LogOpenEventNotification - Example Code

The following example opens error-logging event notification. It will initialize an event-notification filter that specifies any Error Log entry that has a product manufacturer named "IBM" and a severity less than 4.

  #define INCL_LOGGING
  #include <unidef.h>
  #include <os2.h>
  #include <stdio.h>
  #include <lfdef.h>
  #define ERROR_LOG_FILE_ID 1

  ULONG service;
  ULONG severity = 4;
  ULONG entry_id = 12;
  LOENREQUEST open_event_packet;
  HLOGNOTIFY log_notify;
  SUBBLOCK subblock1, subblock2, subblock3;
  HEADERBLOCK headerblock1, headerblock2;
  FILTERBLOCK filter;

  UniChar *manufacturer_name = L"IBM";

  service = ERROR_LOGGING_SERVICE;

  /*  Construct an event notification filter with 2 header blocks. */
  /*  The first header block points to a single subblock.          */
  /*  The second header block points to a chain of two subblocks.  */

  filter.packet_size = sizeof(FILTERBLOCK);
  filter.packet_revision_number = LF_UNI_API;
  filter.header_block = &headerblock1;

  /*-------------construct headerblock1---------------------*/
  headerblock1.pSubblock = &subblock1;
  headerblock1.pNextBlock = &headerblock2;

  /*construct subblock1 of headerblock1*/
  subblock1.entry_attribute_ID = LOG_ERROR_DMI_VENDOR_TAG;
  subblock1.comparison_operator = LOG_ERROR_EQUAL;
  subblock1.comparison_data_ptr = &manufacturer_name;
  subblock1.next_subblock = NULL;

  /*------------construct headerblock2----------------------*/
  headerblock2.pSubblock = &subblock2;
  headerblock2.pNextBlock = NULL;

  /*construct subblock2 of headerblock2*/
  subblock2.entry_attribute_ID = LOG_ERROR_SEVERITY;
  subblock2.comparison_operator = LOG_ERROR_LESS_THAN;
  subblock2.comparison_data_ptr = severity;
  subblock2.comparison_data_length = sizeof(ULONG);
  subblock2.next_subblock = &subblock3;

  /*construct subblock3 of headerblock2*/
  subblock3.entry_attribute_ID = LOG_ERROR_ENTRY_ID;
  subblock3.comparison_operator = LOG_ERROR_GREATER_THAN;
  subblock3.comparison_data_ptr = entry_id;
  subblock3.comparison_data_length = sizeof(ULONG);
  subblock3.next_subblock = null;

  /* Construct the LogOpenEventNotification parameter packet.*/
  open_event_packet.packet_size = sizeof(LOENREQUEST);
  open_event_packet.packet_revision_number = LF_UNI_API;
  open_event_packet.log_file_ID = ERROR_LOG_FILE_ID;
  open_event_packet.pLogNotify = &log_notify;
  open_event_packet.pFilter = &filter;
  open_event_packet.read_flags = 0;

  rc = LogOpenEventNotification(service,        /*service*/
                       &open_event_packet); /*parameter packet*/

  if (rc |= 0)
    {
     printf("LogOpenEventNotification error: return code = %d",rc);
     return;
    }