nix-super/src/nix/develop.cc

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#include "eval.hh"
#include "command.hh"
#include "installable-flake.hh"
#include "common-args.hh"
#include "shared.hh"
#include "store-api.hh"
#include "outputs-spec.hh"
#include "derivations.hh"
#include "progress-bar.hh"
#include "run.hh"
#include <memory>
#include <nlohmann/json.hpp>
using namespace nix;
struct DevelopSettings : Config
{
Setting<std::string> bashPrompt{this, "", "bash-prompt",
"The bash prompt (`PS1`) in `nix develop` shells."};
Setting<std::string> bashPromptPrefix{this, "", "bash-prompt-prefix",
"Prefix prepended to the `PS1` environment variable in `nix develop` shells."};
Setting<std::string> bashPromptSuffix{this, "", "bash-prompt-suffix",
"Suffix appended to the `PS1` environment variable in `nix develop` shells."};
};
static DevelopSettings developSettings;
static GlobalConfig::Register rDevelopSettings(&developSettings);
struct BuildEnvironment
{
struct String
{
bool exported;
std::string value;
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bool operator == (const String & other) const
{
return exported == other.exported && value == other.value;
}
};
using Array = std::vector<std::string>;
using Associative = std::map<std::string, std::string>;
using Value = std::variant<String, Array, Associative>;
std::map<std::string, Value> vars;
std::map<std::string, std::string> bashFunctions;
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static BuildEnvironment fromJSON(std::string_view in)
{
BuildEnvironment res;
std::set<std::string> exported;
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auto json = nlohmann::json::parse(in);
for (auto & [name, info] : json["variables"].items()) {
std::string type = info["type"];
if (type == "var" || type == "exported")
res.vars.insert({name, BuildEnvironment::String { .exported = type == "exported", .value = info["value"] }});
else if (type == "array")
res.vars.insert({name, (Array) info["value"]});
else if (type == "associative")
res.vars.insert({name, (Associative) info["value"]});
}
for (auto & [name, def] : json["bashFunctions"].items()) {
res.bashFunctions.insert({name, def});
}
return res;
}
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std::string toJSON() const
{
auto res = nlohmann::json::object();
auto vars2 = nlohmann::json::object();
for (auto & [name, value] : vars) {
auto info = nlohmann::json::object();
if (auto str = std::get_if<String>(&value)) {
info["type"] = str->exported ? "exported" : "var";
info["value"] = str->value;
}
else if (auto arr = std::get_if<Array>(&value)) {
info["type"] = "array";
info["value"] = *arr;
}
else if (auto arr = std::get_if<Associative>(&value)) {
info["type"] = "associative";
info["value"] = *arr;
}
vars2[name] = std::move(info);
}
res["variables"] = std::move(vars2);
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res["bashFunctions"] = bashFunctions;
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auto json = res.dump();
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assert(BuildEnvironment::fromJSON(json) == *this);
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return json;
}
void toBash(std::ostream & out, const std::set<std::string> & ignoreVars) const
{
for (auto & [name, value] : vars) {
if (!ignoreVars.count(name)) {
if (auto str = std::get_if<String>(&value)) {
out << fmt("%s=%s\n", name, shellEscape(str->value));
if (str->exported)
out << fmt("export %s\n", name);
}
else if (auto arr = std::get_if<Array>(&value)) {
out << "declare -a " << name << "=(";
for (auto & s : *arr)
out << shellEscape(s) << " ";
out << ")\n";
}
else if (auto arr = std::get_if<Associative>(&value)) {
out << "declare -A " << name << "=(";
for (auto & [n, v] : *arr)
out << "[" << shellEscape(n) << "]=" << shellEscape(v) << " ";
out << ")\n";
}
}
}
for (auto & [name, def] : bashFunctions) {
out << name << " ()\n{\n" << def << "}\n";
}
}
static std::string getString(const Value & value)
{
if (auto str = std::get_if<String>(&value))
return str->value;
else
throw Error("bash variable is not a string");
}
static Array getStrings(const Value & value)
{
if (auto str = std::get_if<String>(&value))
return tokenizeString<Array>(str->value);
else if (auto arr = std::get_if<Array>(&value)) {
return *arr;
} else if (auto assoc = std::get_if<Associative>(&value)) {
Array assocKeys;
std::for_each(assoc->begin(), assoc->end(), [&](auto & n) { assocKeys.push_back(n.first); });
return assocKeys;
}
else
throw Error("bash variable is not a string or array");
}
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bool operator == (const BuildEnvironment & other) const
{
return vars == other.vars && bashFunctions == other.bashFunctions;
}
std::string getSystem() const
{
if (auto v = get(vars, "system"))
return getString(*v);
else
return settings.thisSystem;
}
};
const static std::string getEnvSh =
#include "get-env.sh.gen.hh"
;
/* Given an existing derivation, return the shell environment as
initialised by stdenv's setup script. We do this by building a
modified derivation with the same dependencies and nearly the same
initial environment variables, that just writes the resulting
environment to a file and exits. */
static StorePath getDerivationEnvironment(ref<Store> store, ref<Store> evalStore, const StorePath & drvPath)
{
auto drv = evalStore->derivationFromPath(drvPath);
auto builder = baseNameOf(drv.builder);
if (builder != "bash")
throw Error("'nix develop' only works on derivations that use 'bash' as their builder");
auto getEnvShPath = evalStore->addTextToStore("get-env.sh", getEnvSh, {});
drv.args = {store->printStorePath(getEnvShPath)};
/* Remove derivation checks. */
drv.env.erase("allowedReferences");
drv.env.erase("allowedRequisites");
drv.env.erase("disallowedReferences");
drv.env.erase("disallowedRequisites");
drv.env.erase("name");
/* Rehash and write the derivation. FIXME: would be nice to use
'buildDerivation', but that's privileged. */
drv.name += "-env";
drv.env.emplace("name", drv.name);
drv.inputSrcs.insert(std::move(getEnvShPath));
if (settings.isExperimentalFeatureEnabled(Xp::CaDerivations)) {
for (auto & output : drv.outputs) {
output.second = DerivationOutput::Deferred {},
drv.env[output.first] = hashPlaceholder(output.first);
}
} else {
for (auto & output : drv.outputs) {
output.second = DerivationOutput::Deferred { };
drv.env[output.first] = "";
}
auto hashesModulo = hashDerivationModulo(*evalStore, drv, true);
for (auto & output : drv.outputs) {
Hash h = hashesModulo.hashes.at(output.first);
auto outPath = store->makeOutputPath(output.first, h, drv.name);
output.second = DerivationOutput::InputAddressed {
.path = outPath,
};
drv.env[output.first] = store->printStorePath(outPath);
}
}
auto shellDrvPath = writeDerivation(*evalStore, drv);
/* Build the derivation. */
store->buildPaths(
{ DerivedPath::Built {
.drvPath = shellDrvPath,
.outputs = OutputsSpec::All { },
}},
bmNormal, evalStore);
for (auto & [_0, optPath] : evalStore->queryPartialDerivationOutputMap(shellDrvPath)) {
assert(optPath);
auto & outPath = *optPath;
assert(store->isValidPath(outPath));
auto outPathS = store->toRealPath(outPath);
if (lstat(outPathS).st_size)
return outPath;
}
throw Error("get-env.sh failed to produce an environment");
}
struct Common : InstallableCommand, MixProfile
{
std::set<std::string> ignoreVars{
"BASHOPTS",
"HOME", // FIXME: don't ignore in pure mode?
"NIX_BUILD_TOP",
"NIX_ENFORCE_PURITY",
"NIX_LOG_FD",
"NIX_REMOTE",
"PPID",
"SHELL",
"SHELLOPTS",
"SSL_CERT_FILE", // FIXME: only want to ignore /no-cert-file.crt
"TEMP",
"TEMPDIR",
"TERM",
"TMP",
"TMPDIR",
"TZ",
"UID",
};
std::vector<std::pair<std::string, std::string>> redirects;
Common()
{
addFlag({
.longName = "redirect",
.description = "Redirect a store path to a mutable location.",
.labels = {"installable", "outputs-dir"},
.handler = {[&](std::string installable, std::string outputsDir) {
redirects.push_back({installable, outputsDir});
}}
});
}
std::string makeRcScript(
ref<Store> store,
const BuildEnvironment & buildEnvironment,
const Path & outputsDir = absPath(".") + "/outputs")
{
// A list of colon-separated environment variables that should be
// prepended to, rather than overwritten, in order to keep the shell usable.
// Please keep this list minimal in order to avoid impurities.
static const char * const savedVars[] = {
"PATH", // for commands
"XDG_DATA_DIRS", // for loadable completion
};
std::ostringstream out;
out << "unset shellHook\n";
for (auto & var : savedVars) {
out << fmt("%s=${%s:-}\n", var, var);
out << fmt("nix_saved_%s=\"$%s\"\n", var, var);
}
buildEnvironment.toBash(out, ignoreVars);
for (auto & var : savedVars)
out << fmt("%s=\"$%s:$nix_saved_%s\"\n", var, var, var);
out << "export NIX_BUILD_TOP=\"$(mktemp -d -t nix-shell.XXXXXX)\"\n";
for (auto & i : {"TMP", "TMPDIR", "TEMP", "TEMPDIR"})
out << fmt("export %s=\"$NIX_BUILD_TOP\"\n", i);
out << "eval \"$shellHook\"\n";
auto script = out.str();
/* Substitute occurrences of output paths. */
auto outputs = buildEnvironment.vars.find("outputs");
assert(outputs != buildEnvironment.vars.end());
// FIXME: properly unquote 'outputs'.
StringMap rewrites;
for (auto & outputName : BuildEnvironment::getStrings(outputs->second)) {
auto from = buildEnvironment.vars.find(outputName);
assert(from != buildEnvironment.vars.end());
// FIXME: unquote
rewrites.insert({BuildEnvironment::getString(from->second), outputsDir + "/" + outputName});
}
/* Substitute redirects. */
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for (auto & [installable_, dir_] : redirects) {
auto dir = absPath(dir_);
auto installable = parseInstallable(store, installable_);
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auto builtPaths = Installable::toStorePaths(
getEvalStore(), store, Realise::Nothing, OperateOn::Output, {installable});
for (auto & path: builtPaths) {
auto from = store->printStorePath(path);
if (script.find(from) == std::string::npos)
warn("'%s' (path '%s') is not used by this build environment", installable->what(), from);
else {
printInfo("redirecting '%s' to '%s'", from, dir);
rewrites.insert({from, dir});
}
}
}
return rewriteStrings(script, rewrites);
}
Strings getDefaultFlakeAttrPaths() override
{
Strings paths{
"devShells." + settings.thisSystem.get() + ".default",
"devShell." + settings.thisSystem.get(),
};
for (auto & p : SourceExprCommand::getDefaultFlakeAttrPaths())
paths.push_back(p);
return paths;
}
Strings getDefaultFlakeAttrPathPrefixes() override
{
auto res = SourceExprCommand::getDefaultFlakeAttrPathPrefixes();
res.emplace_front("devShells." + settings.thisSystem.get() + ".");
return res;
}
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StorePath getShellOutPath(ref<Store> store)
{
auto path = installable->getStorePath();
if (path && hasSuffix(path->to_string(), "-env"))
return *path;
else {
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auto drvs = Installable::toDerivations(store, {installable});
if (drvs.size() != 1)
throw Error("'%s' needs to evaluate to a single derivation, but it evaluated to %d derivations",
installable->what(), drvs.size());
auto & drvPath = *drvs.begin();
return getDerivationEnvironment(store, getEvalStore(), drvPath);
}
}
std::pair<BuildEnvironment, std::string> getBuildEnvironment(ref<Store> store)
{
auto shellOutPath = getShellOutPath(store);
auto strPath = store->printStorePath(shellOutPath);
updateProfile(shellOutPath);
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debug("reading environment file '%s'", strPath);
return {BuildEnvironment::fromJSON(readFile(store->toRealPath(shellOutPath))), strPath};
}
};
struct CmdDevelop : Common, MixEnvironment
{
std::vector<std::string> command;
std::optional<std::string> phase;
CmdDevelop()
{
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addFlag({
.longName = "command",
.shortName = 'c',
.description = "Instead of starting an interactive shell, start the specified command and arguments.",
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.labels = {"command", "args"},
.handler = {[&](std::vector<std::string> ss) {
if (ss.empty()) throw UsageError("--command requires at least one argument");
command = ss;
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}}
});
addFlag({
.longName = "phase",
.description = "The stdenv phase to run (e.g. `build` or `configure`).",
.labels = {"phase-name"},
.handler = {&phase},
});
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addFlag({
.longName = "unpack",
.description = "Run the `unpack` phase.",
.handler = {&phase, {"unpack"}},
});
addFlag({
.longName = "configure",
.description = "Run the `configure` phase.",
.handler = {&phase, {"configure"}},
});
addFlag({
.longName = "build",
.description = "Run the `build` phase.",
.handler = {&phase, {"build"}},
});
addFlag({
.longName = "check",
.description = "Run the `check` phase.",
.handler = {&phase, {"check"}},
});
addFlag({
.longName = "install",
.description = "Run the `install` phase.",
.handler = {&phase, {"install"}},
});
addFlag({
.longName = "installcheck",
.description = "Run the `installcheck` phase.",
.handler = {&phase, {"installCheck"}},
});
}
std::string description() override
{
return "run a bash shell that provides the build environment of a derivation";
}
std::string doc() override
{
return
#include "develop.md"
;
}
void run(ref<Store> store) override
{
auto [buildEnvironment, gcroot] = getBuildEnvironment(store);
auto [rcFileFd, rcFilePath] = createTempFile("nix-shell");
auto script = makeRcScript(store, buildEnvironment);
if (verbosity >= lvlDebug)
script += "set -x\n";
script += fmt("command rm -f '%s'\n", rcFilePath);
if (phase) {
if (!command.empty())
throw UsageError("you cannot use both '--command' and '--phase'");
// FIXME: foundMakefile is set by buildPhase, need to get
// rid of that.
script += fmt("foundMakefile=1\n");
script += fmt("runHook %1%Phase\n", *phase);
}
else if (!command.empty()) {
std::vector<std::string> args;
for (auto s : command)
args.push_back(shellEscape(s));
script += fmt("exec %s\n", concatStringsSep(" ", args));
}
else {
script = "[ -n \"$PS1\" ] && [ -e ~/.bashrc ] && source ~/.bashrc;\n" + script;
if (developSettings.bashPrompt != "")
script += fmt("[ -n \"$PS1\" ] && PS1=%s;\n",
shellEscape(developSettings.bashPrompt.get()));
if (developSettings.bashPromptPrefix != "")
script += fmt("[ -n \"$PS1\" ] && PS1=%s\"$PS1\";\n",
shellEscape(developSettings.bashPromptPrefix.get()));
if (developSettings.bashPromptSuffix != "")
script += fmt("[ -n \"$PS1\" ] && PS1+=%s;\n",
shellEscape(developSettings.bashPromptSuffix.get()));
}
writeFull(rcFileFd.get(), script);
setEnviron();
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// prevent garbage collection until shell exits
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setenv("NIX_GCROOT", gcroot.data(), 1);
Path shell = "bash";
try {
auto state = getEvalState();
auto nixpkgsLockFlags = lockFlags;
nixpkgsLockFlags.inputOverrides = {};
nixpkgsLockFlags.inputUpdates = {};
auto bashInstallable = std::make_shared<InstallableFlake>(
this,
state,
installable->nixpkgsFlakeRef(),
"bashInteractive",
DefaultOutputs(),
Strings{},
Strings{"legacyPackages." + settings.thisSystem.get() + "."},
nixpkgsLockFlags);
bool found = false;
for (auto & path : Installable::toStorePaths(getEvalStore(), store, Realise::Outputs, OperateOn::Output, {bashInstallable})) {
auto s = store->printStorePath(path) + "/bin/bash";
if (pathExists(s)) {
shell = s;
found = true;
break;
}
}
if (!found)
throw Error("package 'nixpkgs#bashInteractive' does not provide a 'bin/bash'");
} catch (Error &) {
ignoreException();
}
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// If running a phase or single command, don't want an interactive shell running after
// Ctrl-C, so don't pass --rcfile
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auto args = phase || !command.empty() ? Strings{std::string(baseNameOf(shell)), rcFilePath}
: Strings{std::string(baseNameOf(shell)), "--rcfile", rcFilePath};
// Need to chdir since phases assume in flake directory
if (phase) {
// chdir if installable is a flake of type git+file or path
auto installableFlake = std::dynamic_pointer_cast<InstallableFlake>(installable);
if (installableFlake) {
auto sourcePath = installableFlake->getLockedFlake()->flake.resolvedRef.input.getSourcePath();
if (sourcePath) {
if (chdir(sourcePath->c_str()) == -1) {
throw SysError("chdir to '%s' failed", *sourcePath);
}
}
}
}
runProgramInStore(store, shell, args, buildEnvironment.getSystem());
}
};
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struct CmdPrintDevEnv : Common, MixJSON
{
std::string description() override
{
return "print shell code that can be sourced by bash to reproduce the build environment of a derivation";
}
std::string doc() override
{
return
#include "print-dev-env.md"
;
}
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Category category() override { return catUtility; }
void run(ref<Store> store) override
{
auto buildEnvironment = getBuildEnvironment(store).first;
stopProgressBar();
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logger->writeToStdout(
json
? buildEnvironment.toJSON()
: makeRcScript(store, buildEnvironment));
}
};
static auto rCmdPrintDevEnv = registerCommand<CmdPrintDevEnv>("print-dev-env");
static auto rCmdDevelop = registerCommand<CmdDevelop>("develop");