build library

src/cgroup_attach.cpp

@@ -0,0 +1,84 @@
+#include "cgroup_attach.hpp"
+
+namespace CGPROXY::CGROUP {
+
+bool exist(string path) {
+  struct stat st;
+  if (stat(path.c_str(), &st) != -1) { return S_ISDIR(st.st_mode); }
+  return false;
+}
+
+bool validate(string pid, string cgroup) {
+  bool pid_v = validPid(pid);
+  bool cg_v = validCgroup(cgroup);
+  if (pid_v && cg_v) return true;
+
+  error("attach paramater validate error");
+  return_error
+}
+
+string get_cgroup2_mount_point(int &status) {
+  char cgroup2_mount_point[100] = "";
+  FILE *fp = popen("findmnt -t cgroup2 -n -o TARGET", "r");
+  int count = fscanf(fp, "%s", cgroup2_mount_point);
+  fclose(fp);
+  if (count == 0) {
+    error("cgroup2 not supported");
+    status = -1;
+    return NULL;
+  }
+  status = 0;
+  return cgroup2_mount_point;
+}
+
+int attach(const string pid, const string cgroup_target) {
+  if (getuid() != 0) {
+    error("need root to attach cgroup");
+    return_error
+  }
+
+  debug("attaching %s to %s", pid.c_str(), cgroup_target.c_str());
+
+  int status;
+  if (!validate(pid, cgroup_target))
+    return_error string cgroup_mount_point = get_cgroup2_mount_point(status);
+  if (status != 0)
+    return_error string cgroup_target_path = cgroup_mount_point + cgroup_target;
+  string cgroup_target_procs = cgroup_target_path + "/cgroup.procs";
+
+  // check if exist, we will create it if not exist
+  if (!exist(cgroup_target_path)) {
+    if (mkdir(cgroup_target_path.c_str(),
+              S_IRWXU | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH) == 0) {
+      debug("created cgroup %s success", cgroup_target.c_str());
+    } else {
+      error("created cgroup %s failed, errno %d", cgroup_target.c_str(), errno);
+      return_error
+    }
+    // error("cgroup %s not exist",cgroup_target.c_str());
+    // return_error
+  }
+
+  // put pid to target cgroup
+  ofstream procs(cgroup_target_procs, ofstream::app);
+  if (!procs.is_open()) {
+    error("open file %s failed", cgroup_target_procs.c_str());
+    return_error
+  }
+  procs << pid.c_str() << endl;
+  procs.close();
+
+  // maybe there some write error, for example process pid may not exist
+  if (!procs) {
+    error("write %s to %s failed, maybe process %s not exist", pid.c_str(),
+          cgroup_target_procs.c_str(), pid.c_str());
+    return_error
+  }
+  return_success
+}
+
+int attach(const int pid, const string cgroup_target) {
+  return attach(to_str(pid), cgroup_target);
+}
+
+} // namespace CGPROXY::CGROUP