lix/src/nix/run.cc
Eelco Dolstra a24f2c9b84 nix run: Mount the Nix store in a private namespace
This is a convenience command to allow users who are not privileged to
create /nix/store to use Nix with regular binary caches. For example,

  $ NIX_REMOTE="local?state=$HOME/nix/var&real=/$HOME/nix/store" nix run firefox bashInteractive

will download Firefox and bash from cache.nixos.org, then start a
shell in which $HOME/nix/store is mounted on /nix/store.
2016-06-02 16:51:43 +02:00

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#include "command.hh"
#include "common-args.hh"
#include "installables.hh"
#include "shared.hh"
#include "store-api.hh"
#include "derivations.hh"
#include "local-store.hh"
#if __linux__
#include <sys/mount.h>
#endif
using namespace nix;
struct CmdRun : StoreCommand, MixInstallables
{
CmdRun()
{
}
std::string name() override
{
return "run";
}
std::string description() override
{
return "run a shell in which the specified packages are available";
}
void run(ref<Store> store) override
{
auto elems = evalInstallables(store);
PathSet pathsToBuild;
for (auto & elem : elems) {
if (elem.isDrv)
pathsToBuild.insert(elem.drvPath);
else
pathsToBuild.insert(elem.outPaths.begin(), elem.outPaths.end());
}
printMissing(store, pathsToBuild);
store->buildPaths(pathsToBuild);
auto store2 = store.dynamic_pointer_cast<LocalStore>();
if (store2 && store->storeDir != store2->realStoreDir) {
#if __linux__
if (unshare(CLONE_NEWUSER | CLONE_NEWNS) == -1)
throw SysError("setting up a private mount namespace");
if (mount(store2->realStoreDir.c_str(), store->storeDir.c_str(), "", MS_BIND, 0) == -1)
throw SysError(format("mounting %s on %s") % store2->realStoreDir % store->storeDir);
#else
throw Error(format("mounting the Nix store on %s is not supported on this platform") % store->storeDir);
#endif
}
PathSet outPaths;
for (auto & path : pathsToBuild)
if (isDerivation(path)) {
Derivation drv = store->derivationFromPath(path);
for (auto & output : drv.outputs)
outPaths.insert(output.second.path);
} else
outPaths.insert(path);
auto unixPath = tokenizeString<Strings>(getEnv("PATH"), ":");
for (auto & path : outPaths)
if (pathExists(path + "/bin"))
unixPath.push_front(path + "/bin");
setenv("PATH", concatStringsSep(":", unixPath).c_str(), 1);
if (execlp("bash", "bash", nullptr) == -1)
throw SysError("unable to exec bash");
}
};
static RegisterCommand r1(make_ref<CmdRun>());