Redistributed with explicit permission from Patrick Ohly. See the
originating URL, http://home.pages.de/~ohly/#mkisofs-root, for
further details and eventual updates.

8<---8<---8<---8<---8<---8<---8<---8<---8<---8<---8<---8<---8<---

This patch adds two new command line options:

       -root dir
              Moves  all  files  and  directories into dir in the
              image.  This  is  essentially  the  same  as  using
              -graft-points  and  adding  dir  in  front of every
              pathspec, but is easier to use.

              dir may actually be several levels deep. It is cre­
              ated  with  the  same  permissions  as  other graft
              points.

       -old-root dir
              This option is necessary when writing  a  multises­
              sion image and the previous (or even older) session
              was written with -root dir.  Using a directory name
              not found in the previous session causes mkisofs to
              abort with an error.

              Without this option, mkisofs would not be  able  to
              find  unmodified files and would be forced to write
              their data into the image once more.

              -root and -old-root are meant to be  used  together
              to  do  incremental  backups.   The initial session
              would e.g. use: mkisofs -root  monday  <dirs>.  The
              next incremental backup with mkisofs -root  tuesday
              -old-root monday <dirs> would take another snapshot
              of these directories. The first snapshot  would  be
              be found in 'monday', the second one in  'tuesday',
              but  only  modified or new files need to be written
              into the second session.

It is applied by unpacking cdrtools-2.0.tar.gz, entering
the cdrtools-2.0/mkisofs directory and typing
   patch -p1 <mkisofs-2.0-root.diff
Then compile normally.

diff -r -c mkisofs/mkisofs.8 mkisofs2/mkisofs.8
*** mkisofs/mkisofs.8	Tue Dec 24 16:39:31 2002
--- mkisofs2/mkisofs.8	Sun Apr  6 13:53:07 2003
***************
*** 899,904 ****
--- 899,953 ----
  written to the CD image - which may be useful in order to optimize the
  data layout on a CD. See README.sort for more details.
  .TP
+ .BI \-root " dir
+ Moves all files and directories into
+ .I dir
+ in the image. This is essentially the
+ same as using 
+ .B -graft-points
+ and adding
+ .I dir
+ in front of every pathspec, but is easier to use.
+ 
+ .I dir
+ may actually be several levels deep. It is
+ created with the same permissions as other graft points.
+ .TP
+ .BI \-old-root " dir
+ This option is necessary when writing a multisession
+ image and the previous (or even older) session was written with
+ .BI -root " dir.
+ Using a directory name not found in the previous session
+ causes
+ .B mkisofs
+ to abort with an error.
+ 
+ Without this option,
+ .B mkisofs
+ would not be able to find unmodified files and would
+ be forced to write their data into the image once more.
+ 
+ .B \-root
+ and
+ .B \-old-root
+ are meant to be used together to do incremental backups.
+ The initial session would e.g. use:
+ mkisofs \-root backup_1 <dirs>.
+ The next incremental backup with mkisofs \-root backup_2
+ \-old-root backup_1 <dirs>
+ would take another snapshot of these directories. The first
+ snapshot would be found in backup_1, the second one in
+ backup_2, but only modified or new files need to be written
+ into the second session.
+ 
+ Without these options, new files would be added and old ones would be
+ preserved. But old ones would be overwritten if the file was
+ modified. Recovering the files by copying the whole directory back
+ from CD would also restore files that were deleted
+ intentionally. Accessing several older versions of a file requires
+ support by the operating system to choose which sessions are to be
+ mounted.
+ .TP
  .B \-split-output
  Split the output image into several files of approximately 1 GB.
  This helps to create DVD sized iso9660 images on operating systems without
diff -r -c mkisofs/mkisofs.c mkisofs2/mkisofs.c
*** mkisofs/mkisofs.c	Sat Dec  7 20:59:41 2002
--- mkisofs2/mkisofs.c	Sun Mar 23 17:56:04 2003
***************
*** 401,406 ****
--- 401,409 ----
  #define OPTION_HFS_BLESS		2040
  #define OPTION_HFS_PARMS		2041
  
+ #define OPTION_RELOC_ROOT     2042
+ #define OPTION_RELOC_OLD_ROOT 2043
+ 
  #endif	/* APPLE_HYB */
  
  static int	save_pname = 0;
***************
*** 510,515 ****
--- 513,522 ----
  	0, NULL, "Do not pad output to a multiple of 32k", ONE_DASH},
  	{{"prev-session", required_argument, NULL, 'M'},
  	'M', "FILE", "Set path to previous session to merge", ONE_DASH},
+ 	{{"root", required_argument, NULL, OPTION_RELOC_ROOT},
+ 	'\0', "DIR", "Set root directory for all new files and directories", ONE_DASH},
+ 	{{"old-root", required_argument, NULL, OPTION_RELOC_OLD_ROOT},
+ 	'\0', "DIR", "Set root directory in previous session that is searched for files", ONE_DASH},
  	{{"omit-version-number", no_argument, NULL, 'N'},
  	'N', NULL, "Omit version number from ISO9660 filename (violates ISO9660)", ONE_DASH},
  	{{"new-dir-mode", required_argument, NULL, OPTION_NEW_DIR_MODE},
***************
*** 1126,1131 ****
--- 1133,1140 ----
  #endif
  	struct stat	statbuf;
  	char		*merge_image = NULL;
+ 	char     *reloc_root = NULL;
+ 	char     *reloc_old_root = NULL;
  	struct iso_directory_record *mrootp = NULL;
  	struct output_fragment *opnt;
  	int		longind;
***************
*** 1469,1474 ****
--- 1478,1489 ----
  		case 'M':
  			merge_image = optarg;
  			break;
+ 		case OPTION_RELOC_ROOT:
+ 			reloc_root = optarg;
+ 			break;
+ 		case OPTION_RELOC_OLD_ROOT:
+ 			reloc_old_root = optarg;
+ 			break;
  		case 'N':
  			omit_version_number++;
  			warn_violate++;
***************
*** 2543,2548 ****
--- 2558,2569 ----
  
  	memset(&de, 0, sizeof(de));
  
+ 	/*
+ 	 * PO:
+ 	 * Isn't root NULL at this time anyway?
+ 	 * I think it is created by the first call to
+ 	 * find_or_create_directory() below.
+ 	 */
  	de.filedir = root;	/* We need this to bootstrap */
  
  	if (cdrecord_data != NULL && merge_image == NULL) {
***************
*** 2652,2664 ****
  
  		short_name = NULL;
  
! 		if (node != NULL) {
  			char		*pnt;
  			char		*xpnt;
  
! 			*node = '\0';
! 			escstrcpy(graft_point, arg);
! 			*node = '=';
  
  			/*
  			 * Remove unwanted "./" & "/" sequences from start...
--- 2673,2700 ----
  
  		short_name = NULL;
  
! 		if (node != NULL || reloc_root) {
  			char		*pnt;
  			char		*xpnt;
+ 			size_t    len;
+ 
+ 			/* insert -root prefix */
+ 			if (reloc_root != NULL) {
+ 				strcpy(graft_point, reloc_root);
+ 				len = strlen(graft_point);
+ 				if (graft_point[len] != '/' ) {
+ 					graft_point[len] = '/';
+ 					len++;
+ 				}
+ 			} else {
+ 				len = 0;
+ 			}
  
! 			if (node) {
! 				*node = '\0';
! 				escstrcpy(graft_point + len, arg);
! 				*node = '=';
! 			}
  
  			/*
  			 * Remove unwanted "./" & "/" sequences from start...
***************
*** 2673,2679 ****
  				strcpy(graft_point, xpnt);
  			} while (xpnt > graft_point);
  
! 			node = escstrcpy(nodename, ++node);
  
  			graft_dir = root;
  			xpnt = graft_point;
--- 2709,2719 ----
  				strcpy(graft_point, xpnt);
  			} while (xpnt > graft_point);
  
! 			if (node) {
! 				node = escstrcpy(nodename, ++node);
! 			} else {
! 				node = arg;
! 			}
  
  			graft_dir = root;
  			xpnt = graft_point;
***************
*** 2834,2840 ****
  	 * side, since we may need to create some additional directories.
  	 */
  	if (merge_image != NULL) {
! 		if (merge_previous_session(root, mrootp) < 0) {
  #ifdef	USE_LIBSCHILY
  			comerrno(EX_BAD, "Cannot merge previous session.\n");
  #else
--- 2874,2881 ----
  	 * side, since we may need to create some additional directories.
  	 */
  	if (merge_image != NULL) {
! 		if (merge_previous_session(root, mrootp,
! 											reloc_root, reloc_old_root) < 0) {
  #ifdef	USE_LIBSCHILY
  			comerrno(EX_BAD, "Cannot merge previous session.\n");
  #else
diff -r -c mkisofs/mkisofs.h mkisofs2/mkisofs.h
*** mkisofs/mkisofs.h	Sat Dec  7 20:59:42 2002
--- mkisofs2/mkisofs.h	Sun Mar 23 17:57:05 2003
***************
*** 494,500 ****
  extern void merge_remaining_entries __PR((struct directory *,
  		                struct directory_entry **, int));
  extern int merge_previous_session __PR((struct directory *,
! 		                struct iso_directory_record *));
  extern int get_session_start __PR((int *));
  
  /* joliet.c */
--- 494,501 ----
  extern void merge_remaining_entries __PR((struct directory *,
  		                struct directory_entry **, int));
  extern int merge_previous_session __PR((struct directory *,
! 		                struct iso_directory_record *,
! 							 char *, char *));
  extern int get_session_start __PR((int *));
  
  /* joliet.c */
diff -r -c mkisofs/multi.c mkisofs2/multi.c
*** mkisofs/multi.c	Wed Dec 25 15:15:24 2002
--- mkisofs2/multi.c	Sat Apr  5 17:33:11 2003
***************
*** 1512,1520 ****
   * directory entries, so that we can determine how large each directory is.
   */
  int
! merge_previous_session(this_dir, mrootp)
  	struct directory *this_dir;
  	struct iso_directory_record *mrootp;
  {
  	struct directory_entry **orig_contents = NULL;
  	struct directory_entry *odpnt = NULL;
--- 1512,1522 ----
   * directory entries, so that we can determine how large each directory is.
   */
  int
! merge_previous_session(this_dir, mrootp, reloc_root, reloc_old_root)
  	struct directory *this_dir;
  	struct iso_directory_record *mrootp;
+ 	char *reloc_root;
+ 	char *reloc_old_root;
  {
  	struct directory_entry **orig_contents = NULL;
  	struct directory_entry *odpnt = NULL;
***************
*** 1526,1540 ****
--- 1528,1659 ----
  			lstatbuf;
  	int		retcode;
  
+ 	/* skip leading slash */
+ 	while (reloc_old_root && reloc_old_root[0] == PATH_SEPARATOR) {
+ 		reloc_old_root++;
+ 	}
+ 	while (reloc_root && reloc_root[0] == PATH_SEPARATOR) {
+ 		reloc_root++;
+ 	}
+ 	 
  	/*
  	 * Parse the same directory in the image that we are merging for
  	 * multisession stuff.
  	 */
  	orig_contents = read_merging_directory(mrootp, &n_orig);
  	if (orig_contents == NULL) {
+ 		if (reloc_old_root) {
+ #ifdef	USE_LIBSCHILY
+ 			comerrno(EX_BAD, "Reading old session failed, cannot execute -old-root.\n");
+ #else
+ 			fprintf(stderr, "Reading old session failed, cannot execute -old-root.\n");
+ #endif
+ 			return (-1);
+ 		}
  		return (0);
  	}
  
+ 	if (reloc_old_root && reloc_old_root[0]) {
+ 		struct directory_entry **new_orig_contents = orig_contents;
+ 		int		new_n_orig = n_orig;
+ 
+ 		/* decend until we reach the original root */
+ 		while (reloc_old_root[0]) {
+ 			int i;
+ 			char *next;
+ 			int last;
+ 
+ 			for (next = reloc_old_root; *next && *next != PATH_SEPARATOR; next++);
+ 			if (*next) {
+ 				last = 0;
+ 				*next = 0;
+ 				next++;
+ 			} else {
+ 				last = 1;
+ 			}
+ 			while (*next == PATH_SEPARATOR) {
+ 				next++;
+ 			}
+ 
+ 			for (i = 0; i < new_n_orig; i++) {
+ 				struct iso_directory_record subroot;
+ 
+ 				if (new_orig_contents[i]->name != NULL
+ 					 && strcmp(new_orig_contents[i]->name, reloc_old_root) != 0) {
+ 					/* Not the same name continue */
+ 					continue;
+ 				}
+ 				/*
+ 				 * enter directory, free old one only if not the top level,
+ 				 * which is still needed
+ 				 */
+ 				subroot = new_orig_contents[i]->isorec;
+ 				if (new_orig_contents != orig_contents) {
+ 					free_mdinfo(new_orig_contents, new_n_orig);
+ 				}				
+ 				new_orig_contents = read_merging_directory(&subroot, &new_n_orig);
+ 
+ 				if (!new_orig_contents) {
+ #ifdef	USE_LIBSCHILY
+ 					comerrno(EX_BAD, "Reading directory %s in old session failed, cannot execute -old-root.\n", reloc_old_root );
+ #else
+ 					fprintf(stderr, "Reading directory %s in old session failed, cannot execute -old-root.\n", reloc_old_root );
+ #endif
+ 					return (-1);
+ 				}
+ 				
+ 				i = -1;
+ 				break;
+ 			}
+ 
+ 			if (i == new_n_orig) {
+ 				#ifdef	USE_LIBSCHILY
+ 				comerrno(EX_BAD, "-old-root (sub)directory %s not found in old session.\n", reloc_old_root );
+ #else
+ 				fprintf(stderr, "-old-root (sub)directory %s not found in old session.\n", reloc_old_root );
+ #endif
+ 				return (-1);
+ 			}
+ 
+ 			/* restore string, proceed to next sub directory */
+ 			if (!last) {
+ 				reloc_old_root[strlen(reloc_old_root)] = PATH_SEPARATOR;
+ 			}
+ 			reloc_old_root = next;
+ 		}
+ 
+ 		/*
+ 		 * preserve the old session, skipping those dirs/files that are found again
+ 		 * in the new root
+ 		 */
+ 		for (s_entry = this_dir->contents; s_entry; s_entry = s_entry->next) {
+ 			status = stat_filter(s_entry->whole_name, &statbuf);
+ 			lstatus = lstat_filter(s_entry->whole_name, &lstatbuf);
+ 
+ 			/* check_prev_session() will search for s_entry and remove it from
+ 				orig_contents if found */
+ 			retcode = check_prev_session(orig_contents, n_orig, s_entry,
+ 												  &statbuf, &lstatbuf, NULL);
+ 			if (retcode == -1)
+ 				return (-1);
+ 		}
+ 		merge_remaining_entries(this_dir, orig_contents, n_orig);
+ 
+ 		/* use new directory */
+ 		free_mdinfo(orig_contents, n_orig);
+ 		orig_contents = new_orig_contents;
+ 		n_orig = new_n_orig;		
+ 		
+ 		if (reloc_root && reloc_root[0]) {
+ 			/* also decend into new root before searching for files */
+ 			this_dir = find_or_create_directory(this_dir, reloc_root, NULL, TRUE);
+ 			if (!this_dir) {
+ 				return (-1);
+ 			}
+ 		}
+ 	}
+ 
+ 
  	/*
  	 * Now we scan the directory itself, and look at what is inside of it.
  	 */
***************
*** 1595,1601 ****
  					s_entry->whole_name,
  					s_entry, 1);
  				dflag = merge_previous_session(child,
! 					&odpnt->isorec);
  				if (dflag == -1) {
  					return (-1);
  				}
--- 1728,1735 ----
  					s_entry->whole_name,
  					s_entry, 1);
  				dflag = merge_previous_session(child,
! 					&odpnt->isorec,
! 					reloc_old_root, NULL );
  				if (dflag == -1) {
  					return (-1);
  				}
***************
*** 1605,1615 ****
  		}
  	}
  
! 	/*
! 	 * Whatever is left over, are things which are no longer in the tree on
! 	 * disk. We need to also merge these into the tree.
! 	 */
! 	merge_remaining_entries(this_dir, orig_contents, n_orig);
  	free_mdinfo(orig_contents, n_orig);
  	return (1);
  }
--- 1739,1751 ----
  		}
  	}
  
! 	if (!reloc_old_root) {
! 		/*
! 		 * Whatever is left over, are things which are no longer in the tree on
! 		 * disk. We need to also merge these into the tree.
! 		 */
! 		merge_remaining_entries(this_dir, orig_contents, n_orig);
! 	}
  	free_mdinfo(orig_contents, n_orig);
  	return (1);
  }