New version of up to use in the upcomming patch/pullbin.

Reference: /n/patches.lsub.org/patch/newup
Date: Wed Apr 18 15:53:29 CES 2012
Signed-off-by: nemo@lsub.org

Binary files up.orig and up differ
--- /sys/src/cmd/up.c	Sat Apr 14 23:00:56 2012
+++ /sys/src/cmd/up.c	Wed Apr 18 12:41:55 2012
@@ -19,6 +19,7 @@
 static int omode = Rc;
 static char *droot;
 static Biobuf bout;
+static int usemtime;
 
 static int
 realerror(void)
@@ -30,6 +31,14 @@
 }
 
 static int
+samemeta(Dir *sd, Dir *dd)
+{
+	if(dd->mtime > sd->mtime)
+		return -1;
+	return sd->length == sd->length && dd->mtime == sd->mtime;
+}
+
+static int
 samecontent(char *f1, char *f2)
 {
 	Waitmsg *m;
@@ -250,10 +259,21 @@
 	}
 
 	if((sd->mode&DMDIR) == 0){
-		if(samecontent(src, dst) == 0){
-			updatecp(src, dst, 0);
-			return 0;
-		}
+		if(usemtime){
+			switch(samemeta(sd, dd)){
+			case 0:
+				updatecp(src, dst, 0);
+				return 0;
+			case -1:
+				Bflush(&bout);
+				fprint(2, "%s is newer: ignored\n", dst);
+				return 0;
+			}
+		}else
+			if(samecontent(src, dst) == 0){
+				updatecp(src, dst, 0);
+				return 0;
+			}
 		if(omode == Chg &&
 			(samemode(sd, dd) == 0 ||
 			(dogids && strcmp(sd->gid, dd->gid) != 0) ||
@@ -276,7 +296,7 @@
 static void
 usage(void)
 {
-	fprint(2, "usage: %s [-cugs] src dst\n", argv0);
+	fprint(2, "usage: %s [-cutgs] src dst\n", argv0);
 	exits("usage");
 }
 
@@ -286,6 +306,9 @@
 	Dir *sd, *dd;
 
 	ARGBEGIN{
+	case 't':
+		usemtime = 1;
+		break;
 	case 'c':
 		omode = Chg;
 		break;
--- /sys/man/1/up	Sat Apr 14 22:46:33 2012
+++ /sys/man/1/up	Wed Apr 18 12:49:29 2012
@@ -4,7 +4,7 @@
 .SH SYNOPSIS
 .B up
 [
-.B -cugs
+.B -cugst
 ]
 .I src
 .I dst
@@ -45,6 +45,13 @@
 and
 .I dst
 differ. 
+.PP
+Flag
+.B -t
+relies on the file length and modification time to guess if two
+files are the same or differ. Under this flag, no update is reported
+for files that exist both in the destination and the origin and are
+newer in the destination.
 .SH SOURCE
 .B /sys/src/cmd/up.c
 .SH EXAMPLE