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https://github.com/privatevoid-net/nix-super.git
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nar-accessor: use tree, fixes readDirectory missing children
Previously, if a directory `foo` existed and a file `foo-` (where `-` is any character that is sorted before `/`), then `readDirectory` would return an empty list. To fix this, we now use a tree where we can just access the children of the node, and do not need to rely on sorting behavior to list the contents of a directory.
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510bc1735b
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1 changed files with 76 additions and 33 deletions
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@ -2,6 +2,8 @@
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#include "archive.hh"
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#include <map>
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#include <stack>
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#include <algorithm>
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namespace nix {
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@ -16,16 +18,36 @@ struct NarMember
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size_t start, size;
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std::string target;
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/* If this is a directory, all the children of the directory. */
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std::map<std::string, NarMember> children;
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NarMember* find(const Path & path)
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{
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if(path == "") return this;
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if(type != FSAccessor::Type::tDirectory) {
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return nullptr;
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}
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auto split = std::find(path.begin() + 1, path.end(), '/');
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std::string child_name(path.begin() + 1, split);
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std::string remaining(split, path.end());
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auto child = children.find(child_name);
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if(child == children.end()) return nullptr;
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return child->second.find(remaining);
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}
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};
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struct NarIndexer : ParseSink, StringSource
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{
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// FIXME: should store this as a tree. Now we're vulnerable to
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// O(nm) memory consumption (e.g. for x_0/.../x_n/{y_0..y_m}).
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typedef std::map<Path, NarMember> Members;
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Members members;
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NarMember root;
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std::stack<NarMember*> parents;
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Path currentPath;
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std::string currentName;
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std::string currentStart;
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bool isExec = false;
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@ -33,28 +55,45 @@ struct NarIndexer : ParseSink, StringSource
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{
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}
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void createMember(const Path & path, NarMember member) {
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size_t level = std::count(path.begin(), path.end(), '/');
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while(parents.size() > level) {
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parents.pop();
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}
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if(parents.empty()) {
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root = std::move(member);
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parents.push(&root);
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} else {
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if(parents.top()->type != FSAccessor::Type::tDirectory) {
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throw Error(format("NAR file missing parent directory of path ‘%1%’") % path);
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}
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auto result = parents.top()->children.emplace(baseNameOf(path), std::move(member));
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parents.push(&result.first->second);
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}
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}
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void createDirectory(const Path & path) override
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{
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members.emplace(path,
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NarMember{FSAccessor::Type::tDirectory, false, 0, 0});
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createMember(path, {FSAccessor::Type::tDirectory, false, 0, 0 });
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}
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void createRegularFile(const Path & path) override
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{
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currentPath = path;
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createMember(path, {FSAccessor::Type::tRegular, false, 0, 0 });
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}
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void isExecutable() override
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{
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isExec = true;
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parents.top()->isExecutable = true;
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}
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void preallocateContents(unsigned long long size) override
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{
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currentStart = string(s, pos, 16);
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assert(size <= std::numeric_limits<size_t>::max());
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members.emplace(currentPath,
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NarMember{FSAccessor::Type::tRegular, isExec, pos, (size_t) size});
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parents.top()->size = (size_t)size;
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parents.top()->start = pos;
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}
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void receiveContents(unsigned char * data, unsigned int len) override
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@ -68,16 +107,23 @@ struct NarIndexer : ParseSink, StringSource
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void createSymlink(const Path & path, const string & target) override
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{
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members.emplace(path,
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createMember(path,
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NarMember{FSAccessor::Type::tSymlink, false, 0, 0, target});
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}
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Members::iterator find(const Path & path)
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NarMember* find(const Path & path)
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{
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auto i = members.find(path);
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if (i == members.end())
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Path canon = path == "" ? "" : canonPath(path);
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NarMember* result = root.find(canon);
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return result;
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}
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NarMember& at(const Path & path) {
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auto result = find(path);
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if(result == nullptr) {
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throw Error(format("NAR file does not contain path ‘%1%’") % path);
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return i;
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}
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return *result;
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}
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};
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@ -93,44 +139,41 @@ struct NarAccessor : public FSAccessor
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Stat stat(const Path & path) override
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{
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auto i = indexer.members.find(path);
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if (i == indexer.members.end())
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auto i = indexer.find(path);
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if (i == nullptr)
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return {FSAccessor::Type::tMissing, 0, false};
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return {i->second.type, i->second.size, i->second.isExecutable};
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return {i->type, i->size, i->isExecutable};
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}
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StringSet readDirectory(const Path & path) override
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{
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auto i = indexer.find(path);
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auto i = indexer.at(path);
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if (i->second.type != FSAccessor::Type::tDirectory)
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if (i.type != FSAccessor::Type::tDirectory)
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throw Error(format("path ‘%1%’ inside NAR file is not a directory") % path);
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++i;
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StringSet res;
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while (i != indexer.members.end() && isInDir(i->first, path)) {
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// FIXME: really bad performance.
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if (i->first.find('/', path.size() + 1) == std::string::npos)
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res.insert(std::string(i->first, path.size() + 1));
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++i;
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for(auto&& child : i.children) {
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res.insert(child.first);
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}
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return res;
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}
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std::string readFile(const Path & path) override
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{
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auto i = indexer.find(path);
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if (i->second.type != FSAccessor::Type::tRegular)
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auto i = indexer.at(path);
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if (i.type != FSAccessor::Type::tRegular)
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throw Error(format("path ‘%1%’ inside NAR file is not a regular file") % path);
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return std::string(*nar, i->second.start, i->second.size);
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return std::string(*nar, i.start, i.size);
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}
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std::string readLink(const Path & path) override
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{
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auto i = indexer.find(path);
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if (i->second.type != FSAccessor::Type::tSymlink)
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auto i = indexer.at(path);
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if (i.type != FSAccessor::Type::tSymlink)
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throw Error(format("path ‘%1%’ inside NAR file is not a symlink") % path);
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return i->second.target;
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return i.target;
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}
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};
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