Switched test/merge_debian_isos to /bin/sh, added signal handling, fixed harmless flaws found by shellcheck, added more sanity checks, enabled XORRISO=dummy for test runs without ISO production

test/merge_debian_isos

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/sh
 # Copyright 2022 Thomas Schmitt <scdbackup@gmx.net> , libburnia project.
 # Provided under BSD license: Use, modify, and distribute as you like.
 
@@ -22,9 +22,9 @@ usage() {
   echo "Further it creates and finally removes directories mount_template*" >&2
   echo "if they are needed and do not exist when the script starts." >&2
   echo "It depends on the following programs:" >&2
-  echo "  awk, basename, bash, cat, chmod, cp, dirname, expr, fgrep, grep," >&2
+  echo "  awk, basename, cat, chmod, cp, dirname, expr, fgrep, grep," >&2
-  echo "  gunzip, gzip, head, ls, mkdir, mount, mv, rm, rmdir, sha256sum," >&2
+  echo "  gunzip, gzip, head, ls, mkdir, mount, mv, rm, rmdir, sed, sh," >&2
-  echo "  sed, sort, stat, sudo, umount, xorriso" >&2
+  echo "  sha256sum, sort, stat, sudo, umount, xorriso" >&2
   echo "Recommended are: md5sum, sha1sum, sha512sum" >&2
   echo >&2
   echo "Exported non-empty variable MERGE_DATE enforces a particular" >&2
@@ -34,9 +34,10 @@ usage() {
   echo "such directory is found and thus no need to set MERGE_FOR_DIST." >&2
   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 >&2
   echo "Example using GNU xorriso-1.5.4 instead of /usr/bin/xorriso:" >&2
-  echo "  export XORRISO="'$HOME'"/xorriso-1.5.4/xorriso/xorriso" >&2
+  echo "  export XORRISO="'"$HOME"'"/xorriso-1.5.4/xorriso/xorriso" >&2
   echo "  mkdir merge_mount" >&2
   echo "  $(basename "$0") merged.iso merge_mount/iso "'\' >&2
   echo "                    debian-11.2.0-amd64-DVD-[12345].iso" >&2
@@ -51,15 +52,28 @@ check_single_word() {
     then
       empty=0
     else
-      echo "--- Argument $2 is not a single word:" >&2
+      if test "$2" = "dists"
-      echo "--- '${1}'" >&2
+      then
+        echo "WARNING: A file name in /dists is not a single word:" >&2
+        echo "         '${1}'" >&2
+      else
+        echo "--- Argument $2 is not a single word:" >&2
+        echo "--- '${1}'" >&2
+      fi
       return 1
     fi
   done
   if test "$empty" = 1
   then
-    echo "--- Argument $2 is empty or entirely white space:" >&2
+    if test "$2" = "dists"
-    echo "--- '${1}'" >&2
+    then
+      echo "WARNING: A file name in /dists is empty or entirely white space:" \
+           >&2
+      echo "         '${1}'" >&2
+    else
+      echo "--- Argument $2 is empty or entirely white space:" >&2
+      echo "--- '${1}'" >&2
+    fi
     return 1
   fi
   return 0
@@ -70,10 +84,34 @@ UMOUNT_LIST=
 RMDIR_LIST=
 TEMPFILE_LIST="merged_dists merged_md5sum.txt merged_README.txt temp_file"
 
+finish_cleanup() {
+  if test -n "$1"
+  then
+    echo >&2
+    if test "$1" -gt 0
+    then
+      echo "--- Merge run aborted !" >&2
+    else
+      echo "Merge run ended with success indication." >&2
+    fi
+    exit "$1" 
+  fi
+  return 0
+}
+
 # Cleanup temporary files, mount points and made directories
+cleanup_ran=0
+
 cleanup_and_end() {
   # Remove trap
-  trap EXIT
+  trap - INT TERM QUIT EXIT
+
+  if test "$cleanup_ran" = 1
+  then
+    finish_cleanup "$1"
+    return 0
+  fi
+  cleanup_ran=1
 
   echo >&2
   echo "Cleaning up temporary files and mount points ..." 2>&1
@@ -122,26 +160,18 @@ cleanup_and_end() {
     echo "--- Cleanup could not be fully completed." >&2
   fi
 
-  if test -n "$1"
+  # Might exit
-  then
+  finish_cleanup "$1"
-    echo >&2
-    if test "$1" -gt 0
-    then
-      echo "--- Merge run aborted !" >&2
-    else
-      echo "Merge run ended with success indication." >&2
-    fi
-    exit "$1" 
-  fi
 
   return $ret
 }
 
 
-## Check arguments
-
 # +++ No cleanup_and_end before TEMPFILE_LIST is verified to be missing +++
 
+
+## Check arguments and dependencies
+
 if test "$#" -lt 4
 then
   usage
@@ -151,6 +181,53 @@ fi
 echo >&2
 echo "$(basename "$0") starting with $(expr $# - 2) ISO image files ..." >&2
 
+dep="awk basename cat chmod cp dirname expr fgrep grep"
+dep="$dep gunzip gzip head ls mkdir mount mv rm rmdir sed"
+dep="$dep sha256sum sort stat sudo umount"
+missing=0
+for i in $dep
+do
+  if type "$i" >/dev/null 2>&1
+  then
+    dummy=dummy
+  else
+    echo "--- Missing a helper program: $i" 2>&1
+    missing=1
+  fi
+done
+if test -z "$XORRISO"
+then
+  XORRISO=xorriso
+fi
+if test "$XORRISO" = dummy
+then
+  echo 'NOTE: Variable XORRISO is set to "dummy".' >&2
+  echo '      Will not perform xorriso run but only show its arguments.' >&2
+elif "$XORRISO" -no_rc -version >/dev/null 2>&1
+then
+  if "$XORRISO" -no_rc -help 2>/dev/null | fgrep '"replay"' >/dev/null 2>&1
+  then
+    dummy=dummy
+  else
+    echo '--- Help text of xorriso program '"$XORRISO"' lacks word "replay".' \
+         2>&1
+    echo "--- It will fail when trying to make the new ISO bootable." 2>&1
+    echo "    Consider to get and compile GNU xorriso from" 2>&1
+    echo "      https://www.gnu.org/software/xorriso" 2>&1
+    echo "    and to export variable XORRISO with the binary's path." 2>&1
+    echo >&2
+    missing=1
+  fi
+else
+  echo "--- Test run of xorriso program failed: $XORRISO -no_rc -version" 2>&1
+  missing=1
+fi
+if test "$missing" = 1
+then
+  echo "--- Merge run aborted !" >&2
+  exit 5
+fi
+
 existing_tempfiles=
 for i in $TEMPFILE_LIST
 do
@@ -169,7 +246,7 @@ then
 fi
 
 # +++ From here on: Always call cleanup_and_end to perform exit +++
-trap cleanup_and_end EXIT
+trap cleanup_and_end INT TERM QUIT EXIT
 
 RESULT_ISO="$1"
 check_single_word "$2" "result_iso" || cleanup_and_end 1
@@ -342,7 +419,7 @@ extract_checksum_paths() {
   cat "$1" | \
   while true
   do
-    read x || break
+    read -r x || break
     if test "$x" = "MD5Sum:" || test "$x" = "SHA1:" \
        || test "$x" = "SHA256:" || test "$x" = "SHA512:"
     then
@@ -365,7 +442,7 @@ extract_release_head() {
   cat "$1" | \
   while true
   do
-    read x || break
+    read -r x || break
     if test "$x" = "MD5Sum:" || test "$x" = "SHA1:" \
        || test "$x" = "SHA256:" || test "$x" = "SHA512:"
     then
@@ -381,8 +458,14 @@ echo >&2
 echo "Determining Debian release in first ISO ..." >&2
 
 dist=
-for i in $(ls -1d "$mount_point_1"/dists/*)
+for i in "$mount_point_1"/dists/*
 do
+  if check_single_word "$i" "dists"
+  then
+    dummy=dummy
+  else
+continue
+  fi
   if test -d "$i"
   then
     if test -L "$i"
@@ -390,7 +473,7 @@ do
 continue
     fi
     test -n "$dist" && dist="$dist "
-    dist="${dist}$(basename $i)"
+    dist="${dist}$(basename "$i")"
   fi
 done
 if test -z "$dist"
@@ -446,7 +529,7 @@ then
   MERGE_DATE=$(date +'%Y%m%d-%H:%M')
 fi
 printf 'Result of a run of %s at %s\r\n' \
-       "$(basename $0)" "$MERGE_DATE" >temp_file
+       "$(basename "$0")" "$MERGE_DATE" >temp_file
 printf 'Package pools and Packages lists were merged.\r\n' >>temp_file
 printf 'The other files stem from the first input ISO.\r\n' >>temp_file
 printf '\r\n' >>temp_file
@@ -564,7 +647,7 @@ do
     continue
       fi
       list_path=$(echo "$file" | sed -e 's/^merged_dists\/'"$dist"'\///')
-      printf ' %s %8ld %s\n' "$sum" "$size" "$list_path" 
+      printf ' %s %8d %s\n' "$sum" "$size" "$list_path" 
     done 
   fi
 done >>temp_file
@@ -582,7 +665,6 @@ for mount_point in $MOUNT_LIST
 do
   if test "$mount_point" = "$mount_point_1"
   then
-    dummy=dummy
     echo "Planned as imported package pool     : ${mount_point}/pool" >&2
   else
     echo "Planned for merging into package pool: ${mount_point}/pool" >&2
@@ -590,17 +672,14 @@ do
   fi
 done
 
-if test -z "$XORRISO"
+if test "$XORRISO" = dummy
 then
-  XORRISO=xorriso
+  echo >&2
-fi
+  echo 'NOTE: Variable XORRISO is set to "dummy".' >&2
-
+  echo '      Will not perform xorriso run but only show its arguments:' >&2
-x=$(type -p "$XORRISO")
+  XORRISO=echo
-if test -z "$x"
-then
-  echo "Running as xorriso program: $XORRISO" >&2
 else
-  echo "Running as xorriso program: $x" >&2
+  echo "Running as xorriso program: $XORRISO" >&2
 fi
 echo >&2
 
@@ -621,9 +700,10 @@ if "$XORRISO" \
   -padding included \
   -compliance no_emul_toc
 then
-  echo "Run of xorriso program completed without error indication." >&2
+  test "$XORRISO" = echo || \
+    echo "Run of xorriso program ended without error indication." >&2
 else
-  echo "--- Run of xorriso program ended with problem indication." >&2
+  echo "--- Run of xorriso program ended with error indication." >&2
   cleanup_and_end 4
 fi