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#! @shell@ -e
# FIXME: rewrite this in a more suitable language.
usage () {
exec man nixos-option
exit 1
}
#####################
# Process Arguments #
#####################
xml=false
verbose=false
option=""
argfun=""
for arg; do
if test -z "$argfun"; then
case $arg in
-*)
sarg="$arg"
longarg=""
while test "$sarg" != "-"; do
case $sarg in
--*) longarg=$arg; sarg="--";;
-*) usage;;
esac
# remove the first letter option
sarg="-${sarg#??}"
done
;;
*) longarg=$arg;;
esac
for larg in $longarg; do
case $larg in
--xml) xml=true;;
--verbose) verbose=true;;
--help) usage;;
-*) usage;;
*) if test -z "$option"; then
option="$larg"
else
usage
fi;;
esac
done
else
case $argfun in
set_*)
var=$(echo $argfun | sed 's,^set_,,')
eval $var=$arg
;;
esac
argfun=""
fi
done
if $verbose; then
set -x
else
set +x
fi
#############################
# Process the configuration #
#############################
evalNix(){
nix-instantiate - --eval-only "$@"
}
evalAttr(){
local prefix="$1"
local strict="$2"
local suffix="$3"
echo "(import <nixos> {}).$prefix${option:+.$option}${suffix:+.$suffix}" | evalNix ${strict:+--strict}
}
evalOpt(){
evalAttr "options" "" "$@"
}
evalCfg(){
local strict="$1"
evalAttr "config" "$strict"
}
findSources(){
local suffix=$1
echo "(import <nixos> {}).options${option:+.$option}.$suffix" |
evalNix --strict
}
# Given a result from nix-instantiate, recover the list of attributes it
# contains.
attrNames() {
local attributeset=$1
# sed is used to replace un-printable subset by 0s, and to remove most of
# the inner-attribute set, which reduce the likelyhood to encounter badly
# pre-processed input.
echo "builtins.attrNames $attributeset" | \
sed 's,<[A-Z]*>,0,g; :inner; s/{[^\{\}]*};/0;/g; t inner;' | \
evalNix --strict
}
# map a simple list which contains strings or paths.
nixMap() {
local fun="$1"
local list="$2"
local elem
for elem in $list; do
test $elem = '[' -o $elem = ']' && continue;
$fun $elem
done
}
# This duplicates the work made below, but it is useful for processing
# the output of nixos-option with other tools such as nixos-gui.
if $xml; then
evalNix --xml --no-location <<EOF
let
reach = attrs: attrs${option:+.$option};
nixos = import <nixos> {};
nixpkgs = import <nixpkgs> {};
sources = builtins.map (f: f.source);
opt = reach nixos.options;
cfg = reach nixos.config;
in
with nixpkgs.lib;
let
optStrict = v:
let
traverse = x :
if isAttrs x then
if x ? outPath then true
else all id (mapAttrsFlatten (n: traverseNoAttrs) x)
else traverseNoAttrs x;
traverseNoAttrs = x:
# do not continue in attribute sets
if isAttrs x then true
else if isList x then all id (map traverse x)
else true;
in assert traverse v; v;
in
if isOption opt then
optStrict ({}
// optionalAttrs (opt ? default) { inherit (opt) default; }
// optionalAttrs (opt ? example) { inherit (opt) example; }
// optionalAttrs (opt ? description) { inherit (opt) description; }
// optionalAttrs (opt ? type) { typename = opt.type.name; }
// optionalAttrs (opt ? options) { inherit (opt) options; }
// {
# to disambiguate the xml output.
_isOption = true;
declarations = sources opt.declarations;
definitions = sources opt.definitions;
value = cfg;
})
else
opt
EOF
exit $?
fi
if test "$(evalOpt "_type" 2> /dev/null)" = '"option"'; then
echo "Value:"
evalCfg 1
echo
echo "Default:"
if default=$(evalOpt "default" - 2> /dev/null); then
echo "$default"
else
echo "<None>"
fi
echo
if example=$(evalOpt "example" - 2> /dev/null); then
echo "Example: $example"
fi
echo "Description:"
echo
eval printf $(evalOpt "description")
echo $desc;
printPath () { echo " $1"; }
echo "Declared by:"
nixMap printPath "$(findSources "declarations")"
echo
echo "Defined by:"
nixMap printPath "$(findSources "files")"
echo
else
# echo 1>&2 "Warning: This value is not an option."
result=$(evalCfg "")
if names=$(attrNames "$result" 2> /dev/null); then
echo 1>&2 "This attribute set contains:"
escapeQuotes () { eval echo "$1"; }
nixMap escapeQuotes "$names"
else
echo 1>&2 "An error occurred while looking for attribute names."
echo $result
fi
fi