141 lines
3.7 KiB
C++
141 lines
3.7 KiB
C++
#include "nar-accessor.hh"
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#include "archive.hh"
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#include <map>
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namespace nix {
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struct NarMember
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{
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FSAccessor::Type type;
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bool isExecutable;
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/* If this is a regular file, position of the contents of this
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file in the NAR. */
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size_t start, size;
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std::string target;
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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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Path currentPath;
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std::string currentStart;
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bool isExec;
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NarIndexer(const std::string & nar) : StringSource(nar)
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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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}
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void createRegularFile(const Path & path) override
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{
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currentPath = path;
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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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}
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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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members.emplace(currentPath,
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NarMember{FSAccessor::Type::tRegular, isExec, pos, size});
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}
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void receiveContents(unsigned char * data, unsigned int len) override
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{
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// Sanity check
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if (!currentStart.empty()) {
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assert(len < 16 || currentStart == string((char *) data, 16));
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currentStart.clear();
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}
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}
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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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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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{
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auto i = members.find(path);
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if (i == members.end())
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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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};
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struct NarAccessor : public FSAccessor
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{
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ref<const std::string> nar;
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NarIndexer indexer;
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NarAccessor(ref<const std::string> nar) : nar(nar), indexer(*nar)
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{
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parseDump(indexer, indexer);
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}
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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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return {FSAccessor::Type::tMissing, 0, false};
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return {i->second.type, i->second.size, i->second.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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if (i->second.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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}
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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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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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}
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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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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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}
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};
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ref<FSAccessor> makeNarAccessor(ref<const std::string> nar)
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{
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return make_ref<NarAccessor>(nar);
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}
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}
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