lix/src/libstore/globals.cc
Shea Levy 0bb8db257d Add exec primop behind allow-unsafe-native-code-during-evaluation.
Execute a given program with the (optional) given arguments as the
user running the evaluation, parsing stdout as an expression to be
evaluated.

There are many use cases for nix that would benefit from being able to
run arbitrary code during evaluation, including but not limited to:

* Automatic git fetching to get a sha256 from a git revision
* git rev-parse HEAD
* Automatic extraction of information from build specifications from
  other tools, particularly language-specific package managers like
  cabal or npm
* Secrets decryption (e.g. with nixops)
* Private repository fetching

Ideally, we would add this functionality in a more principled way to
nix, but in the mean time 'builtins.exec' can be used to get these
tasks done.

The primop is only available when the
'allow-unsafe-native-code-during-evaluation' nix option is true. That
flag also enables the 'importNative' primop, which is strictly more
powerful but less convenient (since it requires compiling a plugin
against the running version of nix).
2017-03-30 08:04:21 -04:00

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#include "globals.hh"
#include "util.hh"
#include "archive.hh"
#include <algorithm>
#include <map>
#include <thread>
namespace nix {
/* The default location of the daemon socket, relative to nixStateDir.
The socket is in a directory to allow you to control access to the
Nix daemon by setting the mode/ownership of the directory
appropriately. (This wouldn't work on the socket itself since it
must be deleted and recreated on startup.) */
#define DEFAULT_SOCKET_PATH "/daemon-socket/socket"
Settings settings;
Settings::Settings()
{
nixPrefix = NIX_PREFIX;
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));
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));
nixDaemonSocketFile = canonPath(nixStateDir + DEFAULT_SOCKET_PATH);
// should be set with the other config options, but depends on nixLibexecDir
#ifdef __APPLE__
preBuildHook = nixLibexecDir + "/nix/resolve-system-dependencies";
#endif
keepFailed = false;
keepGoing = false;
tryFallback = false;
maxBuildJobs = 1;
buildCores = std::max(1U, std::thread::hardware_concurrency());
readOnlyMode = false;
thisSystem = SYSTEM;
maxSilentTime = 0;
buildTimeout = 0;
useBuildHook = true;
reservedSize = 8 * 1024 * 1024;
fsyncMetadata = true;
useSQLiteWAL = true;
syncBeforeRegistering = false;
useSubstitutes = true;
buildUsersGroup = getuid() == 0 ? "nixbld" : "";
useSshSubstituter = true;
impersonateLinux26 = false;
keepLog = true;
compressLog = true;
maxLogSize = 0;
pollInterval = 5;
checkRootReachability = false;
gcKeepOutputs = false;
gcKeepDerivations = true;
autoOptimiseStore = false;
envKeepDerivations = false;
lockCPU = getEnv("NIX_AFFINITY_HACK", "1") == "1";
showTrace = false;
enableNativeCode = false;
netrcFile = fmt("%s/%s", nixConfDir, "netrc");
caFile = getEnv("NIX_SSL_CERT_FILE", getEnv("SSL_CERT_FILE", "/etc/ssl/certs/ca-certificates.crt"));
enableImportFromDerivation = true;
}
void Settings::loadConfFile()
{
Path settingsFile = (format("%1%/%2%") % nixConfDir % "nix.conf").str();
if (!pathExists(settingsFile)) return;
string contents = readFile(settingsFile);
unsigned int pos = 0;
while (pos < contents.size()) {
string line;
while (pos < contents.size() && contents[pos] != '\n')
line += contents[pos++];
pos++;
string::size_type hash = line.find('#');
if (hash != string::npos)
line = string(line, 0, hash);
vector<string> tokens = tokenizeString<vector<string> >(line);
if (tokens.empty()) continue;
if (tokens.size() < 2 || tokens[1] != "=")
throw Error(format("illegal configuration line %1% in %2%") % line % settingsFile);
string name = tokens[0];
vector<string>::iterator i = tokens.begin();
advance(i, 2);
settings[name] = concatStringsSep(" ", Strings(i, tokens.end())); // FIXME: slow
};
}
void Settings::set(const string & name, const string & value)
{
settings[name] = value;
overrides[name] = value;
}
string Settings::get(const string & name, const string & def)
{
auto i = settings.find(name);
if (i == settings.end()) return def;
return i->second;
}
Strings Settings::get(const string & name, const Strings & def)
{
auto i = settings.find(name);
if (i == settings.end()) return def;
return tokenizeString<Strings>(i->second);
}
bool Settings::get(const string & name, bool def)
{
bool res = def;
_get(res, name);
return res;
}
int Settings::get(const string & name, int def)
{
int res = def;
_get(res, name);
return res;
}
void Settings::update()
{
_get(tryFallback, "build-fallback");
auto s = get("build-max-jobs", std::string("1"));
if (s == "auto")
maxBuildJobs = std::max(1U, std::thread::hardware_concurrency());
else
if (!string2Int(s, maxBuildJobs))
throw Error("configuration setting build-max-jobs should be auto or an integer");
_get(buildCores, "build-cores");
_get(thisSystem, "system");
_get(maxSilentTime, "build-max-silent-time");
_get(buildTimeout, "build-timeout");
_get(reservedSize, "gc-reserved-space");
_get(fsyncMetadata, "fsync-metadata");
_get(useSQLiteWAL, "use-sqlite-wal");
_get(syncBeforeRegistering, "sync-before-registering");
_get(useSubstitutes, "build-use-substitutes");
_get(buildUsersGroup, "build-users-group");
_get(impersonateLinux26, "build-impersonate-linux-26");
_get(keepLog, "build-keep-log");
_get(compressLog, "build-compress-log");
_get(maxLogSize, "build-max-log-size");
_get(pollInterval, "build-poll-interval");
_get(checkRootReachability, "gc-check-reachability");
_get(gcKeepOutputs, "gc-keep-outputs");
_get(gcKeepDerivations, "gc-keep-derivations");
_get(autoOptimiseStore, "auto-optimise-store");
_get(envKeepDerivations, "env-keep-derivations");
_get(sshSubstituterHosts, "ssh-substituter-hosts");
_get(useSshSubstituter, "use-ssh-substituter");
_get(enableNativeCode, "allow-unsafe-native-code-during-evaluation");
_get(useCaseHack, "use-case-hack");
_get(preBuildHook, "pre-build-hook");
_get(keepGoing, "keep-going");
_get(keepFailed, "keep-failed");
_get(netrcFile, "netrc-file");
_get(enableImportFromDerivation, "allow-import-from-derivation");
}
void Settings::_get(string & res, const string & name)
{
SettingsMap::iterator i = settings.find(name);
if (i == settings.end()) return;
res = i->second;
}
void Settings::_get(bool & res, const string & name)
{
SettingsMap::iterator i = settings.find(name);
if (i == settings.end()) return;
if (i->second == "true") res = true;
else if (i->second == "false") res = false;
else throw Error(format("configuration option %1% should be either true or false, not %2%")
% name % i->second);
}
void Settings::_get(StringSet & res, const string & name)
{
SettingsMap::iterator i = settings.find(name);
if (i == settings.end()) return;
res.clear();
Strings ss = tokenizeString<Strings>(i->second);
res.insert(ss.begin(), ss.end());
}
void Settings::_get(Strings & res, const string & name)
{
SettingsMap::iterator i = settings.find(name);
if (i == settings.end()) return;
res = tokenizeString<Strings>(i->second);
}
template<class N> void Settings::_get(N & res, const string & name)
{
SettingsMap::iterator i = settings.find(name);
if (i == settings.end()) return;
if (!string2Int(i->second, res))
throw Error(format("configuration setting %1% should have an integer value") % name);
}
string Settings::pack()
{
string s;
for (auto & i : settings) {
if (i.first.find('\n') != string::npos ||
i.first.find('=') != string::npos ||
i.second.find('\n') != string::npos)
throw Error("illegal option name/value");
s += i.first; s += '='; s += i.second; s += '\n';
}
return s;
}
void Settings::unpack(const string & pack) {
Strings lines = tokenizeString<Strings>(pack, "\n");
for (auto & i : lines) {
string::size_type eq = i.find('=');
if (eq == string::npos)
throw Error("illegal option name/value");
set(i.substr(0, eq), i.substr(eq + 1));
}
}
Settings::SettingsMap Settings::getOverrides()
{
return overrides;
}
const string nixVersion = PACKAGE_VERSION;
}