feat: add COMMAND config option allowing override the default one

Author: fkzys

README.md

@@ -166,6 +166,7 @@ Edit `/etc/atomic.conf`:
 | `MAPPER_NAME` | `root_crypt` | dm-crypt mapper name (fallback if auto-detection fails) |
 | `KERNEL_PKG` | `linux` | Kernel package (linux/linux-lts/linux-zen) |
 | `KERNEL_PARAMS` | *(security defaults)* | Kernel command line parameters |
+| `COMMAND` | *(none)* | Default command in snapshot chroot (overrides built-in `pacman -Syu`) |
 | `SBCTL_SIGN` | `0` | Sign UKI files with sbctl for Secure Boot (`0`=off, `1`=on) |
 | `UPGRADE_GUARD` | `1` | Upgrade guard: block direct `pacman -Syu` (`0`=off, `1`=on) |
 | `HOME_COPY_FILES` | *(empty)* | Files to copy into isolated home subvolumes (see [Home isolation](#home-isolation)) |

bin/atomic-upgrade

@@ -106,9 +106,11 @@ if [[ -n "$CUSTOM_TAG" ]]; then
     fi
 fi
 
-# Default chroot command
+# Default chroot command: use COMMAND from config (or default in common.sh).
+# Note: COMMAND uses simple word splitting; args with spaces inside
+# are not supported (same limitation as HOME_COPY_FILES).
 if [[ ${#CHROOT_CMD[@]} -eq 0 ]]; then
-    CHROOT_CMD=(/usr/bin/pacman -Syu)
+    read -ra CHROOT_CMD <<< "$COMMAND"
 fi
 
 # Verify required variables are set

etc/atomic.conf

@@ -7,6 +7,11 @@
 #KERNEL_PKG="linux"
 #KERNEL_PARAMS="rw slab_nomerge init_on_alloc=1 page_alloc.shuffle=1 pti=on vsyscall=none randomize_kstack_offset=on debugfs=off"
 
+# Default command to run in the snapshot chroot (overrides built-in default)
+# Command-line -- COMMAND... overrides this setting
+# Note: args with spaces inside are not supported (simple word splitting)
+#COMMAND="/usr/bin/pacman -Syu"
+
 # Note: inline comments start at ' #' (space + hash).
 # Values containing a literal ' #' will be truncated at that point.
 

lib/atomic/common.sh

@@ -29,6 +29,8 @@ UPGRADE_GUARD=1
 HOME_COPY_FILES=""
 # Kernel security parameters
 KERNEL_PARAMS="rw slab_nomerge init_on_alloc=1 page_alloc.shuffle=1 pti=on vsyscall=none randomize_kstack_offset=on debugfs=off"
+# Default chroot command (overridden by config or CLI -- COMMAND...)
+COMMAND="/usr/bin/pacman -Syu"
 
 # ── Config loading (safe parser, no arbitrary code execution) ───────
 
@@ -46,7 +48,7 @@ load_config() {
     fi
 
     # Whitelist of allowed config keys
-    local -a allowed=(BTRFS_MOUNT NEW_ROOT ESP KEEP_GENERATIONS MAPPER_NAME KERNEL_PARAMS KERNEL_PKG SBCTL_SIGN UPGRADE_GUARD HOME_COPY_FILES)
+    local -a allowed=(BTRFS_MOUNT NEW_ROOT ESP KEEP_GENERATIONS MAPPER_NAME KERNEL_PARAMS KERNEL_PKG COMMAND SBCTL_SIGN UPGRADE_GUARD HOME_COPY_FILES)
 
     while IFS='=' read -r key value; do
         # Strip leading/trailing whitespace from key

man/atomic.conf.5

@@ -71,6 +71,15 @@ device arguments.
 Default: \f[B]rw slab_nomerge init_on_alloc=1 page_alloc.shuffle=1
 pti=on vsyscall=none randomize_kstack_offset=on debugfs=off\f[R].
 .TP
+\f[B]COMMAND\f[R]
+Default command to run in the snapshot chroot, overriding the built\-in
+default of \f[B]pacman \-Syu\f[R].
+Command\-line \f[B]\-\-\f[R] \f[I]COMMAND...\f[R] takes priority over
+this setting.
+Note: arguments with spaces inside are not supported due to simple word
+splitting.
+Default: \f[I](none)\f[R].
+.TP
 \f[B]SBCTL_SIGN\f[R]
 Enable UKI signing with \f[B]sbctl\f[R](8) for Secure Boot.
 Set to \f[B]1\f[R] to enable, \f[B]0\f[R] to disable.

man/atomic.conf.5.md

@@ -66,6 +66,12 @@ rejected entirely.
     page_alloc.shuffle=1 pti=on vsyscall=none randomize_kstack_offset=on
     debugfs=off**.
 
+**COMMAND**
+:   Default command to run in the snapshot chroot, overriding the built-in
+    default of **pacman -Syu**. Command-line **-- COMMAND...** takes priority
+    over this setting. Note: arguments with spaces inside are not supported
+    due to simple word splitting. Default: *(none)*.
+
 **SBCTL_SIGN**
 :   Enable UKI signing with **sbctl**(8) for Secure Boot. Set to **1** to
     enable, **0** to disable. When disabled, UKI files are built unsigned.

tests/test_config.sh

@@ -276,7 +276,40 @@ assert_eq "HOME_COPY_FILES absent → stays empty" "" "$HOME_COPY_FILES"
 # Restore
 HOME_COPY_FILES=""
 
+# ── COMMAND config ───────────────────────────────────
 
+section "COMMAND config"
+
+# Test: COMMAND loaded from config
+CONFIG_FILE="${TESTDIR}/command.conf"
+cat > "$CONFIG_FILE" <<'EOF'
+COMMAND=/usr/bin/pacman -Syu
+EOF
+COMMAND=""
+load_config
+assert_eq "COMMAND loaded from config" "/usr/bin/pacman -Syu" "$COMMAND"
+COMMAND=""
+
+# Test: COMMAND with quotes
+CONFIG_FILE="${TESTDIR}/command_quoted.conf"
+cat > "$CONFIG_FILE" <<'EOF'
+COMMAND="/usr/bin/pacman -S nvidia"
+EOF
+COMMAND=""
+load_config
+assert_eq "COMMAND with double quotes" "/usr/bin/pacman -S nvidia" "$COMMAND"
+COMMAND=""
+
+# Test: COMMAND absent → stays empty
+CONFIG_FILE="${TESTDIR}/command_absent.conf"
+cat > "$CONFIG_FILE" <<'EOF'
+KEEP_GENERATIONS=3
+EOF
+COMMAND=""
+load_config
+assert_eq "COMMAND absent → stays empty" "" "$COMMAND"
+
+#
 # ── config key whitespace trimming ─────────────
 
 section "Config key whitespace trimming"

tests/test_upgrade.sh

@@ -196,6 +196,82 @@ assert_eq "default cmd count" "CHROOT_CMD_COUNT=2" "$(echo "$_out" | grep '^CHRO
 assert_eq "default cmd[0]" "CHROOT_CMD_0=/usr/bin/pacman" "$(echo "$_out" | grep '^CHROOT_CMD_0=')"
 assert_eq "default cmd[1]" "CHROOT_CMD_1=-Syu" "$(echo "$_out" | grep '^CHROOT_CMD_1=')"
 
+# ── Word splitting limitation: args with spaces ────────────
+
+section "Word splitting limitation (space in args)"
+
+CONFIG_FILE="${TESTDIR}/word_split.conf"
+cat > "$CONFIG_FILE" <<'EOF'
+COMMAND=/usr/bin/pacman -S nvidia driver
+EOF
+
+_TEST_SCRIPT_WS="${TESTDIR}/atomic-upgrade-word-split"
+sed \
+    -e 's|^\(export ATOMIC_UPGRADE=1\)$|\1\nCONFIG_FILE="${CONFIG_FILE:-/etc/atomic.conf}"|' \
+    -e 's/^\(\[\[ \$EUID -eq 0 \]\]\)/# \1/' \
+    -e '/^# Verify required variables are set$/i\
+if [[ "${ATOMIC_EXIT_AFTER_PARSE:-}" == "1" ]]; then\
+    echo "PARSE_OK"\
+    echo "CHROOT_CMD_COUNT=${#CHROOT_CMD[@]}"\
+    for i in "${!CHROOT_CMD[@]}"; do\
+        echo "CHROOT_CMD_${i}=${CHROOT_CMD[$i]}"\
+    done\
+    exit 0\
+fi\
+' \
+    "$SCRIPT" > "$_TEST_SCRIPT_WS"
+chmod +x "$_TEST_SCRIPT_WS"
+
+run_cmd env CONFIG_FILE="$CONFIG_FILE" ATOMIC_EXIT_AFTER_PARSE=1 bash "$_TEST_SCRIPT_WS"
+assert_eq "word split: PARSE_OK" "0" "$_rc"
+assert_eq "word split: count is 4" "CHROOT_CMD_COUNT=4" "$(echo "$_out" | grep '^CHROOT_CMD_COUNT=')"
+assert_eq "word split: arg[2]" "CHROOT_CMD_2=nvidia" "$(echo "$_out" | grep '^CHROOT_CMD_2=')"
+assert_eq "word split: arg[3]" "CHROOT_CMD_3=driver" "$(echo "$_out" | grep '^CHROOT_CMD_3=')"
+
+rm -f "$_TEST_SCRIPT_WS"
+
+# ── CLI -- COMMAND priority over config COMMAND= ────────────
+
+section "CLI -- COMMAND priority over config COMMAND="
+
+CONFIG_FILE="${TESTDIR}/cli_priority.conf"
+cat > "$CONFIG_FILE" <<'EOF'
+COMMAND=/usr/bin/pacman -Syu
+EOF
+
+_TEST_SCRIPT_CLI="${TESTDIR}/atomic-upgrade-cli-priority"
+sed \
+    -e 's|^\(export ATOMIC_UPGRADE=1\)$|\1\nCONFIG_FILE="${CONFIG_FILE:-/etc/atomic.conf}"|' \
+    -e 's/^\(\[\[ \$EUID -eq 0 \]\]\)/# \1/' \
+    -e '/^# Verify required variables are set$/i\
+if [[ "${ATOMIC_EXIT_AFTER_PARSE:-}" == "1" ]]; then\
+    echo "PARSE_OK"\
+    echo "DRY_RUN=${DRY_RUN}"\
+    echo "CUSTOM_TAG=${CUSTOM_TAG}"\
+    echo "NO_GC=${NO_GC}"\
+    echo "SEPARATE_HOME=${SEPARATE_HOME}"\
+    echo "COPY_FILES=${COPY_FILES}"\
+    echo "CHROOT_CMD_COUNT=${#CHROOT_CMD[@]}"\
+    for i in "${!CHROOT_CMD[@]}"; do\
+        echo "CHROOT_CMD_${i}=${CHROOT_CMD[$i]}"\
+    done\
+    echo "COMMAND_FROM_CONFIG=${COMMAND:-}"\
+    exit 0\
+fi\
+' \
+    "$SCRIPT" > "$_TEST_SCRIPT_CLI"
+chmod +x "$_TEST_SCRIPT_CLI"
+
+run_cmd env CONFIG_FILE="$CONFIG_FILE" ATOMIC_EXIT_AFTER_PARSE=1 bash "$_TEST_SCRIPT_CLI" -- /usr/bin/pacman -S nvidia
+assert_eq "CLI priority: PARSE_OK" "0" "$_rc"
+assert_contains "CLI priority: uses CLI args" "CHROOT_CMD_0=/usr/bin/pacman" "$_out"
+assert_contains "CLI priority: CLI arg[1]" "CHROOT_CMD_1=-S" "$_out"
+assert_contains "CLI priority: CLI arg[2]" "CHROOT_CMD_2=nvidia" "$_out"
+assert_eq "CLI priority: count is 3" "CHROOT_CMD_COUNT=3" "$(echo "$_out" | grep '^CHROOT_CMD_COUNT=')"
+assert_contains "CLI priority: COMMAND loaded from config" "COMMAND_FROM_CONFIG=/usr/bin/pacman -Syu" "$_out"
+
+rm -f "$_TEST_SCRIPT_CLI"
+
 # ── GEN_ID format validation ────────────────────────────────
 
 section "GEN_ID format validation"