refactor(bash_completion): refactor { => _comp_}{dequote,quote}

bash_completion

@@ -148,6 +148,16 @@ _comp_readline_variable_on()
 _comp_deprecate_func _rl_enabled _comp_readline_variable_on
 
 # This function shell-quotes the argument
+# @param    $1  String to be quoted
+# @var[out] ret Resulting string
+_comp_quote()
+{
+    ret=\'${1//\'/\'\\\'\'}\'
+}
+
+# This function shell-quotes the argument
+# @deprecated Use `_comp_quote` instead.  Note that `_comp_quote` stores
+#   the results in the variable `ret` instead of writing them to stdout.
 quote()
 {
     local quoted=${1//\'/\'\\\'\'}
@@ -162,10 +172,77 @@ quote_readline()
     printf %s "$ret"
 } # quote_readline()
 
+# shellcheck disable=SC1003
+_comp_dequote__initialize()
+{
+    unset -f "$FUNCNAME"
+    local regex_param='\$([_a-zA-Z][_a-zA-Z0-9]*|[-*@#?$!0-9_])|\$\{[!#]?([_a-zA-Z][_a-zA-Z0-9]*(\[([0-9]+|[*@])\])?|[-*@#?$!0-9_])\}'
+    local regex_quoted='\\.|'\''[^'\'']*'\''|\$?"([^\"$`!]|'$regex_param'|\\.)*"|\$'\''([^\'\'']|\\.)*'\'''
+    _comp_dequote__regex_safe_word='^([^\'\''"$`;&|<>()!]|'$regex_quoted'|'$regex_param')*$'
+}
+_comp_dequote__initialize
+
+# This function expands a word using `eval` in a safe way.  This function can
+# be typically used to get the expanded value of `${word[i]}` as
+# `_comp_dequote "${word[i]}"`.  When the word contains unquoted shell special
+# characters, command substitutions, and other unsafe strings, the function
+# call fails before applying `eval`.  Otherwise, `eval` is applied to the
+# string to generate the result.
+#
+# @param    $1  String to be expanded.  A safe word consists of the following
+#               sequence of substrings:
+#
+#               - Shell non-special characaters: [^\'"$`;&|<>()!].
+#               - Parameter expansions of the forms $PARAM, ${!PARAM},
+#                 ${#PARAM}, ${NAME[INDEX]}, ${!NAME[INDEX]}, ${#NAME[INDEX]}
+#                 where INDEX is an integer, `*` or `@`, NAME is a valid
+#                 variable name [_a-zA-Z][_a-zA-Z0-9]*, and PARAM is NAME or a
+#                 parameter [-*@#?$!0-9_].
+#               - Quotes \?, '...', "...", $'...', and $"...".  In the double
+#                 quotations, parameter expansions are allowed.
+#
+# @var[out] ret Array that contains the expanded results.  Multiple words or no
+#               words may be generated through pathname expansions.
+#
+# Note: This function allows parameter expansions as safe strings, which might
+# cause unexpected results:
+#
+# * This allows execution of arbitrary commands through extra expansions of
+#   array subscripts in name references. For example,
+#
+#     declare -n v='dummy[$(echo xxx >/dev/tty)]'
+#     echo "$v"            # This line executes the command 'echo xxx'.
+#     _comp_dequote '"$v"' # This line also executes it.
+#
+# * This may change the internal state of the variable that has side effects.
+#   For example, the state of the random number generator of RANDOM can change:
+#
+#     RANDOM=1234               # Set seed
+#     echo "$RANDOM"            # This produces 30658.
+#     RANDOM=1234               # Reset seed
+#     _comp_dequote '"$RANDOM"' # This line changes the internal state.
+#     echo "$RANDOM"            # This fails to reproduce 30658.
+#
+# We allow these parameter expansions as a part of safe strings assuming the
+# referential transparency of the simple parameter expansions and the sane
+# setup of the variables by the user or other frameworks that the user loads.
+_comp_dequote()
+{
+    ret=() # fallback value for unsafe word and failglob
+    [[ $1 =~ $_comp_dequote__regex_safe_word ]] || return 1
+    eval "ret=($1)" 2>/dev/null # may produce failglob
+}
+
 # This function shell-dequotes the argument
+# @deprecated Use `_comp_dequote' instead.  Note that `_comp_dequote` stores
+#   the results in the array `ret` instead of writing them to stdout.
 dequote()
 {
-    eval printf %s "$1" 2>/dev/null
+    local ret
+    _comp_dequote "$1"
+    local rc=$?
+    printf %s "$ret"
+    return $rc
 }
 
 # Unset the given variables across a scope boundary. Useful for unshadowing
@@ -1030,14 +1107,14 @@ _parse_help()
     shopt -s lastpipe
     set -o noglob
 
-    eval local cmd="$(quote "$1")"
+    local cmd=$1
     local line rc=1
-    {
+    (
         case $cmd in
-            -) cat ;;
-            *) LC_ALL=C "$(dequote "$cmd")" ${2:---help} 2>&1 ;;
+            -) exec cat ;;
+            *) _comp_dequote "$cmd" && LC_ALL=C "$ret" ${2:---help} 2>&1 ;;
         esac
-    } |
+    ) |
         while read -r line; do
 
             [[ $line == *([[:blank:]])-* ]] || continue
@@ -1067,14 +1144,14 @@ _parse_usage()
     shopt -s lastpipe
     set -o noglob
 
-    eval local cmd="$(quote "$1")"
+    local cmd=$1
     local line match option i char rc=1
-    {
+    (
         case $cmd in
-            -) cat ;;
-            *) LC_ALL=C "$(dequote "$cmd")" ${2:---usage} 2>&1 ;;
+            -) exec cat ;;
+            *) _comp_dequote "$cmd" && LC_ALL=C "$ret" ${2:---usage} 2>&1 ;;
         esac
-    } |
+    ) |
         while read -r line; do
 
             while [[ $line =~ \[[[:space:]]*(-[^]]+)[[:space:]]*\] ]]; do

completions/_umount.linux

@@ -15,8 +15,10 @@ _reply_compgen_array()
     # argument.
     local i wlist
     for i in ${!COMPREPLY[*]}; do
-        local q=$(quote "$(printf %q "${COMPREPLY[i]}")")
-        wlist+=$q$'\n'
+        local ret
+        printf -v ret %q "${COMPREPLY[i]}"
+        _comp_quote "$ret"
+        wlist+=$ret$'\n'
     done
 
     # We also have to add another round of escaping to $cur.

completions/export

@@ -30,7 +30,10 @@ _export()
 
     case $cur in
         *=)
-            local pval=$(quote "$(eval printf %s \"\$\{${cur%=}-\}\")")
+            local pname=${cur%=}
+            local ret
+            _comp_quote "${!pname-}"
+            local pval=$ret
             # Complete previous value if it's not empty.
             if [[ $pval != \'\' ]]; then
                 COMPREPLY=("$pval")

completions/make

@@ -135,8 +135,11 @@ _make()
         # with -C/--directory
         for ((i = 1; i < ${#words[@]}; i++)); do
             if [[ ${words[i]} == -@(C|-directory) ]]; then
-                # eval for tilde expansion
-                eval "makef_dir=( -C \"${words[i + 1]}\" )"
+                # Expand tilde expansion
+                local ret
+                _comp_dequote "${words[i + 1]-}" &&
+                    [[ -d ${ret-} ]] &&
+                    makef_dir=(-C "$ret")
                 break
             fi
         done
@@ -145,8 +148,11 @@ _make()
         # specified with -f/--file/--makefile
         for ((i = 1; i < ${#words[@]}; i++)); do
             if [[ ${words[i]} == -@(f|-?(make)file) ]]; then
-                # eval for tilde expansion
-                eval "makef=( -f \"${words[i + 1]}\" )"
+                # Expand tilde expansion
+                local ret
+                _comp_dequote "${words[i + 1]-}" &&
+                    [[ -f ${ret-} ]] &&
+                    makef=(-f "$ret")
                 break
             fi
         done

completions/mutt

@@ -16,22 +16,24 @@ _muttaddr()
 # @output  muttrc filename
 _muttrc()
 {
+    local muttrc=
     # Search COMP_WORDS for '-F muttrc' or '-Fmuttrc' argument
     set -- "${words[@]}"
     while (($# > 0)); do
         if [[ $1 == -F* ]]; then
+            local ret
             if ((${#1} > 2)); then
-                muttrc="$(dequote "${1:2}")"
+                _comp_dequote "${1:2}" && muttrc=$ret
             else
                 shift
-                [[ $1 ]] && muttrc="$(dequote "$1")"
+                [[ ${1-} ]] && _comp_dequote "$1" && muttrc=$ret
             fi
             break
         fi
         shift
     done
 
-    if [[ ! -v muttrc ]]; then
+    if [[ ! $muttrc ]]; then
         if [[ -f ~/.${muttcmd}rc ]]; then
             muttrc=\~/.${muttcmd}rc
         elif [[ -f ~/.${muttcmd}/${muttcmd}rc ]]; then
@@ -42,27 +44,48 @@ _muttrc()
 }
 
 # Recursively build list of sourced config files
-# @param $1  List of config files found so far
-# @param $2  Config file to process
-# @output  List of config files
-_muttconffiles()
+# @param $1...   Config file to process
+# @var[out] ret  List of config files
+# @return 0 if any conffiles are generated, 1 if none is generated.
+_comp_cmd_mutt__get_conffiles()
 {
-    local file sofar
-    local -a newconffiles
-
-    sofar=" $1 "
-    shift
-    while [[ ${1-} ]]; do
-        newconffiles=($(command sed -n 's|^source[[:space:]]\{1,\}\([^[:space:]]\{1,\}\).*$|\1|p' "$(eval printf %s $1)"))
-        for file in ${newconffiles+"${newconffiles[@]}"}; do
-            __expand_tilde_by_ref file
-            [[ ! -f $file || $sofar == *\ $file\ * ]] && continue
-            sofar+=" $file"
-            sofar=" $(eval _muttconffiles \"$sofar\" $file) "
-        done
-        shift
+    local -a conffiles=()
+    local -A visited=()
+    local file
+    for file; do
+        _comp_dequote "$file"
+        _comp_cmd_mutt__get_conffiles__visit "$ret"
+    done
+    ((${#conffiles[@]})) || return 1
+    ret=("${conffiles[@]}")
+}
+# Recursion function for _comp_cmd_mutt__get_conffiles
+# @var[ref] conffiles  List of config files found so far
+# @var[ref] visited    Dictionary of config files already visited
+_comp_cmd_mutt__get_conffiles__visit()
+{
+    [[ -f $1 && ${visited[$1]-} != yes ]] || return 0
+    visited[$1]=yes
+    conffiles+=("$1")
+
+    local -a newconffiles=($(command sed -n 's|^source[[:space:]]\{1,\}\([^[:space:]]\{1,\}\).*$|\1|p' "$1"))
+    ((${#newconffiles[@]})) || return 0
+
+    local file
+    for file in "${newconffiles[@]}"; do
+        __expand_tilde_by_ref file
+        _comp_cmd_mutt__get_conffiles__visit "$file"
     done
-    printf '%s\n' $sofar
+}
+
+# Recursively build list of sourced config files
+# @param $1...  Config file to process
+# @output       List of config files
+_muttconffiles()
+{
+    local ret
+    _comp_cmd_mutt__get_conffiles "$@" &&
+        printf '%s\n' "${ret[@]}"
 }
 
 # @param $1 (cur) Current word to complete
@@ -74,11 +97,14 @@ _muttaliases()
     muttrc=$(_muttrc)
     [[ ! $muttrc ]] && return
 
-    conffiles=($(eval _muttconffiles $muttrc $muttrc))
+    local ret
+    _comp_cmd_mutt__get_conffiles "$muttrc" || return 0
+    conffiles=("${ret[@]}")
     # shellcheck disable=SC2046
-    aliases=("$(command sed -n 's|^alias[[:space:]]\{1,\}\([^[:space:]]\{1,\}\).*$|\1|p' \
-        "${conffiles[@]}")")
-    COMPREPLY+=($(compgen -W "${aliases[*]}" -- "$cur"))
+    aliases=($(command sed -n 's|^alias[[:space:]]\{1,\}\([^[:space:]]\{1,\}\).*$|\1|p' \
+        "${conffiles[@]}"))
+    ((${#aliases[@]})) &&
+        COMPREPLY+=($(compgen -W '"${aliases[@]}"' -- "$cur"))
 }
 
 # @param $1 (cur) Current word to complete

completions/pkgadd

@@ -49,7 +49,9 @@ _pkgadd()
                     done
                     pkginst_list="${tmplist[*]}"
                 else
-                    pkginst_list="$(strings "$(dequote $device)" |
+                    local ret
+                    _comp_dequote "$device"
+                    pkginst_list="$(strings "$ret" |
                         command grep ^PKG= | sort -u | cut -d= -f2)"
                 fi
                 COMPREPLY=($(compgen -W "$pkginst_list" -- ${cur}))

completions/pkgutil

@@ -29,7 +29,9 @@ _pkgutil()
             local catalog=$(_pkgutil_url2catalog "$url")
             catalog_files=("$catalog")
         elif [[ ${words[i]} == --config ]]; then
-            configuration_files=("$(dequote ${words[i + 1]})")
+            local ret
+            _comp_dequote "${words[i + 1]}"
+            [[ ${ret-} ]] && configuration_files=("$ret")
         elif [[ ${words[i]} == -@([iurdacUS]|-install|-upgrade|-remove|-download|-available|-compare|-catalog|-stream) ]]; then
             command="${words[i]}"
         fi

completions/ssh

@@ -233,11 +233,12 @@ _ssh_configfile()
     set -- "${words[@]}"
     while (($# > 0)); do
         if [[ $1 == -F* ]]; then
+            local ret
             if ((${#1} > 2)); then
-                configfile="$(dequote "${1:2}")"
+                _comp_dequote "${1:2}" && configfile=$ret
             else
                 shift
-                [[ ${1-} ]] && configfile="$(dequote "$1")"
+                [[ ${1-} ]] && _comp_dequote "$1" && configfile=$ret
             fi
             break
         fi