[patch] add -m option to dumpfs

[Eric <ejc@xxxxxxxxxxxxxxxxxx>]

Add -m from FreeBSD's dumpfs.  According to the man page:

  If -m is specified, a newfs(8) command is printed that can be used to
  generate a new file system with equivalent settings.


Index: sbin/dumpfs/dumpfs.8
===================================================================
RCS file: /home/dcvs/src/sbin/dumpfs/dumpfs.8,v
retrieving revision 1.2
diff -u -p -r1.2 dumpfs.8
--- sbin/dumpfs/dumpfs.8	17 Jun 2003 04:27:32 -0000	1.2
+++ sbin/dumpfs/dumpfs.8	28 Nov 2007 00:27:27 -0000
@@ -41,16 +41,26 @@
 .Nd dump file system information
 .Sh SYNOPSIS
 .Nm
-.Op Ar filesys No \&| Ar device
+.Op Fl m
+.Ar filesys No \&| Ar device
 .Sh DESCRIPTION
 The
 .Nm
 utility prints out the super block and cylinder group information
-for the file system or special device specified.
+for the file system or special device specified, unless
+.Fl m
+is specified.
 The listing is very long and detailed.  This
 command is useful mostly for finding out certain file system
 information such as the file system block size and minimum
 free space percentage.
+.Pp
+If
+.Fl m
+is specified, a
+.Xr newfs 8
+command is printed that can be used to generate a new file system
+with equivalent settings.
 .Sh SEE ALSO
 .Xr disktab 5 ,
 .Xr fs 5 ,
Index: sbin/dumpfs/dumpfs.c
===================================================================
RCS file: /home/dcvs/src/sbin/dumpfs/dumpfs.c,v
retrieving revision 1.8
diff -u -p -r1.8 dumpfs.c
--- sbin/dumpfs/dumpfs.c	3 Apr 2006 01:58:49 -0000	1.8
+++ sbin/dumpfs/dumpfs.c	28 Nov 2007 00:27:27 -0000
@@ -47,6 +47,7 @@
 #include <fstab.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <unistd.h>
 
 union {
@@ -65,6 +66,7 @@ long	dev_bsize = 1;
 
 int	dumpfs(char *);
 int	dumpcg(char *, int, int);
+int	marshal(const char*);
 void	pbits(void *, int);
 void	usage(void);
 
@@ -72,10 +74,15 @@ int
 main(int argc, char **argv)
 {
 	struct fstab *fs;
-	int ch, eval;
+	int ch, domarshal, eval;
 
-	while ((ch = getopt(argc, argv, "")) != -1)
+	domarshal = 0;
+
+	while ((ch = getopt(argc, argv, "m")) != -1)
 		switch(ch) {
+		case 'm':
+			domarshal = 1;
+			break;
 		case '?':
 		default:
 			usage();
@@ -88,9 +95,15 @@ main(int argc, char **argv)
 
 	for (eval = 0; *argv; ++argv)
 		if ((fs = getfsfile(*argv)) == NULL)
-			eval |= dumpfs(*argv);
+			if (domarshal)
+				eval |= marshal(*argv);
+			else
+				eval |= dumpfs(*argv);
 		else
-			eval |= dumpfs(fs->fs_spec);
+			if (domarshal)
+				eval |= marshal(fs->fs_spec);
+			else
+				eval |= dumpfs(fs->fs_spec);
 	exit(eval);
 }
 
@@ -297,6 +310,80 @@ dumpcg(char *name, int fd, int c)
 	return (0);
 };
 
+int
+marshal(const char *name)
+{
+	ssize_t n;
+	int fd;
+	static char realname[12];
+
+	if ((fd = open(name, O_RDONLY, 0)) < 0)
+		goto err;
+	if (lseek(fd, (off_t)SBOFF, SEEK_SET) == (off_t)-1)
+		goto err;
+	if ((n = read(fd, &afs, SBSIZE)) == -1)
+		goto err;
+
+	if (n != SBSIZE) {
+		warnx("%s: non-existent or truncated superblock, skipped",
+		    name);
+		close(fd);
+ 		return (1);
+	}
+ 	if (afs.fs_magic != FS_MAGIC) {
+		warnx("%s: superblock has bad magic number, skipped", name);
+		close(fd);
+ 		return (1);
+ 	}
+
+	if(strncmp(name, "/dev", 4) == 0) {
+		snprintf(realname, 12, "%s", name);
+	} else {
+		snprintf(realname, 12, "/dev/%s", name);
+	}
+
+	printf("# newfs command for %s (%s)\n", name, realname);
+	printf("newfs ");
+	if (afs.fs_flags & FS_DOSOFTDEP)
+		printf("-U ");
+	printf("-a %d ", afs.fs_maxcontig);
+	printf("-b %d ", afs.fs_bsize);
+	/* -c calculated */
+	/* -d should be 0 per manpage */
+	printf("-e %d ", afs.fs_maxbpg);
+	printf("-f %d ", afs.fs_fsize);
+	printf("-g %d ", afs.fs_avgfilesize);
+	printf("-h %d ", afs.fs_avgfpdir);
+	/* -i calculated */
+	/* -j..l not implemented */
+	printf("-m %d ", afs.fs_minfree);
+	/* -n not implemented */
+	printf(" -o ");
+	switch (afs.fs_optim) {
+	case FS_OPTSPACE:
+		printf("space ");
+		break;
+	case FS_OPTTIME:
+		printf("time ");
+		break;
+	default:
+		printf("unknown ");
+		break;
+	}
+	/* -p..r not implemented */
+	printf("-s %jd ", (intmax_t)afs.fs_size);
+	printf("%s ", realname);
+	printf("\n");
+
+	return (0);
+
+err:    if (fd != -1)
+                close(fd);
+        warn("%s", name);
+        return (1);
+
+}
+
 void
 pbits(void *vp, int max)
 {