text: #ifndef AWS_COMMON_PROCESS_H
  #define AWS_COMMON_PROCESS_H
  /*
   * Copyright 2010-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   *
   * Licensed under the Apache License, Version 2.0 (the "License").
   * You may not use this file except in compliance with the License.
   * A copy of the License is located at
   *
   *  http://aws.amazon.com/apache2.0
   *
   * or in the "license" file accompanying this file. This file 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 <aws/common/common.h>
  
  struct aws_run_command_result {
      /* return code from running the command. */
      int ret_code;
  
      /**
       * captured stdout message from running the command,
       * caller is responsible for releasing the memory.
       */
      struct aws_string *std_out;
  
      /**
       * captured stderr message from running the command,
       * caller is responsible for releasing the memory.
       * It's currently not implemented and the value will be set to NULL.
       */
      struct aws_string *std_err;
  };
  
  struct aws_run_command_options {
      /**
       * command path and commandline options of running that command.
       */
      const char *command;
  };
  
  AWS_EXTERN_C_BEGIN
  
  /**
   * Returns the current process's PID (process id).
   * @return PID as int
   */
  AWS_COMMON_API int aws_get_pid(void);
  
  /**
   * Returns the soft limit for max io handles (max fds in unix terminology). This limit is one more than the actual
   * limit. The soft limit can be changed up to the hard limit by any process regardless of permissions.
   */
  AWS_COMMON_API size_t aws_get_soft_limit_io_handles(void);
  
  /**
   * Returns the hard limit for max io handles (max fds in unix terminology). This limit is one more than the actual
   * limit. This limit cannot be increased without sudo permissions.
   */
  AWS_COMMON_API size_t aws_get_hard_limit_io_handles(void);
  
  /**
   * Sets the new soft limit for io_handles (max fds). This can be up to the hard limit but may not exceed it.
   *
   * This operation will always fail with AWS_ERROR_UNIMPLEMENTED error code on Windows.
   */
  AWS_COMMON_API int aws_set_soft_limit_io_handles(size_t max_handles);
  
  AWS_COMMON_API int aws_run_command_result_init(struct aws_allocator *allocator, struct aws_run_command_result *result);
  
  AWS_COMMON_API void aws_run_command_result_cleanup(struct aws_run_command_result *result);
  
  /**
   * Currently this API is implemented using popen on Posix system and
   * _popen on Windows to capture output from running a command. Note
   * that popen only captures stdout, and doesn't provide an option to
   * capture stderr. We will add more options, such as acquire stderr
   * in the future so probably will alter the underlying implementation
   * as well.
   */
  AWS_COMMON_API int aws_run_command(
      struct aws_allocator *allocator,
      struct aws_run_command_options *options,
      struct aws_run_command_result *result);
  
  AWS_EXTERN_C_END
  
  #endif /* AWS_COMMON_PROCESS_H */
  