Do not duplicate grub.cfg in efiboot.img

Instruct the embeded grub.cfg to search for a volume with a
`/.disk/%UUID_SEARCH_FILENAME%.uuid` file and load `/EFI/BOOT/grub.cfg`
from it.

This avoid duplicating GRUB configuration files in two places (ISO 9660
and FAT) and ensures there is no confusion about which is the _correct_
configuration file.

Since nothing besides EFI binaries is copied to `efibootimg`, the
`_make_common_bootmode_grub_copy_to_efibootimg` function is removed.

Fixes #208

2 files changed, 36 insertions, 20 deletions

diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index d55c15d..e00ebcb 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -20,6 +20,8 @@ Changed
 - Identify the ISO volume via a UUID instead of a file system label to avoid collisions of multiple ISOs created in the
   same month.
 - Honor ``SOURCE_DATE_EPOCH`` in the ``date`` command used by ``profiledef.sh`` of the shipped profiles.
+- Do not duplicate ``grub.cfg`` in both ISO 9660 and the EFI system partition / El Torito image. GRUB will search for
+  the ISO volume and load the ``grub.cfg`` from there.
 
 Removed
 -------
diff --git a/archiso/mkarchiso b/archiso/mkarchiso
index c116a27..00c974e 100755
--- a/archiso/mkarchiso
+++ b/archiso/mkarchiso
@@ -544,18 +544,7 @@ _make_efibootimg() {
     mmd -i "${efibootimg}" ::/EFI ::/EFI/BOOT
 }
 
-# Copy GRUB files to efiboot.img which is used by both IA32 UEFI and x64 UEFI.
-_make_common_bootmode_grub_copy_to_efibootimg() {
-    local files_to_copy=()
-
-    files_to_copy+=("${work_dir}/grub/"*)
-    if compgen -G "${profile}/grub/!(*.cfg)" &> /dev/null; then
-        files_to_copy+=("${profile}/grub/"!(*.cfg))
-    fi
-    mcopy -i "${efibootimg}" "${files_to_copy[@]}" ::/EFI/BOOT/
-}
-
-# Copy GRUB files to efiboot.img which is used by both IA32 UEFI and x64 UEFI.
+# Copy GRUB files to ISO 9660 which is used by both IA32 UEFI and x64 UEFI
 _make_common_bootmode_grub_copy_to_isofs() {
     local files_to_copy=()
 
@@ -563,6 +552,7 @@ _make_common_bootmode_grub_copy_to_isofs() {
     if compgen -G "${profile}/grub/!(*.cfg)" &> /dev/null; then
         files_to_copy+=("${profile}/grub/"!(*.cfg))
     fi
+    install -d -m 0755 -- "${isofs_dir}/EFI/BOOT"
     install -m 0644 -- "${files_to_copy[@]}" "${isofs_dir}/EFI/BOOT/"
 }
 
@@ -586,9 +576,6 @@ _make_common_bootmode_grub_cfg(){
              s|%UUID_SEARCH_FILENAME%|${uuid_search_filename}|g" \
              "${_cfg}" > "${work_dir}/grub/${_cfg##*/}"
     done
-    # Add all GRUB files to the list of files used to calculate the required FAT image size.
-    efiboot_files+=("${work_dir}/grub/"
-                    "${profile}/grub/"!(*.cfg))
 
     # Prepare grub.cfg that will be embedded inside the GRUB binaries
     IFS='' read -r -d '' grubembedcfg <<'EOF' || true
@@ -597,12 +584,39 @@ if ! [ -d "$cmdpath" ]; then
     # launched from a case-insensitive FAT-formatted EFI system partition, but it seemingly cannot access that partition
     # and sets cmdpath to the whole cd# device which has case-sensitive ISO 9660 + Rock Ridge + Joliet file systems.
     # See https://gitlab.archlinux.org/archlinux/archiso/-/issues/183 and https://savannah.gnu.org/bugs/?62886
-    if regexp --set=1:isodevice '^(\([^)]+\))\/?[Ee][Ff][Ii]\/[Bb][Oo][Oo][Tt]\/?$' "$cmdpath"; then
-        cmdpath="${isodevice}/EFI/BOOT"
+    if regexp --set=1:archiso_bootdevice '^\(([^)]+)\)\/?[Ee][Ff][Ii]\/[Bb][Oo][Oo][Tt]\/?$' "${cmdpath}"; then
+        set cmdpath="(${archiso_bootdevice})/EFI/BOOT"
+        set ARCHISO_HINT="${archiso_bootdevice}"
     fi
 fi
-configfile "${cmdpath}/grub.cfg"
+
+# Prepare a hint for the search command using the device in cmdpath
+if [ -z "${ARCHISO_HINT}" ]; then
+    regexp --set=1:ARCHISO_HINT '^\(([^)]+)\)' "${cmdpath}"
+fi
+
+# Search for the ISO volume
+if search --no-floppy --set=archiso_device --file '/.disk/%UUID_SEARCH_FILENAME%.uuid' --hint "${ARCHISO_HINT}"; then
+    set ARCHISO_HINT="${archiso_device}"
+    if probe --set ARCHISO_UUID --fs-uuid "${ARCHISO_HINT}"; then
+        export ARCHISO_UUID
+    fi
+else
+    echo "Could not find a volume with a '/.disk/%UUID_SEARCH_FILENAME%.uuid' file on it!"
+fi
+
+# Load grub.cfg
+if [ "${ARCHISO_HINT}" == 'memdisk' -o -z "${ARCHISO_HINT}" ]; then
+    echo 'Could not find the ISO volume!'
+elif [ -e "(${ARCHISO_HINT})/EFI/BOOT/grub.cfg" ]; then
+    export ARCHISO_HINT
+    set root="${ARCHISO_HINT}"
+    configfile "(${ARCHISO_HINT})/EFI/BOOT/grub.cfg"
+else
+    echo "File '(${ARCHISO_HINT})/EFI/BOOT/grub.cfg' not found!"
+fi
 EOF
+    grubembedcfg="${grubembedcfg//'%UUID_SEARCH_FILENAME%'/"${uuid_search_filename}"}"
     printf '%s\n' "$grubembedcfg" > "${work_dir}/grub-embed.cfg"
 }
 
@@ -645,7 +659,7 @@ _make_bootmode_uefi-ia32.grub.esp() {
     mcopy -i "${efibootimg}" "${work_dir}/BOOTIA32.EFI" ::/EFI/BOOT/BOOTIA32.EFI
 
     # Copy GRUB files
-    _run_once _make_common_bootmode_grub_copy_to_efibootimg
+    _run_once _make_common_bootmode_grub_copy_to_isofs
 
     if [[ -e "${pacstrap_dir}/usr/share/edk2-shell/ia32/Shell_Full.efi" ]]; then
         mcopy -i "${efibootimg}" "${pacstrap_dir}/usr/share/edk2-shell/ia32/Shell_Full.efi" ::/shellia32.efi
@@ -716,7 +730,7 @@ _make_bootmode_uefi-x64.grub.esp() {
     mcopy -i "${efibootimg}" "${work_dir}/BOOTx64.EFI" ::/EFI/BOOT/BOOTx64.EFI
 
     # Copy GRUB files
-    _run_once _make_common_bootmode_grub_copy_to_efibootimg
+    _run_once _make_common_bootmode_grub_copy_to_isofs
 
     if [[ -e "${pacstrap_dir}/usr/share/edk2-shell/x64/Shell_Full.efi" ]]; then
         mcopy -i "${efibootimg}" "${pacstrap_dir}/usr/share/edk2-shell/x64/Shell_Full.efi" ::/shellx64.efi