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-rw-r--r--src/nix/shell.cc317
1 files changed, 317 insertions, 0 deletions
diff --git a/src/nix/shell.cc b/src/nix/shell.cc
new file mode 100644
index 000000000..50d0f9c88
--- /dev/null
+++ b/src/nix/shell.cc
@@ -0,0 +1,317 @@
+#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;
+
+ 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_/:\.\-1\+]*))re";
+
+ static std::string quotedStringRegex =
+ R"re((?:\$?'[^']*'))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. */
+Path 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 >> $out "};
+
+ /* Remove derivation checks. */
+ drv.env.erase("allowedReferences");
+ drv.env.erase("allowedRequisites");
+ drv.env.erase("disallowedReferences");
+ drv.env.erase("disallowedRequisites");
+
+ // FIXME: handle structured attrs
+
+ /* Rehash and write the derivation. FIXME: would be nice to use
+ 'buildDerivation', but that's privileged. */
+ auto drvName = drv.env["name"] + "-env";
+ for (auto & output : drv.outputs)
+ drv.env.erase(output.first);
+ drv.env["out"] = "";
+ drv.env["outputs"] = "out";
+ drv.outputs["out"] = DerivationOutput("", "", "");
+ Hash h = hashDerivationModulo(*store, drv);
+ Path shellOutPath = store->makeOutputPath("out", h, drvName);
+ drv.outputs["out"].path = shellOutPath;
+ drv.env["out"] = shellOutPath;
+ Path shellDrvPath2 = writeDerivation(store, drv, drvName);
+
+ /* Build the derivation. */
+ store->buildPaths({shellDrvPath2});
+
+ assert(store->isValidPath(shellOutPath));
+
+ return shellOutPath;
+}
+
+struct Common : InstallableCommand, MixProfile
+{
+ /*
+ std::set<string> keepVars{
+ "DISPLAY",
+ "HOME",
+ "IN_NIX_SHELL",
+ "LOGNAME",
+ "NIX_BUILD_SHELL",
+ "PAGER",
+ "PATH",
+ "TERM",
+ "TZ",
+ "USER",
+ };
+ */
+
+ std::set<string> ignoreVars{
+ "BASHOPTS",
+ "EUID",
+ "HOME", // FIXME: don't ignore in pure mode?
+ "NIX_BUILD_TOP",
+ "NIX_ENFORCE_PURITY",
+ "NIX_LOG_FD",
+ "PPID",
+ "PWD",
+ "SHELLOPTS",
+ "SHLVL",
+ "SSL_CERT_FILE", // FIXME: only want to ignore /no-cert-file.crt
+ "TEMP",
+ "TEMPDIR",
+ "TERM",
+ "TMP",
+ "TMPDIR",
+ "TZ",
+ "UID",
+ };
+
+ void makeRcScript(const BuildEnvironment & buildEnvironment, std::ostream & out)
+ {
+ out << "nix_saved_PATH=\"$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()};
+ }
+
+ Path getShellOutPath(ref<Store> store)
+ {
+ auto path = installable->getStorePath();
+ if (path && hasSuffix(*path, "-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, store->derivationFromPath(drvPath));
+ }
+ }
+
+ BuildEnvironment getBuildEnvironment(ref<Store> store)
+ {
+ auto shellOutPath = getShellOutPath(store);
+
+ updateProfile(shellOutPath);
+
+ return readEnvironment(shellOutPath);
+ }
+};
+
+struct CmdDevShell : Common
+{
+ 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);
+
+ 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 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");
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-23 22:34:52 +0000