lix/src/libexpr/primops/fetchgit.cc
Eelco Dolstra e38382895d
builtins.fetchGit: Return an attrset with revision info
This adds rev, shortRev and revCount attributes, equal to what Hydra
provides. E.g.

  $ nix eval '(fetchGit https://github.com/NixOS/patchelf.git)'
  { outPath = "/nix/store/ghigrkw02l440g8vfxa9wj4c3zpfmw99-source"; rev = "29c085fd9d3fc972f75b3961905d6b4ecce7eb2b"; revCount = 303; shortRev = "29c085f"; }
2017-10-30 11:49:03 +01:00

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#include "fetchgit.hh"
#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 {
GitInfo exportGit(ref<Store> store, const std::string & uri,
const std::string & ref, const std::string & rev,
const std::string & name)
{
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)
{
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));
try {
// FIXME: doesn't handle empty lines
auto json = nlohmann::json::parse(readFile(storeLink));
assert(json["uri"] == uri && 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)
{
// 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;
std::string name = "source";
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") {
PathSet context;
url = state.coerceToString(*attr.pos, *attr.value, context, false, false);
if (hasPrefix(url, "/")) url = "file://" + url;
}
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.forceStringNoCtx(*args[0], pos);
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);
}