path: root/src/libmain/shared.cc

#include "config.h"

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

#include <iostream>
#include <cctype>
#include <exception>

#include <sys/stat.h>
#include <unistd.h>

#if HAVE_BOEHMGC
#include <gc/gc.h>
#endif


namespace nix {


volatile sig_atomic_t blockInt = 0;


static void sigintHandler(int signo)
{
    if (!blockInt) {
        _isInterrupted = 1;
        blockInt = 1;
    }
}


Path makeRootName(const Path & gcRoot, int & counter)
{
    counter++;
    if (counter == 1)
        return gcRoot;
    else
        return (format("%1%-%2%") % gcRoot % counter).str();
}


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


void printMissing(const PathSet & paths)
{
    unsigned long long downloadSize;
    PathSet willBuild, willSubstitute, unknown;
    queryMissing(paths, willBuild, willSubstitute, unknown, downloadSize);

    if (!willBuild.empty()) {
        printMsg(lvlInfo, format("the following derivations will be built:"));
        foreach (PathSet::iterator, i, willBuild)
            printMsg(lvlInfo, format("  %1%") % *i);
    }

    if (!willSubstitute.empty()) {
        printMsg(lvlInfo, format("the following paths will be downloaded/copied (%.2f MiB):") %
            (downloadSize / (1024.0 * 1024.0)));
        foreach (PathSet::iterator, i, willSubstitute)
            printMsg(lvlInfo, format("  %1%") % *i);
    }

    if (!unknown.empty()) {
        printMsg(lvlInfo, format("don't know how to build the following paths%1%:")
            % (readOnlyMode ? " (may be caused by read-only store access)" : ""));
        foreach (PathSet::iterator, i, unknown)
            printMsg(lvlInfo, format("  %1%") % *i);
    }
}


static void setLogType(string lt)
{
    if (lt == "pretty") logType = ltPretty;
    else if (lt == "escapes") logType = ltEscapes;
    else if (lt == "flat") logType = ltFlat;
    else throw UsageError("unknown log type");
}


static void closeStore()
{
    try {
        throw;
    } catch (std::exception & e) {
        printMsg(lvlError,
            format("FATAL: unexpected exception (closing store and aborting): %1%") % e.what());
    }
    try {
        store.reset((StoreAPI *) 0);
    } catch (...) {
        ignoreException();
    }
    abort();
}


RemoveTempRoots::~RemoveTempRoots()
{
    removeTempRoots();
}


static bool showTrace = false;


/* Initialize and reorder arguments, then call the actual argument
   processor. */
static void initAndRun(int argc, char * * argv)
{
    /* Setup Nix paths. */
    nixStore = canonPath(getEnv("NIX_STORE_DIR", getEnv("NIX_STORE", NIX_STORE_DIR)));
    nixDataDir = canonPath(getEnv("NIX_DATA_DIR", NIX_DATA_DIR));
    nixLogDir = canonPath(getEnv("NIX_LOG_DIR", NIX_LOG_DIR));
    nixStateDir = canonPath(getEnv("NIX_STATE_DIR", NIX_STATE_DIR));
    nixDBPath = getEnv("NIX_DB_DIR", nixStateDir + "/db");
    nixConfDir = canonPath(getEnv("NIX_CONF_DIR", NIX_CONF_DIR));
    nixLibexecDir = canonPath(getEnv("NIX_LIBEXEC_DIR", NIX_LIBEXEC_DIR));
    nixBinDir = canonPath(getEnv("NIX_BIN_DIR", NIX_BIN_DIR));

    string subs = getEnv("NIX_SUBSTITUTERS", "default");
    if (subs == "default") {
        substituters.push_back(nixLibexecDir + "/nix/substituters/copy-from-other-stores.pl");
        substituters.push_back(nixLibexecDir + "/nix/substituters/download-using-manifests.pl");
    } else
        substituters = tokenizeString(subs, ":");

    /* Get some settings from the configuration file. */
    thisSystem = querySetting("system", SYSTEM);
    maxBuildJobs = queryIntSetting("build-max-jobs", 1);
    buildCores = queryIntSetting("build-cores", 1);
    maxSilentTime = queryIntSetting("build-max-silent-time", 0);

    /* Catch SIGINT. */
    struct sigaction act;
    act.sa_handler = sigintHandler;
    sigfillset(&act.sa_mask);
    act.sa_flags = 0;
    if (sigaction(SIGINT, &act, 0))
        throw SysError("installing handler for SIGINT");
    if (sigaction(SIGTERM, &act, 0))
        throw SysError("installing handler for SIGTERM");
    if (sigaction(SIGHUP, &act, 0))
        throw SysError("installing handler for SIGHUP");

    /* Ignore SIGPIPE. */
    act.sa_handler = SIG_IGN;
    act.sa_flags = 0;
    if (sigaction(SIGPIPE, &act, 0))
        throw SysError("ignoring SIGPIPE");

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

    /* There is no privacy in the Nix system ;-)  At least not for
       now.  In particular, store objects should be readable by
       everybody.  This prevents nasty surprises when using a shared
       store (with the setuid() hack). */
    umask(0022);

    /* Process the NIX_LOG_TYPE environment variable. */
    string lt = getEnv("NIX_LOG_TYPE");
    if (lt != "") setLogType(lt);

    /* Put the arguments in a vector. */
    Strings args, remaining;
    while (argc--) args.push_back(*argv++);
    args.erase(args.begin());
    
    /* Expand compound dash options (i.e., `-qlf' -> `-q -l -f'), and
       ignore options for the ATerm library. */
    for (Strings::iterator i = args.begin(); i != args.end(); ++i) {
        string arg = *i;
        if (string(arg, 0, 4) == "-at-") ;
        else if (arg.length() > 2 && arg[0] == '-' && arg[1] != '-' && !isdigit(arg[1])) {
            for (unsigned int j = 1; j < arg.length(); j++)
                if (isalpha(arg[j]))
                    remaining.push_back((string) "-" + arg[j]);
                else {
                    remaining.push_back(string(arg, j));
                    break;
                }
        } else remaining.push_back(arg);
    }
    args = remaining;
    remaining.clear();

    /* Process default options. */
    for (Strings::iterator i = args.begin(); i != args.end(); ++i) {
        string arg = *i;
        if (arg == "--verbose" || arg == "-v")
            verbosity = (Verbosity) ((int) verbosity + 1);
        else if (arg == "--log-type") {
            ++i;
            if (i == args.end()) throw UsageError("`--log-type' requires an argument");
            setLogType(*i);
        }
        else if (arg == "--build-output" || arg == "-B")
            ; /* !!! obsolete - remove eventually */
        else if (arg == "--no-build-output" || arg == "-Q")
            buildVerbosity = lvlVomit;
        else if (arg == "--print-build-trace")
            printBuildTrace = true;
        else if (arg == "--help") {
            printHelp();
            return;
        }
        else if (arg == "--version") {
            std::cout << format("%1% (Nix) %2%") % programId % NIX_VERSION << std::endl;
            return;
        }
        else if (arg == "--keep-failed" || arg == "-K")
            keepFailed = true;
        else if (arg == "--keep-going" || arg == "-k")
            keepGoing = true;
        else if (arg == "--fallback")
            tryFallback = true;
        else if (arg == "--max-jobs" || arg == "-j")
            maxBuildJobs = getIntArg<unsigned int>(arg, i, args.end());
        else if (arg == "--cores")
            buildCores = getIntArg<unsigned int>(arg, i, args.end());
        else if (arg == "--readonly-mode")
            readOnlyMode = true;
        else if (arg == "--max-silent-time")
            maxSilentTime = getIntArg<unsigned int>(arg, i, args.end());
        else if (arg == "--no-build-hook")
            useBuildHook = false;
        else if (arg == "--show-trace")
            showTrace = true;
        else if (arg == "--option") {
            ++i; if (i == args.end()) throw UsageError("`--option' requires two arguments");
            string name = *i;
            ++i; if (i == args.end()) throw UsageError("`--option' requires two arguments");
            string value = *i;
            overrideSetting(name, tokenizeString(value));
        }
        else remaining.push_back(arg);
    }

    /* Automatically clean up the temporary roots file when we
       exit. */
    RemoveTempRoots removeTempRoots __attribute__((unused));

    /* Make sure that the database gets closed properly, even if
       terminate() is called (which happens sometimes due to bugs in
       destructor/exceptions interaction, but that needn't preclude a
       clean shutdown of the database). */
    std::set_terminate(closeStore);
    
    run(remaining);

    /* Close the Nix database. */
    store.reset((StoreAPI *) 0);
}


bool setuidMode = false;


static void setuidInit()
{
    /* Don't do anything if this is not a setuid binary. */
    if (getuid() == geteuid() && getgid() == getegid()) return;

    uid_t nixUid = geteuid();
    gid_t nixGid = getegid();
    
    setuidCleanup();

    /* Don't trust the current directory. */
    if (chdir("/") == -1) abort();

    /* Set the real (and preferably also the save) uid/gid to the
       effective uid/gid.  This matters mostly when we're not using
       build-users (bad!), since some builders (like Perl) complain
       when real != effective.

       On systems where setresuid is unavailable, we can't drop the
       saved uid/gid.  This means that we could go back to the
       original real uid (i.e., the uid of the caller).  That's not
       really a problem, except maybe when we execute a builder and
       we're not using build-users.  In that case, the builder may be
       able to switch to the uid of the caller and possibly do bad
       stuff.  But note that when not using build-users, the builder
       could also modify the Nix executables (say, replace them by a
       Trojan horse), so the problem is already there. */

#if HAVE_SETRESUID
    if (setresuid(nixUid, nixUid, nixUid)) abort();
    if (setresgid(nixGid, nixGid, nixGid)) abort();
#elif HAVE_SETREUID
    /* Note: doesn't set saved uid/gid! */
    fprintf(stderr, "warning: cannot set saved uid\n");
    if (setreuid(nixUid, nixUid)) abort();
    if (setregid(nixGid, nixGid)) abort();
#else
    /* Note: doesn't set real and saved uid/gid! */
    fprintf(stderr, "warning: cannot set real and saved uids\n");
    if (setuid(nixUid)) abort();
    if (setgid(nixGid)) abort();
#endif

    setuidMode = true;
}


/* Called when the Boehm GC runs out of memory. */
static void * oomHandler(size_t requested)
{
    /* Convert this to a proper C++ exception. */
    throw std::bad_alloc();
}


}


static char buf[1024];

int main(int argc, char * * argv)
{
    using namespace nix;

    /* If we're setuid, then we need to take some security precautions
       right away. */
    if (argc == 0) abort();
    setuidInit();
    
    /* Turn on buffering for cerr. */
#if HAVE_PUBSETBUF
    std::cerr.rdbuf()->pubsetbuf(buf, sizeof(buf));
#endif

    std::ios::sync_with_stdio(false);

#if HAVE_BOEHMGC
    /* Initialise the Boehm garbage collector.  This isn't necessary
       on most platforms, but for portability we do it anyway. */
    GC_INIT();

    GC_oom_fn = oomHandler;

    /* Set the initial heap size to something fairly big (384 MiB) so
       that in most cases we don't need to garbage collect at all.
       (Collection has a fairly significant overhead, some.)  The heap
       size can be overriden through libgc's GC_INITIAL_HEAP_SIZE
       environment variable.  We should probably also provide a
       nix.conf setting for this.  Note that GC_expand_hp() causes a
       lot of virtual, but not physical (resident) memory to be
       allocated.  This might be a problem on systems that don't
       overcommit. */
    if (!getenv("GC_INITIAL_HEAP_SIZE"))
        GC_expand_hp(384000000);
#endif

    try {
        try {
            initAndRun(argc, argv);
        } 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. */
            blockInt = 1; /* ignore further SIGINTs */
            _isInterrupted = 0;
            throw;
        }
    } catch (UsageError & e) {
        printMsg(lvlError, 
            format(
                "error: %1%\n"
                "Try `%2% --help' for more information.")
            % e.what() % programId);
        return 1;
    } catch (BaseError & e) {
        printMsg(lvlError, format("error: %1%%2%") % (showTrace ? e.prefix() : "") % e.msg());
        if (e.prefix() != "" && !showTrace)
            printMsg(lvlError, "(use `--show-trace' to show detailed location information)");
        return 1;
    } catch (std::exception & e) {
        printMsg(lvlError, format("error: %1%") % e.what());
        return 1;
    }

    return 0;
}