VMS2Linux

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This is the utility from Paul Nankervis as I found it at http://www.goatley.com/hunter/w2k.html and which I updated for Linux.

The (original) source uses gets() to read a command (prompted by "$>"). Building the tool with the gcc tool chain gives you warnings like:

On other systems you may get other (even run-time) warnings or you may not be able to build the tool.
This patch was sent to me to replace the call to gets with one to fgets.

The current ods2 util, as provided in the zip file and built in a 32-bit environment, is not able to mount disks bigger than 2GB. This is caused by using lseek() to position to disk blocks. With bigger disks the usual error is:

To remove this restriction in a 32-bit environment, one can patch phyunix.c to use lseek() with a 64-bit offset.

Also, the current ods2 util is not able to mount ods2 disks initialized without a primary home block, which is the default on I64 unless /NOGPT is specified and can be requested on Alpha with /GPT.

Changes for Linux:

BIG_ENDIAN conflicts with another already defined macro. Something from BSD, I don't know. So I changed it to
USE_BIG_ENDIAN.

The compiler complained about some string routines therefore in some sources I changed strings.h to string.h.

I got it to work. But copying files to Linux directories didn't work. Yes, because of the '/' being an introducer for a qualifier. So I changed cmdsplit


Next I thought it would be nice to have a /PAGE for the directory command and for the type command and for search. But then I thought that this is Linux and usually there is a good pipe implementation which can do that for me. The only thing I missed was a one-liner to start the ods2 reader with some commands. OK, there is the undocumented '@' and there is input redirection. But both require editing a file. For simple command sequences it seems too much overhead. Having a one-liner in the recall buffer and changing that is much easier. So I added command arguments which are interpreted as chained commands to the ods2 reader.

There are no command line options, yet. So everything is accepted as a command string(s). As an internal delimiter I chose '$'.


Now I can use the ods2 reader like


The single quotes are useful if I want to prevent the Linux shell from expanding it's meta characters: '*' etc. The '/bin' is not useful for text files like command procedure. Here it is used just to show the effect of '//'. So the last example gives:


These examples always have an exit command at the end. But that's not necessary. If there is none, the ods2 reader continues reading commands from
stdin:


So on a Linux box an alias can be set up such that I end up on the VMS disk in my directory.
 
I'm not happy with the (error) messages being written to stdout, they should go to stderr, so I can redirect only the wanted output to a file. Maybe I'll change that, later.
 
One note on copy/binary. It is not what one might expect. The ods2 reader checks if the VMS file has the attributes FAB$M_CR | FAB$M_PRN | FAB$M_FTN. If present, the read data is assumed to be text and a "\n" is appended to each record when writing the copy. "/binary" suppresses that. If the VMS file has none of the attributes set, the data is copied as is. Executables with fixed length records will be copied as 512 byte records and will not differ if copied with or without "/binary". Files with variable record length will always be copied without the record length, regardless of "/binary". But if "/binary" is used on a file, which has one of the above attributes set, the file may not be copied: the ods2 reader can't handle empty records in "binary" mode. Anyway, I was not able to copy a Java class file and run it on Linux.
 
On VMS there can be virtual disks (VDAnnn, LDAnnn), which make a disk out of a file. These files, disk images, can be copied to Linux disks. To let ods2 read these virtual disks a simple symbolic link from /dev/diskfile to the file is set up. Then the usual 'mount diskfile' can be used. Sorry, the user needs the right to create the symbolic link in /dev or root has to do that. Or losetup can be used to create a loop device for the disk image, so a 'mount loop0' will work. Again, the needs the right to do that.