Modernize Java launch code

components/scripts/lib/java.sh

@@ -1,101 +1,148 @@
 #!/usr/bin/env bash
 
+# The code within this method is based off of the Gradle application plugin's
+# generated start up script. The template for the start up script can be found
+# here:
+
+# https://github.com/gradle/gradle/blob/3200a204ba96f503f1171b3584258a53ecd91bd2/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#
+# shellcheck disable=SC2128,SC2178
 invoke_java() {
   local classpath="$1"
   shift
-  local args=( "$@" )
 
   # OS specific support (must be 'true' or 'false').
   cygwin=false
   msys=false
+  darwin=false
+  nonstop=false
   case "$(uname)" in
-    CYGWIN*)
-      cygwin=true
-      ;;
-    MINGW*)
-      msys=true
-      ;;
+    CYGWIN*) cygwin=true ;;
+    Darwin*) darwin=true ;;
+    MSYS* | MINGW*) msys=true ;;
+    NONSTOP*) nonstop=true ;;
   esac
 
   # Determine the Java command to use to start the JVM.
   if [ -n "$JAVA_HOME" ]; then
     if [ -x "$JAVA_HOME/jre/sh/java" ]; then
       # IBM's JDK on AIX uses strange locations for the executables
-      JAVACMD="$JAVA_HOME/jre/sh/java"
+      JAVACMD=$JAVA_HOME/jre/sh/java
     else
-      JAVACMD="$JAVA_HOME/bin/java"
+      JAVACMD=$JAVA_HOME/bin/java
     fi
     if [ ! -x "$JAVACMD" ]; then
       die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
 
-  Please set the JAVA_HOME variable in your environment to match the
-  location of your Java installation."
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
     fi
   else
-    JAVACMD="java"
+    JAVACMD=java
     which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
 
-  Please set the JAVA_HOME variable in your environment to match the
-  location of your Java installation."
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+  fi
+
+  # Increase the maximum file descriptors if we can.
+  if ! "$cygwin" && ! "$darwin" && ! "$nonstop"; then
+    case $MAX_FD in
+    max*)
+      # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
+      MAX_FD=$(ulimit -H -n) ||
+        warn "Could not query maximum file descriptor limit"
+      ;;
+    esac
+    case $MAX_FD in
+    '' | soft) : ;;
+    *)
+      # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
+      ulimit -n "$MAX_FD" ||
+        warn "Could not set maximum file descriptor limit to $MAX_FD"
+      ;;
+    esac
   fi
 
+  # Collect all arguments for the java command, stacking in reverse order:
+  #   * args from the command line
+  #   * the main class name
+  #   * -classpath
+  #   * -D...appname settings
+  #   * --module-path (only if needed)
+  #   * DEFAULT_JVM_OPTS, JAVA_OPTS, and APP_OPTS environment variables.
+
   # For Cygwin or MSYS, switch paths to Windows format before running java
-  if [ "$cygwin" = "true" ] || [ "$msys" = "true" ]; then
+  if "$cygwin" || "$msys"; then
     APP_HOME=$(cygpath --path --mixed "$APP_HOME")
-    CLASSPATH=$(cygpath --path --mixed "$CLASSPATH")
+    classpath=$(cygpath --path --mixed "$classpath")
+
     JAVACMD=$(cygpath --unix "$JAVACMD")
 
-    # We build the pattern for arguments to be converted via cygpath
-    ROOTDIRSRAW=$(find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null)
-    SEP=""
-    for dir in $ROOTDIRSRAW; do
-      ROOTDIRS="$ROOTDIRS$SEP$dir"
-      SEP="|"
-    done
-    OURCYGPATTERN="(^($ROOTDIRS))"
-    # Add a user-defined pattern to the cygpath arguments
-    if [ "$GRADLE_CYGPATTERN" != "" ]; then
-      OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
-    fi
     # Now convert the arguments - kludge to limit ourselves to /bin/sh
-    i=0
-    for arg in "${args[@]}"; do
-      CHECK=$(echo "$arg" | grep -E -c "$OURCYGPATTERN" -)
-      CHECK2=$(echo "$arg" | grep -E -c "^-") ### Determine if an option
-
-      # shellcheck disable=SC2046  # we actually want word splitting
-      # shellcheck disable=SC2116  # using echo to expand globs
-      if [ "$CHECK" -ne 0 ] && [ "$CHECK2" -eq 0 ]; then ### Added a condition
-        eval $(echo args$i)=$(cygpath --path --ignore --mixed "$arg")
-      else
-        eval $(echo args$i)="\"$arg\""
+    for arg; do
+      if
+        case $arg in
+        -*) false ;; # don't mess with options
+        /?*)
+          t=${arg#/} t=/${t%%/*} # looks like a POSIX filepath
+          [ -e "$t" ]
+          ;;
+        *) false ;;
+        esac
+      then
+        arg=$(cygpath --path --ignore --mixed "$arg")
       fi
-      # shellcheck disable=SC2003
-      i=$(expr $i + 1)
+      # Roll the args list around exactly as many times as the number of
+      # args, so each arg winds up back in the position where it started, but
+      # possibly modified.
+      #
+      # NB: a `for` loop captures its iteration list before it begins, so
+      # changing the positional parameters here affects neither the number of
+      # iterations, nor the values presented in `arg`.
+      shift              # remove old arg
+      set -- "$@" "$arg" # push replacement arg
     done
-    # shellcheck disable=SC2154
-    case $i in
-      0) set -- ;;
-      1) set -- "$args0" ;;
-      2) set -- "$args0" "$args1" ;;
-      3) set -- "$args0" "$args1" "$args2" ;;
-      4) set -- "$args0" "$args1" "$args2" "$args3" ;;
-      5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
-      6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
-      7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
-      8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
-      9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
-    esac
   fi
 
-  # Escape application args
-  save() {
-    for i; do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/"; done
-    echo " "
-  }
+  # Collect all arguments for the java command;
+  #   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $APP_OPTS can contain fragments of
+  #     shell script including quotes and variable substitutions, so put them in
+  #     double quotes to make sure that they get re-expanded; and
+  #   * put everything else in single quotes, so that it's not re-expanded.
+
+  set -- -Dpicocli.ansi=true -jar "$classpath" "$@"
+
+  # Stop when "xargs" is not available.
+  if ! command -v xargs >/dev/null 2>&1; then
+    die "xargs is not available"
+  fi
+
+  # Use "xargs" to parse quoted args.
+  #
+  # With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+  #
+  # In Bash we could simply go:
+  #
+  #   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+  #   set -- "${ARGS[@]}" "$@"
+  #
+  # but POSIX shell has neither arrays nor command substitution, so instead we
+  # post-process each arg (as a line of input to sed) to backslash-escape any
+  # character that might be a shell metacharacter, then use eval to reverse
+  # that process (while maintaining the separation between arguments), and wrap
+  # the whole thing up as a single "set" statement.
+  #
+  # This will of course break if any of these variables contains a newline or
+  # an unmatched quote.
+  #
 
-  # Collect all arguments for the java command, following the shell quoting and substitution rules
-  eval set -- -Dpicocli.ansi=true -jar "\"$classpath\"" "$(save "${args[@]}")"
+  eval "set -- $(
+    printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $APP_OPTS" |
+      xargs -n1 |
+      sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+      tr '\n' ' '
+  )" '"$@"'
 
   # shellcheck disable=SC2154
   if [[ "${debug_mode}" == "on" ]]; then