Add script to diff two DUMP tapes.

The script takes two file names on the command line: an old tape, and
a new tape.  Any updated files are written to a new tape diffs.tap.
The intent is that diffs.tap can be extradted with a DUMP command like
LOAD CRDIR LINKS to update an ITS system.

The script tries to avoid including binary files that only differ in
the symbol table or creation time.  Some false positives are expected.

build/dump-diff.sh

@@ -0,0 +1,86 @@
+#!/bin/sh
+
+cleanup() {
+    cd "$home"
+    rm -rf "$tmp"
+}
+
+absolute() {
+    case "$1" in
+        /*) echo "$1";;
+        *) echo "$PWD/$1";;
+    esac
+}
+
+tape1="`absolute $1`"
+tape2="`absolute $2`"
+home="$PWD"
+tmp="$PWD/tmp.$$"
+
+trap cleanup EXIT INT TERM QUIT
+
+mkdir "$tmp"
+cd "$tmp"
+
+mkdir tape1
+cd tape1
+itstar xf "$tape1"
+rm -- */_file_.\(dir\) */m_f_d_.\(file\)
+cd "$tmp"
+mkdir tape2
+cd tape2
+itstar xf "$tape2"
+rm -- */_file_.\(dir\) */m_f_d_.\(file\)
+cd "$tmp"
+rm "$home/diffs"
+
+output() {
+    echo "$1: $2"
+    echo "$2" >> "$home/diffs"
+}
+
+diff_file() {
+    file="$1"
+    if test -L "$file"; then
+        if test -L "../tape1/$file"; then
+            l1=`readlink "../tape1/$file"`
+            l2=`readlink "$file"`
+            if test "$l1" \!= "$l2"; then
+                output "UPDATED LINK" "$file"
+            fi
+        else
+            output "NEW LINK" "$file"
+        fi
+    elif test -f "../tape1/$file"; then
+        if cmp -- "$file" "../tape1/$file" > /dev/null; then
+            :
+        else
+            dis10 "$file" 2> /dev/null | grep -v -e 'Creation time:' -e 'Symbol ' -e '^[0-7][0-7][0-7]   [0-7]' > "$tmp/TMP1"
+            dis10 "../tape1/$file" 2> /dev/null | grep -v -e 'Creation time:' -e 'Symbol ' -e '^[0-7][0-7][0-7]   [0-7]' > "$tmp/TMP2"
+            if cmp -- "$tmp/TMP1" "$tmp/TMP2" > /dev/null; then
+                :
+            else
+                output "UPDATED FILE" "$file"
+            fi
+        fi
+    else
+        output "NEW FILE" "$file"
+    fi
+}
+
+cd tape2
+for dir in *; do
+    if test -d "../tape1/$dir"; then
+        for file in $dir/*; do
+            test -r "$file" && diff_file "$file"
+        done
+    else
+        output "NEW DIRECTORY" "$dir"
+    fi
+done
+
+cd "$tmp/tape2"
+head -1 "$home/diffs" | xargs itstar cvf "$home/diffs.tap"
+tail +2 "$home/diffs" | xargs itstar rvf "$home/diffs.tap"
+cd "$home"
+rm "$home/diffs"