lix/src/nix/develop.cc

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#include "eval.hh"
#include "command.hh"
#include "common-args.hh"
#include "shared.hh"
#include "store-api.hh"
#include "derivations.hh"
#include "affinity.hh"
#include "progress-bar.hh"
#include <regex>
using namespace nix;
struct Var
{
bool exported = true;
bool associative = false;
std::string quoted; // quoted string or array
};
struct BuildEnvironment
{
std::map<std::string, Var> env;
std::string bashFunctions;
};
BuildEnvironment readEnvironment(const Path & path)
{
BuildEnvironment res;
std::set<std::string> exported;
debug("reading environment file '%s'", path);
auto file = readFile(path);
auto pos = file.cbegin();
static std::string varNameRegex =
R"re((?:[a-zA-Z_][a-zA-Z0-9_]*))re";
static std::string simpleStringRegex =
R"re((?:[a-zA-Z0-9_/:\.\-\+=]*))re";
static std::string dquotedStringRegex =
R"re((?:\$?"(?:[^"\\]|\\[$`"\\\n])*"))re";
static std::string squotedStringRegex =
R"re((?:\$?'(?:[^'\\]|\\[abeEfnrtv\\'"?])*'))re";
static std::string indexedArrayRegex =
R"re((?:\(( *\[[0-9]+\]="(?:[^"\\]|\\.)*")*\)))re";
static std::regex declareRegex(
"^declare -a?x (" + varNameRegex + ")(=(" +
dquotedStringRegex + "|" + indexedArrayRegex + "))?\n");
static std::regex varRegex(
"^(" + varNameRegex + ")=(" + simpleStringRegex + "|" + squotedStringRegex + "|" + indexedArrayRegex + ")\n");
/* Note: we distinguish between an indexed and associative array
using the space before the closing parenthesis. Will
undoubtedly regret this some day. */
static std::regex assocArrayRegex(
"^(" + varNameRegex + ")=" + R"re((?:\(( *\[[^\]]+\]="(?:[^"\\]|\\.)*")* *\)))re" + "\n");
static std::regex functionRegex(
"^" + varNameRegex + " \\(\\) *\n");
while (pos != file.end()) {
std::smatch match;
if (std::regex_search(pos, file.cend(), match, declareRegex, std::regex_constants::match_continuous)) {
pos = match[0].second;
exported.insert(match[1]);
}
else if (std::regex_search(pos, file.cend(), match, varRegex, std::regex_constants::match_continuous)) {
pos = match[0].second;
res.env.insert({match[1], Var { .exported = exported.count(match[1]) > 0, .quoted = match[2] }});
}
else if (std::regex_search(pos, file.cend(), match, assocArrayRegex, std::regex_constants::match_continuous)) {
pos = match[0].second;
res.env.insert({match[1], Var { .associative = true, .quoted = match[2] }});
}
else if (std::regex_search(pos, file.cend(), match, functionRegex, std::regex_constants::match_continuous)) {
res.bashFunctions = std::string(pos, file.cend());
break;
}
else throw Error("shell environment '%s' has unexpected line '%s'",
path, file.substr(pos - file.cbegin(), 60));
}
res.env.erase("__output");
return res;
}
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. */
StorePath getDerivationEnvironment(ref<Store> store, const StorePath & drvPath)
{
auto drv = store->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 = store->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");
/* Rehash and write the derivation. FIXME: would be nice to use
'buildDerivation', but that's privileged. */
drv.name += "-env";
for (auto & output : drv.outputs) {
output.second = { .output = DerivationOutputInputAddressed { .path = StorePath::dummy } };
drv.env[output.first] = "";
}
drv.inputSrcs.insert(std::move(getEnvShPath));
Hash h = std::get<0>(hashDerivationModulo(*store, drv, true));
for (auto & output : drv.outputs) {
auto outPath = store->makeOutputPath(output.first, h, drv.name);
output.second = { .output = DerivationOutputInputAddressed { .path = outPath } };
drv.env[output.first] = store->printStorePath(outPath);
}
auto shellDrvPath = writeDerivation(*store, drv);
/* Build the derivation. */
store->buildPaths({{shellDrvPath}});
for (auto & [_0, outputAndOptPath] : drv.outputsAndOptPaths(*store)) {
auto & [_1, optPath] = outputAndOptPath;
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<string> ignoreVars{
"BASHOPTS",
"EUID",
"HOME", // FIXME: don't ignore in pure mode?
"HOSTNAME",
"NIX_BUILD_TOP",
"NIX_ENFORCE_PURITY",
"NIX_LOG_FD",
"PPID",
"PWD",
"SHELLOPTS",
"SHLVL",
"SSL_CERT_FILE", // FIXME: only want to ignore /no-cert-file.crt
"TEMP",
"TEMPDIR",
"TERM",
"TMP",
"TMPDIR",
"TZ",
"UID",
};
std::string makeRcScript(
const BuildEnvironment & buildEnvironment,
const Path & outputsDir = absPath(".") + "/outputs")
{
std::ostringstream out;
out << "unset shellHook\n";
out << "nix_saved_PATH=\"$PATH\"\n";
for (auto & i : buildEnvironment.env) {
if (!ignoreVars.count(i.first) && !hasPrefix(i.first, "BASH_")) {
if (i.second.associative)
out << fmt("declare -A %s=(%s)\n", i.first, i.second.quoted);
else {
out << fmt("%s=%s\n", i.first, i.second.quoted);
if (i.second.exported)
out << fmt("export %s\n", i.first);
}
}
}
out << "PATH=\"$PATH:$nix_saved_PATH\"\n";
out << buildEnvironment.bashFunctions << "\n";
out << "export NIX_BUILD_TOP=\"$(mktemp -d --tmpdir nix-shell.XXXXXX)\"\n";
for (auto & i : {"TMP", "TMPDIR", "TEMP", "TEMPDIR"})
out << fmt("export %s=\"$NIX_BUILD_TOP\"\n", i);
out << "eval \"$shellHook\"\n";
/* Substitute occurrences of output paths. */
auto outputs = buildEnvironment.env.find("outputs");
assert(outputs != buildEnvironment.env.end());
// FIXME: properly unquote 'outputs'.
StringMap rewrites;
for (auto & outputName : tokenizeString<std::vector<std::string>>(replaceStrings(outputs->second.quoted, "'", ""))) {
auto from = buildEnvironment.env.find(outputName);
assert(from != buildEnvironment.env.end());
// FIXME: unquote
rewrites.insert({from->second.quoted, outputsDir + "/" + outputName});
}
return rewriteStrings(out.str(), rewrites);
}
Strings getDefaultFlakeAttrPaths() override
{
return {"devShell." + settings.thisSystem.get(), "defaultPackage." + settings.thisSystem.get()};
}
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StorePath getShellOutPath(ref<Store> store)
{
auto path = installable->getStorePath();
if (path && hasSuffix(path->to_string(), "-env"))
return *path;
else {
auto drvs = 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, drvPath);
}
}
std::pair<BuildEnvironment, std::string> getBuildEnvironment(ref<Store> store)
{
auto shellOutPath = getShellOutPath(store);
auto strPath = store->printStorePath(shellOutPath);
updateProfile(shellOutPath);
return {readEnvironment(strPath), 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',
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.description = "command and arguments to be executed instead of an interactive shell",
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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 = "phase to run (e.g. `build` or `configure`)",
.labels = {"phase-name"},
.handler = {&phase},
});
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";
}
Examples examples() override
{
return {
Example{
"To get the build environment of GNU hello:",
"nix develop nixpkgs#hello"
},
Example{
"To get the build environment of the default package of flake in the current directory:",
"nix develop"
},
Example{
"To store the build environment in a profile:",
"nix develop --profile /tmp/my-shell nixpkgs#hello"
},
Example{
"To use a build environment previously recorded in a profile:",
"nix develop /tmp/my-shell"
},
};
}
void run(ref<Store> store) override
{
auto [buildEnvironment, gcroot] = getBuildEnvironment(store);
auto [rcFileFd, rcFilePath] = createTempFile("nix-shell");
auto script = makeRcScript(buildEnvironment);
if (verbosity >= lvlDebug)
script += "set -x\n";
script += fmt("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";
}
writeFull(rcFileFd.get(), script);
stopProgressBar();
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 bashInstallable = std::make_shared<InstallableFlake>(
state,
installable->nixpkgsFlakeRef(),
Strings{"bashInteractive"},
Strings{"legacyPackages." + settings.thisSystem.get() + "."},
lockFlags);
shell = state->store->printStorePath(
toStorePath(state->store, Realise::Outputs, OperateOn::Output, bashInstallable)) + "/bin/bash";
} catch (Error &) {
ignoreException();
}
// If running a phase, don't want an interactive shell running after
// Ctrl-C, so don't pass --rcfile
auto args = phase ? Strings{std::string(baseNameOf(shell)), rcFilePath}
: Strings{std::string(baseNameOf(shell)), "--rcfile", rcFilePath};
restoreAffinity();
restoreSignals();
execvp(shell.c_str(), stringsToCharPtrs(args).data());
throw SysError("executing shell '%s'", shell);
}
};
struct CmdPrintDevEnv : Common
{
std::string description() override
{
return "print shell code that can be sourced by bash to reproduce the build environment of a derivation";
}
Examples examples() override
{
return {
Example{
"To apply the build environment of GNU hello to the current shell:",
". <(nix print-dev-env nixpkgs#hello)"
},
};
}
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Category category() override { return catUtility; }
void run(ref<Store> store) override
{
auto buildEnvironment = getBuildEnvironment(store).first;
stopProgressBar();
std::cout << makeRcScript(buildEnvironment);
}
};
static auto rCmdPrintDevEnv = registerCommand<CmdPrintDevEnv>("print-dev-env");
static auto rCmdDevelop = registerCommand<CmdDevelop>("develop");