bbe97dff8b
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).
130 lines
3.5 KiB
C++
130 lines
3.5 KiB
C++
#include "remote-fs-accessor.hh"
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#include "nar-accessor.hh"
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#include "json.hh"
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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namespace nix {
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RemoteFSAccessor::RemoteFSAccessor(ref<Store> store, const Path & cacheDir)
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: store(store)
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, cacheDir(cacheDir)
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{
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if (cacheDir != "")
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createDirs(cacheDir);
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}
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Path RemoteFSAccessor::makeCacheFile(const Path & storePath, const std::string & ext)
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{
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assert(cacheDir != "");
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return fmt("%s/%s.%s", cacheDir, storePathToHash(storePath), ext);
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}
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void RemoteFSAccessor::addToCache(const Path & storePath, const std::string & nar,
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ref<FSAccessor> narAccessor)
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{
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nars.emplace(storePath, narAccessor);
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if (cacheDir != "") {
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try {
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std::ostringstream str;
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JSONPlaceholder jsonRoot(str);
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listNar(jsonRoot, narAccessor, "", true);
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writeFile(makeCacheFile(storePath, "ls"), str.str());
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/* FIXME: do this asynchronously. */
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writeFile(makeCacheFile(storePath, "nar"), nar);
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} catch (...) {
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ignoreException();
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}
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}
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}
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std::pair<ref<FSAccessor>, Path> RemoteFSAccessor::fetch(const Path & path_)
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{
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auto path = canonPath(path_);
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auto storePath = store->toStorePath(path);
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std::string restPath = std::string(path, storePath.size());
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if (!store->isValidPath(store->parseStorePath(storePath)))
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throw InvalidPath(format("path '%1%' is not a valid store path") % storePath);
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auto i = nars.find(storePath);
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if (i != nars.end()) return {i->second, restPath};
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StringSink sink;
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std::string listing;
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Path cacheFile;
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if (cacheDir != "" && pathExists(cacheFile = makeCacheFile(storePath, "nar"))) {
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try {
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listing = nix::readFile(makeCacheFile(storePath, "ls"));
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auto narAccessor = makeLazyNarAccessor(listing,
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[cacheFile](uint64_t offset, uint64_t length) {
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AutoCloseFD fd = open(cacheFile.c_str(), O_RDONLY | O_CLOEXEC);
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if (!fd)
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throw SysError("opening NAR cache file '%s'", cacheFile);
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if (lseek(fd.get(), offset, SEEK_SET) != (off_t) offset)
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throw SysError("seeking in '%s'", cacheFile);
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std::string buf(length, 0);
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readFull(fd.get(), (unsigned char *) buf.data(), length);
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return buf;
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});
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nars.emplace(storePath, narAccessor);
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return {narAccessor, restPath};
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} catch (SysError &) { }
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try {
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*sink.s = nix::readFile(cacheFile);
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auto narAccessor = makeNarAccessor(sink.s);
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nars.emplace(storePath, narAccessor);
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return {narAccessor, restPath};
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} catch (SysError &) { }
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}
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store->narFromPath(store->parseStorePath(storePath), sink);
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auto narAccessor = makeNarAccessor(sink.s);
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addToCache(storePath, *sink.s, narAccessor);
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return {narAccessor, restPath};
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}
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FSAccessor::Stat RemoteFSAccessor::stat(const Path & path)
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{
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auto res = fetch(path);
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return res.first->stat(res.second);
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}
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StringSet RemoteFSAccessor::readDirectory(const Path & path)
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{
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auto res = fetch(path);
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return res.first->readDirectory(res.second);
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}
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std::string RemoteFSAccessor::readFile(const Path & path)
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{
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auto res = fetch(path);
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return res.first->readFile(res.second);
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}
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std::string RemoteFSAccessor::readLink(const Path & path)
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{
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auto res = fetch(path);
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return res.first->readLink(res.second);
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}
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}
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