commit to some level of style in variable naming

This is an ugly patch, and probably does more than I'd like it to. The
idea is that mkinitcpio adopts some sort of consistent style which I'm
actually happy with. I define 3 kinds of variables:

1) local variables: all lower case, and scoped within functions. Use
freely, as they're well contained.

2) global variables: these are known to mkinitcpio internally, but are
global in scope. They mainly carry runtime configuration and collected
data during the image generation process. These are always lower case,
but carry a leading underscore to denote that they're global.

3) "API" variables: also global in scope, but exist "outside" of
mkinitcpio -- either drawn in from the configuration file, or "exported"
to the install hooks. These are always all upper case. When introducing
new variables, extreme care must be taken to pick names that will not
conflict with the environment inherited by mkinitcpio.

A HACKING file is introduced with a similar description of the above,
and more.

Signed-off-by: Dave Reisner <dreisner@archlinux.org>

1 files changed, 104 insertions, 101 deletions

diff --git a/mkinitcpio b/mkinitcpio
index f92cc44..0300954 100755
--- a/mkinitcpio
+++ b/mkinitcpio
@@ -7,19 +7,22 @@ declare -r version=%VERSION%
 
 shopt -s extglob
 
-# Settings
-FUNCTIONS=functions
-CONFIG=mkinitcpio.conf
-HOOKDIR=(hooks /usr/lib/initcpio/hooks /lib/initcpio/hooks)
-INSTDIR=(install /usr/lib/initcpio/install /lib/initcpio/install)
-PRESETDIR=mkinitcpio.d
-COMPRESSION=gzip
-
-declare MODULE_FILE= GENIMG= PRESET= COMPRESSION_OPTIONS= BUILDROOT=
-declare NC= BOLD= BLUE= GREEN= RED= YELLOW=
-declare -i QUIET=1 SHOW_AUTOMODS=0 SAVELIST=0 COLOR=1
-declare -a SKIPHOOKS MODPATHS
-declare -A RUNHOOKS ADDED_MODULES
+### globals within mkinitcpio, but not intended to be used by hooks
+
+# needed files/directories
+_f_functions=functions
+_f_config=mkinitcpio.conf
+_d_hooks=(hooks /usr/lib/initcpio/hooks /lib/initcpio/hooks)
+_d_install=(install /usr/lib/initcpio/install /lib/initcpio/install)
+_d_presets=mkinitcpio.d
+
+# options and runtime data
+_optmoduleroot= _optkver= _f_autodetect_cache= _optgenimg= _optpreset=
+_optcompress=
+_optshowautomods=0 _optsavetree=0 _optshowmods=0
+_optquiet=1 _optcolor=1
+_optskiphooks=() _optaddhooks=() _modpaths=() _hooks=()
+declare -A _runhooks=() _addedmodules=()
 
 # export a sane PATH
 export PATH='/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin'
@@ -58,12 +61,12 @@ EOF
 cleanup() {
     local err=${1:-$?}
 
-    if [[ $workdir ]]; then
-        # when PRESET is set, we're in the main loop, not a worker process
-        if (( SAVELIST )) && [[ -z $PRESET ]]; then
-            msg "build directory saved in %s" "$workdir"
+    if [[ $_d_workdir ]]; then
+        # when _optpreset is set, we're in the main loop, not a worker process
+        if (( _optsavetree )) && [[ -z $_optpreset ]]; then
+            msg "build directory saved in %s" "$_d_workdir"
         else
-            rm -rf "$workdir"
+            rm -rf "$_d_workdir"
         fi
     fi
 
@@ -71,7 +74,7 @@ cleanup() {
 }
 
 resolve_kernver() {
-    local kernver= kernel=$1
+    local kernel=$1
 
     if [[ -z $kernel ]]; then
         uname -r
@@ -92,7 +95,7 @@ resolve_kernver() {
         return 0
     fi
 
-    error "invalid kernel specified: \`%s'" "$optkver"
+    error "invalid kernel specified: \`%s'" "$_optkver"
 
     return 1
 }
@@ -100,7 +103,7 @@ resolve_kernver() {
 find_moduledir() {
     local d
 
-    for d in "$MODULEROOT"{/usr,}/lib/modules; do
+    for d in "$_optmoduleroot"{/usr,}/lib/modules; do
         if [[ -d $d/$1/ ]]; then
             printf '%s' "$d/$1/"
             return 0
@@ -113,25 +116,27 @@ find_moduledir() {
 }
 
 compute_hookset() {
-    for h in $HOOKS "${ADDHOOKS[@]}"; do
-        in_array "$h" "${SKIPHOOKS[@]}" && continue
-        hooks+=("$h")
+    local h
+
+    for h in $HOOKS "${_optaddhooks[@]}"; do
+        in_array "$h" "${_optskiphooks[@]}" && continue
+        _hooks+=("$h")
     done
 }
 
-. "$FUNCTIONS"
+. "$_f_functions"
 
 trap 'cleanup 130' INT
 trap 'cleanup 143' TERM
 
-OPT_SHORT='A:c:g:H:hk:mnLMp:r:S:st:vz:'
-OPT_LONG=('add:' 'addhooks:' 'config:' 'generate:' 'hookhelp:' 'help'
+_opt_short='A:c:g:H:hk:nLMp:r:S:st:vz:'
+_opt_long=('add:' 'addhooks:' 'config:' 'generate:' 'hookhelp:' 'help'
           'kernel:' 'listhooks' 'automods' 'moduleroot:' 'nocolor'
           'preset:' 'skiphooks:' 'save' 'builddir:' 'verbose' 'compress:')
 
-parseopts "$OPT_SHORT" "${OPT_LONG[@]}" -- "$@" || exit 1
+parseopts "$_opt_short" "${_opt_long[@]}" -- "$@" || exit 1
 set -- "${OPTRET[@]}"
-unset OPT_SHORT OPT_LONG OPTRET
+unset _opt_short _opt_long OPTRET
 
 while :; do
     case $1 in
@@ -139,20 +144,20 @@ while :; do
         -A|--add|--addhooks)
             shift
             IFS=, read -r -a add <<< "$1"
-            ADDHOOKS+=("${add[@]}")
+            _optaddhooks+=("${add[@]}")
             unset add ;;
         -c|--config)
             shift
-            CONFIG=$1 ;;
+            _f_config=$1 ;;
         -k|--kernel)
             shift
-            optkver=$1 ;;
+            _optkver=$1 ;;
         -s|--save)
-            SAVELIST=1 ;;
+            _optsavetree=1 ;;
         -g|--generate)
             shift
             [[ -d $1 ]] && die "Invalid image path -- must not be a directory"
-            if ! GENIMG=$(readlink -f "$1") || [[ ! -e ${GENIMG%/*} ]]; then
+            if ! _optgenimg=$(readlink -f "$1") || [[ ! -e ${_optgenimg%/*} ]]; then
                 die "Unable to write to path: \`%s'" "$1"
             fi ;;
         -h|--help)
@@ -160,19 +165,19 @@ while :; do
             cleanup 0 ;;
         -p|--preset)
             shift
-            PRESET=$1 ;;
+            _optpreset=$1 ;;
         -n|--nocolor)
-            COLOR=0 ;;
+            _optcolor=0 ;;
         -v|--verbose)
-            QUIET=0 ;;
+            _optquiet=0 ;;
         -S|--skiphooks)
             shift
             IFS=, read -r -a skip <<< "$1"
-            SKIPHOOKS+=("${skip[@]}")
+            _optskiphooks+=("${skip[@]}")
             unset skip ;;
         -H|--hookhelp)
             shift
-            if script=$(find_in_dirs "$1" "${INSTDIR[@]}"); then
+            if script=$(find_in_dirs "$1" "${_d_install[@]}"); then
                 . "$script"
                 if ! declare -f help >/dev/null; then
                     error "No help for hook $1"
@@ -188,21 +193,21 @@ while :; do
             exit 0 ;;
         -L|--listhooks)
             msg "Available hooks"
-            for dir in "${INSTDIR[@]}"; do
+            for dir in "${_d_install[@]}"; do
                 ( cd "$dir" &>/dev/null && printf '   %s\n' * )
             done | sort -u | column -c$(tput cols)
             exit 0 ;;
         -M|--automods)
-            SHOW_AUTOMODS=1 ;;
+            _optshowautomods=1 ;;
         -t|--builddir)
             shift
             export TMPDIR=$1 ;;
         -z|--compress)
             shift
-            optcompress=$1 ;;
+            _optcompress=$1 ;;
         -r|--moduleroot)
             shift
-            MODULEROOT=$1 ;;
+            _optmoduleroot=$1 ;;
         --)
             shift
             break 2 ;;
@@ -210,25 +215,24 @@ while :; do
     shift
 done
 
-if [[ -t 1 ]] && (( COLOR )); then
+if [[ -t 1 ]] && (( _optcolor )); then
     # prefer terminal safe colored and bold text when tput is supported
     if tput setaf 0 &>/dev/null; then
-        NC="$(tput sgr0)"
-        BOLD="$(tput bold)"
-        BLUE="$BOLD$(tput setaf 4)"
-        GREEN="$BOLD$(tput setaf 2)"
-        RED="$BOLD$(tput setaf 1)"
-        YELLOW="$BOLD$(tput setaf 3)"
+        _color_none="$(tput sgr0)"
+        _color_bold="$(tput bold)"
+        _color_blue="$_color_bold$(tput setaf 4)"
+        _color_green="$_color_bold$(tput setaf 2)"
+        _color_red="$_color_bold$(tput setaf 1)"
+        _color_yellow="$_color_bold$(tput setaf 3)"
     else
-        NC="\e[1;0m"
-        BOLD="\e[1;1m"
-        BLUE="$BOLD\e[1;34m"
-        GREEN="$BOLD\e[1;32m"
-        RED="$BOLD\e[1;31m"
-        YELLOW="$BOLD\e[1;33m"
+        _color_none="\e[1;0m"
+        _color_bold="\e[1;1m"
+        _color_blue="$_color_bold\e[1;34m"
+        _color_green="$_color_bold\e[1;32m"
+        _color_red="$_color_bold\e[1;31m"
+        _color_yellow="$_color_bold\e[1;33m"
     fi
 fi
-readonly NC BOLD BLUE GREEN RED YELLOW
 
 # insist that /proc and /dev be mounted (important for chroots)
 # NOTE: avoid using mountpoint for this -- look for the paths that we actually
@@ -236,18 +240,18 @@ readonly NC BOLD BLUE GREEN RED YELLOW
 [[ -e /proc/self/mountinfo ]] || die "/proc must be mounted!"
 [[ -e /dev/fd ]] || die "/dev must be mounted!"
 
-# use preset $PRESET
-if [[ $PRESET ]]; then
+# use preset $_optpreset
+if [[ $_optpreset ]]; then
     # allow absolute path to preset file, else resolve it
-    if [[ ${PRESET:0:1} != '/' ]]; then
-        printf -v PRESET '%s/%s.preset' "$PRESETDIR" "$PRESET"
+    if [[ ${_optpreset:0:1} != '/' ]]; then
+        printf -v _optpreset '%s/%s.preset' "$_d_presets" "$_optpreset"
     fi
-    if [[ -f $PRESET ]]; then
+    if [[ -f $_optpreset ]]; then
         # Use -b, -m and -v options specified earlier
         declare -a preset_mkopts preset_cmd
-        (( QUIET )) || preset_mkopts+=(-v)
+        (( _optquiet )) || preset_mkopts+=(-v)
         # Build all images
-        . "$PRESET"
+        . "$_optpreset"
         for p in "${PRESETS[@]}"; do
             msg "Building image from preset: '$p'"
             preset_cmd=("${preset_mkopts[@]}")
@@ -286,53 +290,52 @@ if [[ $PRESET ]]; then
         done
         cleanup 0
     else
-        die "Preset not found: \`%s'" "$PRESET"
+        die "Preset not found: \`%s'" "$_optpreset"
     fi
 fi
 
-KERNELVERSION=$(resolve_kernver "$optkver") || cleanup 1
-MODULEDIR=$(find_moduledir "$KERNELVERSION") || cleanup 1
+KERNELVERSION=$(resolve_kernver "$_optkver") || cleanup 1
+_d_kmoduledir=$(find_moduledir "$KERNELVERSION") || cleanup 1
 
-# initialize the working directory and buildroot
-workdir=$(initialize_buildroot "$KERNELVERSION") || cleanup 1
-BUILDROOT=$workdir/root
+_d_workdir=$(initialize_buildroot "$KERNELVERSION") || cleanup 1
+BUILDROOT=$_d_workdir/root
 
-. "$CONFIG" || die "Failed to read configuration \`%s'" "$CONFIG"
+. "$_f_config" || die "Failed to read configuration \`%s'" "$_f_config"
 
-# after returning, hooks are populated into the array 'hooks'
+# after returning, hooks are populated into the array '_hooks'
 # HOOKS should not be referenced from here on
 compute_hookset
 
-if (( ${#hooks[*]} == 0 )); then
+if (( ${#_hooks[*]} == 0 )); then
     die "Invalid config: No hooks found"
 fi
 
-if [[ ! -d $MODULEDIR ]]; then
-    die "'$MODULEDIR' is not a valid kernel module directory"
+if [[ ! -d $_d_kmoduledir ]]; then
+    die "'$_d_kmoduledir' is not a valid kernel module directory"
 fi
 
-if (( SHOW_AUTOMODS )); then
+if (( _optshowautomods )); then
     msg "Modules autodetected"
-    autodetect=$(find_in_dirs 'autodetect' "${INSTDIR[@]}")
-    . "$autodetect"
+    _f_autodetect_hook=$(find_in_dirs 'autodetect' "${_d_install[@]}")
+    . "$_f_autodetect_hook"
     build
-    cat "$MODULE_FILE"
+    cat "$_f_autodetect_cache"
     cleanup 0
 fi
 
-if [[ -z $GENIMG ]]; then
+if [[ -z $_optgenimg ]]; then
     msg "Starting dry run: %s" "$KERNELVERSION"
 else
     # check for permissions. if the image doesn't already exist,
     # then check the directory
-    if [[ ( -e $GENIMG && ! -w $GENIMG ) ||
-            ( ! -d ${GENIMG%/*} || ! -w ${GENIMG%/*} ) ]]; then
-        die 'Unable to write to %s' "$GENIMG"
+    if [[ ( -e $_optgenimg && ! -w $_optgenimg ) ||
+            ( ! -d ${_optgenimg%/*} || ! -w ${_optgenimg%/*} ) ]]; then
+        die 'Unable to write to %s' "$_optgenimg"
     fi
 
-    COMPRESSION=${optcompress:-$COMPRESSION}
-    if ! type -P "$COMPRESSION" >/dev/null; then
-        die "Unable to locate compression method: %s" "$COMPRESSION"
+    _optcompress=${_optcompress:-${COMPRESSION:-gzip}}
+    if ! type -P "$_optcompress" >/dev/null; then
+        die "Unable to locate compression method: %s" "$_optcompress"
     fi
 
     msg "Starting build: %s" "$KERNELVERSION"
@@ -343,14 +346,14 @@ declare -i builderrors=0
 set -o functrace
 trap '(( $? )) && [[ $FUNCNAME = add_* ]] && (( ++builderrors ))' RETURN
 
-# prime the ADDED_MODULES list with the builtins for this kernel
-if [[ -r $MODULEDIR/modules.builtin ]]; then
+# prime the _addedmodules list with the builtins for this kernel
+if [[ -r $_d_kmoduledir/modules.builtin ]]; then
     while read -a path; do
-        ADDED_MODULES["${path[-1]%.ko}"]=2
-    done <"$MODULEDIR/modules.builtin"
+        _addedmodules["${path[-1]%.ko}"]=2
+    done <"$_d_kmoduledir/modules.builtin"
 fi
 
-for hook in "${hooks[@]}"; do
+for hook in "${_hooks[@]}"; do
     run_build_hook "$hook" || (( ++builderrors ))
 done
 
@@ -362,8 +365,8 @@ write_image_config
 trap -- RETURN
 trap '(( ++builderrors ))' ERR
 
-if (( ${#MODPATHS[*]} )); then
-    printf '%s\0' "${MODPATHS[@]}" | sort -zu |
+if (( ${#_modpaths[*]} )); then
+    printf '%s\0' "${_modpaths[@]}" | sort -zu |
         xargs -0 cp -t "$BUILDROOT/usr/lib/modules/$KERNELVERSION/kernel"
 
     # unzip modules prior to recompression
@@ -371,12 +374,12 @@ if (( ${#MODPATHS[*]} )); then
 
     msg "Generating module dependencies"
     install -m644 -t "$BUILDROOT/usr/lib/modules/$KERNELVERSION" \
-        "$MODULEDIR"/modules.builtin
+        "$_d_kmoduledir"/modules.builtin
 
     # we install all modules into kernel/, making the .order file incorrect
     # for the module tree. munge it, so that we have an accurate index.
     awk -F'/' '{ print "kernel/" $NF }' \
-        "$MODULEDIR"/modules.order >"$BUILDROOT/lib/modules/$KERNELVERSION/modules.order"
+        "$_d_kmoduledir"/modules.order >"$BUILDROOT/lib/modules/$KERNELVERSION/modules.order"
 
     depmod -b "$BUILDROOT" "$KERNELVERSION"
 
@@ -392,17 +395,17 @@ set +o functrace
 trap -- ERR
 
 declare -i status=0
-if [[ $GENIMG ]]; then
-    msg "Creating $COMPRESSION initcpio image: %s" "$GENIMG"
+if [[ $_optgenimg ]]; then
+    msg "Creating $_optcompress initcpio image: %s" "$_optgenimg"
 
-    case $COMPRESSION in
+    case $_optcompress in
         xz)
             COMPRESSION_OPTIONS+=' --check=crc32'
             ;;
     esac
 
     cpio_opts=('-R' '0:0' '-0' '-o' '-H' 'newc')
-    if (( QUIET )); then
+    if (( _optquiet )); then
         cpio_opts+=('--quiet')
     fi
 
@@ -412,7 +415,7 @@ if [[ $GENIMG ]]; then
     pushd "$BUILDROOT" >/dev/null
     find . -print0 |
             LANG=C bsdcpio "${cpio_opts[@]}" |
-            $COMPRESSION $COMPRESSION_OPTIONS > "$GENIMG"
+            $_optcompress $COMPRESSION_OPTIONS > "$_optgenimg"
     pipesave=("${PIPESTATUS[@]}") # save immediately
     popd >/dev/null
 
@@ -421,7 +424,7 @@ if [[ $GENIMG ]]; then
     elif (( pipesave[1] )); then
         errmsg="bsdcpio reported an error"
     elif (( pipesave[2] )); then
-        errmsg="$COMPRESSION reported an error"
+        errmsg="$_optcompress reported an error"
     fi
 
     if (( builderrors )); then