Explicitly model all settings and fail on unrecognized ones

Previously, the Settings class allowed other code to query for string
properties, which led to a proliferation of code all over the place making
up new options without any sort of central registry of valid options. This
commit pulls all those options back into the central Settings class and
removes the public get() methods, to discourage future abuses like that.

Furthermore, because we know the full set of options ahead of time, we
now fail loudly if someone enters an unrecognized option, thus preventing
subtle typos. With some template fun, we could probably also dump the full
set of options (with documentation, defaults, etc.) to the command line,
but I'm not doing that yet here.

src/libstore/globals.cc

@@ -17,12 +17,23 @@ namespace nix {
    must be deleted and recreated on startup.) */
 #define DEFAULT_SOCKET_PATH "/daemon-socket/socket"
 
+/* chroot-like behavior from Apple's sandbox */
+#if __APPLE__
+    #define DEFAULT_ALLOWED_IMPURE_PREFIXES "/System/Library /usr/lib /dev /bin/sh"
+#else
+    #define DEFAULT_ALLOWED_IMPURE_PREFIXES ""
+#endif
 
 Settings settings;
 
 
 Settings::Settings()
 {
+    deprecatedOptions = StringSet({
+        "build-use-chroot", "build-chroot-dirs", "build-extra-chroot-dirs",
+        "this-option-never-existed-but-who-will-know"
+    });
+
     nixPrefix = NIX_PREFIX;
     nixStore = canonPath(getEnv("NIX_STORE_DIR", getEnv("NIX_STORE", NIX_STORE_DIR)));
     nixDataDir = canonPath(getEnv("NIX_DATA_DIR", NIX_DATA_DIR));
@@ -73,6 +84,32 @@ Settings::Settings()
     showTrace = false;
     enableImportNative = false;
     netrcFile = fmt("%s/%s", nixConfDir, "netrc");
+    useSandbox = "false"; // TODO: make into an enum
+
+#if __linux__
+    sandboxPaths = tokenizeString<StringSet>("/bin/sh=" BASH_PATH);
+#endif
+
+    restrictEval = false;
+    buildRepeat = 0;
+    allowedImpureHostPrefixes = tokenizeString<StringSet>(DEFAULT_ALLOWED_IMPURE_PREFIXES);
+    sandboxShmSize = "50%";
+    darwinLogSandboxViolations = false;
+    runDiffHook = false;
+    diffHook = "";
+    enforceDeterminism = true;
+    binaryCachePublicKeys = Strings();
+    secretKeyFiles = Strings();
+    binaryCachesParallelConnections = 25;
+    enableHttp2 = true;
+    tarballTtl = 60 * 60;
+    signedBinaryCaches = "";
+    substituters = Strings();
+    binaryCaches = Strings();
+    extraBinaryCaches = Strings();
+    trustedUsers = Strings({"root"});
+    allowedUsers = Strings({"*"});
+    printMissing = true;
 }
 
 
@@ -115,39 +152,6 @@ void Settings::set(const string & name, const string & 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");
@@ -181,13 +185,71 @@ void Settings::update()
     _get(keepGoing, "keep-going");
     _get(keepFailed, "keep-failed");
     _get(netrcFile, "netrc-file");
+    _get(useSandbox, "build-use-sandbox", "build-use-chroot");
+    _get(sandboxPaths, "build-sandbox-paths", "build-chroot-dirs");
+    _get(extraSandboxPaths, "build-extra-sandbox-paths", "build-extra-chroot-dirs");
+    _get(restrictEval, "restrict-eval");
+    _get(buildRepeat, "build-repeat");
+    _get(allowedImpureHostPrefixes, "allowed-impure-host-deps");
+    _get(sandboxShmSize, "sandbox-dev-shm-size");
+    _get(darwinLogSandboxViolations, "darwin-log-sandbox-violations");
+    _get(runDiffHook, "run-diff-hook");
+    _get(diffHook, "diff-hook");
+    _get(enforceDeterminism, "enforce-determinism");
+    _get(binaryCachePublicKeys, "binary-cache-public-keys");
+    _get(secretKeyFiles, "secret-key-files");
+    _get(binaryCachesParallelConnections, "binary-caches-parallel-connections");
+    _get(enableHttp2, "enable-http2");
+    _get(tarballTtl, "tarball-ttl");
+    _get(signedBinaryCaches, "signed-binary-caches");
+    _get(substituters, "substituters");
+    _get(binaryCaches, "binary-caches");
+    _get(extraBinaryCaches, "extra-binary-caches");
+    _get(trustedUsers, "trusted-users");
+    _get(allowedUsers, "allowed-users");
+    _get(printMissing, "print-missing");
+
+    /* Clear out any deprecated options that might be left, so users know we recognize the option
+       but aren't processing it anymore */
+    for (auto &i : deprecatedOptions) {
+        if (settings.find(i) != settings.end()) {
+            printError(format("warning: deprecated option '%1%' is no longer supported and will be ignored") % i);
+            settings.erase(i);
+        }
+    }
+
+    if (settings.size() != 0) {
+        string bad;
+        for (auto &i : settings)
+            bad += "'" + i.first + "', ";
+        bad.pop_back();
+        bad.pop_back();
+        throw Error(format("unrecognized options: %s") % bad);
+    }
 }
 
+void Settings::checkDeprecated(const string & name)
+{
+    if (deprecatedOptions.find(name) != deprecatedOptions.end())
+        printError(format("warning: deprecated option '%1%' will soon be unsupported") % name);
+}
 
 void Settings::_get(string & res, const string & name)
 {
     SettingsMap::iterator i = settings.find(name);
     if (i == settings.end()) return;
+    checkDeprecated(i->first);
+    settings.erase(i);
+    res = i->second;
+}
+
+void Settings::_get(string & res, const string & name1, const string & name2)
+{
+    SettingsMap::iterator i = settings.find(name1);
+    if (i == settings.end()) i = settings.find(name2);
+    if (i == settings.end()) return;
+    checkDeprecated(i->first);
+    settings.erase(i);
     res = i->second;
 }
 
@@ -196,6 +258,8 @@ void Settings::_get(bool & res, const string & name)
 {
     SettingsMap::iterator i = settings.find(name);
     if (i == settings.end()) return;
+    checkDeprecated(i->first);
+    settings.erase(i);
     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%’")
@@ -207,6 +271,20 @@ void Settings::_get(StringSet & res, const string & name)
 {
     SettingsMap::iterator i = settings.find(name);
     if (i == settings.end()) return;
+    checkDeprecated(i->first);
+    settings.erase(i);
+    res.clear();
+    Strings ss = tokenizeString<Strings>(i->second);
+    res.insert(ss.begin(), ss.end());
+}
+
+void Settings::_get(StringSet & res, const string & name1, const string & name2)
+{
+    SettingsMap::iterator i = settings.find(name1);
+    if (i == settings.end()) i = settings.find(name2);
+    if (i == settings.end()) return;
+    checkDeprecated(i->first);
+    settings.erase(i);
     res.clear();
     Strings ss = tokenizeString<Strings>(i->second);
     res.insert(ss.begin(), ss.end());
@@ -216,6 +294,8 @@ void Settings::_get(Strings & res, const string & name)
 {
     SettingsMap::iterator i = settings.find(name);
     if (i == settings.end()) return;
+    checkDeprecated(i->first);
+    settings.erase(i);
     res = tokenizeString<Strings>(i->second);
 }
 
@@ -224,6 +304,8 @@ template<class N> void Settings::_get(N & res, const string & name)
 {
     SettingsMap::iterator i = settings.find(name);
     if (i == settings.end()) return;
+    checkDeprecated(i->first);
+    settings.erase(i);
     if (!string2Int(i->second, res))
         throw Error(format("configuration setting ‘%1%’ should have an integer value") % name);
 }