patch-iso-debian: use mount for extracting ISO

In a previous commit [1], the script was changed to use 7z
for extracting contents from the input ISO. This was done
because the main alternative was using 'mount', which
requires sudo privileges.

Unfortunately, 7z does not handle ownership and permissions [2],
and keeping them unchanged is required.

This commit changes the script back to using 'mount'
for extracting input ISO contents. This also means running it
now requires sudo privileges.

Ref:
[1] 4f69113d93
[2] https://linux.die.net/man/1/7z

Test Plan:
pass - Generate a pre-patched ISO and check that the permissions
       on the output iso are the same as the ones in the input.

Closes-Bug: 2098385

Change-Id: I1e5e1f8ecdb94cafb577dcfe3651a1717abe19c7
Signed-off-by: Leonardo Fagundes Luz Serrano <Leonardo.FagundesLuzSerrano@windriver.com>

build-tools/patch-iso-debian

@@ -1,6 +1,6 @@
 #!/bin/bash -e
 #
-# Copyright (c) 2024 Wind River Systems, Inc.
+# Copyright (c) 2025 Wind River Systems, Inc.
 #
 # SPDX-License-Identifier: Apache-2.0
 #
@@ -41,6 +41,7 @@ Usage:
 Attention:
 - Either the DEPLOY_DIR or the STX_BUILD_HOME env variable must be defined.
   It's used to find the input ostree repo.
+- Requires sudo privileges for mounting the input ISO
 
 "
 
@@ -146,11 +147,11 @@ function check_requirements {
 
     # Declare "require reqA or reqB" as "reqA__reqB"
     local -a required_utils=(
-        7z                   # p7zip-full
         mkisofs__xorrisofs   # genisoimage / xorriso
         isohybrid            # syslinux-utils
         implantisomd5        # isomd5sum
         ostree               # ostree
+        rsync                # rsync
         xmllint__python3     # libxml2-utils / python3
     )
 
@@ -219,31 +220,36 @@ if [ -z "${BUILDDIR}" ] || [ ! -d "${BUILDDIR}" ]; then
     exit 1
 fi
 
-echo "Extracting Input ISO contents (except ostree repo)..."
-if ! 7z x "${INPUT_ISO}" -o"${BUILDDIR}" -x\!ostree_repo 1>/dev/null ; then
-    echo "ERROR: Failed to extract ISO contents"
+# Create temporary mount directory
+MNTDIR=$(mktemp -d -p "$PWD" patchiso_mount_XXXXXX)
+if [ -z "${MNTDIR}" ] || [ ! -d "${MNTDIR}" ]; then
+    echo "ERROR: Failed to create temporary mount directory"
     exit 1
 fi
 
-# Deleting '[BOOT]' directory. It will be re-created when packing the output ISO.
-if [ -d "${BUILDDIR}/[BOOT]" ]; then
-    rm -rf "${BUILDDIR}/[BOOT]"
+echo "Mounting input ISO..."
+if ! mount -o loop ${INPUT_ISO} ${MNTDIR} ; then
+    echo "ERROR: Failed to mount input ISO. Are you root?"
+    exit 1
 fi
 
-# Fix for permission denied if not running as root
-chmod +w "${BUILDDIR}"
-if [ -d "${BUILDDIR}/isolinux" ]; then
-    chmod -R +w "${BUILDDIR}/isolinux"
+echo "Extracting Input ISO contents (except ostree repo)..."
+if ! rsync -a --exclude 'ostree_repo' ${MNTDIR}/ ${BUILDDIR}/ ; then
+    echo "ERROR: Failed to rsync content from mount dir to build dir" 
+    umount ${MNTDIR}
+    exit 1
 fi
 
+umount ${MNTDIR}
+
 # Erase current patch metadata from ISO if it exists
 # This way, this script can be used on pre-patched ISOs
 if [ -d "${BUILDDIR}/patches" ]; then
     rm -rf "${BUILDDIR}/patches"
 fi
 
-echo "List contents extracted from Input ISO (after adjustments):"
-ls -lh "${BUILDDIR}"
+echo "List contents extracted from Input ISO:"
+ls -lah "${BUILDDIR}"
 
 # Create the directory where patch metadata will be stored
 mkdir -p "${BUILDDIR}/patches"