Re: [Bug-tar] CVS tar "make check" failures on files with ns-resolution time stamps

[Paul Eggert]

"Sergey Poznyakoff" <address@hidden> writes:

> For example, judging by the update.at results, on hosts with nanosecond
> precision, tar will in the majority of cases add non-changed directories
> to the archive when updating, which clearly is a bug. Moreover, even
> simple `tar --diff' has strong chances for issuing a lot of spurious
> 'Mod time differs' diagnostics.

Thanks, I see your point.  I looked over the draft patch you sent me
and it looked good, except it substituted tar_timespec_cmp for
timespec_cmp in a few places where the time stamps came from the file
system and not from a tar archive, which as I understand it isn't the
intended use of tar_timespec_cmp.  These places were OLDER_STAT_TIME,
OLDER_TAR_STAT_TIME, extract_link, and apply_delayed_links.  I undid
that part of the draft patch, verified that the result works on
Solaris 8, and installed the following modified patch.

2005-11-07  Sergey Poznyakoff  <address@hidden>
       and  Paul Eggert  <address@hidden>

        * src/tar.c (NS_PRECISION_FORMAT_MASK): New macro.
        (tar_timespec_cmp): New function. Wrapper over
        timespec_cmp using the timespec precision provided by the
        current archive format.
        * src/common.h (tar_timespec_cmp): New declaration.
        * src/compare.c (diff_file): Use tar_timespec_cmp.
        * src/extract.c (file_newer_p): Likewise.
        * src/update.c (update_archive): Likewise.
        * tests/truncate.at: Reverted changes
        * tests/update.at: Reverted changes

Index: src/common.h
===================================================================
RCS file: /cvsroot/tar/tar/src/common.h,v
retrieving revision 1.64
diff -p -u -r1.64 common.h
--- src/common.h        7 Nov 2005 05:11:55 -0000       1.64
+++ src/common.h        8 Nov 2005 07:18:09 -0000
@@ -600,6 +600,7 @@ void request_stdin (const char *);
 void tar_stat_init (struct tar_stat_info *st);
 void tar_stat_destroy (struct tar_stat_info *st);
 void usage (int) __attribute__ ((noreturn));
+int tar_timespec_cmp (struct timespec a, struct timespec b);
 
 /* Module update.c.  */
 
Index: src/compare.c
===================================================================
RCS file: /cvsroot/tar/tar/src/compare.c,v
retrieving revision 1.30
diff -p -u -r1.30 compare.c
--- src/compare.c       28 Oct 2005 09:28:20 -0000      1.30
+++ src/compare.c       8 Nov 2005 07:18:09 -0000
@@ -224,7 +224,8 @@ diff_file (void)
       if (!sys_compare_gid (&stat_data, &current_stat_info.stat))
        report_difference (&current_stat_info, _("Gid differs"));
 
-      if (timespec_cmp (get_stat_mtime (&stat_data), current_stat_info.mtime))
+      if (tar_timespec_cmp (get_stat_mtime (&stat_data), 
+                            current_stat_info.mtime))
        report_difference (&current_stat_info, _("Mod time differs"));
       if (current_header->header.typeflag != GNUTYPE_SPARSE &&
          stat_data.st_size != current_stat_info.stat.st_size)
Index: src/extract.c
===================================================================
RCS file: /cvsroot/tar/tar/src/extract.c,v
retrieving revision 1.82
diff -p -u -r1.82 extract.c
--- src/extract.c       4 Nov 2005 21:25:47 -0000       1.82
+++ src/extract.c       8 Nov 2005 07:18:09 -0000
@@ -469,7 +469,7 @@ file_newer_p (const char *file_name, str
       return errno != ENOENT;
     }
   if (!S_ISDIR (st.st_mode)
-      && timespec_cmp (tar_stat->mtime, get_stat_mtime (&st)) <= 0)
+      && tar_timespec_cmp (tar_stat->mtime, get_stat_mtime (&st)) <= 0)
     {
       return true;
     }
Index: src/tar.c
===================================================================
RCS file: /cvsroot/tar/tar/src/tar.c,v
retrieving revision 1.127
diff -p -u -r1.127 tar.c
--- src/tar.c   7 Nov 2005 02:50:14 -0000       1.127
+++ src/tar.c   8 Nov 2005 07:18:09 -0000
@@ -162,7 +162,7 @@ archive_format_string (enum archive_form
 static void
 assert_format(unsigned fmt_mask)
 {
-  if ((FORMAT_MASK(archive_format) & fmt_mask) == 0)
+  if ((FORMAT_MASK (archive_format) & fmt_mask) == 0)
     USAGE_ERROR ((0, 0,
                  _("GNU features wanted on incompatible archive format")));
 }
@@ -314,7 +314,7 @@ static struct argp_option options[] = {
   {"occurrence", OCCURRENCE_OPTION, N_("NUMBER"), OPTION_ARG_OPTIONAL,
    N_("process only the NUMBERth occurrence of each file in the archive. This 
option is valid only in conjunction with one of the subcommands --delete, 
--diff, --extract or --list and when a list of files is given either on the 
command line or via -T option. NUMBER defaults to 1."), 21 },
   {"seek", 'n', NULL, 0,
-   N_("archive is seekable"), 21 },    
+   N_("archive is seekable"), 21 },
 
   {NULL, 0, NULL, 0,
    N_("Overwrite control:"), 30},
@@ -557,7 +557,7 @@ static struct argp_option options[] = {
   {"show-stored-names", SHOW_STORED_NAMES_OPTION, 0, 0,
    N_("When creating archive in verbose mode, list member names as stored in 
the archive"),
    102 },
-    
+
   {NULL, 0, NULL, 0,
    N_("Compatibility options:"), 110 },
 
@@ -1047,7 +1047,7 @@ parse_opt (int key, char *arg, struct ar
       set_subcommand_option (LIST_SUBCOMMAND);
       test_label_option = true;
       break;
-      
+
     case 'T':
       update_argv (arg, state);
       /* Indicate we've been given -T option. This is for backward
@@ -1323,7 +1323,7 @@ parse_opt (int key, char *arg, struct ar
     case SHOW_STORED_NAMES_OPTION:
       show_stored_names_option = true;
       break;
-      
+
     case SUFFIX_OPTION:
       backup_option = true;
       args->backup_suffix_string = arg;
@@ -1679,7 +1679,7 @@ decode_options (int argc, char **argv)
 
   if (multi_volume_option)
     assert_format (FORMAT_MASK (OLDGNU_FORMAT) | FORMAT_MASK (GNU_FORMAT));
-  
+
   if (sparse_option)
     assert_format (FORMAT_MASK (OLDGNU_FORMAT)
                   | FORMAT_MASK (GNU_FORMAT)
@@ -1980,4 +1980,18 @@ tar_stat_destroy (struct tar_stat_info *
   free (st->sparse_map);
   free (st->dumpdir);
   memset (st, 0, sizeof (*st));
+}
+
+/* Format mask for all available formats that support nanosecond
+   timestamp resolution. */
+#define NS_PRECISION_FORMAT_MASK FORMAT_MASK (POSIX_FORMAT)
+
+/* Same as timespec_cmp, but ignore nanoseconds if current archive
+   format does not provide sufficient resolution.  */
+int
+tar_timespec_cmp (struct timespec a, struct timespec b)
+{
+  if (!(FORMAT_MASK (current_format) & NS_PRECISION_FORMAT_MASK))
+    a.tv_nsec = b.tv_nsec = 0;
+  return timespec_cmp (a, b);
 }
Index: src/update.c
===================================================================
RCS file: /cvsroot/tar/tar/src/update.c,v
retrieving revision 1.33
diff -p -u -r1.33 update.c
--- src/update.c        17 Sep 2005 06:41:56 -0000      1.33
+++ src/update.c        8 Nov 2005 07:18:09 -0000
@@ -138,8 +138,8 @@ update_archive (void)
                chdir_do (name->change_dir);
                if (deref_stat (dereference_option,
                                current_stat_info.file_name, &s) == 0
-                   && (timespec_cmp (get_stat_mtime (&s),
-                                     current_stat_info.mtime)
+                   && (tar_timespec_cmp (get_stat_mtime (&s),
+                                         current_stat_info.mtime)
                        <= 0))
                  add_avoided_name (current_stat_info.file_name);
              }
Index: tests/truncate.at
===================================================================
RCS file: /cvsroot/tar/tar/tests/truncate.at,v
retrieving revision 1.4
diff -p -u -r1.4 truncate.at
--- tests/truncate.at   7 Nov 2005 04:03:29 -0000       1.4
+++ tests/truncate.at   8 Nov 2005 07:18:09 -0000
@@ -31,7 +31,6 @@ AT_KEYWORDS([truncated files])
 AT_TAR_CHECK([
 genfile --file foo --length 50000k
 genfile --file baz
-touch -t 197001030000 baz # avoid subsecond resolution
 genfile --run 'tar -vcf bar foo baz' --checkpoint 10 --length 49995k 
--truncate foo
 echo separator
 sleep 1
Index: tests/update.at
===================================================================
RCS file: /cvsroot/tar/tar/tests/update.at,v
retrieving revision 1.4
diff -p -u -r1.4 update.at
--- tests/update.at     7 Nov 2005 04:03:30 -0000       1.4
+++ tests/update.at     8 Nov 2005 07:18:09 -0000
@@ -31,7 +31,6 @@ AT_TAR_CHECK([
 mkdir directory
 genfile --length 10240 --pattern zeros --file directory/file1
 genfile --length 10240 --pattern default --file directory/file2
-touch -t 197001030000 directory directory/* # avoid subsecond resolution
 
 tar cf archive directory || exit 1
 echo separator