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Diffstat (limited to 'src/nix/shell.cc')
| -rw-r--r-- | src/nix/shell.cc | 283 |
1 files changed, 283 insertions, 0 deletions
diff --git a/src/nix/shell.cc b/src/nix/shell.cc new file mode 100644 index 000000000..2ccad930f --- /dev/null +++ b/src/nix/shell.cc @@ -0,0 +1,283 @@ +#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" + +using namespace nix; + +struct BuildEnvironment +{ + // FIXME: figure out which vars should be exported. + std::map<std::string, std::string> env; + std::map<std::string, std::string> functions; +}; + +BuildEnvironment readEnvironment(const Path & path) +{ + BuildEnvironment res; + + auto lines = tokenizeString<Strings>(readFile(path), "\n"); + + auto getLine = + [&]() { + if (lines.empty()) + throw Error("shell environment '%s' ends unexpectedly", path); + auto line = lines.front(); + lines.pop_front(); + return line; + }; + + while (!lines.empty()) { + auto line = getLine(); + + auto eq = line.find('='); + if (eq != std::string::npos) { + std::string name(line, 0, eq); + std::string value(line, eq + 1); + // FIXME: parse arrays + res.env.insert({name, value}); + } + + else if (hasSuffix(line, " () ")) { + std::string name(line, 0, line.size() - 4); + // FIXME: validate name + auto l = getLine(); + if (l != "{ ") throw Error("shell environment '%s' has unexpected line '%s'", path, l); + std::string body; + while ((l = getLine()) != "}") { + body += l; + body += '\n'; + } + res.functions.insert({name, body}); + } + + else throw Error("shell environment '%s' has unexpected line '%s'", path, line); + } + + 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. */ +BuildEnvironment 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; if [[ -n $stdenv ]]; then source $stdenv/setup; fi; set > $out"}; + + /* Remove derivation checks. */ + drv.env.erase("allowedReferences"); + drv.env.erase("allowedRequisites"); + drv.env.erase("disallowedReferences"); + drv.env.erase("disallowedRequisites"); + + // FIXME: handle structured attrs + + /* Rehash and write the derivation. FIXME: would be nice to use + 'buildDerivation', but that's privileged. */ + auto drvName = drv.env["name"] + "-env"; + for (auto & output : drv.outputs) + drv.env.erase(output.first); + drv.env["out"] = ""; + drv.env["outputs"] = "out"; + drv.outputs["out"] = DerivationOutput("", "", ""); + Hash h = hashDerivationModulo(*store, drv); + Path shellOutPath = store->makeOutputPath("out", h, drvName); + drv.outputs["out"].path = shellOutPath; + drv.env["out"] = shellOutPath; + Path shellDrvPath2 = writeDerivation(store, drv, drvName); + + /* Build the derivation. */ + store->buildPaths({shellDrvPath2}); + + assert(store->isValidPath(shellOutPath)); + + return readEnvironment(shellOutPath); +} + +struct Common : InstallableCommand +{ + /* + std::set<string> keepVars{ + "DISPLAY", + "HOME", + "IN_NIX_SHELL", + "LOGNAME", + "NIX_BUILD_SHELL", + "PAGER", + "PATH", + "TERM", + "TZ", + "USER", + }; + */ + + std::set<string> ignoreVars{ + "BASHOPTS", + "EUID", + "HOME", // FIXME: don't ignore in pure mode? + "NIX_BUILD_TOP", + "NIX_ENFORCE_PURITY", + "PPID", + "PWD", + "SHELLOPTS", + "SHLVL", + "SSL_CERT_FILE", // FIXME: only want to ignore /no-cert-file.crt + "TEMP", + "TEMPDIR", + "TERM", + "TMP", + "TMPDIR", + "TZ", + "UID", + }; + + void makeRcScript(const BuildEnvironment & buildEnvironment, std::ostream & out) + { + out << "export IN_NIX_SHELL=1\n"; + out << "nix_saved_PATH=\"$PATH\"\n"; + + for (auto & i : buildEnvironment.env) { + // FIXME: shellEscape + // FIXME: figure out what to export + // FIXME: handle arrays + if (!ignoreVars.count(i.first) && !hasPrefix(i.first, "BASH_")) + out << fmt("export %s=%s\n", i.first, i.second); + } + + out << "PATH=\"$PATH:$nix_saved_PATH\"\n"; + + for (auto & i : buildEnvironment.functions) { + out << fmt("%s () {\n%s\n}\n", i.first, i.second); + } + + // 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", "defaultPackage"}; + } +}; + +struct CmdDevShell : Common +{ + + std::string name() override + { + return "dev-shell"; + } + + 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" + }, + }; + } + + void run(ref<Store> store) override + { + 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(); + + auto buildEnvironment = getDerivationEnvironment(store, store->derivationFromPath(drvPath)); + + auto [rcFileFd, rcFilePath] = createTempFile("nix-shell"); + + std::ostringstream ss; + makeRcScript(buildEnvironment, ss); + + ss << fmt("rm -f '%s'\n", rcFilePath); + + writeFull(rcFileFd.get(), ss.str()); + + stopProgressBar(); + + auto shell = getEnv("SHELL", "bash"); + + auto args = Strings{baseNameOf(shell), "--rcfile", rcFilePath}; + + restoreAffinity(); + restoreSignals(); + + execvp(shell.c_str(), stringsToCharPtrs(args).data()); + + throw SysError("executing shell '%s'", shell); + } +}; + +struct CmdPrintDevEnv : Common +{ + + std::string name() override + { + return "print-dev-env"; + } + + 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 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(); + + auto buildEnvironment = getDerivationEnvironment(store, store->derivationFromPath(drvPath)); + + stopProgressBar(); + + makeRcScript(buildEnvironment, std::cout); + } +}; + +static RegisterCommand r1(make_ref<CmdPrintDevEnv>()); +static RegisterCommand r2(make_ref<CmdDevShell>()); |