systemd-verify

systemd-verify.cc

// clang++-3.6 -std=c++11 verify.cc -overify-systemd; ./verify-systemd

#include <sstream>
#include <stdexcept>
#include <string>

#include <string.h>

#include <stdio.h>

#include <sys/types.h>

namespace os {

// Success, result
inline std::string realpath(const std::string& path)
{
  char temp[4096];
  if (::realpath(path.c_str(), temp) == NULL) {
    if (errno == ENOENT || errno == ENOTDIR) {
      throw std::runtime_error("no real path");
    }
    throw std::runtime_error("realpath error");
  }

  return std::string(temp);
}

// Success, result
std::pair<bool, std::string> shell(const std::string& command)
{
  FILE* file;
  std::ostringstream stdout;

  if ((file = popen(command.c_str(), "r")) == NULL) {
    return std::make_pair(false, "Failed to run command");
  }

  char line[1024];
  while (fgets(line, sizeof(line), file) != NULL) {
    stdout << line;
  }

  if (ferror(file) != 0) {
    pclose(file); // Ignoring result since we already have an error.
    return std::make_pair(false, "Error reading output of command");
  }

  int status;
  if ((status = pclose(file)) == -1) {
    return std::make_pair(false, "Failed to get status");
  }

  if (WIFSIGNALED(status)) {
    return std::make_pair(false, "Running command was interrupted");
  } else if ((WEXITSTATUS(status) != EXIT_SUCCESS)) {
    return std::make_pair(false, "Failed to run command");
  }

  return std::make_pair(true, stdout.str());
}

}

int main(int argc, char** argv) {
  bool is_systemd = false;
  printf("Verifying systemd Init check:\n");

  std::string path = os::realpath("/sbin/init");
  printf("Real path of [/sbin/init] = [%s]\n", path.c_str());

  std::string command = path + " --version";
  std::pair<bool, std::string> result = os::shell(command);

  if (result.first) {
    printf("Result of executing [%s] = [%s]\n", command.c_str(), result.second.c_str());
    std::istringstream versionString(result.second);
    std::string name;
    int version;
    versionString >> name >> version;

    if (!versionString.good()) {
      printf("Failed to parse systemd version from [%s]\n", result.second.c_str());
      is_systemd = false;
    } else if (name == "systemd") {
      is_systemd = true;
      printf("Detected systemd version [%d]\n", version);
    }
  } else {
    printf("Executing [%s] failed: [%s]\n", command.c_str(), result.second.c_str());
  }

  if (is_systemd) {
    printf("\n===============================\nThis system WILL be treated as running on systemd\n===============================\n");
  } else {
    printf("===============================\nThis system FAILED to detect systemd\n===============================\n");
  }

  return 0;
}