ReMarkable CUPS print on OS X

[ThorbenJ]

Hi.

The backend script expects 5 or 6 arguments, but the cups printing on OS X appears to pass a lot more:

   26 77165 76719   0 11:07AM ??         0:00.02 /bin/bash /usr/libexec/cups/backend/remarkable 9 thorbenj testprint 1 AP_ColorMatchingMode=AP_ApplicationColorMatching AP_D_InputSlot= nocollate com.apple.print.DocumentTicket.PMSpoolFormat=application/pdf com.apple.print.JobInfo.PMJobName=testprint com.apple.print.PrinterInfo.PMColorDeviceID..n.=5688 com.apple.print.PrintSettings.PMCopies..n.=1 com.apple.print.PrintSettings.PMCopyCollate..b. com.apple.print.PrintSettings.PMDuplexing..n.=1 com.apple.print.PrintSettings.PMFirstPage..n.=1 com.apple.print.PrintSettings.PMLastPage..n.=2147483647 com.apple.print.PrintSettings.PMPageRange..a.0..n.=1 com.apple.print.PrintSettings.PMPageRange..a.1..n.=2147483647 fit-to-page media=A4 pserrorhandler-requested=standard sides=one-sided job-uuid=urn:uuid:b4d64749-0c46-3d8c-51b4-a0918a857fe3 job-originating-host-name=localhost date-time-at-creation= date-time-at-processing= time-at-creation=1561626442 time-at-processing=1561626442 document-name-supplied=testprint PageSize=A4

So the script is currently swollowing the print without error, as there is an exit 0 at the end.

I will maybe try to tweak the script, but first I thought I would document how I got this far on OS X for other users:

The PPD should be gziped and placed here: /Library/Printers/PPDs/Contents/Resources/ReMarkable.ppd.gz
Confirm with:

localhost:~ root# lpinfo -m | grep -i remarkable
Library/Printers/PPDs/Contents/Resources/ReMarkable.ppd.gz Remarkable Tablet, 1.0

The backend script should go here: /usr/libexec/cups/backend/remarkable

the "_lp" user needs to be able to use rmapi.
(as root do the following)

ln -s /Users/USERNAME/.rmapi /var/spool/cups/.rmapi
chown USERNAME:_lp /Users/USERNAME/.rmapi
chmod g+r /Users/USERNAME/.rmapi

Add the printer:

lpadmin -L 'my.ReMarkable Cloud' -D 'my.ReMarkable Cloud Printer' -m /Library/Printers/PPDs/Contents/Resources/ReMarkable.ppd.gz -p remarkable -E -v 'remarkable:/PrintOuts'

[ThorbenJ]

So I've localised the problem to SIP (System Integrity Protection), think SELinux but for OS X.

The script may not write to /tmp. So I edited it to use /var/spool/cups/tmp

rmapi must be in a vaild bin dir, so I copied it to /usr/local/bin; it can now execute.
However rmapi my not open path /var/spool/cups/.rmapi; this is forbidden.

It does not appear that rmapi allow overriding the location of that file. I will have to open a ticket there.

[ThorbenJ]

juruen/rmapi#59

[ThorbenJ]

BTW for debugging, I added this near the top of the script:

DEBUGLOG=/var/spool/cups/tmp/rm.log
date > $DEBUGLOG
id >> $DEBUGLOG
env >> $DEBUGLOG
echo "Args(${#})" >> $DEBUGLOG
exec 1>$DEBUGLOG 2>&1

Note the date print will truncate the log.

With a custom version of rmapi, I can now print on OS X

[ofosos]

Hmm, what to add? @ThorbenJ 👍

[ThorbenJ]

Up to you here is my version of the script:

#!/bin/bash
backend=${0}
jobid=${1}
cupsuser=${2}
jobtitle=${3}
jobcopies=${4}
joboptions=${5}
jobfile=${6}

rmapi="/usr/local/bin/rmapi"

DEBUGLOG=/var/spool/cups/tmp/rm.log
date > $DEBUGLOG
id >> $DEBUGLOG
env >> $DEBUGLOG
echo "Args(${#})" >> $DEBUGLOG
exec 1>$DEBUGLOG 2>&1

tmpdir=/var/spool/cups/tmp
printtime=$(date +%Y-%b-%d-%H-%M)
sanitized_jobtitle="$(echo ${jobtitle} | tr [[:blank:]:/%\&=+?\\\\#\'\`\´\*] _)"
outname=${tmpdir}/${printtime}_${sanitized_jobtitle}

case ${#} in
    0)
        # this case is for "backend discovery mode"
        echo "Remarkable Printer \"Mark Meyer\" \"Backend to print directly to Remarkable cloud\""
        exit 0
        ;;

    5)
        # backend needs to read from stdin if number of arguments is 5
        cat - > ${outname}
	if [ ! -e ${DEVICE_URI#remarkable:} ]; then
	    ${rmapi} put ${outname} ${DEVICE_URI#remarkable:}
	else
	    ${rmapi} put ${outname}
	fi
	rm ${outname}
        ;;
    
    6)
	cat ${6} > ${outname}
        if [ ! -e ${DEVICE_URI#remarkable:} ]; then
	    ${rmapi} put ${outname} ${DEVICE_URI#remarkable:}
	else
	    ${rmapi} put ${outname}
	fi
        ;;
esac

#echo 1>&2

exit 0

Some Notes: the data > .. will truncate the logfile each run
the exec > .. redirect stdout and stderr to that log file
I do not know what echo 1>&2 intended to do, so I commented it out.

Documentation changes/notes:
On OS X the "remarkable" script needs to go in /usr/libexec/cups/backend/remarkable
The PPD needs to be in: /Library/Printers/PPDs/Contents/Resources/ReMarkable.ppd.gz

rmapi needs to be in /usr/local/bin/rmapi
and it must load its config from /etc/cups/rmapi.conf and not ~/.rmapi.
The do this I edited go/src/github.com/juruen/rmapi/config/config.go
adding return "/etc/cups/rmapi.conf" to the begining of func ConfigPath() string {
and then re-run go build.

my lpadmin command was:

lpadmin -E -L 'my.reMarkable Cloud' -D 'my.reMarkable Cloud Printer' -m /Library/Printers/PPDs/Contents/Resources/ReMarkable.ppd.gz -p remarkable -v 'remarkable:/PrintOuts'

BR,
-T