Introduced option -plug_test

xorriso-dd-target/xorriso-dd-target

@@ -56,6 +56,9 @@ print_usage() {
   echo "If device names are given, then they get listed with advice shown."
   echo "If one of the given device names gets not advised, the exit value is 1."
   echo
+  echo "The option -plug_test can determine the desired target device by"
+  echo "inquiring the system with unplugged device and then with plugged one."
+  echo
   echo "Only if option -DO_WRITE is given and -list_all is not, and if exactly"
   echo "one advisable device is listed, it really gets overwritten by the"
   echo "file content of the given -image_file. In this case the exit value"
@@ -64,6 +67,12 @@ print_usage() {
   echo "unmount and write commands on stdout."
   echo
   echo "Options:"
+  echo " -plug_test         Find the target device by asking the user to press"
+  echo "                    Enter when the desired target is _not_ plugged in,"
+  echo "                    to then plug it in, and to press Enter again."
+  echo "                    This overrides device names and option -list_all."
+  echo "                    The found device is then shown with advice, vendor,"
+  echo "                    and model. Option -DO_WRITE is obeyed if given."
   echo " -list_all          Print list of all found devices with advice, vendor"
   echo "                    and model, One per line. Ignore any device names."
   echo "                    Ignore -DO_WRITE."
@@ -99,6 +108,7 @@ print_usage() {
   echo " $0 -with_sudo -list_all"
   echo " $0 sdc"
   echo " $0 -with_sudo -image_file debian-live-10.0.0-amd64-xfce.iso -DO_WRITE"
+  echo " $0 -with_sudo -image_file debian-live-10.0.0-amd64-xfce.iso -DO_WRITE -plug_test"
   echo
 }
 
@@ -123,6 +133,7 @@ reset_job() {
   image_file=
   do_write=
   dummy_run=
+  do_plug_test=
 
   # Status
   sudo_cmd=
@@ -159,6 +170,9 @@ arg_interpreter() {
       list_all=y
       with_vendor_model=y
       show_reasons=y
+    elif test "$i" = "-plug_test"
+    then
+      do_plug_test=y
     elif test "$i" = "-max_size"
     then
       next_is="max_size"
@@ -211,6 +225,77 @@ arg_interpreter() {
   fi
 }
 
+## Trying to find the desired device by watching plug-in effects
+plug_in_watcher() {
+  found_devices=
+  echo
+  echo "Caused by option -plug_test: Attempt to find the desired device"
+  echo "by watching it appear after being plugged in."
+  echo
+  echo "Step 1:"
+  echo "Please make sure that the desired target device is plugged _out_ now."
+  echo "Press the Enter key when ready."
+  read dummy
+  old_device_list=' '$($lsblk_cmd -d -n -o NAME  | grep -v '^sr[0-9]' | grep -v '^fd[0-9]' | tr '\n\r' '  ')' '
+
+# <<< Mock-up to save USB socket wear-off by erasing items from old_device_list
+# <<< Their presence in new_device_list will let them appear as fresh plugs
+# old_device_list=' '$($lsblk_cmd -d -n -o NAME  | grep -v '^sr[0-9]' | grep -v '^fd[0-9]' | tr '\n\r' '  ' | sed -e 's/sd[e-f]//')' '
+
+  echo "Found and noted as _not_ desired: $old_device_list"
+  echo
+  echo "Step 2:"
+  echo "Please plug in the desired target device and then press the Enter key."
+  read dummy
+  echo "Waiting up to 10 seconds for a new device to be listed ..."
+  end_time="$(expr $(date +'%s') + 10)"
+  while test $(date +'%s') -le "$end_time"
+  do
+    new_device_list=' '$($lsblk_cmd -d -n -o NAME  | grep -v '^sr[0-9]' | grep -v '^fd[0-9]' | tr '\n\r' '  ')' '
+    if test "$old_device_list" = "$new_device_list"
+    then
+      sleep 1
+    else
+      for i in $new_device_list
+      do
+        if echo "$old_device_list" | fgrep -v ' '"$i"' ' >/dev/null
+        then
+          found_devices="$found_devices $i"
+        fi
+        # Break the waiting loop
+        end_time=0
+      done
+    fi
+  done
+  if test -z "$found_devices"
+  then
+    echo "SORRY: No new candidate device was found." >&2
+    return 8
+  fi
+  num=$(echo $found_devices | wc -w)
+  if test "$num" -gt 1
+  then
+    echo "SORRY: More than one new candidate device appeared: $found_devices"
+    return 9
+  fi
+  echo "Found and noted as desired device: $found_devices"
+  if test -n "$devs"
+  then
+    echo "(-plug_test is overriding device list given by arguments: $devs )"
+  fi
+  if test -n "$list_all"
+  then
+    echo "(-plug_test is overriding -list_all)"
+    list_all=
+  fi
+  devs_named=y
+  with_vendor_model=y
+  show_reasons=y
+  devs=$(echo -n $found_devices)
+  echo
+  return 0
+}
+
 ## Evaluation of available devices and suitability
 list_devices() {
   if test -n "$list_all"
@@ -468,6 +553,17 @@ write_image() {
 
 reset_job
 arg_interpreter "$@"
+
+if test -n "$do_plug_test"
+then
+  plug_in_watcher
+  ret=$?
+  if test "$ret" -ne 0
+  then
+    exit $ret
+  fi
+fi
+
 list_devices
 if test -n "$list_all"
 then
@@ -496,6 +592,7 @@ then
     devs="$candidates"
     list_devices >&2
     echo "HINT: Unplug the unwanted devices from the machine,"
+    echo "      or work with option -plug_test," >&2
     echo "      or add the desired name out of {$(echo $candidates | sed -e 's/ /,/g')} as additional argument." >&2
     exit 3
   else