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-rw-r--r--src/libexpr/common-eval-args.hh2
-rw-r--r--src/libexpr/eval.cc22
-rw-r--r--src/libexpr/eval.hh2
-rw-r--r--src/libexpr/lexer.l2
-rw-r--r--src/libexpr/parser.y7
-rw-r--r--src/libexpr/primops.cc57
-rw-r--r--src/libexpr/primops/fetchGit.cc223
-rw-r--r--src/libexpr/primops/fetchMercurial.cc202
-rw-r--r--src/libexpr/primops/fetchgit.cc129
-rw-r--r--src/libexpr/primops/fetchgit.hh14
-rw-r--r--src/libstore/build.cc12
-rw-r--r--src/libstore/download.cc6
-rw-r--r--src/libstore/globals.hh6
-rw-r--r--src/libstore/s3-binary-cache-store.cc4
-rw-r--r--src/libstore/sandbox-defaults.sb29
-rw-r--r--src/libutil/archive.cc2
-rw-r--r--src/libutil/archive.hh7
-rw-r--r--src/libutil/hash.hh2
-rw-r--r--src/libutil/util.cc41
-rw-r--r--src/libutil/util.hh23
-rwxr-xr-xsrc/nix-build/nix-build.cc3
21 files changed, 569 insertions, 226 deletions
diff --git a/src/libexpr/common-eval-args.hh b/src/libexpr/common-eval-args.hh
index 09fa406b2cdc..be7fda783783 100644
--- a/src/libexpr/common-eval-args.hh
+++ b/src/libexpr/common-eval-args.hh
@@ -6,7 +6,7 @@ namespace nix {
 
 class Store;
 class EvalState;
-struct Bindings;
+class Bindings;
 
 struct MixEvalArgs : virtual Args
 {
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 78f6b0010523..63de2d60a147 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -149,7 +149,7 @@ string showType(const Value & v)
     switch (v.type) {
         case tInt: return "an integer";
         case tBool: return "a boolean";
-        case tString: return "a string";
+        case tString: return v.string.context ? "a string with context" : "a string";
         case tPath: return "a path";
         case tNull: return "null";
         case tAttrs: return "a set";
@@ -355,6 +355,26 @@ Path EvalState::checkSourcePath(const Path & path_)
 }
 
 
+void EvalState::checkURI(const std::string & uri)
+{
+    if (!restricted) return;
+
+    /* 'uri' should be equal to a prefix, or in a subdirectory of a
+       prefix. Thus, the prefix https://github.co does not permit
+       access to https://github.com. Note: this allows 'http://' and
+       'https://' as prefixes for any http/https URI. */
+    for (auto & prefix : settings.allowedUris.get())
+        if (uri == prefix ||
+            (uri.size() > prefix.size()
+            && prefix.size() > 0
+            && hasPrefix(uri, prefix)
+            && (prefix[prefix.size() - 1] == '/' || uri[prefix.size()] == '/')))
+            return;
+
+    throw RestrictedPathError("access to URI '%s' is forbidden in restricted mode", uri);
+}
+
+
 void EvalState::addConstant(const string & name, Value & v)
 {
     Value * v2 = allocValue();
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 04a36b14cefa..f0ab1435bff3 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -110,6 +110,8 @@ public:
 
     Path checkSourcePath(const Path & path);
 
+    void checkURI(const std::string & uri);
+
     /* Parse a Nix expression from the specified file. */
     Expr * parseExprFromFile(const Path & path);
     Expr * parseExprFromFile(const Path & path, StaticEnv & staticEnv);
diff --git a/src/libexpr/lexer.l b/src/libexpr/lexer.l
index 28a0a6a87896..828356bbf447 100644
--- a/src/libexpr/lexer.l
+++ b/src/libexpr/lexer.l
@@ -90,7 +90,7 @@ FLOAT       (([1-9][0-9]*\.[0-9]*)|(0?\.[0-9]+))([Ee][+-]?[0-9]+)?
 PATH        [a-zA-Z0-9\.\_\-\+]*(\/[a-zA-Z0-9\.\_\-\+]+)+\/?
 HPATH       \~(\/[a-zA-Z0-9\.\_\-\+]+)+\/?
 SPATH       \<[a-zA-Z0-9\.\_\-\+]+(\/[a-zA-Z0-9\.\_\-\+]+)*\>
-URI         [a-zA-Z][a-zA-Z0-9\+\-\.]*\:[a-zA-Z0-9\%\/\?\:\@\&\=\+\$\,\-\_\.\!\~\*\']+
+URI         [a-zA-Z][a-zA-Z0-9\+\-\.]*\:\/\/[a-zA-Z0-9\%\/\?\:\@\&\=\+\$\,\-\_\.\!\~\*\']+|channel\:[a-zA-Z0-9\%\/\?\:\@\&\=\+\$\,\-\_\.\!\~\*\']+
 
 
 %%
diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index 669312bb7cff..ef11dd609217 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -523,7 +523,6 @@ formal
 #include "eval.hh"
 #include "download.hh"
 #include "store-api.hh"
-#include "primops/fetchgit.hh"
 
 
 namespace nix {
@@ -665,11 +664,7 @@ std::pair<bool, std::string> EvalState::resolveSearchPathElem(const SearchPathEl
 
     if (isUri(elem.second)) {
         try {
-            if (hasPrefix(elem.second, "git://") || hasSuffix(elem.second, ".git"))
-                // FIXME: support specifying revision/branch
-                res = { true, exportGit(store, elem.second, "master") };
-            else
-                res = { true, getDownloader()->downloadCached(store, elem.second, true) };
+            res = { true, getDownloader()->downloadCached(store, elem.second, true) };
         } catch (DownloadError & e) {
             printError(format("warning: Nix search path entry '%1%' cannot be downloaded, ignoring") % elem.second);
             res = { false, "" };
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 6a50c99345e4..e3b5dfb420b4 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1009,22 +1009,21 @@ static void prim_toFile(EvalState & state, const Pos & pos, Value * * args, Valu
 }
 
 
-struct FilterFromExpr : PathFilter
+static void prim_filterSource(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    EvalState & state;
-    Value & filter;
-    Pos pos;
+    PathSet context;
+    Path path = state.coerceToPath(pos, *args[1], context);
+    if (!context.empty())
+        throw EvalError(format("string '%1%' cannot refer to other paths, at %2%") % path % pos);
 
-    FilterFromExpr(EvalState & state, Value & filter, const Pos & pos)
-        : state(state), filter(filter), pos(pos)
-    {
-    }
+    state.forceValue(*args[0]);
+    if (args[0]->type != tLambda)
+        throw TypeError(format("first argument in call to 'filterSource' is not a function but %1%, at %2%") % showType(*args[0]) % pos);
 
-    bool operator () (const Path & path)
-    {
-        struct stat st;
-        if (lstat(path.c_str(), &st))
-            throw SysError(format("getting attributes of path '%1%'") % path);
+    path = state.checkSourcePath(path);
+
+    PathFilter filter = [&](const Path & path) {
+        auto st = lstat(path);
 
         /* Call the filter function.  The first argument is the path,
            the second is a string indicating the type of the file. */
@@ -1032,7 +1031,7 @@ struct FilterFromExpr : PathFilter
         mkString(arg1, path);
 
         Value fun2;
-        state.callFunction(filter, arg1, fun2, noPos);
+        state.callFunction(*args[0], arg1, fun2, noPos);
 
         Value arg2;
         mkString(arg2,
@@ -1045,24 +1044,7 @@ struct FilterFromExpr : PathFilter
         state.callFunction(fun2, arg2, res, noPos);
 
         return state.forceBool(res, pos);
-    }
-};
-
-
-static void prim_filterSource(EvalState & state, const Pos & pos, Value * * args, Value & v)
-{
-    PathSet context;
-    Path path = state.coerceToPath(pos, *args[1], context);
-    if (!context.empty())
-        throw EvalError(format("string '%1%' cannot refer to other paths, at %2%") % path % pos);
-
-    state.forceValue(*args[0]);
-    if (args[0]->type != tLambda)
-        throw TypeError(format("first argument in call to 'filterSource' is not a function but %1%, at %2%") % showType(*args[0]) % pos);
-
-    FilterFromExpr filter(state, *args[0], pos);
-
-    path = state.checkSourcePath(path);
+    };
 
     Path dstPath = settings.readOnlyMode
         ? state.store->computeStorePathForPath(path, true, htSHA256, filter).first
@@ -1907,11 +1889,11 @@ static void prim_compareVersions(EvalState & state, const Pos & pos, Value * * a
 
 
 void fetch(EvalState & state, const Pos & pos, Value * * args, Value & v,
-    const string & who, bool unpack)
+    const string & who, bool unpack, const std::string & defaultName)
 {
     string url;
     Hash expectedHash;
-    string name;
+    string name = defaultName;
 
     state.forceValue(*args[0]);
 
@@ -1937,8 +1919,7 @@ void fetch(EvalState & state, const Pos & pos, Value * * args, Value & v,
     } else
         url = state.forceStringNoCtx(*args[0], pos);
 
-    if (state.restricted && !expectedHash)
-        throw Error(format("'%1%' is not allowed in restricted mode") % who);
+    state.checkURI(url);
 
     Path res = getDownloader()->downloadCached(state.store, url, unpack, name, expectedHash);
     mkString(v, res, PathSet({res}));
@@ -1947,13 +1928,13 @@ void fetch(EvalState & state, const Pos & pos, Value * * args, Value & v,
 
 static void prim_fetchurl(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    fetch(state, pos, args, v, "fetchurl", false);
+    fetch(state, pos, args, v, "fetchurl", false, "");
 }
 
 
 static void prim_fetchTarball(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    fetch(state, pos, args, v, "fetchTarball", true);
+    fetch(state, pos, args, v, "fetchTarball", true, "source");
 }
 
 
diff --git a/src/libexpr/primops/fetchGit.cc b/src/libexpr/primops/fetchGit.cc
new file mode 100644
index 000000000000..bca68ed72091
--- /dev/null
+++ b/src/libexpr/primops/fetchGit.cc
@@ -0,0 +1,223 @@
+#include "primops.hh"
+#include "eval-inline.hh"
+#include "download.hh"
+#include "store-api.hh"
+#include "pathlocks.hh"
+
+#include <sys/time.h>
+
+#include <regex>
+
+#include <nlohmann/json.hpp>
+
+using namespace std::string_literals;
+
+namespace nix {
+
+struct GitInfo
+{
+    Path storePath;
+    std::string rev;
+    std::string shortRev;
+    uint64_t revCount = 0;
+};
+
+GitInfo exportGit(ref<Store> store, const std::string & uri,
+    std::experimental::optional<std::string> ref, const std::string & rev,
+    const std::string & name)
+{
+    if (!ref && rev == "" && hasPrefix(uri, "/") && pathExists(uri + "/.git")) {
+
+        bool clean = true;
+
+        try {
+            runProgram("git", true, { "-C", uri, "diff-index", "--quiet", "HEAD", "--" });
+        } catch (ExecError e) {
+            if (!WIFEXITED(e.status) || WEXITSTATUS(e.status) != 1) throw;
+            clean = false;
+        }
+
+        if (!clean) {
+
+            /* This is an unclean working tree. So copy all tracked
+               files. */
+
+            GitInfo gitInfo;
+            gitInfo.rev = "0000000000000000000000000000000000000000";
+            gitInfo.shortRev = std::string(gitInfo.rev, 0, 7);
+
+            auto files = tokenizeString<std::set<std::string>>(
+                runProgram("git", true, { "-C", uri, "ls-files", "-z" }), "\0"s);
+
+            PathFilter filter = [&](const Path & p) -> bool {
+                assert(hasPrefix(p, uri));
+                std::string file(p, uri.size() + 1);
+
+                auto st = lstat(p);
+
+                if (S_ISDIR(st.st_mode)) {
+                    auto i = files.lower_bound(file);
+                    return i != files.end() && hasPrefix(*i, file);
+                }
+
+                return files.count(file);
+            };
+
+            gitInfo.storePath = store->addToStore("source", uri, true, htSHA256, filter);
+
+            return gitInfo;
+        }
+    }
+
+    if (!ref) ref = "master"s;
+
+    if (rev != "") {
+        std::regex revRegex("^[0-9a-fA-F]{40}$");
+        if (!std::regex_match(rev, revRegex))
+            throw Error("invalid Git revision '%s'", rev);
+    }
+
+    Path cacheDir = getCacheDir() + "/nix/git";
+
+    if (!pathExists(cacheDir)) {
+        createDirs(cacheDir);
+        runProgram("git", true, { "init", "--bare", cacheDir });
+    }
+
+    std::string localRef = hashString(htSHA256, fmt("%s-%s", uri, *ref)).to_string(Base32, false);
+
+    Path localRefFile = cacheDir + "/refs/heads/" + localRef;
+
+    /* If the local ref is older than ‘tarball-ttl’ seconds, do a git
+       fetch to update the local ref to the remote ref. */
+    time_t now = time(0);
+    struct stat st;
+    if (stat(localRefFile.c_str(), &st) != 0 ||
+        st.st_mtime <= now - settings.tarballTtl)
+    {
+        if (rev == "" ||
+            chomp(runProgram(
+                RunOptions("git", { "-C", cacheDir, "cat-file", "-t", rev })
+                .killStderr(true)).second) != "commit")
+        {
+            Activity act(*logger, lvlTalkative, actUnknown, fmt("fetching Git repository '%s'", uri));
+
+            // FIXME: git stderr messes up our progress indicator, so
+            // we're using --quiet for now. Should process its stderr.
+            runProgram("git", true, { "-C", cacheDir, "fetch", "--quiet", "--force", "--", uri, *ref + ":" + localRef });
+
+            struct timeval times[2];
+            times[0].tv_sec = now;
+            times[0].tv_usec = 0;
+            times[1].tv_sec = now;
+            times[1].tv_usec = 0;
+
+            utimes(localRefFile.c_str(), times);
+        }
+    }
+
+    // FIXME: check whether rev is an ancestor of ref.
+    GitInfo gitInfo;
+    gitInfo.rev = rev != "" ? rev : chomp(readFile(localRefFile));
+    gitInfo.shortRev = std::string(gitInfo.rev, 0, 7);
+
+    printTalkative("using revision %s of repo '%s'", uri, gitInfo.rev);
+
+    std::string storeLinkName = hashString(htSHA512, name + std::string("\0"s) + gitInfo.rev).to_string(Base32, false);
+    Path storeLink = cacheDir + "/" + storeLinkName + ".link";
+    PathLocks storeLinkLock({storeLink}, fmt("waiting for lock on '%1%'...", storeLink)); // FIXME: broken
+
+    try {
+        auto json = nlohmann::json::parse(readFile(storeLink));
+
+        assert(json["name"] == name && json["rev"] == gitInfo.rev);
+
+        gitInfo.storePath = json["storePath"];
+
+        if (store->isValidPath(gitInfo.storePath)) {
+            gitInfo.revCount = json["revCount"];
+            return gitInfo;
+        }
+
+    } catch (SysError & e) {
+        if (e.errNo != ENOENT) throw;
+    }
+
+    // FIXME: should pipe this, or find some better way to extract a
+    // revision.
+    auto tar = runProgram("git", true, { "-C", cacheDir, "archive", gitInfo.rev });
+
+    Path tmpDir = createTempDir();
+    AutoDelete delTmpDir(tmpDir, true);
+
+    runProgram("tar", true, { "x", "-C", tmpDir }, tar);
+
+    gitInfo.storePath = store->addToStore(name, tmpDir);
+
+    gitInfo.revCount = std::stoull(runProgram("git", true, { "-C", cacheDir, "rev-list", "--count", gitInfo.rev }));
+
+    nlohmann::json json;
+    json["storePath"] = gitInfo.storePath;
+    json["uri"] = uri;
+    json["name"] = name;
+    json["rev"] = gitInfo.rev;
+    json["revCount"] = gitInfo.revCount;
+
+    writeFile(storeLink, json.dump());
+
+    return gitInfo;
+}
+
+static void prim_fetchGit(EvalState & state, const Pos & pos, Value * * args, Value & v)
+{
+    std::string url;
+    std::experimental::optional<std::string> ref;
+    std::string rev;
+    std::string name = "source";
+    PathSet context;
+
+    state.forceValue(*args[0]);
+
+    if (args[0]->type == tAttrs) {
+
+        state.forceAttrs(*args[0], pos);
+
+        for (auto & attr : *args[0]->attrs) {
+            string n(attr.name);
+            if (n == "url")
+                url = state.coerceToString(*attr.pos, *attr.value, context, false, false);
+            else if (n == "ref")
+                ref = state.forceStringNoCtx(*attr.value, *attr.pos);
+            else if (n == "rev")
+                rev = state.forceStringNoCtx(*attr.value, *attr.pos);
+            else if (n == "name")
+                name = state.forceStringNoCtx(*attr.value, *attr.pos);
+            else
+                throw EvalError("unsupported argument '%s' to 'fetchGit', at %s", attr.name, *attr.pos);
+        }
+
+        if (url.empty())
+            throw EvalError(format("'url' argument required, at %1%") % pos);
+
+    } else
+        url = state.coerceToString(pos, *args[0], context, false, false);
+
+    if (!isUri(url)) url = absPath(url);
+
+    // FIXME: git externals probably can be used to bypass the URI
+    // whitelist. Ah well.
+    state.checkURI(url);
+
+    auto gitInfo = exportGit(state.store, url, ref, rev, name);
+
+    state.mkAttrs(v, 8);
+    mkString(*state.allocAttr(v, state.sOutPath), gitInfo.storePath, PathSet({gitInfo.storePath}));
+    mkString(*state.allocAttr(v, state.symbols.create("rev")), gitInfo.rev);
+    mkString(*state.allocAttr(v, state.symbols.create("shortRev")), gitInfo.shortRev);
+    mkInt(*state.allocAttr(v, state.symbols.create("revCount")), gitInfo.revCount);
+    v.attrs->sort();
+}
+
+static RegisterPrimOp r("fetchGit", 1, prim_fetchGit);
+
+}
diff --git a/src/libexpr/primops/fetchMercurial.cc b/src/libexpr/primops/fetchMercurial.cc
new file mode 100644
index 000000000000..7def7103bf3d
--- /dev/null
+++ b/src/libexpr/primops/fetchMercurial.cc
@@ -0,0 +1,202 @@
+#include "primops.hh"
+#include "eval-inline.hh"
+#include "download.hh"
+#include "store-api.hh"
+#include "pathlocks.hh"
+
+#include <sys/time.h>
+
+#include <regex>
+
+#include <nlohmann/json.hpp>
+
+using namespace std::string_literals;
+
+namespace nix {
+
+struct HgInfo
+{
+    Path storePath;
+    std::string branch;
+    std::string rev;
+    uint64_t revCount = 0;
+};
+
+std::regex commitHashRegex("^[0-9a-fA-F]{40}$");
+
+HgInfo exportMercurial(ref<Store> store, const std::string & uri,
+    std::string rev, const std::string & name)
+{
+    if (rev == "" && hasPrefix(uri, "/") && pathExists(uri + "/.hg")) {
+
+        bool clean = runProgram("hg", true, { "status", "-R", uri, "--modified", "--added", "--removed" }) == "";
+
+        if (!clean) {
+
+            /* This is an unclean working tree. So copy all tracked
+               files. */
+
+            printTalkative("copying unclean Mercurial working tree '%s'", uri);
+
+            HgInfo hgInfo;
+            hgInfo.rev = "0000000000000000000000000000000000000000";
+            hgInfo.branch = chomp(runProgram("hg", true, { "branch", "-R", uri }));
+
+            auto files = tokenizeString<std::set<std::string>>(
+                runProgram("hg", true, { "status", "-R", uri, "--clean", "--modified", "--added", "--no-status", "--print0" }), "\0"s);
+
+            PathFilter filter = [&](const Path & p) -> bool {
+                assert(hasPrefix(p, uri));
+                std::string file(p, uri.size() + 1);
+
+                auto st = lstat(p);
+
+                if (S_ISDIR(st.st_mode)) {
+                    auto i = files.lower_bound(file);
+                    return i != files.end() && hasPrefix(*i, file);
+                }
+
+                return files.count(file);
+            };
+
+            hgInfo.storePath = store->addToStore("source", uri, true, htSHA256, filter);
+
+            return hgInfo;
+        }
+    }
+
+    if (rev == "") rev = "default";
+
+    Path cacheDir = fmt("%s/nix/hg/%s", getCacheDir(), hashString(htSHA256, uri).to_string(Base32, false));
+
+    Path stampFile = fmt("%s/.hg/%s.stamp", cacheDir, hashString(htSHA512, rev).to_string(Base32, false));
+
+    /* If we haven't pulled this repo less than ‘tarball-ttl’ seconds,
+       do so now. */
+    time_t now = time(0);
+    struct stat st;
+    if (stat(stampFile.c_str(), &st) != 0 ||
+        st.st_mtime <= now - settings.tarballTtl)
+    {
+        /* Except that if this is a commit hash that we already have,
+           we don't have to pull again. */
+        if (!(std::regex_match(rev, commitHashRegex)
+                && pathExists(cacheDir)
+                && runProgram(
+                    RunOptions("hg", { "log", "-R", cacheDir, "-r", rev, "--template", "1" })
+                    .killStderr(true)).second == "1"))
+        {
+            Activity act(*logger, lvlTalkative, actUnknown, fmt("fetching Mercurial repository '%s'", uri));
+
+            if (pathExists(cacheDir)) {
+                runProgram("hg", true, { "pull", "-R", cacheDir, "--", uri });
+            } else {
+                createDirs(dirOf(cacheDir));
+                runProgram("hg", true, { "clone", "--noupdate", "--", uri, cacheDir });
+            }
+        }
+
+        writeFile(stampFile, "");
+    }
+
+    auto tokens = tokenizeString<std::vector<std::string>>(
+        runProgram("hg", true, { "log", "-R", cacheDir, "-r", rev, "--template", "{node} {rev} {branch}" }));
+    assert(tokens.size() == 3);
+
+    HgInfo hgInfo;
+    hgInfo.rev = tokens[0];
+    hgInfo.revCount = std::stoull(tokens[1]);
+    hgInfo.branch = tokens[2];
+
+    std::string storeLinkName = hashString(htSHA512, name + std::string("\0"s) + hgInfo.rev).to_string(Base32, false);
+    Path storeLink = fmt("%s/.hg/%s.link", cacheDir, storeLinkName);
+
+    try {
+        auto json = nlohmann::json::parse(readFile(storeLink));
+
+        assert(json["name"] == name && json["rev"] == hgInfo.rev);
+
+        hgInfo.storePath = json["storePath"];
+
+        if (store->isValidPath(hgInfo.storePath)) {
+            printTalkative("using cached Mercurial store path '%s'", hgInfo.storePath);
+            return hgInfo;
+        }
+
+    } catch (SysError & e) {
+        if (e.errNo != ENOENT) throw;
+    }
+
+    Path tmpDir = createTempDir();
+    AutoDelete delTmpDir(tmpDir, true);
+
+    runProgram("hg", true, { "archive", "-R", cacheDir, "-r", rev, tmpDir });
+
+    deletePath(tmpDir + "/.hg_archival.txt");
+
+    hgInfo.storePath = store->addToStore(name, tmpDir);
+
+    nlohmann::json json;
+    json["storePath"] = hgInfo.storePath;
+    json["uri"] = uri;
+    json["name"] = name;
+    json["branch"] = hgInfo.branch;
+    json["rev"] = hgInfo.rev;
+    json["revCount"] = hgInfo.revCount;
+
+    writeFile(storeLink, json.dump());
+
+    return hgInfo;
+}
+
+static void prim_fetchMercurial(EvalState & state, const Pos & pos, Value * * args, Value & v)
+{
+    std::string url;
+    std::string rev;
+    std::string name = "source";
+    PathSet context;
+
+    state.forceValue(*args[0]);
+
+    if (args[0]->type == tAttrs) {
+
+        state.forceAttrs(*args[0], pos);
+
+        for (auto & attr : *args[0]->attrs) {
+            string n(attr.name);
+            if (n == "url")
+                url = state.coerceToString(*attr.pos, *attr.value, context, false, false);
+            else if (n == "rev")
+                rev = state.forceStringNoCtx(*attr.value, *attr.pos);
+            else if (n == "name")
+                name = state.forceStringNoCtx(*attr.value, *attr.pos);
+            else
+                throw EvalError("unsupported argument '%s' to 'fetchMercurial', at %s", attr.name, *attr.pos);
+        }
+
+        if (url.empty())
+            throw EvalError(format("'url' argument required, at %1%") % pos);
+
+    } else
+        url = state.coerceToString(pos, *args[0], context, false, false);
+
+    if (!isUri(url)) url = absPath(url);
+
+    // FIXME: git externals probably can be used to bypass the URI
+    // whitelist. Ah well.
+    state.checkURI(url);
+
+    auto hgInfo = exportMercurial(state.store, url, rev, name);
+
+    state.mkAttrs(v, 8);
+    mkString(*state.allocAttr(v, state.sOutPath), hgInfo.storePath, PathSet({hgInfo.storePath}));
+    mkString(*state.allocAttr(v, state.symbols.create("branch")), hgInfo.branch);
+    mkString(*state.allocAttr(v, state.symbols.create("rev")), hgInfo.rev);
+    mkString(*state.allocAttr(v, state.symbols.create("shortRev")), std::string(hgInfo.rev, 0, 12));
+    mkInt(*state.allocAttr(v, state.symbols.create("revCount")), hgInfo.revCount);
+    v.attrs->sort();
+}
+
+static RegisterPrimOp r("fetchMercurial", 1, prim_fetchMercurial);
+
+}
diff --git a/src/libexpr/primops/fetchgit.cc b/src/libexpr/primops/fetchgit.cc
deleted file mode 100644
index 9db4adbc9da2..000000000000
--- a/src/libexpr/primops/fetchgit.cc
+++ /dev/null
@@ -1,129 +0,0 @@
-#include "primops.hh"
-#include "eval-inline.hh"
-#include "download.hh"
-#include "store-api.hh"
-#include "pathlocks.hh"
-
-#include <sys/time.h>
-
-#include <regex>
-
-namespace nix {
-
-Path exportGit(ref<Store> store, const std::string & uri,
-    const std::string & ref, const std::string & rev)
-{
-    if (rev != "") {
-        std::regex revRegex("^[0-9a-fA-F]{40}$");
-        if (!std::regex_match(rev, revRegex))
-            throw Error("invalid Git revision '%s'", rev);
-    }
-
-    Path cacheDir = getCacheDir() + "/nix/git";
-
-    if (!pathExists(cacheDir)) {
-        createDirs(cacheDir);
-        runProgram("git", true, { "init", "--bare", cacheDir });
-    }
-
-    //Activity act(*logger, lvlInfo, format("fetching Git repository '%s'") % uri);
-
-    std::string localRef = hashString(htSHA256, fmt("%s-%s", uri, ref)).to_string(Base32, false);
-
-    Path localRefFile = cacheDir + "/refs/heads/" + localRef;
-
-    /* If the local ref is older than ‘tarball-ttl’ seconds, do a git
-       fetch to update the local ref to the remote ref. */
-    time_t now = time(0);
-    struct stat st;
-    if (stat(localRefFile.c_str(), &st) != 0 ||
-        st.st_mtime < now - settings.tarballTtl)
-    {
-        runProgram("git", true, { "-C", cacheDir, "fetch", "--force", "--", uri, ref + ":" + localRef });
-
-        struct timeval times[2];
-        times[0].tv_sec = now;
-        times[0].tv_usec = 0;
-        times[1].tv_sec = now;
-        times[1].tv_usec = 0;
-
-        utimes(localRefFile.c_str(), times);
-    }
-
-    // FIXME: check whether rev is an ancestor of ref.
-    std::string commitHash =
-        rev != "" ? rev : chomp(readFile(localRefFile));
-
-    printTalkative("using revision %s of repo '%s'", uri, commitHash);
-
-    Path storeLink = cacheDir + "/" + commitHash + ".link";
-    PathLocks storeLinkLock({storeLink}, fmt("waiting for lock on '%1%'...", storeLink));
-
-    if (pathExists(storeLink)) {
-        auto storePath = readLink(storeLink);
-        store->addTempRoot(storePath);
-        if (store->isValidPath(storePath)) {
-            return storePath;
-        }
-    }
-
-    // FIXME: should pipe this, or find some better way to extract a
-    // revision.
-    auto tar = runProgram("git", true, { "-C", cacheDir, "archive", commitHash });
-
-    Path tmpDir = createTempDir();
-    AutoDelete delTmpDir(tmpDir, true);
-
-    runProgram("tar", true, { "x", "-C", tmpDir }, tar);
-
-    auto storePath = store->addToStore("git-export", tmpDir);
-
-    replaceSymlink(storePath, storeLink);
-
-    return storePath;
-}
-
-static void prim_fetchgit(EvalState & state, const Pos & pos, Value * * args, Value & v)
-{
-    // FIXME: cut&paste from fetch().
-    if (state.restricted) throw Error("'fetchgit' is not allowed in restricted mode");
-
-    std::string url;
-    std::string ref = "master";
-    std::string rev;
-
-    state.forceValue(*args[0]);
-
-    if (args[0]->type == tAttrs) {
-
-        state.forceAttrs(*args[0], pos);
-
-        for (auto & attr : *args[0]->attrs) {
-            string name(attr.name);
-            if (name == "url") {
-                PathSet context;
-                url = state.coerceToString(*attr.pos, *attr.value, context, false, false);
-                if (hasPrefix(url, "/")) url = "file://" + url;
-            }
-            else if (name == "ref")
-                ref = state.forceStringNoCtx(*attr.value, *attr.pos);
-            else if (name == "rev")
-                rev = state.forceStringNoCtx(*attr.value, *attr.pos);
-            else
-                throw EvalError("unsupported argument '%s' to 'fetchgit', at %s", attr.name, *attr.pos);
-        }
-
-        if (url.empty())
-            throw EvalError(format("'url' argument required, at %1%") % pos);
-
-    } else
-        url = state.forceStringNoCtx(*args[0], pos);
-
-    Path storePath = exportGit(state.store, url, ref, rev);
-
-    mkString(v, storePath, PathSet({storePath}));
-}
-
-static RegisterPrimOp r("__fetchgit", 1, prim_fetchgit);
-
-}
diff --git a/src/libexpr/primops/fetchgit.hh b/src/libexpr/primops/fetchgit.hh
deleted file mode 100644
index ff228f3b3c6a..000000000000
--- a/src/libexpr/primops/fetchgit.hh
+++ /dev/null
@@ -1,14 +0,0 @@
-#pragma once
-
-#include <string>
-
-#include "ref.hh"
-
-namespace nix {
-
-class Store;
-
-Path exportGit(ref<Store> store, const std::string & uri,
-    const std::string & ref, const std::string & rev = "");
-
-}
diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index 9f8edc826a04..061682377257 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -2833,10 +2833,10 @@ void DerivationGoal::runChild()
                     sandboxProfile += "(deny default (with no-log))\n";
                 }
 
-                sandboxProfile += "(import \"sandbox-defaults.sb\")";
+                sandboxProfile += "(import \"sandbox-defaults.sb\")\n";
 
                 if (fixedOutput)
-                    sandboxProfile += "(import \"sandbox-network.sb\")";
+                    sandboxProfile += "(import \"sandbox-network.sb\")\n";
 
                 /* Our rwx outputs */
                 sandboxProfile += "(allow file-read* file-write* process-exec\n";
@@ -2879,7 +2879,7 @@ void DerivationGoal::runChild()
 
                 sandboxProfile += additionalSandboxProfile;
             } else
-                sandboxProfile += "(import \"sandbox-minimal.sb\")";
+                sandboxProfile += "(import \"sandbox-minimal.sb\")\n";
 
             debug("Generated sandbox profile:");
             debug(sandboxProfile);
@@ -2888,6 +2888,8 @@ void DerivationGoal::runChild()
 
             writeFile(sandboxFile, sandboxProfile);
 
+            bool allowLocalNetworking = get(drv->env, "__darwinAllowLocalNetworking") == "1";
+
             /* The tmpDir in scope points at the temporary build directory for our derivation. Some packages try different mechanisms
                to find temporary directories, so we want to open up a broader place for them to dump their files, if needed. */
             Path globalTmpDir = canonPath(getEnv("TMPDIR", "/tmp"), true);
@@ -2903,6 +2905,10 @@ void DerivationGoal::runChild()
             args.push_back("_GLOBAL_TMP_DIR=" + globalTmpDir);
             args.push_back("-D");
             args.push_back("IMPORT_DIR=" + settings.nixDataDir + "/nix/sandbox/");
+            if (allowLocalNetworking) {
+                args.push_back("-D");
+                args.push_back(string("_ALLOW_LOCAL_NETWORKING=1"));
+            }
             args.push_back(drv->builder);
         }
 #endif
diff --git a/src/libstore/download.cc b/src/libstore/download.cc
index 608b8fd399b4..70f9b1f5eacb 100644
--- a/src/libstore/download.cc
+++ b/src/libstore/download.cc
@@ -23,6 +23,8 @@
 #include <cmath>
 #include <random>
 
+using namespace std::string_literals;
+
 namespace nix {
 
 double getTime()
@@ -604,7 +606,7 @@ Path Downloader::downloadCached(ref<Store> store, const string & url_, bool unpa
     Path cacheDir = getCacheDir() + "/nix/tarballs";
     createDirs(cacheDir);
 
-    string urlHash = hashString(htSHA256, url).to_string(Base32, false);
+    string urlHash = hashString(htSHA256, name + std::string("\0"s) + url).to_string(Base32, false);
 
     Path dataFile = cacheDir + "/" + urlHash + ".info";
     Path fileLink = cacheDir + "/" + urlHash + "-file";
@@ -705,7 +707,7 @@ bool isUri(const string & s)
     size_t pos = s.find("://");
     if (pos == string::npos) return false;
     string scheme(s, 0, pos);
-    return scheme == "http" || scheme == "https" || scheme == "file" || scheme == "channel" || scheme == "git" || scheme == "s3";
+    return scheme == "http" || scheme == "https" || scheme == "file" || scheme == "channel" || scheme == "git" || scheme == "s3" || scheme == "ssh";
 }
 
 
diff --git a/src/libstore/globals.hh b/src/libstore/globals.hh
index 880527322794..a4aa842d70fd 100644
--- a/src/libstore/globals.hh
+++ b/src/libstore/globals.hh
@@ -225,7 +225,7 @@ public:
 
     Setting<bool> restrictEval{this, false, "restrict-eval",
         "Whether to restrict file system access to paths in $NIX_PATH, "
-        "and to disallow fetching files from the network."};
+        "and network access to the URI prefixes listed in 'allowed-uris'."};
 
     Setting<size_t> buildRepeat{this, 0, "repeat",
         "The number of times to repeat a build in order to verify determinism.",
@@ -271,7 +271,7 @@ public:
         "Number of parallel HTTP connections.",
         {"binary-caches-parallel-connections"}};
 
-    Setting<bool> enableHttp2{this, true, "enable-http2",
+    Setting<bool> enableHttp2{this, true, "http2",
         "Whether to enable HTTP/2 support."};
 
     Setting<unsigned int> tarballTtl{this, 60 * 60, "tarball-ttl",
@@ -353,6 +353,8 @@ public:
     Setting<uint64_t> maxFree{this, std::numeric_limits<uint64_t>::max(), "max-free",
         "Stop deleting garbage when free disk space is above the specified amount."};
 
+    Setting<Strings> allowedUris{this, {}, "allowed-uris",
+        "Prefixes of URIs that builtin functions such as fetchurl and fetchGit are allowed to fetch."};
 };
 
 
diff --git a/src/libstore/s3-binary-cache-store.cc b/src/libstore/s3-binary-cache-store.cc
index 5fc7371a5198..6a0f19238add 100644
--- a/src/libstore/s3-binary-cache-store.cc
+++ b/src/libstore/s3-binary-cache-store.cc
@@ -241,8 +241,8 @@ struct S3BinaryCacheStoreImpl : public S3BinaryCacheStore
             auto & error = res.GetError();
             if (error.GetErrorType() == Aws::S3::S3Errors::RESOURCE_NOT_FOUND
                 || error.GetErrorType() == Aws::S3::S3Errors::NO_SUCH_KEY
-                || (error.GetErrorType() == Aws::S3::S3Errors::UNKNOWN // FIXME
-                    && error.GetMessage().find("404") != std::string::npos))
+                // If bucket listing is disabled, 404s turn into 403s
+                || error.GetErrorType() == Aws::S3::S3Errors::ACCESS_DENIED)
                 return false;
             throw Error(format("AWS error fetching '%s': %s") % path % error.GetMessage());
         }
diff --git a/src/libstore/sandbox-defaults.sb b/src/libstore/sandbox-defaults.sb
index d63c8f813c9e..c8436d9866c5 100644
--- a/src/libstore/sandbox-defaults.sb
+++ b/src/libstore/sandbox-defaults.sb
@@ -21,6 +21,9 @@
 ; Allow sending signals within the sandbox.
 (allow signal (target same-sandbox))
 
+; Allow getpwuid.
+(allow mach-lookup (global-name "com.apple.system.opendirectoryd.libinfo"))
+
 ; Access to /tmp.
 (allow file* process-exec (literal "/tmp") (subpath TMPDIR))
 
@@ -30,6 +33,29 @@
 ; Without this line clang cannot write to /dev/null, breaking some configure tests.
 (allow file-read-metadata (literal "/dev"))
 
+; Many packages like to do local networking in their test suites, but let's only
+; allow it if the package explicitly asks for it.
+(if (param "_ALLOW_LOCAL_NETWORKING")
+    (begin
+      (allow network* (local ip) (local tcp) (local udp))
+
+      ; Allow access to /etc/resolv.conf (which is a symlink to
+      ; /private/var/run/resolv.conf).
+      ; TODO: deduplicate with sandbox-network.sb
+      (allow file-read-metadata
+             (literal "/var")
+             (literal "/etc")
+             (literal "/etc/resolv.conf")
+             (literal "/private/etc/resolv.conf"))
+
+      (allow file-read*
+             (literal "/private/var/run/resolv.conf"))
+
+      ; Allow DNS lookups. This is even needed for localhost, which lots of tests rely on
+      (allow file-read-metadata (literal "/etc/hosts"))
+      (allow file-read*         (literal "/private/etc/hosts"))
+      (allow network-outbound (remote unix-socket (path-literal "/private/var/run/mDNSResponder")))))
+
 ; Standard devices.
 (allow file*
        (literal "/dev/null")
@@ -54,5 +80,4 @@
 (allow file-read-metadata
        (literal "/etc")
        (literal "/var")
-       (literal "/private/var/tmp")
-       )
+       (literal "/private/var/tmp"))
diff --git a/src/libutil/archive.cc b/src/libutil/archive.cc
index ea1deb924e67..f71229d8fdd6 100644
--- a/src/libutil/archive.cc
+++ b/src/libutil/archive.cc
@@ -29,7 +29,7 @@ const std::string narVersionMagic1 = "nix-archive-1";
 
 static string caseHackSuffix = "~nix~case~hack~";
 
-PathFilter defaultPathFilter;
+PathFilter defaultPathFilter = [](const Path &) { return true; };
 
 
 static void dumpContents(const Path & path, size_t size,
diff --git a/src/libutil/archive.hh b/src/libutil/archive.hh
index 607ebf8b28f9..8a15e849c7b8 100644
--- a/src/libutil/archive.hh
+++ b/src/libutil/archive.hh
@@ -44,13 +44,6 @@ namespace nix {
 
      `+' denotes string concatenation. */
 
-struct PathFilter
-{
-    virtual ~PathFilter() { }
-    virtual bool operator () (const Path & path) { return true; }
-};
-
-extern PathFilter defaultPathFilter;
 
 void dumpPath(const Path & path, Sink & sink,
     PathFilter & filter = defaultPathFilter);
diff --git a/src/libutil/hash.hh b/src/libutil/hash.hh
index d83049b02368..fd7a61df8e46 100644
--- a/src/libutil/hash.hh
+++ b/src/libutil/hash.hh
@@ -93,8 +93,6 @@ Hash hashFile(HashType ht, const Path & path);
 
 /* Compute the hash of the given path.  The hash is defined as
    (essentially) hashString(ht, dumpPath(path)). */
-struct PathFilter;
-extern PathFilter defaultPathFilter;
 typedef std::pair<Hash, unsigned long long> HashResult;
 HashResult hashPath(HashType ht, const Path & path,
     PathFilter & filter = defaultPathFilter);
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 9346d5dc4cf8..f56153cd4a8a 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -896,31 +896,45 @@ std::vector<char *> stringsToCharPtrs(const Strings & ss)
 string runProgram(Path program, bool searchPath, const Strings & args,
     const std::experimental::optional<std::string> & input)
 {
+    RunOptions opts(program, args);
+    opts.searchPath = searchPath;
+    opts.input = input;
+
+    auto res = runProgram(opts);
+
+    if (!statusOk(res.first))
+        throw ExecError(res.first, fmt("program '%1%' %2%", program, statusToString(res.first)));
+
+    return res.second;
+}
+
+std::pair<int, std::string> runProgram(const RunOptions & options)
+{
     checkInterrupt();
 
     /* Create a pipe. */
     Pipe out, in;
     out.create();
-    if (input) in.create();
+    if (options.input) in.create();
 
     /* Fork. */
     Pid pid = startProcess([&]() {
         if (dup2(out.writeSide.get(), STDOUT_FILENO) == -1)
             throw SysError("dupping stdout");
-        if (input && dup2(in.readSide.get(), STDIN_FILENO) == -1)
+        if (options.input && dup2(in.readSide.get(), STDIN_FILENO) == -1)
             throw SysError("dupping stdin");
 
-        Strings args_(args);
-        args_.push_front(program);
+        Strings args_(options.args);
+        args_.push_front(options.program);
 
         restoreSignals();
 
-        if (searchPath)
-            execvp(program.c_str(), stringsToCharPtrs(args_).data());
+        if (options.searchPath)
+            execvp(options.program.c_str(), stringsToCharPtrs(args_).data());
         else
-            execv(program.c_str(), stringsToCharPtrs(args_).data());
+            execv(options.program.c_str(), stringsToCharPtrs(args_).data());
 
-        throw SysError(format("executing '%1%'") % program);
+        throw SysError("executing '%1%'", options.program);
     });
 
     out.writeSide = -1;
@@ -935,11 +949,11 @@ string runProgram(Path program, bool searchPath, const Strings & args,
     });
 
 
-    if (input) {
+    if (options.input) {
         in.readSide = -1;
         writerThread = std::thread([&]() {
             try {
-                writeFull(in.writeSide.get(), *input);
+                writeFull(in.writeSide.get(), *options.input);
                 promise.set_value();
             } catch (...) {
                 promise.set_exception(std::current_exception());
@@ -952,14 +966,11 @@ string runProgram(Path program, bool searchPath, const Strings & args,
 
     /* Wait for the child to finish. */
     int status = pid.wait();
-    if (!statusOk(status))
-        throw ExecError(status, format("program '%1%' %2%")
-            % program % statusToString(status));
 
     /* Wait for the writer thread to finish. */
-    if (input) promise.get_future().get();
+    if (options.input) promise.get_future().get();
 
-    return result;
+    return {status, result};
 }
 
 
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index fccf5d854800..a3494e09b09b 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -245,6 +245,23 @@ string runProgram(Path program, bool searchPath = false,
     const Strings & args = Strings(),
     const std::experimental::optional<std::string> & input = {});
 
+struct RunOptions
+{
+    Path program;
+    bool searchPath = true;
+    Strings args;
+    std::experimental::optional<std::string> input;
+    bool _killStderr = false;
+
+    RunOptions(const Path & program, const Strings & args)
+        : program(program), args(args) { };
+
+    RunOptions & killStderr(bool v) { _killStderr = true; return *this; }
+};
+
+std::pair<int, std::string> runProgram(const RunOptions & options);
+
+
 class ExecError : public Error
 {
 public:
@@ -481,4 +498,10 @@ struct MaintainCount
 std::pair<unsigned short, unsigned short> getWindowSize();
 
 
+/* Used in various places. */
+typedef std::function<bool(const Path & path)> PathFilter;
+
+extern PathFilter defaultPathFilter;
+
+
 }
diff --git a/src/nix-build/nix-build.cc b/src/nix-build/nix-build.cc
index 8e56e5a46b19..21b0a18dd887 100755
--- a/src/nix-build/nix-build.cc
+++ b/src/nix-build/nix-build.cc
@@ -167,6 +167,9 @@ void mainWrapped(int argc, char * * argv)
             buildMode = bmRepair;
         }
 
+        else if (*arg == "--hash")
+            buildMode = bmHash;
+
         else if (*arg == "--run-env") // obsolete
             runEnv = true;