1 files changed, 223 insertions, 0 deletions
diff --git a/test/util/cgroup_util.cc b/test/util/cgroup_util.cc
new file mode 100644
index 000000000..65d9c4986
--- /dev/null
+++ b/test/util/cgroup_util.cc
@@ -0,0 +1,223 @@
+// Copyright 2021 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "test/util/cgroup_util.h"
+
+#include <sys/syscall.h>
+#include <unistd.h>
+
+#include "absl/strings/str_split.h"
+#include "test/util/fs_util.h"
+#include "test/util/mount_util.h"
+
+namespace gvisor {
+namespace testing {
+
+Cgroup::Cgroup(std::string path) : cgroup_path_(path) {
+  id_ = ++Cgroup::next_id_;
+  std::cerr << absl::StreamFormat("[cg#%d] <= %s", id_, cgroup_path_)
+            << std::endl;
+}
+
+PosixErrorOr<std::string> Cgroup::ReadControlFile(
+    absl::string_view name) const {
+  std::string buf;
+  RETURN_IF_ERRNO(GetContents(Relpath(name), &buf));
+
+  const std::string alias_path = absl::StrFormat("[cg#%d]/%s", id_, name);
+  std::cerr << absl::StreamFormat("<contents of %s>", alias_path) << std::endl;
+  std::cerr << buf;
+  std::cerr << absl::StreamFormat("<end of %s>", alias_path) << std::endl;
+
+  return buf;
+}
+
+PosixErrorOr<int64_t> Cgroup::ReadIntegerControlFile(
+    absl::string_view name) const {
+  ASSIGN_OR_RETURN_ERRNO(const std::string buf, ReadControlFile(name));
+  ASSIGN_OR_RETURN_ERRNO(const int64_t val, Atoi<int64_t>(buf));
+  return val;
+}
+
+PosixErrorOr<absl::flat_hash_set<pid_t>> Cgroup::Procs() const {
+  ASSIGN_OR_RETURN_ERRNO(std::string buf, ReadControlFile("cgroup.procs"));
+  return ParsePIDList(buf);
+}
+
+PosixErrorOr<absl::flat_hash_set<pid_t>> Cgroup::Tasks() const {
+  ASSIGN_OR_RETURN_ERRNO(std::string buf, ReadControlFile("tasks"));
+  return ParsePIDList(buf);
+}
+
+PosixError Cgroup::ContainsCallingProcess() const {
+  ASSIGN_OR_RETURN_ERRNO(const absl::flat_hash_set<pid_t> procs, Procs());
+  ASSIGN_OR_RETURN_ERRNO(const absl::flat_hash_set<pid_t> tasks, Tasks());
+  const pid_t pid = getpid();
+  const pid_t tid = syscall(SYS_gettid);
+  if (!procs.contains(pid)) {
+    return PosixError(
+        ENOENT, absl::StrFormat("Cgroup doesn't contain process %d", pid));
+  }
+  if (!tasks.contains(tid)) {
+    return PosixError(ENOENT,
+                      absl::StrFormat("Cgroup doesn't contain task %d", tid));
+  }
+  return NoError();
+}
+
+PosixErrorOr<absl::flat_hash_set<pid_t>> Cgroup::ParsePIDList(
+    absl::string_view data) const {
+  absl::flat_hash_set<pid_t> res;
+  std::vector<absl::string_view> lines = absl::StrSplit(data, '\n');
+  for (const std::string_view& line : lines) {
+    if (line.empty()) {
+      continue;
+    }
+    ASSIGN_OR_RETURN_ERRNO(const int32_t pid, Atoi<int32_t>(line));
+    res.insert(static_cast<pid_t>(pid));
+  }
+  return res;
+}
+
+int64_t Cgroup::next_id_ = 0;
+
+PosixErrorOr<Cgroup> Mounter::MountCgroupfs(std::string mopts) {
+  ASSIGN_OR_RETURN_ERRNO(TempPath mountpoint,
+                         TempPath::CreateDirIn(root_.path()));
+  ASSIGN_OR_RETURN_ERRNO(
+      Cleanup mount, Mount("none", mountpoint.path(), "cgroup", 0, mopts, 0));
+  const std::string mountpath = mountpoint.path();
+  std::cerr << absl::StreamFormat(
+                   "Mount(\"none\", \"%s\", \"cgroup\", 0, \"%s\", 0) => OK",
+                   mountpath, mopts)
+            << std::endl;
+  Cgroup cg = Cgroup(mountpath);
+  mountpoints_[cg.id()] = std::move(mountpoint);
+  mounts_[cg.id()] = std::move(mount);
+  return cg;
+}
+
+PosixError Mounter::Unmount(const Cgroup& c) {
+  auto mount = mounts_.find(c.id());
+  auto mountpoint = mountpoints_.find(c.id());
+
+  if (mount == mounts_.end() || mountpoint == mountpoints_.end()) {
+    return PosixError(
+        ESRCH, absl::StrFormat("No mount found for cgroupfs containing cg#%d",
+                               c.id()));
+  }
+
+  std::cerr << absl::StreamFormat("Unmount([cg#%d])", c.id()) << std::endl;
+
+  // Simply delete the entries, their destructors will unmount and delete the
+  // mountpoint. Note the order is important to avoid errors: mount then
+  // mountpoint.
+  mounts_.erase(mount);
+  mountpoints_.erase(mountpoint);
+
+  return NoError();
+}
+
+constexpr char kProcCgroupsHeader[] =
+    "#subsys_name\thierarchy\tnum_cgroups\tenabled";
+
+PosixErrorOr<absl::flat_hash_map<std::string, CgroupsEntry>>
+ProcCgroupsEntries() {
+  std::string content;
+  RETURN_IF_ERRNO(GetContents("/proc/cgroups", &content));
+
+  bool found_header = false;
+  absl::flat_hash_map<std::string, CgroupsEntry> entries;
+  std::vector<std::string> lines = absl::StrSplit(content, '\n');
+  std::cerr << "<contents of /proc/cgroups>" << std::endl;
+  for (const std::string& line : lines) {
+    std::cerr << line << std::endl;
+
+    if (!found_header) {
+      EXPECT_EQ(line, kProcCgroupsHeader);
+      found_header = true;
+      continue;
+    }
+    if (line.empty()) {
+      continue;
+    }
+
+    // Parse a single entry from /proc/cgroups.
+    //
+    // Example entries, fields are tab separated in the real file:
+    //
+    // #subsys_name    hierarchy       num_cgroups     enabled
+    // cpuset  12      35      1
+    // cpu     3       222     1
+    //   ^     ^       ^       ^
+    //   0     1       2       3
+
+    CgroupsEntry entry;
+    std::vector<std::string> fields =
+        StrSplit(line, absl::ByAnyChar(": \t"), absl::SkipEmpty());
+
+    entry.subsys_name = fields[0];
+    ASSIGN_OR_RETURN_ERRNO(entry.hierarchy, Atoi<uint32_t>(fields[1]));
+    ASSIGN_OR_RETURN_ERRNO(entry.num_cgroups, Atoi<uint64_t>(fields[2]));
+    ASSIGN_OR_RETURN_ERRNO(const int enabled, Atoi<int>(fields[3]));
+    entry.enabled = enabled != 0;
+
+    entries[entry.subsys_name] = entry;
+  }
+  std::cerr << "<end of /proc/cgroups>" << std::endl;
+
+  return entries;
+}
+
+PosixErrorOr<absl::flat_hash_map<std::string, PIDCgroupEntry>>
+ProcPIDCgroupEntries(pid_t pid) {
+  const std::string path = absl::StrFormat("/proc/%d/cgroup", pid);
+  std::string content;
+  RETURN_IF_ERRNO(GetContents(path, &content));
+
+  absl::flat_hash_map<std::string, PIDCgroupEntry> entries;
+  std::vector<std::string> lines = absl::StrSplit(content, '\n');
+
+  std::cerr << absl::StreamFormat("<contents of %s>", path) << std::endl;
+  for (const std::string& line : lines) {
+    std::cerr << line << std::endl;
+
+    if (line.empty()) {
+      continue;
+    }
+
+    // Parse a single entry from /proc/<pid>/cgroup.
+    //
+    // Example entries:
+    //
+    // 2:cpu:/path/to/cgroup
+    // 1:memory:/
+
+    PIDCgroupEntry entry;
+    std::vector<std::string> fields =
+        absl::StrSplit(line, absl::ByChar(':'), absl::SkipEmpty());
+
+    ASSIGN_OR_RETURN_ERRNO(entry.hierarchy, Atoi<uint32_t>(fields[0]));
+    entry.controllers = fields[1];
+    entry.path = fields[2];
+
+    entries[entry.controllers] = entry;
+  }
+  std::cerr << absl::StreamFormat("<end of %s>", path) << std::endl;
+
+  return entries;
+}
+
+}  // namespace testing
+}  // namespace gvisor