New cdrskin option --grow_overwriteable_iso

cdrskin/cdrskin.1

@@ -2,7 +2,7 @@
 .\" First parameter, NAME, should be all caps
 .\" Second parameter, SECTION, should be 1-8, maybe w/ subsection
 .\" other parameters are allowed: see man(7), man(1)
-.TH CDRSKIN 1 "August 12, 2007"
+.TH CDRSKIN 1 "August 26, 2007"
 .\" Please adjust this date whenever revising the manpage.
 .\"
 .\" Some roff macros, for reference:
@@ -202,8 +202,13 @@ Currently types DVD+RW, DVD-RW and DVD-RAM can be overwritten via cdrskin.
 .br
 DVD+RW and DVD-RAM media get treated as blank media regardless wether they
 hold data or not. They need no special initial formatting.
-Options -audio and -multi are not allowed. Only one track is allowed.
--toc does not return information about the media content.
+Option -audio is not allowed. Only one track is allowed.
+Option -multi cannot mark a recognizeable end of overwriteable media.
+Therefore -multi is banned unless ISO-9660 images shall be expandable by help
+of option --grow_overwriteable_iso.
+Without this option or without an ISO-9660 filesystem image present
+on media, -toc does not return information about the media content.
+.br
 Currently there is no difference between -sao and -tao. If ever, then -tao
 will be the mode which preserves the current behavior.
 .br
@@ -451,6 +456,9 @@ The result string shall be used as argument of option -C with said programs.
 It gives the start address of the most recent session and the predicted
 start address of the next session to be appended. The string is empty if
 the most recent session was not written with option -multi.
+.br
+To have a chance for working on overwriteable media, this option has to be
+accompanied by option --grow_overwriteable_iso.
 .TP
 .BI \-multi
 This option keeps the CD or unformatted DVD-R[W] appendable after the current
@@ -459,9 +467,14 @@ Without it the disc gets closed and may not be written any more  - unless it
 is a -RW and gets blanked which causes loss of its content.
 .br
 The following sessions can only be written in -tao mode. -multi is prohibited
-with overwriteable DVD media and with DVD-R[W] DAO write mode.
-Option --prodvd_cli_compatible eventually makes -multi tolerable but cannot
-make it work.
+with DVD-R[W] DAO write mode. Option --prodvd_cli_compatible eventually makes
+-multi tolerable but cannot make it work.
+.br
+With overwriteable DVD media, -multi cannot mark the end of the session.
+So when adding a new session this end has to be determined from the payload.
+Currently only ISO-9660 filesystems can be used that way. See option
+.B \--grow_overwriteable_iso
+for lifting the ban on -multi. 
 .br
 In order to have all filesystem content accessible, the eventual ISO-9660
 filesystem of a follow-up
@@ -686,6 +699,36 @@ the software protection against buffer underun is as weak as the size of
 fifo_start_at= . So it is best if the drive offers hardware protection which
 is enabled automatically if not driveropts=noburnfree is given.
 .TP
+.BI \--grow_overwriteable_iso
+Enable emulation of multi-session writing on overwriteable media which
+contain an ISO-9660 filesystem. This emulation is learned from growisofs -M
+but adapted to the usage model of
+.br
+.B cdrskin -msinfo ; mkisofs -C -M | cdrskin [-multi] -
+.br
+--grow_overwriteable_iso does not hamper the use of true multi-session media.
+It demands nevertheless that the track source is a ISO-9660 filesystem image.
+With overwriteable media and no option blank=fast|all present it expands an
+eventual ISO-9660 filesystem. It is assumed that this image's inner size
+description points to the end of the valuable data on media.
+.br
+Options -msinfo and -toc will then work for overwriteables. -toc will always
+show a single session with its size increasing with every added mkisofs image.
+.br
+--grow_overwriteable_iso causes option blank=fast|all to invalidate an
+eventual ISO-9660 image by altering the first few bytes of block 16 on
+overwriteable media.
+.br
+If not overriden by option write_start_address=, the track with the new image
+will be placed at the end of the old one. One may use option assert_write_lba=
+to make sure that media state and mkisofs job do match.
+.br
+Note: The equivalent of growisofs -Z is
+.br
+(mkisofs | cdrskin --grow_overwriteable_iso blank=fast [-multi])
+.br
+growisofs -dvd-compat is roughly equivalent to cdrskin without option -multi.
+.TP
 .BI \--list_ignored_options
 List all ignored cdrecord options. The "-" options cannot be used as addresses
 of track sources. No track source address may begin with a text equal to an