//
// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2026
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#include "td/utils/port/user.h"

#include "td/utils/port/config.h"
#include "td/utils/port/platform.h"

#if TD_PORT_POSIX
#include "td/utils/SliceBuilder.h"

#include <grp.h>
#include <pwd.h>
#if TD_DARWIN || TD_FREEBSD || TD_NETBSD
#include <sys/param.h>
#endif
#include <sys/types.h>
#include <unistd.h>
#endif

namespace td {

Status change_user(CSlice username, CSlice groupname) {
#if TD_PORT_POSIX
  passwd *pw = getpwnam(username.c_str());
  if (pw == nullptr) {
    return OS_ERROR(PSTRING() << "Can't find the user '" << username << "' to switch to");
  }
  uid_t uid = pw->pw_uid;
  gid_t gid = pw->pw_gid;
  if (setgroups(1, &gid) == -1) {
    return OS_ERROR("Failed to clear supplementary group list");
  }
  if (!groupname.empty()) {
    group *g = getgrnam(groupname.c_str());
    if (g == nullptr) {
      return OS_ERROR("Can't find the group to switch to");
    }
    gid = g->gr_gid;
  } else if (initgroups(username.c_str(), gid) == -1) {
    return OS_ERROR("Failed to load groups of user");
  }
  if (setgid(gid) == -1) {
    return OS_ERROR("failed to set effective group ID");
  }
  if (setuid(uid) == -1) {
    return OS_ERROR("failed to set effective user ID");
  }
  return Status::OK();
#else
  return Status::Error("Changing effective user is not supported");
#endif
}

}  // namespace td
