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.
This commit is contained in:
Benno Fünfstück 2017-05-15 10:17:53 +02:00
parent 510bc1735b
commit 75a1d9849d

View File

@ -2,6 +2,8 @@
#include "archive.hh"
#include <map>
#include <stack>
#include <algorithm>
namespace nix {
@ -16,16 +18,36 @@ struct NarMember
size_t start, size;
std::string target;
/* If this is a directory, all the children of the directory. */
std::map<std::string, NarMember> children;
NarMember* find(const Path & path)
{
if(path == "") return this;
if(type != FSAccessor::Type::tDirectory) {
return nullptr;
}
auto split = std::find(path.begin() + 1, path.end(), '/');
std::string child_name(path.begin() + 1, split);
std::string remaining(split, path.end());
auto child = children.find(child_name);
if(child == children.end()) return nullptr;
return child->second.find(remaining);
}
};
struct NarIndexer : ParseSink, StringSource
{
// FIXME: should store this as a tree. Now we're vulnerable to
// O(nm) memory consumption (e.g. for x_0/.../x_n/{y_0..y_m}).
typedef std::map<Path, NarMember> Members;
Members members;
NarMember root;
std::stack<NarMember*> parents;
Path currentPath;
std::string currentName;
std::string currentStart;
bool isExec = false;
@ -33,28 +55,45 @@ struct NarIndexer : ParseSink, StringSource
{
}
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()) {
root = std::move(member);
parents.push(&root);
} else {
if(parents.top()->type != FSAccessor::Type::tDirectory) {
throw Error(format("NAR file missing parent directory of path %1%") % path);
}
auto result = parents.top()->children.emplace(baseNameOf(path), std::move(member));
parents.push(&result.first->second);
}
}
void createDirectory(const Path & path) override
{
members.emplace(path,
NarMember{FSAccessor::Type::tDirectory, false, 0, 0});
createMember(path, {FSAccessor::Type::tDirectory, false, 0, 0 });
}
void createRegularFile(const Path & path) override
{
currentPath = path;
createMember(path, {FSAccessor::Type::tRegular, false, 0, 0 });
}
void isExecutable() override
{
isExec = true;
parents.top()->isExecutable = true;
}
void preallocateContents(unsigned long long size) override
{
currentStart = string(s, pos, 16);
assert(size <= std::numeric_limits<size_t>::max());
members.emplace(currentPath,
NarMember{FSAccessor::Type::tRegular, isExec, pos, (size_t) size});
parents.top()->size = (size_t)size;
parents.top()->start = pos;
}
void receiveContents(unsigned char * data, unsigned int len) override
@ -68,16 +107,23 @@ struct NarIndexer : ParseSink, StringSource
void createSymlink(const Path & path, const string & target) override
{
members.emplace(path,
createMember(path,
NarMember{FSAccessor::Type::tSymlink, false, 0, 0, target});
}
Members::iterator find(const Path & path)
NarMember* find(const Path & path)
{
auto i = members.find(path);
if (i == members.end())
Path canon = path == "" ? "" : canonPath(path);
NarMember* result = root.find(canon);
return result;
}
NarMember& at(const Path & path) {
auto result = find(path);
if(result == nullptr) {
throw Error(format("NAR file does not contain path %1%") % path);
return i;
}
return *result;
}
};
@ -93,44 +139,41 @@ struct NarAccessor : public FSAccessor
Stat stat(const Path & path) override
{
auto i = indexer.members.find(path);
if (i == indexer.members.end())
auto i = indexer.find(path);
if (i == nullptr)
return {FSAccessor::Type::tMissing, 0, false};
return {i->second.type, i->second.size, i->second.isExecutable};
return {i->type, i->size, i->isExecutable};
}
StringSet readDirectory(const Path & path) override
{
auto i = indexer.find(path);
auto i = indexer.at(path);
if (i->second.type != FSAccessor::Type::tDirectory)
if (i.type != FSAccessor::Type::tDirectory)
throw Error(format("path %1% inside NAR file is not a directory") % path);
++i;
StringSet res;
while (i != indexer.members.end() && isInDir(i->first, path)) {
// FIXME: really bad performance.
if (i->first.find('/', path.size() + 1) == std::string::npos)
res.insert(std::string(i->first, path.size() + 1));
++i;
for(auto&& child : i.children) {
res.insert(child.first);
}
return res;
}
std::string readFile(const Path & path) override
{
auto i = indexer.find(path);
if (i->second.type != FSAccessor::Type::tRegular)
auto i = indexer.at(path);
if (i.type != FSAccessor::Type::tRegular)
throw Error(format("path %1% inside NAR file is not a regular file") % path);
return std::string(*nar, i->second.start, i->second.size);
return std::string(*nar, i.start, i.size);
}
std::string readLink(const Path & path) override
{
auto i = indexer.find(path);
if (i->second.type != FSAccessor::Type::tSymlink)
auto i = indexer.at(path);
if (i.type != FSAccessor::Type::tSymlink)
throw Error(format("path %1% inside NAR file is not a symlink") % path);
return i->second.target;
return i.target;
}
};