forked from lix-project/lix
272 lines
8 KiB
C++
272 lines
8 KiB
C++
#include "command.hh"
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#include "common-args.hh"
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#include "shared.hh"
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#include "store-api.hh"
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#include "derivations.hh"
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#include "local-store.hh"
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#include "finally.hh"
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#include "fs-accessor.hh"
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#include "progress-bar.hh"
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#include "affinity.hh"
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#include "eval.hh"
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#if __linux__
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#include <sys/mount.h>
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#endif
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#include <queue>
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using namespace nix;
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std::string chrootHelperName = "__run_in_chroot";
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struct RunCommon : virtual Command
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{
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using Command::run;
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void runProgram(ref<Store> store,
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const std::string & program,
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const Strings & args)
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{
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stopProgressBar();
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restoreSignals();
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restoreAffinity();
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/* If this is a diverted store (i.e. its "logical" location
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(typically /nix/store) differs from its "physical" location
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(e.g. /home/eelco/nix/store), then run the command in a
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chroot. For non-root users, this requires running it in new
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mount and user namespaces. Unfortunately,
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unshare(CLONE_NEWUSER) doesn't work in a multithreaded
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program (which "nix" is), so we exec() a single-threaded
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helper program (chrootHelper() below) to do the work. */
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auto store2 = store.dynamic_pointer_cast<LocalStore>();
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if (store2 && store->storeDir != store2->realStoreDir) {
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Strings helperArgs = { chrootHelperName, store->storeDir, store2->realStoreDir, program };
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for (auto & arg : args) helperArgs.push_back(arg);
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execv(readLink("/proc/self/exe").c_str(), stringsToCharPtrs(helperArgs).data());
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throw SysError("could not execute chroot helper");
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}
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execvp(program.c_str(), stringsToCharPtrs(args).data());
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throw SysError("unable to execute '%s'", program);
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}
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};
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struct CmdShell : InstallablesCommand, RunCommon, MixEnvironment
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{
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using InstallablesCommand::run;
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std::vector<std::string> command = { getEnv("SHELL").value_or("bash") };
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CmdShell()
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{
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addFlag({
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.longName = "command",
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.shortName = 'c',
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.description = "command and arguments to be executed; defaults to '$SHELL'",
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.labels = {"command", "args"},
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.handler = {[&](std::vector<std::string> ss) {
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if (ss.empty()) throw UsageError("--command requires at least one argument");
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command = ss;
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}}
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});
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}
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std::string description() override
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{
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return "run a shell in which the specified packages are available";
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}
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std::string doc() override
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{
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return
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#include "shell.md"
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;
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}
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void run(ref<Store> store) override
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{
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auto outPaths = toStorePaths(store, Realise::Outputs, OperateOn::Output, installables);
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auto accessor = store->getFSAccessor();
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std::unordered_set<StorePath> done;
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std::queue<StorePath> todo;
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for (auto & path : outPaths) todo.push(path);
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setEnviron();
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auto unixPath = tokenizeString<Strings>(getEnv("PATH").value_or(""), ":");
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while (!todo.empty()) {
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auto path = todo.front();
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todo.pop();
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if (!done.insert(path).second) continue;
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if (true)
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unixPath.push_front(store->printStorePath(path) + "/bin");
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auto propPath = store->printStorePath(path) + "/nix-support/propagated-user-env-packages";
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if (accessor->stat(propPath).type == FSAccessor::tRegular) {
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for (auto & p : tokenizeString<Paths>(readFile(propPath)))
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todo.push(store->parseStorePath(p));
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}
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}
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setenv("PATH", concatStringsSep(":", unixPath).c_str(), 1);
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Strings args;
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for (auto & arg : command) args.push_back(arg);
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runProgram(store, *command.begin(), args);
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}
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};
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static auto rCmdShell = registerCommand<CmdShell>("shell");
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struct CmdRun : InstallableCommand, RunCommon
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{
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using InstallableCommand::run;
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std::vector<std::string> args;
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CmdRun()
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{
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expectArgs({
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.label = "args",
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.handler = {&args},
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.completer = completePath
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});
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}
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std::string description() override
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{
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return "run a Nix application";
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}
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std::string doc() override
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{
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return
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#include "run.md"
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;
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}
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Strings getDefaultFlakeAttrPaths() override
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{
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Strings res{"defaultApp." + settings.thisSystem.get()};
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for (auto & s : SourceExprCommand::getDefaultFlakeAttrPaths())
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res.push_back(s);
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return res;
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}
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Strings getDefaultFlakeAttrPathPrefixes() override
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{
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Strings res{"apps." + settings.thisSystem.get() + ".", "packages"};
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for (auto & s : SourceExprCommand::getDefaultFlakeAttrPathPrefixes())
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res.push_back(s);
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return res;
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}
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void run(ref<Store> store) override
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{
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auto state = getEvalState();
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auto app = installable->toApp(*state);
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state->store->buildPaths(app.context);
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Strings allArgs{app.program};
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for (auto & i : args) allArgs.push_back(i);
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runProgram(store, app.program, allArgs);
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}
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};
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static auto rCmdRun = registerCommand<CmdRun>("run");
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void chrootHelper(int argc, char * * argv)
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{
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int p = 1;
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std::string storeDir = argv[p++];
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std::string realStoreDir = argv[p++];
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std::string cmd = argv[p++];
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Strings args;
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while (p < argc)
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args.push_back(argv[p++]);
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#if __linux__
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uid_t uid = getuid();
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uid_t gid = getgid();
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if (unshare(CLONE_NEWUSER | CLONE_NEWNS) == -1)
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/* Try with just CLONE_NEWNS in case user namespaces are
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specifically disabled. */
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if (unshare(CLONE_NEWNS) == -1)
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throw SysError("setting up a private mount namespace");
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/* Bind-mount realStoreDir on /nix/store. If the latter mount
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point doesn't already exists, we have to create a chroot
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environment containing the mount point and bind mounts for the
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children of /. Would be nice if we could use overlayfs here,
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but that doesn't work in a user namespace yet (Ubuntu has a
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patch for this:
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https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1478578). */
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if (!pathExists(storeDir)) {
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// FIXME: Use overlayfs?
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Path tmpDir = createTempDir();
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createDirs(tmpDir + storeDir);
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if (mount(realStoreDir.c_str(), (tmpDir + storeDir).c_str(), "", MS_BIND, 0) == -1)
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throw SysError("mounting '%s' on '%s'", realStoreDir, storeDir);
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for (auto entry : readDirectory("/")) {
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auto src = "/" + entry.name;
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Path dst = tmpDir + "/" + entry.name;
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if (pathExists(dst)) continue;
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auto st = lstat(src);
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if (S_ISDIR(st.st_mode)) {
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if (mkdir(dst.c_str(), 0700) == -1)
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throw SysError("creating directory '%s'", dst);
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if (mount(src.c_str(), dst.c_str(), "", MS_BIND | MS_REC, 0) == -1)
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throw SysError("mounting '%s' on '%s'", src, dst);
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} else if (S_ISLNK(st.st_mode))
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createSymlink(readLink(src), dst);
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}
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char * cwd = getcwd(0, 0);
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if (!cwd) throw SysError("getting current directory");
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Finally freeCwd([&]() { free(cwd); });
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if (chroot(tmpDir.c_str()) == -1)
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throw SysError("chrooting into '%s'", tmpDir);
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if (chdir(cwd) == -1)
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throw SysError("chdir to '%s' in chroot", cwd);
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} else
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if (mount(realStoreDir.c_str(), storeDir.c_str(), "", MS_BIND, 0) == -1)
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throw SysError("mounting '%s' on '%s'", realStoreDir, storeDir);
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writeFile("/proc/self/setgroups", "deny");
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writeFile("/proc/self/uid_map", fmt("%d %d %d", uid, uid, 1));
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writeFile("/proc/self/gid_map", fmt("%d %d %d", gid, gid, 1));
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execvp(cmd.c_str(), stringsToCharPtrs(args).data());
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throw SysError("unable to exec '%s'", cmd);
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#else
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throw Error("mounting the Nix store on '%s' is not supported on this platform", storeDir);
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#endif
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}
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