/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 "config.h"
#include "configuration.h"
#include "container-executor.h"

#include <errno.h>
#include <grp.h>
#include <limits.h>
#include <unistd.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>

#define CONF_FILENAME "container-executor.cfg"

// When building as part of a Maven build this value gets defined by using
// container-executor.conf.dir property. See:
//   hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/pom.xml
// for details.
// NOTE: if this ends up being a relative path it gets resolved relative to
//       the location of the container-executor binary itself, not getwd(3)
#ifndef HADOOP_CONF_DIR
  #error HADOOP_CONF_DIR must be defined
#endif

static void display_usage(FILE *stream) {
  char *usage_template =
      "Usage: container-executor --checksetup\n" \
      "       container-executor --mount-cgroups <hierarchy> <controller=path>...\n" \
      "       container-executor --tc-modify-state <command-file>\n" \
      "       container-executor --tc-read-state <command-file>\n" \
      "       container-executor --tc-read-stats <command-file>\n" \
      "       container-executor <user> <yarn-user> <command> <command-args>\n"  \
      "       where command and command-args: \n" \
      "            initialize container:  %2d appid tokens nm-local-dirs nm-log-dirs cmd app...\n" \
      "            launch container:      %2d appid containerid workdir container-script " \
                              "tokens pidfile nm-local-dirs nm-log-dirs resources optional-tc-command-file\n" \
      "            signal container:      %2d container-pid signal\n" \
      "            delete as user:        %2d relative-path\n" ;


  fprintf(stream, usage_template, INITIALIZE_CONTAINER, LAUNCH_CONTAINER,
          SIGNAL_CONTAINER, DELETE_AS_USER);
}

/* Sets up log files for normal/error logging */
static void open_log_files() {
  if (LOGFILE == NULL) {
    LOGFILE = stdout;
  }

  if (ERRORFILE == NULL) {
    ERRORFILE = stderr;
  }
}

/* Flushes and closes log files */
static void flush_and_close_log_files() {
  if (LOGFILE != NULL) {
    fflush(LOGFILE);
    fclose(LOGFILE);
    LOGFILE = NULL;
  }
  
if (ERRORFILE != NULL) {
    fflush(ERRORFILE);
    fclose(ERRORFILE);
    ERRORFILE = NULL;
  }
}

/** Validates the current container-executor setup. Causes program exit
in case of validation failures. Also sets up configuration / group information etc.,
This function is to be called in every invocation of container-executor, irrespective
of whether an explicit checksetup operation is requested. */

static void assert_valid_setup(char *current_executable) {
  char *executable_file = get_executable();

  char *orig_conf_file = HADOOP_CONF_DIR "/" CONF_FILENAME;
  char *conf_file = resolve_config_path(orig_conf_file, current_executable);

  if (conf_file == NULL) {
    fprintf(ERRORFILE, "Configuration file %s not found.\n", orig_conf_file);
    flush_and_close_log_files();
    exit(INVALID_CONFIG_FILE);
  }

  if (check_configuration_permissions(conf_file) != 0) {
    flush_and_close_log_files();
    exit(INVALID_CONFIG_FILE);
  }
  read_config(conf_file);
  free(conf_file);

  // look up the node manager group in the config file
  char *nm_group = get_value(NM_GROUP_KEY);
  if (nm_group == NULL) {
    fprintf(ERRORFILE, "Can't get configured value for %s.\n", NM_GROUP_KEY);
    flush_and_close_log_files();
    exit(INVALID_CONFIG_FILE);
  }
  struct group *group_info = getgrnam(nm_group);
  if (group_info == NULL) {
    fprintf(ERRORFILE, "Can't get group information for %s - %s.\n", nm_group,
            strerror(errno));
    flush_and_close_log_files();
    exit(INVALID_CONFIG_FILE);
  }
  set_nm_uid(getuid(), group_info->gr_gid);
  // if we are running from a setuid executable, make the real uid root
  setuid(0);
  // set the real and effective group id to the node manager group
  setgid(group_info->gr_gid);

  if (check_executor_permissions(executable_file) != 0) {
    fprintf(ERRORFILE, "Invalid permissions on container-executor binary.\n");
    flush_and_close_log_files();
    exit(INVALID_CONTAINER_EXEC_PERMISSIONS);
  }
}


/* Use to store parsed input parmeters for various operations */
static struct {
  char *cgroups_hierarchy;
  char *traffic_control_command_file;
  const char * run_as_user_name;
  const char * yarn_user_name;
  char *local_dirs;
  char *log_dirs;
  char *resources_key;
  char *resources_value;
  char **resources_values;
  const char * app_id;
  const char * container_id;
  const char * cred_file;
  const char * script_file;
  const char * current_dir;
  const char * pid_file;
  const char *dir_to_be_deleted;
  int container_pid;
  int signal;
} cmd_input;

static int validate_run_as_user_commands(int argc, char **argv, int *operation);

/* Validates that arguments used in the invocation are valid. In case of validation
failure, an 'errorcode' is returned. In case of successful validation, a zero is
returned and 'operation' is populated based on the operation being requested.
Ideally, we should re-factor container-executor to use a more structured, command
line parsing mechanism (e.g getopt). For the time being, we'll use this manual
validation mechanism so that we don't have to change the invocation interface.
*/

static int validate_arguments(int argc, char **argv , int *operation) {
  if (argc < 2) {
    display_usage(stdout);
    return INVALID_ARGUMENT_NUMBER;
  }

  if (strcmp("--checksetup", argv[1]) == 0) {
    *operation = CHECK_SETUP;
    return 0;
  }

  if (strcmp("--mount-cgroups", argv[1]) == 0) {
    if (argc < 4) {
      display_usage(stdout);
      return INVALID_ARGUMENT_NUMBER;
    }
    optind++;
    cmd_input.cgroups_hierarchy = argv[optind++];
    *operation = MOUNT_CGROUPS;
    return 0;
  }

  if (strcmp("--tc-modify-state", argv[1]) == 0) {
    if (argc != 3) {
      display_usage(stdout);
      return INVALID_ARGUMENT_NUMBER;
    }
    optind++;
    cmd_input.traffic_control_command_file = argv[optind++];
    *operation = TRAFFIC_CONTROL_MODIFY_STATE;
    return 0;
  }

  if (strcmp("--tc-read-state", argv[1]) == 0) {
    if (argc != 3) {
      display_usage(stdout);
      return INVALID_ARGUMENT_NUMBER;
    }
    optind++;
    cmd_input.traffic_control_command_file = argv[optind++];
    *operation = TRAFFIC_CONTROL_READ_STATE;
    return 0;
  }

  if (strcmp("--tc-read-stats", argv[1]) == 0) {
    if (argc != 3) {
      display_usage(stdout);
      return INVALID_ARGUMENT_NUMBER;
    }
    optind++;
    cmd_input.traffic_control_command_file = argv[optind++];
    *operation = TRAFFIC_CONTROL_READ_STATS;
    return 0;
  }

  /* Now we have to validate 'run as user' operations that don't use
    a 'long option' - we should fix this at some point. The validation/argument
    parsing here is extensive enough that it done in a separate function */

  return validate_run_as_user_commands(argc, argv, operation);
}

/* Parse/validate 'run as user' commands */
static int validate_run_as_user_commands(int argc, char **argv, int *operation) {
  /* We need at least the following arguments in order to proceed further :
    <user>, <yarn-user> <command> - i.e at argc should be at least 4 */

  if (argc < 4) {
    display_usage(stdout);
    return INVALID_ARGUMENT_NUMBER;
  }

  cmd_input.run_as_user_name = argv[optind++];
  cmd_input.yarn_user_name = argv[optind++];
  int command = atoi(argv[optind++]);

  fprintf(LOGFILE, "main : command provided %d\n", command);
  fprintf(LOGFILE, "main : run as user is %s\n", cmd_input.run_as_user_name);
  fprintf(LOGFILE, "main : requested yarn user is %s\n", cmd_input.yarn_user_name);
  fflush(LOGFILE);

  switch (command) {
  case INITIALIZE_CONTAINER:
    if (argc < 9) {
      fprintf(ERRORFILE, "Too few arguments (%d vs 9) for initialize container\n",
       argc);
      fflush(ERRORFILE);
      return INVALID_ARGUMENT_NUMBER;
    }
    cmd_input.app_id = argv[optind++];
    cmd_input.cred_file = argv[optind++];
    cmd_input.local_dirs = argv[optind++];// good local dirs as a comma separated list
    cmd_input.log_dirs = argv[optind++];// good log dirs as a comma separated list

    *operation = RUN_AS_USER_INITIALIZE_CONTAINER;
    return 0;

  case LAUNCH_CONTAINER:
    //kill me now.
    if (!(argc == 13 || argc == 14)) {
      fprintf(ERRORFILE, "Wrong number of arguments (%d vs 13 or 14) for launch container\n",
       argc);
      fflush(ERRORFILE);
      return INVALID_ARGUMENT_NUMBER;
    }

    cmd_input.app_id = argv[optind++];
    cmd_input.container_id = argv[optind++];
    cmd_input.current_dir = argv[optind++];
    cmd_input.script_file = argv[optind++];
    cmd_input.cred_file = argv[optind++];
    cmd_input.pid_file = argv[optind++];
    cmd_input.local_dirs = argv[optind++];// good local dirs as a comma separated list
    cmd_input.log_dirs = argv[optind++];// good log dirs as a comma separated list
    char * resources = argv[optind++];// key,value pair describing resources
    char * resources_key = malloc(strlen(resources));
    char * resources_value = malloc(strlen(resources));

    if (get_kv_key(resources, resources_key, strlen(resources)) < 0 ||
        get_kv_value(resources, resources_value, strlen(resources)) < 0) {
        fprintf(ERRORFILE, "Invalid arguments for cgroups resources: %s",
                           resources);
        fflush(ERRORFILE);
        free(resources_key);
        free(resources_value);
        return INVALID_ARGUMENT_NUMBER;
    }

    //network isolation through tc
    if (argc == 14) {
      cmd_input.traffic_control_command_file = argv[optind++];
    }

    cmd_input.resources_key = resources_key;
    cmd_input.resources_value = resources_value;
    cmd_input.resources_values = extract_values(resources_value);
    *operation = RUN_AS_USER_LAUNCH_CONTAINER;
    return 0;

  case SIGNAL_CONTAINER:
    if (argc != 6) {
      fprintf(ERRORFILE, "Wrong number of arguments (%d vs 6) for " \
          "signal container\n", argc);
      fflush(ERRORFILE);
      return INVALID_ARGUMENT_NUMBER;
    }

    char* end_ptr = NULL;
    char* option = argv[optind++];
    cmd_input.container_pid = strtol(option, &end_ptr, 10);
    if (option == end_ptr || *end_ptr != '\0') {
      fprintf(ERRORFILE, "Illegal argument for container pid %s\n", option);
      fflush(ERRORFILE);
      return INVALID_ARGUMENT_NUMBER;
    }
    option = argv[optind++];
    cmd_input.signal = strtol(option, &end_ptr, 10);
    if (option == end_ptr || *end_ptr != '\0') {
      fprintf(ERRORFILE, "Illegal argument for signal %s\n", option);
      fflush(ERRORFILE);
      return INVALID_ARGUMENT_NUMBER;
    }

    *operation = RUN_AS_USER_SIGNAL_CONTAINER;
    return 0;

  case DELETE_AS_USER:
    cmd_input.dir_to_be_deleted = argv[optind++];
    *operation = RUN_AS_USER_DELETE;
    return 0;
  default:
    fprintf(ERRORFILE, "Invalid command %d not supported.",command);
    fflush(ERRORFILE);
    return INVALID_COMMAND_PROVIDED;
  }
}

int main(int argc, char **argv) {
  open_log_files();
  assert_valid_setup(argv[0]);

  int operation;
  int ret = validate_arguments(argc, argv, &operation);

  if (ret != 0) {
    flush_and_close_log_files();
    return ret;
  }

  int exit_code = 0;

  switch (operation) {
  case CHECK_SETUP:
    //we already did this
    exit_code = 0;
    break;
  case MOUNT_CGROUPS:
    exit_code = 0;

    while (optind < argc && exit_code == 0) {
      exit_code = mount_cgroup(argv[optind++], cmd_input.cgroups_hierarchy);
    }

    break;
  case TRAFFIC_CONTROL_MODIFY_STATE:
    exit_code = traffic_control_modify_state(cmd_input.traffic_control_command_file);
    break;
  case TRAFFIC_CONTROL_READ_STATE:
    exit_code = traffic_control_read_state(cmd_input.traffic_control_command_file);
    break;
  case TRAFFIC_CONTROL_READ_STATS:
    exit_code = traffic_control_read_stats(cmd_input.traffic_control_command_file);
    break;
  case RUN_AS_USER_INITIALIZE_CONTAINER:
    exit_code = set_user(cmd_input.run_as_user_name);
    if (exit_code != 0) {
      break;
    }

    exit_code = initialize_app(cmd_input.yarn_user_name,
                            cmd_input.app_id,
                            cmd_input.cred_file,
                            extract_values(cmd_input.local_dirs),
                            extract_values(cmd_input.log_dirs),
                            argv + optind);
    break;
  case RUN_AS_USER_LAUNCH_CONTAINER:
    if (cmd_input.traffic_control_command_file != NULL) {
      //apply tc rules before switching users and launching the container
      exit_code = traffic_control_modify_state(cmd_input.traffic_control_command_file);
      if( exit_code != 0) {
        //failed to apply tc rules - break out before launching the container
        break;
      }
    }

    exit_code = set_user(cmd_input.run_as_user_name);
    if (exit_code != 0) {
      break;
    }

    exit_code = launch_container_as_user(cmd_input.yarn_user_name,
                    cmd_input.app_id,
                    cmd_input.container_id,
                    cmd_input.current_dir,
                    cmd_input.script_file,
                    cmd_input.cred_file,
                    cmd_input.pid_file,
                    extract_values(cmd_input.local_dirs),
                    extract_values(cmd_input.log_dirs),
                    cmd_input.resources_key,
                    cmd_input.resources_values);
    free(cmd_input.resources_key);
    free(cmd_input.resources_value);
    free(cmd_input.resources_values);
    break;
  case RUN_AS_USER_SIGNAL_CONTAINER:
    exit_code = set_user(cmd_input.run_as_user_name);
    if (exit_code != 0) {
      break;
    }

    exit_code = signal_container_as_user(cmd_input.yarn_user_name,
                                  cmd_input.container_pid,
                                  cmd_input.signal);
    break;
  case RUN_AS_USER_DELETE:
    exit_code = set_user(cmd_input.run_as_user_name);
    if (exit_code != 0) {
      break;
    }

    exit_code = delete_as_user(cmd_input.yarn_user_name,
                        cmd_input.dir_to_be_deleted,
                        argv + optind);
    break;
  }

  flush_and_close_log_files();
  return exit_code;
}
