diff options
Diffstat (limited to 'third_party/nix/src/libstore/nar-accessor.cc')
| -rw-r--r-- | third_party/nix/src/libstore/nar-accessor.cc | 266 |
1 files changed, 266 insertions, 0 deletions
diff --git a/third_party/nix/src/libstore/nar-accessor.cc b/third_party/nix/src/libstore/nar-accessor.cc new file mode 100644 index 0000000000..b74480684f --- /dev/null +++ b/third_party/nix/src/libstore/nar-accessor.cc @@ -0,0 +1,266 @@ +#include "nar-accessor.hh" +#include "archive.hh" +#include "json.hh" + +#include <map> +#include <stack> +#include <algorithm> + +#include <nlohmann/json.hpp> + +namespace nix { + +struct NarMember +{ + FSAccessor::Type type = FSAccessor::Type::tMissing; + + bool isExecutable = false; + + /* If this is a regular file, position of the contents of this + file in the NAR. */ + size_t start = 0, size = 0; + + std::string target; + + /* If this is a directory, all the children of the directory. */ + std::map<std::string, NarMember> children; +}; + +struct NarAccessor : public FSAccessor +{ + std::shared_ptr<const std::string> nar; + + GetNarBytes getNarBytes; + + NarMember root; + + struct NarIndexer : ParseSink, StringSource + { + NarAccessor & acc; + + std::stack<NarMember *> parents; + + std::string currentStart; + bool isExec = false; + + NarIndexer(NarAccessor & acc, const std::string & nar) + : StringSource(nar), acc(acc) + { } + + void createMember(const Path & path, NarMember member) { + size_t level = std::count(path.begin(), path.end(), '/'); + while (parents.size() > level) parents.pop(); + + if (parents.empty()) { + acc.root = std::move(member); + parents.push(&acc.root); + } else { + if (parents.top()->type != FSAccessor::Type::tDirectory) + throw Error("NAR file missing parent directory of path '%s'", path); + auto result = parents.top()->children.emplace(baseNameOf(path), std::move(member)); + parents.push(&result.first->second); + } + } + + void createDirectory(const Path & path) override + { + createMember(path, {FSAccessor::Type::tDirectory, false, 0, 0}); + } + + void createRegularFile(const Path & path) override + { + createMember(path, {FSAccessor::Type::tRegular, false, 0, 0}); + } + + void isExecutable() override + { + parents.top()->isExecutable = true; + } + + void preallocateContents(unsigned long long size) override + { + currentStart = string(s, pos, 16); + assert(size <= std::numeric_limits<size_t>::max()); + parents.top()->size = (size_t)size; + parents.top()->start = pos; + } + + void receiveContents(unsigned char * data, unsigned int len) override + { + // Sanity check + if (!currentStart.empty()) { + assert(len < 16 || currentStart == string((char *) data, 16)); + currentStart.clear(); + } + } + + void createSymlink(const Path & path, const string & target) override + { + createMember(path, + NarMember{FSAccessor::Type::tSymlink, false, 0, 0, target}); + } + }; + + NarAccessor(ref<const std::string> nar) : nar(nar) + { + NarIndexer indexer(*this, *nar); + parseDump(indexer, indexer); + } + + NarAccessor(const std::string & listing, GetNarBytes getNarBytes) + : getNarBytes(getNarBytes) + { + using json = nlohmann::json; + + std::function<void(NarMember &, json &)> recurse; + + recurse = [&](NarMember & member, json & v) { + std::string type = v["type"]; + + if (type == "directory") { + member.type = FSAccessor::Type::tDirectory; + for (auto i = v["entries"].begin(); i != v["entries"].end(); ++i) { + std::string name = i.key(); + recurse(member.children[name], i.value()); + } + } else if (type == "regular") { + member.type = FSAccessor::Type::tRegular; + member.size = v["size"]; + member.isExecutable = v.value("executable", false); + member.start = v["narOffset"]; + } else if (type == "symlink") { + member.type = FSAccessor::Type::tSymlink; + member.target = v.value("target", ""); + } else return; + }; + + json v = json::parse(listing); + recurse(root, v); + } + + NarMember * find(const Path & path) + { + Path canon = path == "" ? "" : canonPath(path); + NarMember * current = &root; + auto end = path.end(); + for (auto it = path.begin(); it != end; ) { + // because it != end, the remaining component is non-empty so we need + // a directory + if (current->type != FSAccessor::Type::tDirectory) return nullptr; + + // skip slash (canonPath above ensures that this is always a slash) + assert(*it == '/'); + it += 1; + + // lookup current component + auto next = std::find(it, end, '/'); + auto child = current->children.find(std::string(it, next)); + if (child == current->children.end()) return nullptr; + current = &child->second; + + it = next; + } + + return current; + } + + NarMember & get(const Path & path) { + auto result = find(path); + if (result == nullptr) + throw Error("NAR file does not contain path '%1%'", path); + return *result; + } + + Stat stat(const Path & path) override + { + auto i = find(path); + if (i == nullptr) + return {FSAccessor::Type::tMissing, 0, false}; + return {i->type, i->size, i->isExecutable, i->start}; + } + + StringSet readDirectory(const Path & path) override + { + auto i = get(path); + + if (i.type != FSAccessor::Type::tDirectory) + throw Error(format("path '%1%' inside NAR file is not a directory") % path); + + StringSet res; + for (auto & child : i.children) + res.insert(child.first); + + return res; + } + + std::string readFile(const Path & path) override + { + auto i = get(path); + if (i.type != FSAccessor::Type::tRegular) + throw Error(format("path '%1%' inside NAR file is not a regular file") % path); + + if (getNarBytes) return getNarBytes(i.start, i.size); + + assert(nar); + return std::string(*nar, i.start, i.size); + } + + std::string readLink(const Path & path) override + { + auto i = get(path); + if (i.type != FSAccessor::Type::tSymlink) + throw Error(format("path '%1%' inside NAR file is not a symlink") % path); + return i.target; + } +}; + +ref<FSAccessor> makeNarAccessor(ref<const std::string> nar) +{ + return make_ref<NarAccessor>(nar); +} + +ref<FSAccessor> makeLazyNarAccessor(const std::string & listing, + GetNarBytes getNarBytes) +{ + return make_ref<NarAccessor>(listing, getNarBytes); +} + +void listNar(JSONPlaceholder & res, ref<FSAccessor> accessor, + const Path & path, bool recurse) +{ + auto st = accessor->stat(path); + + auto obj = res.object(); + + switch (st.type) { + case FSAccessor::Type::tRegular: + obj.attr("type", "regular"); + obj.attr("size", st.fileSize); + if (st.isExecutable) + obj.attr("executable", true); + if (st.narOffset) + obj.attr("narOffset", st.narOffset); + break; + case FSAccessor::Type::tDirectory: + obj.attr("type", "directory"); + { + auto res2 = obj.object("entries"); + for (auto & name : accessor->readDirectory(path)) { + if (recurse) { + auto res3 = res2.placeholder(name); + listNar(res3, accessor, path + "/" + name, true); + } else + res2.object(name); + } + } + break; + case FSAccessor::Type::tSymlink: + obj.attr("type", "symlink"); + obj.attr("target", accessor->readLink(path)); + break; + default: + throw Error("path '%s' does not exist in NAR", path); + } +} + +} |