Enabled writing by merge_debian_isos to USB sticks and optical media

test/merge_debian_isos

@@ -12,9 +12,20 @@ usage() {
   echo "Mounts by sudo the ISO 9660 images iso1 to isoN at directories" >&2
   echo "mount_template1 to mount_templateN, if not already mounted that way." >&2
   echo "Then the Debian pools and package lists get merged and a new" >&2
-  echo "ISO 9660 image result_iso is produced, which must not yet exist." >&2
-  echo "If iso1 is bootable then the new image will be bootable by the" >&2
-  echo "same means." >&2
+  echo "ISO 9660 image result_iso is produced. If iso1 is bootable then" >&2
+  echo "then the new image will be bootable by the same means." >&2
+  echo >&2
+  echo "The file depicted by result_iso must not yet exist or has to be a" >&2
+  echo "device which is acceptable for Linux-specific helper script" >&2
+  echo "xorriso-dd-target. If xorriso-dd-target agrees and the user" >&2
+  echo 'confirms by input "yes" then xoriso will be run under sudo.' >&2
+  echo 'Exempted from this evaluation are addresses which begin by "mmc:"' >&2
+  echo 'for an optical drive on Linux, BSDs, Solaris, or by "stdio:/dev/"' >&2
+  echo 'for which the user takes full and dangerous responsibility.' >&2
+  echo 'Special result_iso path "xorriso-dd-target-plug-test" determines' >&2
+  echo "on Linux the target USB stick by a dialog around plugging it in." >&2
+  echo "xorriso will be run under sudo, if xorriso-dd-target agrees." >&2
+  echo >&2
   echo "At least the parent directory of mount_template must already exist." >&2
   echo "All arguments must be single words without using quotation marks." >&2
   echo "None of the isoN must be equal to another isoM." >&2
@@ -41,6 +52,9 @@ usage() {
   echo "Exported non-empty variable XORRISO overrides command xorriso." >&2
   echo "This may be needed if installed xorriso is older than 1.4.2." >&2
   echo 'If XORRISO is set to "dummy" then no new ISO will emerge.' >&2
+  echo "Exported non-empty variable XORRISO_DD_TARGET_PATH names the" >&2
+  echo "directory where to find xorriso-dd-target, which evaluates the" >&2
+  echo "suitability of result_iso devices or does the plug-test dialog." >&2
   echo >&2
   echo "Example using GNU xorriso-1.5.4 instead of /usr/bin/xorriso:" >&2
   echo "  export XORRISO="'"$HOME"'"/xorriso-1.5.4/xorriso/xorriso" >&2
@@ -48,6 +62,20 @@ usage() {
   echo "  $(basename "$0") merged.iso merge_mount/iso "'\' >&2
   echo "                    debian-11.2.0-amd64-DVD-[12345].iso" >&2
   echo "  rmdir merge_mount" >&2
+  echo >&2
+  echo "Example writing to optical drive /dev/sr0 :" >&2
+  echo "  $(basename "$0") mmc:/dev/sr0 merge_mount/iso "'\' >&2
+  echo "                    debian-11.2.0-amd64-DVD-[12345].iso" >&2
+  echo >&2
+  echo \
+  "Example on Linux writing to USB stick with xorriso-dd-target-plug-test:" >&2
+  echo "  wget https://dev.lovelyhq.com/libburnia/libisoburn/raw/master/xorriso-dd-target/xorriso-dd-target" >&2
+  echo "  chmod u+x xorriso-dd-target" >&2
+  echo '  export XORRISO_DD_TARGET_PATH="$(pwd)"' >&2
+  echo "  $(basename "$0") xorriso-dd-target-plug-test merge_mount/iso "'\' >&2
+  echo "                    debian-11.2.0-amd64-DVD-[12345].iso" >&2
+  echo "This leads to the first two steps of the xorriso-dd-target device" >&2
+  echo "plug dialog. See: https://wiki.debian.org/XorrisoDdTarget" >&2
 }
 
 check_single_word() {
@@ -289,6 +317,14 @@ then
   exit 5
 fi
 
+XORRISO_DD_TARGET=
+if test -z "$XORRISO_DD_TARGET_PATH"
+then
+  XORRISO_DD_TARGET=xorriso-dd-target
+else
+  XORRISO_DD_TARGET="$XORRISO_DD_TARGET_PATH"/xorriso-dd-target
+fi
+
 existing_tempfiles=
 for i in merged_dists merged_md5sum.txt merged_README.txt temp_file
 do
@@ -316,16 +352,147 @@ trap cleanup_and_end INT TERM QUIT
 trap cleanup_for_exit EXIT
 
 RESULT_ISO="$1"
-check_single_word "$2" "result_iso" || cleanup_and_end 1
-if test -e "$RESULT_ISO"
+check_single_word "$1" "result_iso" || cleanup_and_end 1
+XORRISO_STDIO_DEV=
+XORRISO_SUDO=
+XORRISO_BLANK_CMD=
+XORRISO_STDIO_SYNC=off
+xorriso_rm_result_iso=1
+if test "$RESULT_ISO" = xorriso-dd-target-plug-test
 then
-  echo "--- A file '${RESULT_ISO}' is already existing." >&2
-  echo "--- Will not overwrite it by the resulting ISO image." >&2
-  cleanup_and_end 1
+  # Get device name from xorriso-dd-target
+  advice=NO
+  echo >&2
+  echo \
+    'Special result_iso path "xorriso-dd-target-plug-test" causes a run of' >&2
+  echo "  $XORRISO_DD_TARGET -with_sudo -plug_test" >&2
+  echo "to determine the USB stick or memory card:" >&2
+  echo "---------------------------------------------------------" >&2
+  plugged="$("$XORRISO_DD_TARGET" -with_sudo -plug_test)"
+  ret=$?
+  echo "---------------------------------------------------------" >&2
+  if test "$ret" = 0 && test -n "$plugged"
+  then
+    name="$(echo "$plugged" | awk '{print $1}')"
+    advice="$(echo "$plugged" | awk '{print $3}')"
+  fi
+  if test "$advice" = YES
+  then
+    RESULT_ISO=/dev/"$name"
+    XORRISO_STDIO_DEV=stdio:
+    XORRISO_SUDO=sudo
+    XORRISO_BLANK_CMD="-blank as_needed"
+    XORRISO_STDIO_SYNC=16m
+    xorriso_rm_result_iso=0
+    echo "Will use sudo with xorriso and write to ${RESULT_ISO}" >&2
+  else
+    echo "--- No suitable device was determined." >&2
+    cleanup_and_end 1
+  fi
+elif echo "$RESULT_ISO" | grep '^mmc:' >/dev/null
+then
+  xorriso_rm_result_iso=0
+  # Let xorriso judge over optical drives
+  # (The /dev/sr patterns are Linux specific. The mmc: prefix is not.)
+  if test "$XORRISO" = dummy
+  then
+    echo "Dummy mode: Accepting '${RESULT_ISO}' as optical drive." >&2
+    XORRISO_BLANK_CMD="-blank as_needed"
+  elif "$XORRISO" -outdev "$RESULT_ISO" 2>/dev/null
+  then
+    echo "${XORRISO} accepts '${RESULT_ISO}' as optical drive." >&2
+    XORRISO_BLANK_CMD="-blank as_needed"
+  else
+    echo "--- $XORRISO refuses to accept '${RESULT_ISO}' as optical drive." >&2
+    cleanup_and_end 1
+  fi
+elif echo "$RESULT_ISO" | grep '^stdio:/dev/' >/dev/null
+then
+  xorriso_rm_result_iso=0
+  echo \
+"WARNING: User insists in using '${RESULT_ISO}' without further preparations" \
+       >&2
+  echo \
+  "         or safety checks. The device might need blanking by xorriso" >&2
+  echo \
+ "         before it will be willing to write to it. Permissions might not" >&2
+  echo \
+  "         suffice. Be cautious when removing such obstacles. They might be" \
+       >&2
+  echo \
+  "         there for a good reason." >&2
+  echo \
+ "If you agree to xorriso trying to overwrite the content of '${RESULT_ISO}'" \
+             >&2
+  echo "then enter 'yes' :" >&2
+  answer=
+  read answer
+  if test "$answer" = yes
+  then
+    echo \
+  "Will try to overwrite the device content without sudo or pseudo-blanking." \
+        >&2
+  else
+    echo "--- Answer was not 'yes'. Will not write to device." >&2
+    cleanup_and_end 1
+  fi
+elif test -e "$RESULT_ISO"
+then
+  if test "$(dirname $RESULT_ISO)" = "/dev"
+  then
+    echo >&2
+    echo "The result_iso path '${RESULT_ISO}' is an existing File in /dev." >&2
+    echo "Will only write to it if $XORRISO_DD_TARGET agrees." >&2
+    if type "$XORRISO_DD_TARGET"
+    then
+      echo >&2
+      echo \
+       "Performing: $XORRISO_DD_TARGET -with_sudo $(basename $RESULT_ISO)" >&2
+      echo "---------------------------------------------------------" >&2
+      "$XORRISO_DD_TARGET" -with_sudo "$(basename $RESULT_ISO)"
+      ret=$?
+      echo "---------------------------------------------------------" >&2
+      if test "$ret" = 0
+      then
+        echo "$XORRISO_DD_TARGET agrees that this is a suitable device." >&2
+        echo \
+     "If you agree to xorriso running under sudo and overwriting the content" \
+             >&2
+        echo "of '${RESULT_ISO}', then enter 'yes' :" >&2
+        answer=
+        read answer
+        if test "$answer" = yes
+        then
+          XORRISO_STDIO_DEV=stdio:
+          XORRISO_SUDO=sudo
+          XORRISO_BLANK_CMD="-blank as_needed"
+          XORRISO_STDIO_SYNC=16m
+          xorriso_rm_result_iso=0
+          echo "Will use sudo with xorriso and write to device." >&2
+        else
+          echo "--- Answer was not 'yes'. Will not write to device." >&2
+        fi
+      else
+        echo \
+       "--- $XORRISO_DD_TARGET refuses to accept this device as result_iso" >&2
+      fi
+    else
+      echo "--- Helper program $XORRISO_DD_TARGET is missing." >&2
+      echo \
+      "--- Cannot evaluate suitability of '${RESULT_ISO}' as result_iso path" \
+           >&2
+    fi
+  fi
+  if test -z "$XORRISO_STDIO_DEV"
+  then
+    echo "--- A file '${RESULT_ISO}' is already existing." >&2
+    echo "--- Will not overwrite it by the resulting ISO image." >&2
+    cleanup_and_end 1
+  fi
 fi
 
 MOUNT_TEMPLATE="$2"
-check_single_word "$1" "mount_template" || cleanup_and_end 1
+check_single_word "$2" "mount_template" || cleanup_and_end 1
 x=$(dirname "$MOUNT_TEMPLATE")
 if test -d "$x"
 then
@@ -858,6 +1025,11 @@ then
   echo "Planned xorriso commands in temp_file:" >&2
   cat temp_file
   echo >&2
+  if test -n "$XORRISO_SUDO"
+  then
+    echo "NOTE: xorriso would run under control of '${XORRISO_SUDO}'" >&2
+    XORRISO_SUDO=
+  fi
   echo 'NOTE: Variable XORRISO is set to "dummy".' >&2
   echo '      Will not perform xorriso run but only show its arguments:' >&2
   XORRISO=echo
@@ -867,12 +1039,17 @@ fi
 echo >&2
 
 # Mark the result path for possible removal by cleanup
-EMERGING_ISO="$RESULT_ISO"
-
-if "$XORRISO" \
+if test -z "$XORRISO_STDIO_DEV"
+then
+  EMERGING_ISO="$RESULT_ISO"
+else
+  EMERGING_ISO=
+fi
+if $XORRISO_SUDO "$XORRISO" \
   -no_rc \
   -indev "$iso_1" \
-  -outdev "$RESULT_ISO" \
+  -outdev "$XORRISO_STDIO_DEV""$RESULT_ISO" \
+  $XORRISO_BLANK_CMD \
   -options_from_file temp_file \
   -map merged_dists /dists \
   -map merged_md5sum.txt /md5sum.txt \
@@ -882,8 +1059,10 @@ if "$XORRISO" \
   -chmod_r a-w /dists /md5sum.txt -- \
   -chmod_r a=r /README.txt -- \
   -boot_image any replay \
-  -stdio_sync off \
+  -fs 16m \
+  -stdio_sync "$XORRISO_STDIO_SYNC" \
   -padding included \
+  -stream_recording on \
   -compliance no_emul_toc
 then
   # Revoke mark for possible removal by cleanup