67 lines
2.2 KiB
C++
67 lines
2.2 KiB
C++
 
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#include "cgroup.hpp"
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#include <unistd.h>
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#include <chrono>
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#include <thread>
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#include "spec.hpp"
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#include "util.hpp"
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namespace fs = std::filesystem;
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namespace doos {
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std::unique_ptr<Cgroup> Cgroup::create(const std::string& name, std::string& whyNot) {
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try {
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std::string self = fsutil::readFile("/proc/self/cgroup");
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std::string marker = "user@" + std::to_string(::geteuid()) + ".service";
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auto at = self.find(marker);
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if (self.rfind("0::", 0) != 0 || at == std::string::npos) {
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whyNot = "no cgroup v2 delegated to the user manager (" + marker + " not found)";
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return nullptr;
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}
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fs::path base = fs::path("/sys/fs/cgroup") / self.substr(3, at + marker.size() - 3).substr(1);
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fs::path dir = base / std::string(spec::kCgroupDir);
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std::error_code ec;
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fs::create_directory(dir, ec);
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if (ec && ec != std::errc::file_exists) {
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whyNot = "cannot create " + dir.string() + ": " + ec.message();
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return nullptr;
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}
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fs::path leaf = dir / name;
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fs::create_directory(leaf, ec);
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if (ec && ec != std::errc::file_exists) {
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whyNot = "cannot create " + leaf.string() + ": " + ec.message();
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return nullptr;
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}
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if (::access((leaf / "cgroup.freeze").c_str(), W_OK) != 0) {
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whyNot = "cgroup.freeze not writable in " + leaf.string();
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fs::remove(leaf, ec);
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return nullptr;
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}
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return std::unique_ptr<Cgroup>(new Cgroup(leaf));
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} catch (const std::exception& e) {
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whyNot = e.what();
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return nullptr;
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}
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}
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Cgroup::~Cgroup() {
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// Processes die with the container; give the kernel a moment to empty the group, then remove it.
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for (int i = 0; i < 20; ++i) {
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std::error_code ec;
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if (fs::remove(dir_, ec)) return;
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std::this_thread::sleep_for(std::chrono::milliseconds(25));
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}
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}
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void Cgroup::add(pid_t pid) const { fsutil::writeFile(dir_ / "cgroup.procs", std::to_string(pid)); }
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void Cgroup::freeze(bool on) const {
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fsutil::writeFile(dir_ / "cgroup.freeze", on ? "1" : "0");
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frozen_ = on;
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}
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} // namespace doos
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