lix/src/libmain/shared.cc

#include "globals.hh"
#include "shared.hh"
#include "store-api.hh"
#include "util.hh"
#include "loggers.hh"

#include <algorithm>
#include <cctype>
#include <exception>
#include <iostream>
#include <mutex>

#include <cstdlib>
#include <sys/time.h>
#include <sys/stat.h>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>

#include <openssl/crypto.h>

#include <sodium.h>


namespace nix {


static bool gcWarning = true;

void printGCWarning()
{
    if (!gcWarning) return;
    static bool haveWarned = false;
    warnOnce(haveWarned,
        "you did not specify '--add-root'; "
        "the result might be removed by the garbage collector");
}


void printMissing(ref<Store> store, const std::vector<DerivedPath> & paths, Verbosity lvl)
{
    uint64_t downloadSize, narSize;
    StorePathSet willBuild, willSubstitute, unknown;
    store->queryMissing(paths, willBuild, willSubstitute, unknown, downloadSize, narSize);
    printMissing(store, willBuild, willSubstitute, unknown, downloadSize, narSize, lvl);
}


void printMissing(ref<Store> store, const StorePathSet & willBuild,
    const StorePathSet & willSubstitute, const StorePathSet & unknown,
    uint64_t downloadSize, uint64_t narSize, Verbosity lvl)
{
    if (!willBuild.empty()) {
        if (willBuild.size() == 1)
            printMsg(lvl, fmt("this derivation will be built:"));
        else
            printMsg(lvl, fmt("these %d derivations will be built:", willBuild.size()));
        auto sorted = store->topoSortPaths(willBuild);
        reverse(sorted.begin(), sorted.end());
        for (auto & i : sorted)
            printMsg(lvl, fmt("  %s", store->printStorePath(i)));
    }

    if (!willSubstitute.empty()) {
        const float downloadSizeMiB = downloadSize / (1024.f * 1024.f);
        const float narSizeMiB = narSize / (1024.f * 1024.f);
        if (willSubstitute.size() == 1) {
            printMsg(lvl, fmt("this path will be fetched (%.2f MiB download, %.2f MiB unpacked):",
                downloadSizeMiB,
                narSizeMiB));
        } else {
            printMsg(lvl, fmt("these %d paths will be fetched (%.2f MiB download, %.2f MiB unpacked):",
                willSubstitute.size(),
                downloadSizeMiB,
                narSizeMiB));
        }
        for (auto & i : willSubstitute)
            printMsg(lvl, fmt("  %s", store->printStorePath(i)));
    }

    if (!unknown.empty()) {
        printMsg(lvl, fmt("don't know how to build these paths%s:",
                (settings.readOnlyMode ? " (may be caused by read-only store access)" : "")));
        for (auto & i : unknown)
            printMsg(lvl, fmt("  %s", store->printStorePath(i)));
    }
}


string getArg(const string & opt,
    Strings::iterator & i, const Strings::iterator & end)
{
    ++i;
    if (i == end) throw UsageError("'%1%' requires an argument", opt);
    return *i;
}


#if OPENSSL_VERSION_NUMBER < 0x10101000L
/* OpenSSL is not thread-safe by default - it will randomly crash
   unless the user supplies a mutex locking function. So let's do
   that. */
static std::vector<std::mutex> opensslLocks;

static void opensslLockCallback(int mode, int type, const char * file, int line)
{
    if (mode & CRYPTO_LOCK)
        opensslLocks[type].lock();
    else
        opensslLocks[type].unlock();
}
#endif

static std::once_flag dns_resolve_flag;

static void preloadNSS() {
    /* builtin:fetchurl can trigger a DNS lookup, which with glibc can trigger a dynamic library load of
       one of the glibc NSS libraries in a sandboxed child, which will fail unless the library's already
       been loaded in the parent. So we force a lookup of an invalid domain to force the NSS machinery to
       load its lookup libraries in the parent before any child gets a chance to. */
    std::call_once(dns_resolve_flag, []() {
        struct addrinfo *res = NULL;

        /* nss will only force the "local" (not through nscd) dns resolution if its on the LOCALDOMAIN.
           We need the resolution to be done locally, as nscd socket will not be accessible in the
           sandbox. */
        char * previous_env = getenv("LOCALDOMAIN");
        setenv("LOCALDOMAIN", "invalid", 1);
        if (getaddrinfo("this.pre-initializes.the.dns.resolvers.invalid.", "http", NULL, &res) == 0) {
            if (res) freeaddrinfo(res);
        }
        if (previous_env) {
             setenv("LOCALDOMAIN", previous_env, 1);
        } else {
             unsetenv("LOCALDOMAIN");
        }
    });
}

static void sigHandler(int signo) { }


void initNix()
{
    /* Turn on buffering for cerr. */
#if HAVE_PUBSETBUF
    static char buf[1024];
    std::cerr.rdbuf()->pubsetbuf(buf, sizeof(buf));
#endif

#if OPENSSL_VERSION_NUMBER < 0x10101000L
    /* Initialise OpenSSL locking. */
    opensslLocks = std::vector<std::mutex>(CRYPTO_num_locks());
    CRYPTO_set_locking_callback(opensslLockCallback);
#endif

    if (sodium_init() == -1)
        throw Error("could not initialise libsodium");

    loadConfFile();

    startSignalHandlerThread();

    /* Reset SIGCHLD to its default. */
    struct sigaction act;
    sigemptyset(&act.sa_mask);
    act.sa_handler = SIG_DFL;
    act.sa_flags = 0;
    if (sigaction(SIGCHLD, &act, 0))
        throw SysError("resetting SIGCHLD");

    /* Install a dummy SIGUSR1 handler for use with pthread_kill(). */
    act.sa_handler = sigHandler;
    if (sigaction(SIGUSR1, &act, 0)) throw SysError("handling SIGUSR1");

#if __APPLE__
    /* HACK: on darwin, we need can’t use sigprocmask with SIGWINCH.
     * Instead, add a dummy sigaction handler, and signalHandlerThread
     * can handle the rest. */
    struct sigaction sa;
    sa.sa_handler = sigHandler;
    if (sigaction(SIGWINCH, &sa, 0)) throw SysError("handling SIGWINCH");
#endif

    /* Register a SIGSEGV handler to detect stack overflows. */
    detectStackOverflow();

    /* There is no privacy in the Nix system ;-)  At least not for
       now.  In particular, store objects should be readable by
       everybody. */
    umask(0022);

    /* Initialise the PRNG. */
    struct timeval tv;
    gettimeofday(&tv, 0);
    srandom(tv.tv_usec);

    /* On macOS, don't use the per-session TMPDIR (as set e.g. by
       sshd). This breaks build users because they don't have access
       to the TMPDIR, in particular in ‘nix-store --serve’. */
#if __APPLE__
    if (hasPrefix(getEnv("TMPDIR").value_or("/tmp"), "/var/folders/"))
        unsetenv("TMPDIR");
#endif

    preloadNSS();
}


LegacyArgs::LegacyArgs(const std::string & programName,
    std::function<bool(Strings::iterator & arg, const Strings::iterator & end)> parseArg)
    : MixCommonArgs(programName), parseArg(parseArg)
{
    addFlag({
        .longName = "no-build-output",
        .shortName = 'Q',
        .description = "Do not show build output.",
        .handler = {[&]() {setLogFormat(LogFormat::raw); }},
    });

    addFlag({
        .longName = "keep-failed",
        .shortName ='K',
        .description = "Keep temporary directories of failed builds.",
        .handler = {&(bool&) settings.keepFailed, true},
    });

    addFlag({
        .longName = "keep-going",
        .shortName ='k',
        .description = "Keep going after a build fails.",
        .handler = {&(bool&) settings.keepGoing, true},
    });

    addFlag({
        .longName = "fallback",
        .description = "Build from source if substitution fails.",
        .handler = {&(bool&) settings.tryFallback, true},
    });

    auto intSettingAlias = [&](char shortName, const std::string & longName,
        const std::string & description, const std::string & dest)
    {
        addFlag({
            .longName = longName,
            .shortName = shortName,
            .description = description,
            .labels = {"n"},
            .handler = {[=](std::string s) {
                auto n = string2IntWithUnitPrefix<uint64_t>(s);
                settings.set(dest, std::to_string(n));
            }}
        });
    };

    intSettingAlias(0, "cores", "Maximum number of CPU cores to use inside a build.", "cores");
    intSettingAlias(0, "max-silent-time", "Number of seconds of silence before a build is killed.", "max-silent-time");
    intSettingAlias(0, "timeout", "Number of seconds before a build is killed.", "timeout");

    addFlag({
        .longName = "readonly-mode",
        .description = "Do not write to the Nix store.",
        .handler = {&settings.readOnlyMode, true},
    });

    addFlag({
        .longName = "no-gc-warning",
        .description = "Disable warnings about not using `--add-root`.",
        .handler = {&gcWarning, false},
    });

    addFlag({
        .longName = "store",
        .description = "The URL of the Nix store to use.",
        .labels = {"store-uri"},
        .handler = {&(std::string&) settings.storeUri},
    });
}


bool LegacyArgs::processFlag(Strings::iterator & pos, Strings::iterator end)
{
    if (MixCommonArgs::processFlag(pos, end)) return true;
    bool res = parseArg(pos, end);
    if (res) ++pos;
    return res;
}


bool LegacyArgs::processArgs(const Strings & args, bool finish)
{
    if (args.empty()) return true;
    assert(args.size() == 1);
    Strings ss(args);
    auto pos = ss.begin();
    if (!parseArg(pos, ss.end()))
        throw UsageError("unexpected argument '%1%'", args.front());
    return true;
}


void parseCmdLine(int argc, char * * argv,
    std::function<bool(Strings::iterator & arg, const Strings::iterator & end)> parseArg)
{
    parseCmdLine(std::string(baseNameOf(argv[0])), argvToStrings(argc, argv), parseArg);
}


void parseCmdLine(const string & programName, const Strings & args,
    std::function<bool(Strings::iterator & arg, const Strings::iterator & end)> parseArg)
{
    LegacyArgs(programName, parseArg).parseCmdline(args);
}


void printVersion(const string & programName)
{
    std::cout << format("%1% (Nix) %2%") % programName % nixVersion << std::endl;
    if (verbosity > lvlInfo) {
        Strings cfg;
#if HAVE_BOEHMGC
        cfg.push_back("gc");
#endif
        cfg.push_back("signed-caches");
        std::cout << "System type: " << settings.thisSystem << "\n";
        std::cout << "Additional system types: " << concatStringsSep(", ", settings.extraPlatforms.get()) << "\n";
        std::cout << "Features: " << concatStringsSep(", ", cfg) << "\n";
        std::cout << "System configuration file: " << settings.nixConfDir + "/nix.conf" << "\n";
        std::cout << "User configuration files: " <<
            concatStringsSep(":", settings.nixUserConfFiles)
            << "\n";
        std::cout << "Store directory: " << settings.nixStore << "\n";
        std::cout << "State directory: " << settings.nixStateDir << "\n";
    }
    throw Exit();
}


void showManPage(const string & name)
{
    restoreProcessContext();
    setenv("MANPATH", settings.nixManDir.c_str(), 1);
    execlp("man", "man", name.c_str(), nullptr);
    throw SysError("command 'man %1%' failed", name.c_str());
}


int handleExceptions(const string & programName, std::function<void()> fun)
{
    ReceiveInterrupts receiveInterrupts; // FIXME: need better place for this

    ErrorInfo::programName = baseNameOf(programName);

    string error = ANSI_RED "error:" ANSI_NORMAL " ";
    try {
        try {
            fun();
        } catch (...) {
            /* Subtle: we have to make sure that any `interrupted'
               condition is discharged before we reach printMsg()
               below, since otherwise it will throw an (uncaught)
               exception. */
            setInterruptThrown();
            throw;
        }
    } catch (Exit & e) {
        return e.status;
    } catch (UsageError & e) {
        logError(e.info());
        printError("Try '%1% --help' for more information.", programName);
        return 1;
    } catch (BaseError & e) {
        logError(e.info());
        if (e.hasTrace() && !loggerSettings.showTrace.get())
            printError("(use '--show-trace' to show detailed location information)");
        return e.status;
    } catch (std::bad_alloc & e) {
        printError(error + "out of memory");
        return 1;
    } catch (std::exception & e) {
        printError(error + e.what());
        return 1;
    }

    return 0;
}


RunPager::RunPager()
{
    if (!isatty(STDOUT_FILENO)) return;
    char * pager = getenv("NIX_PAGER");
    if (!pager) pager = getenv("PAGER");
    if (pager && ((string) pager == "" || (string) pager == "cat")) return;

    Pipe toPager;
    toPager.create();

    pid = startProcess([&]() {
        if (dup2(toPager.readSide.get(), STDIN_FILENO) == -1)
            throw SysError("dupping stdin");
        if (!getenv("LESS"))
            setenv("LESS", "FRSXMK", 1);
        restoreProcessContext();
        if (pager)
            execl("/bin/sh", "sh", "-c", pager, nullptr);
        execlp("pager", "pager", nullptr);
        execlp("less", "less", nullptr);
        execlp("more", "more", nullptr);
        throw SysError("executing '%1%'", pager);
    });

    pid.setKillSignal(SIGINT);

    if (dup2(toPager.writeSide.get(), STDOUT_FILENO) == -1)
        throw SysError("dupping stdout");
}


RunPager::~RunPager()
{
    try {
        if (pid != -1) {
            std::cout.flush();
            close(STDOUT_FILENO);
            pid.wait();
        }
    } catch (...) {
        ignoreException();
    }
}


PrintFreed::~PrintFreed()
{
    if (show)
        std::cout << fmt("%d store paths deleted, %s freed\n",
            results.paths.size(),
            showBytes(results.bytesFreed));
}

Exit::~Exit() { }

}