#include "nar-accessor.hh"
#include <algorithm>
#include <map>
#include <nlohmann/json.hpp>
#include <stack>
#include "archive.hh"
#include "json.hh"
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);
}
}
} // namespace nix
