lix/src/nix/run.cc
Eelco Dolstra 8d9f7048cd Use eval-store in more places
In particular, this now works:

  $ nix path-info --eval-store auto --store https://cache.nixos.org nixpkgs#hello

Previously this would fail as it would try to upload the hello .drv to
cache.nixos.org. Now the .drv is instantiated in the local store, and
then we check for the existence of the outputs in cache.nixos.org.
2021-07-22 09:59:51 +02:00

268 lines
8 KiB
C++

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