1 files changed, 87 insertions, 0 deletions
diff --git a/src/libstore/cgroup.cc b/src/libstore/cgroup.cc
new file mode 100644
index 000000000..5d31609da
--- /dev/null
+++ b/src/libstore/cgroup.cc
@@ -0,0 +1,87 @@
+#if __linux__
+
+#include "cgroup.hh"
+#include "util.hh"
+
+#include <chrono>
+#include <cmath>
+#include <regex>
+#include <unordered_set>
+#include <thread>
+
+#include <dirent.h>
+
+namespace nix {
+
+std::map<std::string, std::string> getCgroups(const Path & cgroupFile)
+{
+    std::map<std::string, std::string> cgroups;
+
+    for (auto & line : tokenizeString<std::vector<std::string>>(readFile(cgroupFile), "\n")) {
+        static std::regex regex("([0-9]+):([^:]*):(.*)");
+        std::smatch match;
+        if (!std::regex_match(line, match, regex))
+            throw Error("invalid line '%s' in '%s'", line, cgroupFile);
+
+        std::string name = hasPrefix(std::string(match[2]), "name=") ? std::string(match[2], 5) : match[2];
+        cgroups.insert_or_assign(name, match[3]);
+    }
+
+    return cgroups;
+}
+
+void destroyCgroup(const Path & cgroup)
+{
+    if (!pathExists(cgroup)) return;
+
+    for (auto & entry : readDirectory(cgroup)) {
+        if (entry.type != DT_DIR) continue;
+        destroyCgroup(cgroup + "/" + entry.name);
+    }
+
+    int round = 1;
+
+    std::unordered_set<pid_t> pidsShown;
+
+    while (true) {
+        auto pids = tokenizeString<std::vector<std::string>>(readFile(cgroup + "/cgroup.procs"));
+
+        if (pids.empty()) break;
+
+        if (round > 20)
+            throw Error("cannot kill cgroup '%s'", cgroup);
+
+        for (auto & pid_s : pids) {
+            pid_t pid;
+            if (auto o = string2Int<pid_t>(pid_s))
+                pid = *o;
+            else
+                throw Error("invalid pid '%s'", pid);
+            if (pidsShown.insert(pid).second) {
+                try {
+                    auto cmdline = readFile(fmt("/proc/%d/cmdline", pid));
+                    using namespace std::string_literals;
+                    warn("killing stray builder process %d (%s)...",
+                        pid, trim(replaceStrings(cmdline, "\0"s, " ")));
+                } catch (SysError &) {
+                }
+            }
+            // FIXME: pid wraparound
+            if (kill(pid, SIGKILL) == -1 && errno != ESRCH)
+                throw SysError("killing member %d of cgroup '%s'", pid, cgroup);
+        }
+
+        auto sleep = std::chrono::milliseconds((int) std::pow(2.0, std::min(round, 10)));
+        if (sleep.count() > 100)
+            printError("waiting for %d ms for cgroup '%s' to become empty", sleep.count(), cgroup);
+        std::this_thread::sleep_for(sleep);
+        round++;
+    }
+
+    if (rmdir(cgroup.c_str()) == -1)
+        throw SysError("deleting cgroup '%s'", cgroup);
+}
+
+}
+
+#endif