1 files changed, 246 insertions, 0 deletions
diff --git a/third_party/nix/src/libexpr/primops/fetchMercurial.cc b/third_party/nix/src/libexpr/primops/fetchMercurial.cc
new file mode 100644
index 000000000000..13dc61766fe0
--- /dev/null
+++ b/third_party/nix/src/libexpr/primops/fetchMercurial.cc
@@ -0,0 +1,246 @@
+#include <nlohmann/json.hpp>
+#include <regex>
+
+#include <absl/strings/ascii.h>
+#include <absl/strings/match.h>
+#include <absl/strings/str_split.h>
+#include <glog/logging.h>
+#include <sys/time.h>
+
+#include "libexpr/eval-inline.hh"
+#include "libexpr/primops.hh"
+#include "libstore/download.hh"
+#include "libstore/pathlocks.hh"
+#include "libstore/store-api.hh"
+
+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 (evalSettings.pureEval && rev == "") {
+    throw Error(
+        "in pure evaluation mode, 'fetchMercurial' requires a Mercurial "
+        "revision");
+  }
+
+  if (rev == "" && absl::StartsWith(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. */
+
+      DLOG(INFO) << "copying unclean Mercurial working tree '" << uri << "'";
+
+      HgInfo hgInfo;
+      hgInfo.rev = "0000000000000000000000000000000000000000";
+      hgInfo.branch = absl::StripTrailingAsciiWhitespace(
+          runProgram("hg", true, {"branch", "-R", uri}));
+
+      std::set<std::string> files = absl::StrSplit(
+          runProgram("hg", true,
+                     {"status", "-R", uri, "--clean", "--modified", "--added",
+                      "--no-status", "--print0"}),
+          absl::ByChar('\0'), absl::SkipEmpty());
+
+      PathFilter filter = [&](const Path& p) -> bool {
+        assert(absl::StartsWith(p, uri));
+        std::string file(p, uri.size() + 1);
+
+        auto st = lstat(p);
+
+        if (S_ISDIR(st.st_mode)) {
+          auto prefix = file + "/";
+          auto i = files.lower_bound(prefix);
+          return i != files.end() && absl::StartsWith(*i, prefix);
+        }
+
+        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 ||
+      static_cast<uint64_t>(st.st_mtime) + settings.tarballTtl <=
+          static_cast<uint64_t>(now)) {
+    /* 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")) {
+      DLOG(INFO) << "fetching Mercurial repository '" << uri << "'";
+
+      if (pathExists(cacheDir)) {
+        try {
+          runProgram("hg", true, {"pull", "-R", cacheDir, "--", uri});
+        } catch (ExecError& e) {
+          std::string transJournal = cacheDir + "/.hg/store/journal";
+          /* hg throws "abandoned transaction" error only if this file exists */
+          if (pathExists(transJournal)) {
+            runProgram("hg", true, {"recover", "-R", cacheDir});
+            runProgram("hg", true, {"pull", "-R", cacheDir, "--", uri});
+          } else {
+            throw ExecError(e.status,
+                            fmt("'hg pull' %s", statusToString(e.status)));
+          }
+        }
+      } else {
+        createDirs(dirOf(cacheDir));
+        runProgram("hg", true, {"clone", "--noupdate", "--", uri, cacheDir});
+      }
+    }
+
+    writeFile(stampFile, "");
+  }
+
+  std::vector<std::string> tokens =
+      absl::StrSplit(runProgram("hg", true,
+                                {"log", "-R", cacheDir, "-r", rev, "--template",
+                                 "{node} {rev} {branch}"}),
+                     absl::ByAnyChar(" \t\n\r"), absl::SkipEmpty());
+  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)) {
+      DLOG(INFO) << "using cached Mercurial store path '" << 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_iter : *args[0]->attrs) {
+      auto& attr = attr_iter.second;
+      std::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);
+  }
+
+  // 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);
+
+  if (state.allowedPaths) {
+    state.allowedPaths->insert(state.store->toRealPath(hgInfo.storePath));
+  }
+}
+
+static RegisterPrimOp r("fetchMercurial", 1, prim_fetchMercurial);
+
+}  // namespace nix