check -o redirected and piped output

releng/releng_isocontent

@@ -166,6 +166,28 @@ ln "$on_disk"/file_1 "$on_disk"/file_1_link_b || exit 1
 ln "$on_disk"/file_2 "$on_disk"/file_2_link_a || exit 1
 ls -l "$on_disk"/*
 
+is_valid_iso9660() {
+ ISOfile="$1"
+ if [ ! -f ${ISOfile} ]; then
+   failure=1
+   printf "=== FAIL Not found: ${ISOfile}\n"
+ fi
+ if file ${ISOfile} | grep -P "ISO\s+9660\s+CD-ROM\s+filesystem\s+data" >/dev/null 2>&1; then
+   printf "=== ${ISOfile} OK\n"
+ else
+   failure=1
+   printf "=== FAIL: ${ISOfile} does not look like ISO 9660 filesystem data\n"   
+ fi
+}
+
+echo "=== Producing simple images via -o, redirect, and pipe" >&2
+"$xorriso" -as mkisofs "$on_disk" -o      "$workdir"/image_minus_o.iso
+is_valid_iso9660                          "$workdir"/image_minus_o.iso
+"$xorriso" -as mkisofs "$on_disk" >       "$workdir"/image_redirected.iso
+is_valid_iso9660                          "$workdir"/image_redirected.iso
+"$xorriso" -as mkisofs "$on_disk" | cat > "$workdir"/image_piped.iso
+is_valid_iso9660                          "$workdir"/image_piped.iso
+
 
 echo "=== Producing simple image" >&2
 "$xorriso" \