input file might be a tape.  */
   in_file_des = archive_des;
-- 
2.32.0