Add ability to not save mtime in metadata files

If you're storing metadata in a version control system with multiple
branches, mtime differences are going to produce a whole bunch of
conflicts that you likely don't care about. This allows you to not
save mtime and avoid those.

Note that we use a sentinel value of -1 for the mentry `mtimensec` field
to indicate this in the data, as all values of `mtime` are theoretically
valid, but `mtimensec` must always be between 0 and 999,999,999 in the
real world.

I'm not 100% sure about the mechanism for selecting this feature. The
legacy behaviour for metastore was to save mtimes in the metadata files,
but ignore them for compare/apply by default, with a `--mtime` option to
use the mtime data.

Keeping the legacy behaviour for backwards compatibility, but adding a
`--no-mtime` option to ignore mtimes when saving felt like a reasonable
way of making this happen, but something about it doesn't feel great.

Maybe I just didn't figure out how to make the documentation clear
enough.  ¯\_(ツ)_/¯

1 files changed, 9 insertions, 6 deletions

diff --git a/src/metastore.c b/src/metastore.c
index 2bc2a89..bc5787e 100644
--- a/src/metastore.c
+++ b/src/metastore.c
@@ -43,7 +43,7 @@
 /* metastore settings */
 static struct metasettings settings = {
 	.metafile = METAFILE,
-	.do_mtime = false,
+	.do_mtime = 0,
 	.do_emptydirs = false,
 	.do_removeemptydirs = false,
 	.do_git = false,
@@ -286,7 +286,7 @@ compare_fix(struct metaentry *real, struct metaentry *stored, int cmp)
  * recreating them.
  */
 static void
-fixup_emptydirs(void)
+fixup_emptydirs(int do_mtime)
 {
 	struct metaentry *entry;
 	struct metaentry *cur;
@@ -364,7 +364,7 @@ fixup_emptydirs(void)
 		}
 		msg(MSG_QUIET, "ok\n");
 
-		new = mentry_create(cur->path);
+		new = mentry_create(cur->path, do_mtime >= 0);
 		if (!new) {
 			msg(MSG_QUIET, "Failed to get metadata for %s\n", cur->path);
 			continue;
@@ -459,6 +459,7 @@ usage(const char *arg0, const char *message)
 "  -v, --verbose            Print more verbose messages\n"
 "  -q, --quiet              Print less verbose messages\n"
 "  -m, --mtime              Also take mtime into account for diff or apply\n"
+"  -M, --no-mtime           Do not save mtime into metadata\n"
 "  -e, --empty-dirs         Recreate missing empty directories\n"
 "  -E, --remove-empty-dirs  Remove extra empty directories\n"
 "  -g, --git                Do not omit .git directories\n"
@@ -480,6 +481,7 @@ static struct option long_options[] = {
 	{ "verbose",           no_argument,       NULL, 'v' },
 	{ "quiet",             no_argument,       NULL, 'q' },
 	{ "mtime",             no_argument,       NULL, 'm' },
+	{ "no-mtime",          no_argument,       NULL, 'M' },
 	{ "empty-dirs",        no_argument,       NULL, 'e' },
 	{ "remove-empty-dirs", no_argument,       NULL, 'E' },
 	{ "git",               no_argument,       NULL, 'g' },
@@ -501,7 +503,7 @@ main(int argc, char **argv)
 	i = 0;
 	while (1) {
 		int option_index = 0;
-		c = getopt_long(argc, argv, "csadVhvqmeEgf:r:",
+		c = getopt_long(argc, argv, "csadVhvqmMeEgf:r:",
 		                long_options, &option_index);
 		if (c == -1)
 			break;
@@ -514,7 +516,8 @@ main(int argc, char **argv)
 		case 'h': /* help */              action |= ACTION_HELP;  i++;   break;
 		case 'v': /* verbose */           adjust_verbosity(1);           break;
 		case 'q': /* quiet */             adjust_verbosity(-1);          break;
-		case 'm': /* mtime */             settings.do_mtime = true;      break;
+		case 'm': /* mtime */             settings.do_mtime = 1;         break;
+		case 'M': /* no-mtime */          settings.do_mtime = -1;        break;
 		case 'e': /* empty-dirs */        settings.do_emptydirs = true;  break;
 		case 'E': /* remove-empty-dirs */ settings.do_removeemptydirs = true;
 			                              break;
@@ -577,7 +580,7 @@ main(int argc, char **argv)
 	case ACTION_APPLY:
 		mentries_compare(real, stored, compare_fix, &settings);
 		if (settings.do_emptydirs)
-			fixup_emptydirs();
+			fixup_emptydirs(settings.do_mtime);
 		if (settings.do_removeemptydirs)
 			fixup_newemptydirs();
 		break;