fix(cryptsetup): parse --help and man for actions

Author: akinomyoga

completions/cryptsetup

@@ -10,6 +10,50 @@ _comp_cmd_cryptsetup__device()
     _comp_compgen -c "${cur:-/dev/}" filedir
 }
 
+_comp_cmd_cryptsetup__action()
+{
+    local ret IFS=$' \t\n'
+    _comp_dequote "$1" || return 1
+    local cmd=${ret:-cryptsetup}
+    local actions=$(
+        {
+            LC_ALL=C "$cmd" --help 2>&1 |
+                sed -n '/^<action> is one of:/,/^[^[:space:]]/s/^[[:space:]]\{1,\}\([^[:space:]]\{1,\}\).*/\1/p'
+            LC_ALL=C man cryptsetup 2>&1 |
+                awk '/^[[:space:]]+[[:alnum:]_]+([[:space:]]+(-[^[:space:].]+|<[^<>]+>|\[[^][]+\]|or))*$/ {print $1}'
+        } | sort -u
+    )
+
+    if [[ ! $actions ]]; then
+        # The fallback action list is extracted from the following source:
+        # https://gitlab.com/cryptsetup/cryptsetup/-/blob/main/src/cryptsetup.c#L3154-3208 (search for "Handle aliases")
+        # https://gitlab.com/cryptsetup/cryptsetup/-/blob/main/src/cryptsetup.c#L2831-2867 (search for "struct action_type")
+        # https://gitlab.com/cryptsetup/cryptsetup/-/blob/main/src/cryptsetup_args.h#L28-53 (see the macros "*_ACTION")
+        actions='benchmark bitlkClose bitlkDump bitlkOpen close config convert
+            create erase isLuks loopaesClose loopaesOpen luksAddKey
+            luksChangeKey luksClose luksConfig luksConvertKey luksDump
+            luksErase luksFormat luksHeaderBackup luksHeaderRestore
+            luksKillSlot luksOpen luksRemoveKey luksResume luksSuspend luksUUID
+            open plainClose plainOpen reencrypt refresh remove repair resize
+            status tcryptClose tcryptDump tcryptOpen token'
+
+        # We attempt to filter the supported actions by the strings in the binary.
+        local path
+        if path=$(type -P -- "$cmd" 2>/dev/null || type -P -- cryptsetup 2>/dev/null); then
+            local filtering_pattern
+            printf -v filtering_pattern '%s\n' $actions
+            filtering_pattern=${filtering_pattern%$'\n'}
+
+            local filtered_actions
+            filtered_actions=$(strings "$path" | grep -Fx "$filtering_pattern" | sort -u) &&
+                [[ $filtered_actions ]] &&
+                actions=$filtered_actions
+        fi
+    fi
+
+    _comp_compgen -- -W "$actions"
+}
+
 _comp_cmd_cryptsetup()
 {
     local cur prev words cword was_split comp_args
@@ -41,14 +85,7 @@ _comp_cmd_cryptsetup()
             _comp_compgen_help
             [[ ${COMPREPLY-} == *= ]] && compopt -o nospace
         else
-            _comp_compgen -- -W 'benchmark bitlkClose bitlkDump bitlkOpen close
-                config convert create erase isLuks loopaesClose loopaesOpen
-                luksAddKey luksChangeKey luksClose luksConfig luksConvertKey
-                luksDump luksErase luksFormat luksHeaderBackup
-                luksHeaderRestore luksKillSlot luksOpen luksRemoveKey
-                luksResume luksSuspend luksUUID open plainClose plainOpen
-                reencrypt refresh remove repair resize status tcryptClose
-                tcryptDump tcryptOpen token'
+            _comp_cmd_cryptsetup__action "$1"
         fi
     else
         local args