New demo script frontend/xorriso_broker.sh (see Debian bug 805495)

README

@@ -190,8 +190,18 @@ In particular it connects to xorriso via two pipes, sends commands, waits
 for all replies of a command, picks info out of the xorriso message sieve,
 and parses reply message lines into words.
 
-The bash script frontend/sh_on_named_pipes.sh forks a xorriso process and
+The bash script frontend/sh_on_named_pipes.sh forks a xorriso process
-operates it via two named pipes which it creates.
+connected to two pipes. It then runs a dialog loop, sends commands to xorriso,
+and displays the replies.
+
+The sh script frontend/xorriso_broker.sh is intended to execute xorriso
+commands on a permanently running xorriso process.
+It gets an id_string by which it looks for named pipes with a running xorriso
+process. If no such pipe is found, then it starts a xorriso connected to
+newly created pipes.
+After this is done, the optionally given xorriso arguments are written into
+the stdin pipe from where xorriso will read and execute them. The script will
+end but the xorriso process will go on and wait for more commands.
 
 
                        Drives and Disk File Objects 

frontend/xorriso_broker.sh

@@ -0,0 +1,203 @@
+#!/bin/sh
+
+# Copyright (C) 2015
+# Thomas Schmitt <scdbackup@gmx.net>, libburnia-project.org
+# Provided under BSD license: Use, modify, and distribute as you like.
+
+# set -x
+
+# ---------------------------- functions ---------------------------
+
+usage() {
+  echo >&2
+  echo "usage: $0 "'\' >&2
+  echo "       [-xorriso path] id_string [-dev] iso_adr [xorriso_arguments ...]" >&2
+  echo >&2
+  echo "       This script looks for named pipe" >&2
+  echo '         /tmp/xorriso_stdin_pipe_${id_string}' >&2
+  echo "       which is supposed to be connected to a xorriso process." >&2
+  echo "       If not found, the stdin pipe and a stdout pipe get created" >&2
+  echo "       and a xorriso dialog process gets started and connected." >&2
+  echo "       Each character in id_string must match [-+:.,=@0-9A-Za-z]." >&2
+  echo "       If iso_adr differs from the previous run with the same id_string," >&2
+  echo "       then any changes on the previous ISO are committed as session" >&2
+  echo "       before command -dev is performed to load the meta data of" >&2
+  echo "       the newly addressed ISO." >&2
+  echo "       After this is done, the optionally given xorriso_arguments" >&2
+  echo "       are written into the stdin pipe from where xorriso will read" >&2
+  echo "       them as commands and their parameters." >&2
+  echo >&2
+}
+
+
+# Make filenames safe for transport by wrapping them in quotes and
+# escaping quotes in their text
+xorriso_esc() {
+  echo -n "'"
+  echo -n "$1" | sed -e "s/'/'"'"'"'"'"'"'/g"
+  echo -n "'"
+}
+
+
+# Send one or more command lines to xorriso
+xorriso_send_cmd() {
+  # $1 : the lines to send
+
+  # >>> is it possible to have a timeout on echo ?
+
+  if test -p "$cmd_pipe"
+  then
+    echo " $1" >"$cmd_pipe"
+  else
+    xorriso_is_running=0
+    return 1
+  fi
+}
+
+
+# Send command and wait for answer
+xorriso_cmd_and_result() {
+  # $1: command line for xorriso
+  # $2: if not empty, grep expression for stdout
+  if test "$xorriso_is_running" = 0
+  then
+    return 1
+  fi
+  xorriso_send_cmd "$1" || return 1
+  if test -n "$2" 
+  then
+    cat "$result_pipe"
+  else
+    grep "$2" <"$result_pipe"
+  fi
+  return 0
+}
+
+
+# ------------------------------- main -----------------------------
+
+# Argument interpreter
+
+if test "$#" -lt 2
+then
+  usage "$0"
+  exit 1
+fi
+
+xorriso=xorriso
+if test o"$1" = o"-xorriso"
+then
+  xorriso="$2"
+  shift 2
+fi
+export xorriso_is_running=0
+
+if test "$#" -lt 2
+then
+  usage "$0"
+  exit 1
+fi
+
+id_string=$(echo "$1" | sed -e 's/[^-+:.,=@0-9A-Za-z]/_/g' )
+shift 1
+
+# Ignore second argument -dev
+if test o"$1" = o"-dev"
+then
+  shift 1
+  if test "$#" -lt 1
+  then
+    usage "$0"
+    exit 1
+  fi
+fi
+device="$1"
+shift 1
+
+# Perform the action
+
+export cmd_pipe=/tmp/xorriso_stdin_pipe_$id_string
+export result_pipe=/tmp/xorriso_stdout_pipe_$id_string
+
+if test -p "$cmd_pipe"
+then
+  xorriso_is_running=1
+else
+  xorriso_is_running=0
+fi
+if test "$xorriso_is_running" = "0"
+then
+  # xorriso is not started yet
+
+  # Check for xorriso version which knows command -named_pipe_loop
+  xorriso_version_req="1.3.2"
+  version=$("$xorriso" -version | grep '^xorriso version' |
+            sed -e 's/^xorriso version   :  //')
+  smallest=$( (echo "$xorriso_version_req" ; echo "$version" ) | \
+             sort | head -1)
+  if test "$smallest" = "$xorriso_version_req"
+  then
+    dummy=dummy
+  else
+    echo "$0 : FATAL : Need xorriso version >= $xorriso_version_req" >&2
+    echo "Found version: $version" >&2
+    exit 2
+  fi
+
+  mknod "$cmd_pipe" p
+  mknod "$result_pipe" p
+  "$xorriso" -abort_on NEVER -for_backup \
+             -named_pipe_loop cleanup:buffered "$cmd_pipe" "$result_pipe" "-" \
+             >&2 &
+  # (stdout is redirected to stderr, in order not to keep a pipe waiting for
+  #  input from the still open stdout copy of the background process.
+  #  -named_pipe_loop will disconnect xorriso result channel from stdout.)
+  xorriso_is_running=1
+fi
+
+# Inquire current xorriso -dev
+xorriso_device=$(xorriso_cmd_and_result "-status -dev" "^-dev" | \
+                 sed -e 's/^-dev //')
+if echo " $device" | grep "^ '" >/dev/null
+then
+  quoted="$device"
+else
+  quoted=$(xorriso_esc "$device")
+fi
+if test "$xorriso_device" = "$quoted"
+then
+  dummy=dummy
+else
+  # Inquire the need for a -commit command
+  pending=$(xorriso_cmd_and_result "-changes_pending show_status" \
+                                   "^-changes_pending" \
+            | sed -e 's/^-changes_pending //')
+  if test "$pending" = "yes"
+  then
+    if xorriso_cmd_and_result "-commit"
+    then
+      dummy=dummy
+    else
+      exit 1
+    fi
+  fi
+  # Now change ISO filesystem
+  if xorriso_cmd_and_result "-dev $device"
+  then
+    xorriso_device="$device"
+  else
+    exit 1
+  fi
+fi
+
+test "$*" = "" && exit 0
+
+if xorriso_cmd_and_result "$*"
+then
+  dummy=dummy
+else
+  exit 1
+fi
+
+exit 0
+

xorriso/README_gnu_xorriso

@@ -182,8 +182,18 @@ In particular it connects to xorriso via two pipes, sends commands, waits
 for all replies of a command, picks info out of the xorriso message sieve, 
 and parses reply message lines into words.
 
-The bash script frontend/sh_on_named_pipes.sh forks a xorriso process and
+The bash script frontend/sh_on_named_pipes.sh forks a xorriso process 
-operates it via two named pipes which it creates.
+connected to two pipes. It then runs a dialog loop, sends commands to xorriso,
+and displays the replies.
+
+The sh script frontend/xorriso_broker.sh is intended to execute xorriso
+commands on a permanently running xorriso process.
+It gets an id_string by which it looks for named pipes with a running xorriso 
+process. If no such pipe is found, then it starts a xorriso connected to 
+newly created pipes.
+After this is done, the optionally given xorriso arguments are written into
+the stdin pipe from where xorriso will read and execute them. The script will
+end but the xorriso process will go on and wait for more commands.
 
 
                        Drives and Disk File Objects