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-rw-r--r--src/nix/dev-shell.cc347
1 files changed, 347 insertions, 0 deletions
diff --git a/src/nix/dev-shell.cc b/src/nix/dev-shell.cc
new file mode 100644
index 000000000..092ff8b10
--- /dev/null
+++ b/src/nix/dev-shell.cc
@@ -0,0 +1,347 @@
+#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 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 indexedArrayRegex =
+ R"re((?:\(( *\[[0-9]+]="(?:[^"\\]|\\.)*")**\)))re";
+
+ static std::regex varRegex(
+ "^(" + varNameRegex + ")=(" + simpleStringRegex + "|" + quotedStringRegex + "|" + 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)) {
+ 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 { .exported = exported.count(match[1]) > 0, .value = match[2] }});
+ }
+
+ else if (std::regex_search(pos, file.cend(), match, assocArrayRegex)) {
+ pos = match[0].second;
+ res.env.insert({match[1], Var { .associative = true, .value = 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;
+}
+
+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 dev-shell' 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. */
+ auto drvName = std::string(drvPath.name());
+ assert(hasSuffix(drvName, ".drv"));
+ drvName.resize(drvName.size() - 4);
+ drvName += "-env";
+ for (auto & output : drv.outputs)
+ drv.env.erase(output.first);
+ drv.env["out"] = "";
+ drv.env["outputs"] = "out";
+ drv.inputSrcs.insert(std::move(getEnvShPath));
+ Hash h = hashDerivationModulo(*store, drv, true);
+ auto shellOutPath = store->makeOutputPath("out", h, drvName);
+ drv.outputs.insert_or_assign("out", DerivationOutput(shellOutPath.clone(), FileSystemHash {
+ .method = FileIngestionMethod::Flat,
+ .hash = Hash { }
+ }));
+ 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> 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 << "unset shellHook\n";
+
+ out << "nix_saved_PATH=\"$PATH\"\n";
+
+ for (auto & i : buildEnvironment.env) {
+ if (!ignoreVars.count(i.first) && !hasPrefix(i.first, "BASH_")) {
+ if (i.second.associative)
+ out << fmt("declare -A %s=(%s)\n", i.first, i.second.value);
+ else {
+ out << fmt("%s=%s\n", i.first, i.second.value);
+ if (i.second.exported)
+ out << fmt("export %s\n", i.first);
+ }
+ }
+ }
+
+ out << "PATH=\"$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";
+ }
+
+ 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, 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 CmdDevShell : Common, MixEnvironment
+{
+ std::vector<std::string> command;
+
+ CmdDevShell()
+ {
+ addFlag({
+ .longName = "command",
+ .shortName = 'c',
+ .description = "command and arguments to be executed insted of an interactive shell",
+ .labels = {"command", "args"},
+ .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 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, gcroot] = 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();
+ // prevent garbage collection until shell exits
+ setenv("NIX_GCROOT", gcroot.data(), 1);
+
+ 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)"
+ },
+ };
+ }
+
+ Category category() override { return catUtility; }
+
+ void run(ref<Store> store) override
+ {
+ auto buildEnvironment = getBuildEnvironment(store).first;
+
+ 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 05:44:48 +0000