nixpkgs/nixos/modules/installer/tools/nixos-option/nixos-option.cc

589 lines
19 KiB
C++

#include <nix/config.h> // for nix/globals.hh's reference to SYSTEM
#include <algorithm> // for sort
#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 <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::EvalState;
using nix::Path;
using nix::PathSet;
using nix::Strings;
using nix::Symbol;
using nix::tAttrs;
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), write_since_sep(true) {}
Out(Out &o, std::string const &start, std::string const &end,
LinePolicy policy);
Out(Out &o, std::string const &start, std::string const &end, int count)
: Out(o, start, end, count < 2 ? ONE_LINE : MULTI_LINE) {}
Out(Out const &) = delete;
Out(Out &&) = default;
Out &operator=(Out const &) = delete;
Out &operator=(Out &&) = delete;
~Out() { ostream << end; }
private:
std::ostream &ostream;
std::string indentation;
std::string end;
LinePolicy policy;
bool write_since_sep;
template <typename T> friend Out &operator<<(Out &o, T thing);
};
template <typename T> Out &operator<<(Out &o, T thing) {
if (!o.write_since_sep && o.policy == Out::MULTI_LINE) {
o.ostream << o.indentation;
}
o.write_since_sep = 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.write_since_sep = false;
return o;
}
Out::Out(Out &o, std::string const &start, std::string const &end,
LinePolicy policy)
: ostream(o.ostream),
indentation(policy == ONE_LINE ? o.indentation : o.indentation + " "),
end(policy == ONE_LINE ? end : o.indentation + end), policy(policy),
write_since_sep(true) {
o << start;
*this << Out::sep;
}
// Stuff needed for evaluation
struct Context {
Context(EvalState *state, Bindings *autoArgs, Value options_root,
Value config_root)
: state(state), autoArgs(autoArgs), options_root(options_root),
config_root(config_root),
underscore_type(state->symbols.create("_type")) {}
EvalState *state;
Bindings *autoArgs;
Value options_root;
Value config_root;
Symbol underscore_type;
};
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, Value const &v) {
if (v.type != tAttrs) {
return false;
}
auto const &actual_type = v.attrs->find(ctx->underscore_type);
if (actual_type == v.attrs->end()) {
return false;
}
try {
Value evaluated_type = evaluateValue(ctx, actual_type->value);
if (evaluated_type.type != tString) {
return false;
}
return evaluated_type.string.s == static_cast<std::string>("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(std::string const &attribute) {
if (isVarName(attribute)) {
return attribute;
}
std::ostringstream buf;
printStringValue(buf, attribute.c_str());
return buf.str();
}
std::string const appendPath(std::string const &prefix,
std::string const &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(std::string const &path,
std::variant<Value, Error>)> &f,
Context *ctx, Value v, std::string const &path) {
std::variant<Value, Error> evaluated;
try {
evaluated = evaluateValue(ctx, &v);
} catch (Error &e) {
evaluated = e;
}
if (!f(path, evaluated)) {
return;
}
if (std::holds_alternative<Error>(evaluated)) {
return;
}
Value const &evaluated_value = std::get<Value>(evaluated);
if (evaluated_value.type != tAttrs) {
return;
}
for (auto const &child : evaluated_value.attrs->lexicographicOrder()) {
if (forbiddenRecursionName(child->name)) {
continue;
}
recurse(f, ctx, *child->value, appendPath(path, child->name));
}
}
// Calls f on all the option names
void mapOptions(const std::function<void(std::string const &path)> &f,
Context *ctx, Value root) {
recurse(
[f, ctx](std::string const &path, std::variant<Value, Error> v) {
bool isOpt = std::holds_alternative<Error>(v) ||
isOption(ctx, std::get<Value>(v));
if (isOpt) {
f(path);
}
return !isOpt;
},
ctx, root, "");
}
// 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(std::string const &path,
std::variant<Value, Error> v)> &f,
std::string const &path, Context *ctx) {
Value *option;
try {
option =
findAlongAttrPath(*ctx->state, path, *ctx->autoArgs, ctx->config_root);
} catch (Error &e) {
f(path, e);
return;
}
recurse(
[f, ctx](std::string const &path, std::variant<Value, Error> v) {
bool leaf = std::holds_alternative<Error>(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(Error const &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, std::string const &expression,
std::string const &path) {
Value v{};
state->eval(state->parseExprFromString(expression, absPath(path)), v);
return v;
}
void printValue(Context *ctx, Out &out, std::variant<Value, Error> maybe_value,
std::string const &path);
void printUnsortedList(Context *ctx, Out &out, Value &v) {
Out list_out(out, "[", "]", v.listSize());
for (unsigned int n = 0; n < v.listSize(); ++n) {
printValue(ctx, list_out, *v.listElems()[n], "");
list_out << Out::sep;
}
}
void printSortedList(Context *ctx, Out &out, Value &v) {
std::vector<std::string> results;
for (unsigned int n = 0; n < v.listSize(); ++n) {
std::ostringstream buf;
Out buf_out(buf);
printValue(ctx, buf_out, *v.listElems()[n], "");
results.push_back(buf.str());
}
std::sort(results.begin(), results.end());
Out list_out(out, "[", "]", v.listSize());
for (auto const &v : results) {
list_out << v << Out::sep;
}
}
bool shouldSort(Context *ctx, Value &v) {
// Some lists should clearly be printed in sorted order, like
// environment.systemPackages. Some clearly should not, like
// services.xserver.multitouch.buttonsMap. As a conservative heuristic, sort
// lists of derivations.
return v.listSize() > 0 && ctx->state->isDerivation(*v.listElems()[0]);
}
void printList(Context *ctx, Out &out, Value &v) {
if (shouldSort(ctx, v)) {
printSortedList(ctx, out, v);
} else {
printUnsortedList(ctx, out, v);
}
}
void printAttrs(Context *ctx, Out &out, Value &v, std::string const &path) {
Out attrs_out(out, "{", "}", v.attrs->size());
for (const auto &a : v.attrs->lexicographicOrder()) {
std::string name = a->name;
attrs_out << name << " = ";
printValue(ctx, attrs_out, *a->value, appendPath(path, name));
attrs_out << ";" << Out::sep;
}
}
void multiLineStringEscape(Out &out, std::string const &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, Value const &v) {
std::string s = v.string.s;
Out str_out(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(str_out, s.substr(begin, s.size() - begin));
break;
}
multiLineStringEscape(str_out, s.substr(begin, end - begin));
str_out << Out::sep;
begin = end + 1;
}
}
void printValue(Context *ctx, Out &out, std::variant<Value, Error> maybe_value,
std::string const &path) {
try {
if (std::holds_alternative<Error>(maybe_value)) {
throw Error{std::get<Error>(maybe_value)};
}
Value v = evaluateValue(ctx, &std::get<Value>(maybe_value));
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 (Error &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-options-summary, 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);
}
}
}
void printConfigValue(Context *ctx, Out &out, std::string const &path,
std::variant<Value, Error> v) {
out << path << " = ";
printValue(ctx, out, std::move(v), path);
out << ";\n";
}
void printAll(Context *ctx, Out &out) {
mapOptions(
[ctx, &out](std::string const &option_path) {
mapConfigValuesInOption(
[ctx, &out](std::string const &config_path,
std::variant<Value, Error> v) {
printConfigValue(ctx, out, config_path, v);
},
option_path, ctx);
},
ctx, ctx->options_root);
}
void printAttr(Context *ctx, Out &out, std::string const &path, Value *root) {
try {
printValue(ctx, out,
*findAlongAttrPath(*ctx->state, path, *ctx->autoArgs, *root),
path);
} catch (Error &e) {
out << describeError(e);
}
}
void printOption(Context *ctx, Out &out, std::string const &path,
Value *option) {
out << "Value:\n";
printAttr(ctx, out, path, &ctx->config_root);
out << "\n\nDefault:\n";
printAttr(ctx, out, "default", option);
out << "\n\nType:\n";
printAttr(ctx, out, "type.description", 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) {
// Print this header on stderr rather than stdout because the old shell script
// implementation did. I don't know why.
std::cerr << "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";
}
}
}
// Carefully walk an option path, looking for sub-options when a path walks past
// an option value.
Value findAlongOptionPath(Context *ctx, std::string const &path) {
Strings tokens = parseAttrPath(path);
Value v = ctx->options_root;
for (auto i = tokens.begin(); i != tokens.end(); i++) {
bool last_attribute = std::next(i) == tokens.end();
auto const &attr = *i;
v = evaluateValue(ctx, &v);
if (attr.empty()) {
throw Error("empty attribute name in selection path '" + path + "'");
}
if (isOption(ctx, v) && !last_attribute) {
Value getSubOptions = evaluateValue(
ctx, findAlongAttrPath(*ctx->state, "type.getSubOptions",
*ctx->autoArgs, v));
if (getSubOptions.type != tLambda) {
throw Error("Option's type.getSubOptions isn't a function at '" + attr +
"' in path '" + path + "'");
}
Value emptyString{};
nix::mkString(emptyString, "");
ctx->state->callFunction(getSubOptions, emptyString, v, nix::Pos{});
// Note that we've consumed attr, but didn't actually use it.
} else if (v.type != tAttrs) {
throw Error("attribute '" + attr + "' in path '" + path +
"' attempts to index a value that should be a set but is " +
showType(v));
} else {
auto const &next = v.attrs->find(ctx->state->symbols.create(attr));
if (next == v.attrs->end()) {
throw Error("attribute '" + attr + "' in path '" + path +
"' not found");
}
v = *next->value;
}
}
return v;
}
void printOne(Context *ctx, Out &out, std::string const &path) {
try {
Value option = findAlongOptionPath(ctx, path);
option = evaluateValue(ctx, &option);
if (isOption(ctx, option)) {
printOption(ctx, out, 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 all = false;
std::string path = ".";
std::string options_expr = "(import <nixpkgs/nixos> {}).options";
std::string config_expr = "(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-options-summary");
} else if (*arg == "--version") {
nix::printVersion("nixos-options-summary");
} else if (*arg == "--all") {
all = true;
} else if (*arg == "--path") {
path = nix::getArg(*arg, arg, end);
} else if (*arg == "--options_expr") {
options_expr = nix::getArg(*arg, arg, end);
} else if (*arg == "--config_expr") {
config_expr = 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 options_root = parseAndEval(state.get(), options_expr, path);
Value config_root = parseAndEval(state.get(), config_expr, path);
Context ctx{state.get(), myArgs.getAutoArgs(*state), options_root,
config_root};
Out out(std::cout);
if (all) {
if (!args.empty()) {
throw UsageError("--all cannot be used with arguments");
}
printAll(&ctx, out);
} else {
if (args.empty()) {
printOne(&ctx, out, "");
}
for (auto const &arg : args) {
printOne(&ctx, out, arg);
}
}
ctx.state->printStats();
return 0;
}