#include <nix/config.h> // for nix/globals.hh's reference to SYSTEM
#include <exception> // for exception_ptr, current_exception
#include <functional> // for function
#include <iostream> // for operator<<, basic_ostream, ostrin...
#include <iterator> // for next
#include <list> // for _List_iterator
#include <memory> // for allocator, unique_ptr, make_unique
#include <new> // for operator new
#include <nix/args.hh> // for argvToStrings, UsageError
#include <nix/attr-path.hh> // for findAlongAttrPath
#include <nix/attr-set.hh> // for Attr, Bindings, Bindings::iterator
#include <nix/common-eval-args.hh> // for MixEvalArgs
#include <nix/eval-inline.hh> // for EvalState::forceValue
#include <nix/eval.hh> // for EvalState, initGC, operator<<
#include <nix/globals.hh> // for initPlugins, Settings, settings
#include <nix/nixexpr.hh> // for Pos
#include <nix/shared.hh> // for getArg, LegacyArgs, printVersion
#include <nix/store-api.hh> // for openStore
#include <nix/symbol-table.hh> // for Symbol, SymbolTable
#include <nix/types.hh> // for Error, Path, Strings, PathSet
#include <nix/util.hh> // for absPath, baseNameOf
#include <nix/value.hh> // for Value, Value::(anonymous), Value:...
#include <string> // for string, operator+, operator==
#include <utility> // for move
#include <variant> // for get, holds_alternative, variant
#include <vector> // for vector<>::iterator, vector
#include "libnix-copy-paste.hh"
using nix::absPath;
using nix::Bindings;
using nix::Error;
using nix::EvalError;
using nix::EvalState;
using nix::Path;
using nix::PathSet;
using nix::Strings;
using nix::Symbol;
using nix::tAttrs;
using nix::ThrownError;
using nix::tLambda;
using nix::tString;
using nix::UsageError;
using nix::Value;
// An ostream wrapper to handle nested indentation
class Out
{
public:
class Separator
{};
const static Separator sep;
enum LinePolicy
{
ONE_LINE,
MULTI_LINE
};
explicit Out(std::ostream & ostream) : ostream(ostream), policy(ONE_LINE), writeSinceSep(true) {}
Out(Out & o, const std::string & start, const std::string & end, LinePolicy policy);
Out(Out & o, const std::string & start, const std::string & end, int count)
: Out(o, start, end, count < 2 ? ONE_LINE : MULTI_LINE)
{}
Out(const Out &) = delete;
Out(Out &&) = default;
Out & operator=(const Out &) = delete;
Out & operator=(Out &&) = delete;
~Out() { ostream << end; }
private:
std::ostream & ostream;
std::string indentation;
std::string end;
LinePolicy policy;
bool writeSinceSep;
template <typename T> friend Out & operator<<(Out & o, T thing);
};
template <typename T> Out & operator<<(Out & o, T thing)
{
if (!o.writeSinceSep && o.policy == Out::MULTI_LINE) {
o.ostream << o.indentation;
}
o.writeSinceSep = true;
o.ostream << thing;
return o;
}
template <> Out & operator<<<Out::Separator>(Out & o, Out::Separator /* thing */)
{
o.ostream << (o.policy == Out::ONE_LINE ? " " : "\n");
o.writeSinceSep = false;
return o;
}
Out::Out(Out & o, const std::string & start, const std::string & end, LinePolicy policy)
: ostream(o.ostream), indentation(policy == ONE_LINE ? o.indentation : o.indentation + " "),
end(policy == ONE_LINE ? end : o.indentation + end), policy(policy), writeSinceSep(true)
{
o << start;
*this << Out::sep;
}
// Stuff needed for evaluation
struct Context
{
Context(EvalState & state, Bindings & autoArgs, Value optionsRoot, Value configRoot)
: state(state), autoArgs(autoArgs), optionsRoot(optionsRoot), configRoot(configRoot),
underscoreType(state.symbols.create("_type"))
{}
EvalState & state;
Bindings & autoArgs;
Value optionsRoot;
Value configRoot;
Symbol underscoreType;
};
Value evaluateValue(Context & ctx, Value & v)
{
ctx.state.forceValue(v);
if (ctx.autoArgs.empty()) {
return v;
}
Value called{};
ctx.state.autoCallFunction(ctx.autoArgs, v, called);
return called;
}
bool isOption(Context & ctx, const Value & v)
{
if (v.type != tAttrs) {
return false;
}
const auto & actualType = v.attrs->find(ctx.underscoreType);
if (actualType == v.attrs->end()) {
return false;
}
try {
Value evaluatedType = evaluateValue(ctx, *actualType->value);
if (evaluatedType.type != tString) {
return false;
}
return static_cast<std::string>(evaluatedType.string.s) == "option";
} catch (Error &) {
return false;
}
}
// Add quotes to a component of a path.
// These are needed for paths like:
// fileSystems."/".fsType
// systemd.units."dbus.service".text
std::string quoteAttribute(const std::string & attribute)
{
if (isVarName(attribute)) {
return attribute;
}
std::ostringstream buf;
printStringValue(buf, attribute.c_str());
return buf.str();
}
const std::string appendPath(const std::string & prefix, const std::string & suffix)
{
if (prefix.empty()) {
return quoteAttribute(suffix);
}
return prefix + "." + quoteAttribute(suffix);
}
bool forbiddenRecursionName(std::string name) { return (!name.empty() && name[0] == '_') || name == "haskellPackages"; }
void recurse(const std::function<bool(const std::string & path, std::variant<Value, std::exception_ptr>)> & f,
Context & ctx, Value v, const std::string & path)
{
std::variant<Value, std::exception_ptr> evaluated;
try {
evaluated = evaluateValue(ctx, v);
} catch (Error &) {
evaluated = std::current_exception();
}
if (!f(path, evaluated)) {
return;
}
if (std::holds_alternative<std::exception_ptr>(evaluated)) {
return;
}
const Value & evaluated_value = std::get<Value>(evaluated);
if (evaluated_value.type != tAttrs) {
return;
}
for (const auto & child : evaluated_value.attrs->lexicographicOrder()) {
if (forbiddenRecursionName(child->name)) {
continue;
}
recurse(f, ctx, *child->value, appendPath(path, child->name));
}
}
bool optionTypeIs(Context & ctx, Value & v, const std::string & soughtType)
{
try {
const auto & typeLookup = v.attrs->find(ctx.state.sType);
if (typeLookup == v.attrs->end()) {
return false;
}
Value type = evaluateValue(ctx, *typeLookup->value);
if (type.type != tAttrs) {
return false;
}
const auto & nameLookup = type.attrs->find(ctx.state.sName);
if (nameLookup == type.attrs->end()) {
return false;
}
Value name = evaluateValue(ctx, *nameLookup->value);
if (name.type != tString) {
return false;
}
return name.string.s == soughtType;
} catch (Error &) {
return false;
}
}
bool isAggregateOptionType(Context & ctx, Value & v)
{
return optionTypeIs(ctx, v, "attrsOf") || optionTypeIs(ctx, v, "listOf");
}
MakeError(OptionPathError, EvalError);
Value getSubOptions(Context & ctx, Value & option)
{
Value getSubOptions = evaluateValue(ctx, *findAlongAttrPath(ctx.state, "type.getSubOptions", ctx.autoArgs, option));
if (getSubOptions.type != tLambda) {
throw OptionPathError("Option's type.getSubOptions isn't a function");
}
Value emptyString{};
nix::mkString(emptyString, "");
Value v;
ctx.state.callFunction(getSubOptions, emptyString, v, nix::Pos{});
return v;
}
// Carefully walk an option path, looking for sub-options when a path walks past
// an option value.
struct FindAlongOptionPathRet
{
Value option;
std::string path;
};
FindAlongOptionPathRet findAlongOptionPath(Context & ctx, const std::string & path)
{
Strings tokens = parseAttrPath(path);
Value v = ctx.optionsRoot;
std::string processedPath;
for (auto i = tokens.begin(); i != tokens.end(); i++) {
const auto & attr = *i;
try {
bool lastAttribute = std::next(i) == tokens.end();
v = evaluateValue(ctx, v);
if (attr.empty()) {
throw OptionPathError("empty attribute name");
}
if (isOption(ctx, v) && optionTypeIs(ctx, v, "submodule")) {
v = getSubOptions(ctx, v);
}
if (isOption(ctx, v) && isAggregateOptionType(ctx, v)) {
auto subOptions = getSubOptions(ctx, v);
if (lastAttribute && subOptions.attrs->empty()) {
break;
}
v = subOptions;
// Note that we've consumed attr, but didn't actually use it. This is the path component that's looked
// up in the list or attribute set that doesn't name an option -- the "root" in "users.users.root.name".
} else if (v.type != tAttrs) {
throw OptionPathError("Value is %s while a set was expected", showType(v));
} else {
const auto & next = v.attrs->find(ctx.state.symbols.create(attr));
if (next == v.attrs->end()) {
throw OptionPathError("Attribute not found", attr, path);
}
v = *next->value;
}
processedPath = appendPath(processedPath, attr);
} catch (OptionPathError & e) {
throw OptionPathError("At '%s' in path '%s': %s", attr, path, e.msg());
}
}
return {v, processedPath};
}
// Calls f on all the option names at or below the option described by `path`.
// Note that "the option described by `path`" is not trivial -- if path describes a value inside an aggregate
// option (such as users.users.root), the *option* described by that path is one path component shorter
// (eg: users.users), which results in f being called on sibling-paths (eg: users.users.nixbld1). If f
// doesn't want these, it must do its own filtering.
void mapOptions(const std::function<void(const std::string & path)> & f, Context & ctx, const std::string & path)
{
auto root = findAlongOptionPath(ctx, path);
recurse(
[f, &ctx](const std::string & path, std::variant<Value, std::exception_ptr> v) {
bool isOpt = std::holds_alternative<std::exception_ptr>(v) || isOption(ctx, std::get<Value>(v));
if (isOpt) {
f(path);
}
return !isOpt;
},
ctx, root.option, root.path);
}
// Calls f on all the config values inside one option.
// Simple options have one config value inside, like sound.enable = true.
// Compound options have multiple config values. For example, the option
// "users.users" has about 1000 config values inside it:
// users.users.avahi.createHome = false;
// users.users.avahi.cryptHomeLuks = null;
// users.users.avahi.description = "`avahi-daemon' privilege separation user";
// ...
// users.users.avahi.openssh.authorizedKeys.keyFiles = [ ];
// users.users.avahi.openssh.authorizedKeys.keys = [ ];
// ...
// users.users.avahi.uid = 10;
// users.users.avahi.useDefaultShell = false;
// users.users.cups.createHome = false;
// ...
// users.users.cups.useDefaultShell = false;
// users.users.gdm = ... ... ...
// users.users.messagebus = ... .. ...
// users.users.nixbld1 = ... .. ...
// ...
// users.users.systemd-timesync = ... .. ...
void mapConfigValuesInOption(
const std::function<void(const std::string & path, std::variant<Value, std::exception_ptr> v)> & f,
const std::string & path, Context & ctx)
{
Value * option;
try {
option = findAlongAttrPath(ctx.state, path, ctx.autoArgs, ctx.configRoot);
} catch (Error &) {
f(path, std::current_exception());
return;
}
recurse(
[f, ctx](const std::string & path, std::variant<Value, std::exception_ptr> v) {
bool leaf = std::holds_alternative<std::exception_ptr>(v) || std::get<Value>(v).type != tAttrs ||
ctx.state.isDerivation(std::get<Value>(v));
if (!leaf) {
return true; // Keep digging
}
f(path, v);
return false;
},
ctx, *option, path);
}
std::string describeError(const Error & e) { return "«error: " + e.msg() + "»"; }
void describeDerivation(Context & ctx, Out & out, Value v)
{
// Copy-pasted from nix/src/nix/repl.cc :(
Bindings::iterator i = v.attrs->find(ctx.state.sDrvPath);
PathSet pathset;
try {
Path drvPath = i != v.attrs->end() ? ctx.state.coerceToPath(*i->pos, *i->value, pathset) : "???";
out << "«derivation " << drvPath << "»";
} catch (Error & e) {
out << describeError(e);
}
}
Value parseAndEval(EvalState & state, const std::string & expression, const std::string & path)
{
Value v{};
state.eval(state.parseExprFromString(expression, absPath(path)), v);
return v;
}
void printValue(Context & ctx, Out & out, std::variant<Value, std::exception_ptr> maybeValue, const std::string & path);
void printList(Context & ctx, Out & out, Value & v)
{
Out listOut(out, "[", "]", v.listSize());
for (unsigned int n = 0; n < v.listSize(); ++n) {
printValue(ctx, listOut, *v.listElems()[n], "");
listOut << Out::sep;
}
}
void printAttrs(Context & ctx, Out & out, Value & v, const std::string & path)
{
Out attrsOut(out, "{", "}", v.attrs->size());
for (const auto & a : v.attrs->lexicographicOrder()) {
std::string name = a->name;
if (!forbiddenRecursionName(name)) {
attrsOut << name << " = ";
printValue(ctx, attrsOut, *a->value, appendPath(path, name));
attrsOut << ";" << Out::sep;
}
}
}
void multiLineStringEscape(Out & out, const std::string & s)
{
int i;
for (i = 1; i < s.size(); i++) {
if (s[i - 1] == '$' && s[i] == '{') {
out << "''${";
i++;
} else if (s[i - 1] == '\'' && s[i] == '\'') {
out << "'''";
i++;
} else {
out << s[i - 1];
}
}
if (i == s.size()) {
out << s[i - 1];
}
}
void printMultiLineString(Out & out, const Value & v)
{
std::string s = v.string.s;
Out strOut(out, "''", "''", Out::MULTI_LINE);
std::string::size_type begin = 0;
while (begin < s.size()) {
std::string::size_type end = s.find('\n', begin);
if (end == std::string::npos) {
multiLineStringEscape(strOut, s.substr(begin, s.size() - begin));
break;
}
multiLineStringEscape(strOut, s.substr(begin, end - begin));
strOut << Out::sep;
begin = end + 1;
}
}
void printValue(Context & ctx, Out & out, std::variant<Value, std::exception_ptr> maybeValue, const std::string & path)
{
try {
if (auto ex = std::get_if<std::exception_ptr>(&maybeValue)) {
std::rethrow_exception(*ex);
}
Value v = evaluateValue(ctx, std::get<Value>(maybeValue));
if (ctx.state.isDerivation(v)) {
describeDerivation(ctx, out, v);
} else if (v.isList()) {
printList(ctx, out, v);
} else if (v.type == tAttrs) {
printAttrs(ctx, out, v, path);
} else if (v.type == tString && std::string(v.string.s).find('\n') != std::string::npos) {
printMultiLineString(out, v);
} else {
ctx.state.forceValueDeep(v);
out << v;
}
} catch (ThrownError & e) {
if (e.msg() == "The option `" + path + "' is used but not defined.") {
// 93% of errors are this, and just letting this message through would be
// misleading. These values may or may not actually be "used" in the
// config. The thing throwing the error message assumes that if anything
// ever looks at this value, it is a "use" of this value. But here in
// nixos-option, we are looking at this value only to print it.
// In order to avoid implying that this undefined value is actually
// referenced, eat the underlying error message and emit "«not defined»".
out << "«not defined»";
} else {
out << describeError(e);
}
} catch (Error & e) {
out << describeError(e);
}
}
void printConfigValue(Context & ctx, Out & out, const std::string & path, std::variant<Value, std::exception_ptr> v)
{
out << path << " = ";
printValue(ctx, out, std::move(v), path);
out << ";\n";
}
// Replace with std::starts_with when C++20 is available
bool starts_with(const std::string & s, const std::string & prefix)
{
return s.size() >= prefix.size() &&
std::equal(s.begin(), std::next(s.begin(), prefix.size()), prefix.begin(), prefix.end());
}
void printRecursive(Context & ctx, Out & out, const std::string & path)
{
mapOptions(
[&ctx, &out, &path](const std::string & optionPath) {
mapConfigValuesInOption(
[&ctx, &out, &path](const std::string & configPath, std::variant<Value, std::exception_ptr> v) {
if (starts_with(configPath, path)) {
printConfigValue(ctx, out, configPath, v);
}
},
optionPath, ctx);
},
ctx, path);
}
void printAttr(Context & ctx, Out & out, const std::string & path, Value & root)
{
try {
printValue(ctx, out, *findAlongAttrPath(ctx.state, path, ctx.autoArgs, root), path);
} catch (Error & e) {
out << describeError(e);
}
}
bool hasExample(Context & ctx, Value & option)
{
try {
findAlongAttrPath(ctx.state, "example", ctx.autoArgs, option);
return true;
} catch (Error &) {
return false;
}
}
void printOption(Context & ctx, Out & out, const std::string & path, Value & option)
{
out << "Value:\n";
printAttr(ctx, out, path, ctx.configRoot);
out << "\n\nDefault:\n";
printAttr(ctx, out, "default", option);
out << "\n\nType:\n";
printAttr(ctx, out, "type.description", option);
if (hasExample(ctx, option)) {
out << "\n\nExample:\n";
printAttr(ctx, out, "example", option);
}
out << "\n\nDescription:\n";
printAttr(ctx, out, "description", option);
out << "\n\nDeclared by:\n";
printAttr(ctx, out, "declarations", option);
out << "\n\nDefined by:\n";
printAttr(ctx, out, "files", option);
out << "\n";
}
void printListing(Out & out, Value & v)
{
out << "This attribute set contains:\n";
for (const auto & a : v.attrs->lexicographicOrder()) {
std::string name = a->name;
if (!name.empty() && name[0] != '_') {
out << name << "\n";
}
}
}
void printOne(Context & ctx, Out & out, const std::string & path)
{
try {
auto result = findAlongOptionPath(ctx, path);
Value & option = result.option;
option = evaluateValue(ctx, option);
if (path != result.path) {
out << "Note: showing " << result.path << " instead of " << path << "\n";
}
if (isOption(ctx, option)) {
printOption(ctx, out, result.path, option);
} else {
printListing(out, option);
}
} catch (Error & e) {
std::cerr << "error: " << e.msg()
<< "\nAn error occurred while looking for attribute names. Are "
"you sure that '"
<< path << "' exists?\n";
}
}
int main(int argc, char ** argv)
{
bool recursive = false;
std::string path = ".";
std::string optionsExpr = "(import <nixpkgs/nixos> {}).options";
std::string configExpr = "(import <nixpkgs/nixos> {}).config";
std::vector<std::string> args;
struct MyArgs : nix::LegacyArgs, nix::MixEvalArgs
{
using nix::LegacyArgs::LegacyArgs;
};
MyArgs myArgs(nix::baseNameOf(argv[0]), [&](Strings::iterator & arg, const Strings::iterator & end) {
if (*arg == "--help") {
nix::showManPage("nixos-option");
} else if (*arg == "--version") {
nix::printVersion("nixos-option");
} else if (*arg == "-r" || *arg == "--recursive") {
recursive = true;
} else if (*arg == "--path") {
path = nix::getArg(*arg, arg, end);
} else if (*arg == "--options_expr") {
optionsExpr = nix::getArg(*arg, arg, end);
} else if (*arg == "--config_expr") {
configExpr = nix::getArg(*arg, arg, end);
} else if (!arg->empty() && arg->at(0) == '-') {
return false;
} else {
args.push_back(*arg);
}
return true;
});
myArgs.parseCmdline(nix::argvToStrings(argc, argv));
nix::initPlugins();
nix::initGC();
nix::settings.readOnlyMode = true;
auto store = nix::openStore();
auto state = std::make_unique<EvalState>(myArgs.searchPath, store);
Value optionsRoot = parseAndEval(*state, optionsExpr, path);
Value configRoot = parseAndEval(*state, configExpr, path);
Context ctx{*state, *myArgs.getAutoArgs(*state), optionsRoot, configRoot};
Out out(std::cout);
auto print = recursive ? printRecursive : printOne;
if (args.empty()) {
print(ctx, out, "");
}
for (const auto & arg : args) {
print(ctx, out, arg);
}
ctx.state.printStats();
return 0;
}
