Make imagehash create the .sig file with the same modtime as the image.

This is a cheap verification mechanism.  Also install imagehash now with
all the other image tools, it will be used soon.

os/imagezip/GNUmakefile.in

@@ -164,7 +164,7 @@ imagehash.o: imagehdr.h
 version.c: imagezip.c imageunzip.c imagedump.c
 	echo >$@ "char build_info[] = \"Built `date +%d-%b-%Y` by `id -nu`@`hostname | sed 's/\..*//'`:`pwd`\";"
 
-install: $(INSTALL_BINDIR)/imagezip $(INSTALL_BINDIR)/imageunzip $(INSTALL_BINDIR)/imagedump
+install: $(INSTALL_BINDIR)/imagezip $(INSTALL_BINDIR)/imageunzip $(INSTALL_BINDIR)/imagedump $(INSTALL_BINDIR)/imagehash
 
 client: all
 client-install: client

os/imagezip/TODO.hash

@@ -208,8 +208,8 @@ or Linux zero blocks that get freed nor do they chain free blocks together
 using part of the block as a link field.  So I think still hashing the
 blocks might pay off, but we'll have to do some tests.
 
-Another issue is how does imagezip know how much of the file it should look
-at when creating a delta.  If a users only loads FreeBSD in partition 1,
+Another issue is how does imagezip know how much of the disk it should look
+at when creating a delta.  If a user only loads FreeBSD in partition 1,
 but then puts data in the other partitions, how do we know that we should
 save that in the delta?  In a sense, the mechanism will just work.  If the
 signature used for comparison only covers partition 1, and imagezip is

os/imagezip/imagehash.c

@@ -428,6 +428,8 @@ createhash(char *name, struct hashinfo **hinfop)
 	int ofd, cc;
 	int count;
 	struct hashinfo *hinfo;
+	struct stat sb;
+	struct timeval tm[2];
 
 	hfile = signame(name);
 	ofd = open(hfile, O_RDWR|O_CREAT, 0666);
@@ -466,6 +468,21 @@ createhash(char *name, struct hashinfo **hinfop)
 	}
 
 	free(hfile);
+
+	/*
+	 * Set the modtime of the hash file to match that of the image.
+	 * This is a crude (but fast!) method for matching images with
+	 * signatures.
+	 */
+	cc = stat(name, &sb);
+	if (cc >= 0) {
+		TIMESPEC_TO_TIMEVAL(&tm[0], &sb.st_atimespec);
+		TIMESPEC_TO_TIMEVAL(&tm[1], &sb.st_mtimespec);
+		cc = utimes(hfile, tm);
+	}
+	if (cc < 0)
+		fprintf(stderr, "%s: WARNING: could not set mtime\n", hfile);
+
 	nhregions = hinfo->nregions;
 	printf("%s: %lu chunks, %lu regions, %lu hashregions, %llu data bytes\n",
 	       name, nchunks, nregions, nhregions, ndatabytes);