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Diffstat (limited to 'src/nix/shell.cc')
| -rw-r--r-- | src/nix/shell.cc | 343 |
1 files changed, 343 insertions, 0 deletions
diff --git a/src/nix/shell.cc b/src/nix/shell.cc new file mode 100644 index 000000000..bee0bddcc --- /dev/null +++ b/src/nix/shell.cc @@ -0,0 +1,343 @@ +#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; + std::string value; // 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::regex declareRegex( + "^declare -x (" + varNameRegex + ")" + + R"re((?:="((?:[^"\\]|\\.)*)")?\n)re"); + + static std::string simpleStringRegex = + R"re((?:[a-zA-Z0-9_/:\.\-\+=]*))re"; + + static std::string quotedStringRegex = + R"re((?:\$?'(?:[^'\\]|\\[abeEfnrtv\\'"?])*'))re"; + + static std::string arrayRegex = + R"re((?:\(( *\[[^\]]+\]="(?:[^"\\]|\\.)*")*\)))re"; + + static std::regex varRegex( + "^(" + varNameRegex + ")=(" + simpleStringRegex + "|" + quotedStringRegex + "|" + arrayRegex + ")\n"); + + static std::regex functionRegex( + "^" + varNameRegex + " \\(\\) *\n"); + + while (pos != file.end()) { + + std::smatch match; + + if (std::regex_search(pos, file.cend(), match, declareRegex)) { + pos = match[0].second; + exported.insert(match[1]); + } + + else if (std::regex_search(pos, file.cend(), match, varRegex)) { + pos = match[0].second; + res.env.insert({match[1], Var { (bool) exported.count(match[1]), match[2] }}); + } + + else if (std::regex_search(pos, file.cend(), match, functionRegex)) { + 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)); + } + + return res; +} + +/* 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, Derivation drv) +{ + auto builder = baseNameOf(drv.builder); + if (builder != "bash") + throw Error("'nix shell' only works on derivations that use 'bash' as their builder"); + + drv.args = { + "-c", + "set -e; " + "export IN_NIX_SHELL=impure; " + "export dontAddDisableDepTrack=1; " + "if [[ -n $stdenv ]]; then " + " source $stdenv/setup; " + "fi; " + "export > $out; " + "set >> $out "}; + + /* Remove derivation checks. */ + drv.env.erase("allowedReferences"); + drv.env.erase("allowedRequisites"); + drv.env.erase("disallowedReferences"); + drv.env.erase("disallowedRequisites"); + + // FIXME: handle structured attrs + + /* Rehash and write the derivation. FIXME: would be nice to use + 'buildDerivation', but that's privileged. */ + auto drvName = drv.env["name"] + "-env"; + for (auto & output : drv.outputs) + drv.env.erase(output.first); + drv.env["out"] = ""; + drv.env["outputs"] = "out"; + Hash h = hashDerivationModulo(*store, drv, true); + auto shellOutPath = store->makeOutputPath("out", h, drvName); + drv.outputs.insert_or_assign("out", DerivationOutput(shellOutPath.clone(), "", "")); + drv.env["out"] = store->printStorePath(shellOutPath); + auto shellDrvPath2 = writeDerivation(store, drv, drvName); + + /* Build the derivation. */ + store->buildPaths({shellDrvPath2}); + + assert(store->isValidPath(shellOutPath)); + + return shellOutPath; +} + +struct Common : InstallableCommand, MixProfile +{ + /* + std::set<string> keepVars{ + "DISPLAY", + "HOME", + "IN_NIX_SHELL", + "LOGNAME", + "NIX_BUILD_SHELL", + "PAGER", + "PATH", + "TERM", + "TZ", + "USER", + }; + */ + + std::set<string> ignoreVars{ + "BASHOPTS", + "EUID", + "HOME", // FIXME: don't ignore in pure mode? + "NIX_BUILD_TOP", + "NIX_ENFORCE_PURITY", + "NIX_LOG_FD", + "PPID", + "PWD", + "SHELLOPTS", + "SHLVL", + "SSL_CERT_FILE", // FIXME: only want to ignore /no-cert-file.crt + "TEMP", + "TEMPDIR", + "TERM", + "TMP", + "TMPDIR", + "TZ", + "UID", + }; + + void makeRcScript(const BuildEnvironment & buildEnvironment, std::ostream & out) + { + out << "nix_saved_PATH=\"$PATH\"\n"; + + for (auto & i : buildEnvironment.env) { + if (!ignoreVars.count(i.first) && !hasPrefix(i.first, "BASH_")) { + out << fmt("%s=%s\n", i.first, i.second.value); + if (i.second.exported) + out << fmt("export %s\n", i.first); + } + } + + out << "PATH=\"$PATH:$nix_saved_PATH\"\n"; + + out << buildEnvironment.bashFunctions << "\n"; + + // FIXME: set outputs + + 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"; + } + + Strings getDefaultFlakeAttrPaths() override + { + return {"devShell." + settings.thisSystem.get(), "defaultPackage." + settings.thisSystem.get()}; + } + + StorePath getShellOutPath(ref<Store> store) + { + auto path = installable->getStorePath(); + if (path && hasSuffix(path->to_string(), "-env")) + return path->clone(); + 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, store->derivationFromPath(drvPath)); + } + } + + BuildEnvironment getBuildEnvironment(ref<Store> store) + { + auto shellOutPath = getShellOutPath(store); + + updateProfile(shellOutPath); + + return readEnvironment(store->printStorePath(shellOutPath)); + } +}; + +struct CmdDevShell : Common, MixEnvironment +{ + std::vector<std::string> command; + + CmdDevShell() + { + mkFlag() + .longName("command") + .shortName('c') + .description("command and arguments to be executed insted of an interactive shell") + .labels({"command", "args"}) + .arity(ArityAny) + .handler([&](std::vector<std::string> ss) { + if (ss.empty()) throw UsageError("--command requires at least one argument"); + command = ss; + }); + } + + 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 dev-shell nixpkgs:hello" + }, + Example{ + "To get the build environment of the default package of flake in the current directory:", + "nix dev-shell" + }, + Example{ + "To store the build environment in a profile:", + "nix dev-shell --profile /tmp/my-shell nixpkgs:hello" + }, + Example{ + "To use a build environment previously recorded in a profile:", + "nix dev-shell /tmp/my-shell" + }, + }; + } + + void run(ref<Store> store) override + { + auto buildEnvironment = getBuildEnvironment(store); + + auto [rcFileFd, rcFilePath] = createTempFile("nix-shell"); + + std::ostringstream ss; + makeRcScript(buildEnvironment, ss); + + ss << fmt("rm -f '%s'\n", rcFilePath); + + if (!command.empty()) { + std::vector<std::string> args; + for (auto s : command) + args.push_back(shellEscape(s)); + ss << fmt("exec %s\n", concatStringsSep(" ", args)); + } + + writeFull(rcFileFd.get(), ss.str()); + + stopProgressBar(); + + auto shell = getEnv("SHELL").value_or("bash"); + + setEnviron(); + + auto args = 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)" + }, + }; + } + + void run(ref<Store> store) override + { + auto buildEnvironment = getBuildEnvironment(store); + + stopProgressBar(); + + makeRcScript(buildEnvironment, std::cout); + } +}; + +static auto r1 = registerCommand<CmdPrintDevEnv>("print-dev-env"); +static auto r2 = registerCommand<CmdDevShell>("dev-shell"); |