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Make the Store API more type-safe

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Most functions now take a StorePath argument rather than a Path (which
is just an alias for std::string). The StorePath constructor ensures
that the path is syntactically correct (i.e. it looks like
<store-dir>/<base32-hash>-<name>). Similarly, functions like
buildPaths() now take a StorePathWithOutputs, rather than abusing Path
by adding a '!<outputs>' suffix.

Note that the StorePath type is implemented in Rust. This involves
some hackery to allow Rust values to be used directly in C++, via a
helper type whose destructor calls the Rust type's drop()
function. The main issue is the dynamic nature of C++ move semantics:
after we have moved a Rust value, we should not call the drop function
on the original value. So when we move a value, we set the original
value to bitwise zero, and the destructor only calls drop() if the
value is not bitwise zero. This should be sufficient for most types.

Also lots of minor cleanups to the C++ API to make it more modern
(e.g. using std::optional and std::string_view in some places).
This commit is contained in:
Eelco Dolstra 2019-12-05 19:11:09 +01:00
parent ebd89999c2
commit bbe97dff8b
98 changed files with 2638 additions and 2880 deletions
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69
src/libstore/download.cc
View file

@ -650,10 +650,10 @@ struct CurlDownloader : public Downloader
#ifdef ENABLE_S3
auto [bucketName, key, params] = parseS3Uri(request.uri);
std::string profile = get(params, "profile", "");
std::string region = get(params, "region", Aws::Region::US_EAST_1);
std::string scheme = get(params, "scheme", "");
std::string endpoint = get(params, "endpoint", "");
std::string profile = get(params, "profile").value_or("");
std::string region = get(params, "region").value_or(Aws::Region::US_EAST_1);
std::string scheme = get(params, "scheme").value_or("");
std::string endpoint = get(params, "endpoint").value_or("");
S3Helper s3Helper(profile, region, scheme, endpoint);
@ -811,13 +811,13 @@ CachedDownloadResult Downloader::downloadCached(
if (p != string::npos) name = string(url, p + 1);
}
Path expectedStorePath;
std::optional<StorePath> expectedStorePath;
if (request.expectedHash) {
expectedStorePath = store->makeFixedOutputPath(request.unpack, request.expectedHash, name);
if (store->isValidPath(expectedStorePath)) {
if (store->isValidPath(*expectedStorePath)) {
CachedDownloadResult result;
result.storePath = expectedStorePath;
result.path = store->toRealPath(expectedStorePath);
result.storePath = store->printStorePath(*expectedStorePath);
result.path = store->toRealPath(result.storePath);
return result;
}
}
@ -832,7 +832,7 @@ CachedDownloadResult Downloader::downloadCached(
PathLocks lock({fileLink}, fmt("waiting for lock on '%1%'...", fileLink));
Path storePath;
std::optional<StorePath> storePath;
string expectedETag;
@ -841,9 +841,10 @@ CachedDownloadResult Downloader::downloadCached(
CachedDownloadResult result;
if (pathExists(fileLink) && pathExists(dataFile)) {
storePath = readLink(fileLink);
store->addTempRoot(storePath);
if (store->isValidPath(storePath)) {
storePath = store->parseStorePath(readLink(fileLink));
// FIXME
store->addTempRoot(*storePath);
if (store->isValidPath(*storePath)) {
auto ss = tokenizeString<vector<string>>(readFile(dataFile), "\n");
if (ss.size() >= 3 && ss[0] == url) {
time_t lastChecked;
@ -857,7 +858,7 @@ CachedDownloadResult Downloader::downloadCached(
}
}
} else
storePath = "";
storePath.reset();
}
if (!skip) {
@ -870,65 +871,65 @@ CachedDownloadResult Downloader::downloadCached(
result.etag = res.etag;
if (!res.cached) {
ValidPathInfo info;
StringSink sink;
dumpString(*res.data, sink);
Hash hash = hashString(request.expectedHash ? request.expectedHash.type : htSHA256, *res.data);
info.path = store->makeFixedOutputPath(false, hash, name);
ValidPathInfo info(store->makeFixedOutputPath(false, hash, name));
info.narHash = hashString(htSHA256, *sink.s);
info.narSize = sink.s->size();
info.ca = makeFixedOutputCA(false, hash);
store->addToStore(info, sink.s, NoRepair, NoCheckSigs);
storePath = info.path;
storePath = info.path.clone();
}
assert(!storePath.empty());
replaceSymlink(storePath, fileLink);
assert(storePath);
replaceSymlink(store->printStorePath(*storePath), fileLink);
writeFile(dataFile, url + "\n" + res.etag + "\n" + std::to_string(time(0)) + "\n");
} catch (DownloadError & e) {
if (storePath.empty()) throw;
if (!storePath) throw;
warn("warning: %s; using cached result", e.msg());
result.etag = expectedETag;
}
}
if (request.unpack) {
Path unpackedLink = cacheDir + "/" + baseNameOf(storePath) + "-unpacked";
Path unpackedLink = cacheDir + "/" + ((std::string) storePath->to_string()) + "-unpacked";
PathLocks lock2({unpackedLink}, fmt("waiting for lock on '%1%'...", unpackedLink));
Path unpackedStorePath;
std::optional<StorePath> unpackedStorePath;
if (pathExists(unpackedLink)) {
unpackedStorePath = readLink(unpackedLink);
store->addTempRoot(unpackedStorePath);
if (!store->isValidPath(unpackedStorePath))
unpackedStorePath = "";
unpackedStorePath = store->parseStorePath(readLink(unpackedLink));
// FIXME
store->addTempRoot(*unpackedStorePath);
if (!store->isValidPath(*unpackedStorePath))
unpackedStorePath.reset();
}
if (unpackedStorePath.empty()) {
if (!unpackedStorePath) {
printInfo("unpacking '%s'...", url);
Path tmpDir = createTempDir();
AutoDelete autoDelete(tmpDir, true);
unpackTarfile(store->toRealPath(storePath), tmpDir, baseNameOf(url));
unpackTarfile(store->toRealPath(store->printStorePath(*storePath)), tmpDir, std::string(baseNameOf(url)));
auto members = readDirectory(tmpDir);
if (members.size() != 1)
throw nix::Error("tarball '%s' contains an unexpected number of top-level files", url);
auto topDir = tmpDir + "/" + members.begin()->name;
unpackedStorePath = store->addToStore(name, topDir, true, htSHA256, defaultPathFilter, NoRepair);
}
replaceSymlink(unpackedStorePath, unpackedLink);
storePath = unpackedStorePath;
replaceSymlink(store->printStorePath(*unpackedStorePath), unpackedLink);
storePath = std::move(*unpackedStorePath);
}
if (expectedStorePath != "" && storePath != expectedStorePath) {
if (expectedStorePath && *storePath != *expectedStorePath) {
unsigned int statusCode = 102;
Hash gotHash = request.unpack
? hashPath(request.expectedHash.type, store->toRealPath(storePath)).first
: hashFile(request.expectedHash.type, store->toRealPath(storePath));
? hashPath(request.expectedHash.type, store->toRealPath(store->printStorePath(*storePath))).first
: hashFile(request.expectedHash.type, store->toRealPath(store->printStorePath(*storePath)));
throw nix::Error(statusCode, "hash mismatch in file downloaded from '%s':\n wanted: %s\n got: %s",
url, request.expectedHash.to_string(), gotHash.to_string());
}
result.storePath = storePath;
result.path = store->toRealPath(storePath);
result.storePath = store->printStorePath(*storePath);
result.path = store->toRealPath(result.storePath);
return result;
}