informix_backend.ec

来自「gxsnmp SNMP MANAGER 的实现」· EC 代码 · 共 659 行 · 第 1/2 页

      return TRUE;
    }
  g_warning("DATABASE %s failed.", database);
  print_error();
  
  return FALSE;
}

/*******************************************************************************
**
**  sql_query ()  --  Issue a database query to an open Informix server connection
**
**  Returns Values:
**
**  The return value is an open database query structure, or NULL if the
**  operation failed.
**
*******************************************************************************/

static G_sql_query  * 
sql_query (G_sql_connection * dbc, gchar * query, gint querylen)
{
  EXEC SQL BEGIN DECLARE SECTION;
  char *execstr;
  char *cname;
  char *qname;
  char *dname;
  EXEC SQL END DECLARE SECTION;
  G_sql_query  *dbq;

  if (!(dbq = (G_sql_query *) g_new0 (G_sql_query, 1)))
    {
      g_print ("Informix backend: out of memory\n");
      return NULL;
    }

  dbq->connection = dbc;
  g_snprintf(dbq->curname, sizeof(dbq->curname), "c_%d", cursor_cnt);
  g_snprintf(dbq->desname, sizeof(dbq->desname), "d_%d", cursor_cnt);
  g_snprintf(dbq->qidname, sizeof(dbq->qidname), "q_%d", cursor_cnt++);
  cname = dbq->curname;
  dname = dbq->desname;
  qname = dbq->qidname;
  g_print ("cname: %s, dname: %s, qname: %s\n", cname, dname, qname);

  execstr=query;

  EXEC SQL PREPARE :qname FROM :execstr;
  EXEC SQL ALLOCATE DESCRIPTOR :dname;
  EXEC SQL DESCRIBE :qname USING SQL DESCRIPTOR :dname;

  if (SQLCODE)          /* no SELECT statement */
    {
      g_print("No select statement in %s, no cursor needed.\n", query);
      strcpy(dbq->curname, "");
      EXEC SQL EXECUTE :qname;
      return dbq;
    }

  EXEC SQL DECLARE :cname CURSOR FOR :qname;

  if(SQLCODE)
    {
      g_warning("Error in SELECT statement.");
      print_error();

      EXEC SQL FREE :cname;
      EXEC SQL FREE :qname;
      EXEC SQL DEALLOCATE DESCRIPTOR :dname;

      return NULL;
    }

  g_print("Opening CURSOR for %s.\n",query);
  EXEC SQL OPEN :cname;
  return dbq;

}


/*******************************************************************************
**
**  sql_free_query ()  --  Free up a query structure
**
*******************************************************************************/

static gboolean
sql_free_query (G_sql_query *dbq)
{
  EXEC SQL BEGIN DECLARE SECTION;
  char *cname;
  char *qname;
  char *dname;
  EXEC SQL END DECLARE SECTION;

  cname = dbq->curname;
  dname = dbq->desname;
  qname = dbq->qidname;

  if (strcmp(cname,""))
    {
      EXEC SQL CLOSE :cname;
      EXEC SQL FREE :cname;
    }
  EXEC SQL FREE :qname;
  EXEC SQL DEALLOCATE DESCRIPTOR :dname;

  g_free (dbq);
  return TRUE;
}

/*******************************************************************************
**
**  sql_next_row ()  --  Select the next row in a query result
**
**  This subroutine returns the private handle of the next available row
**  in a query result.
**
**  Return values:
**
**  TRUE  --  If the operation succeeded
**  FALSE --  If the operation failed
**
*******************************************************************************/

static gboolean 
sql_next_row (G_sql_query * dbq)
{
  EXEC SQL BEGIN DECLARE SECTION;
  char *cname;
  char *qname;
  char *dname;
  EXEC SQL END DECLARE SECTION;

  cname = dbq->curname;
  dname = dbq->desname;
  qname = dbq->qidname;

  EXEC SQL fetch :cname USING SQL DESCRIPTOR :dname;

  if(!SQLCODE)
    {
      return TRUE;
    }

  return FALSE;
}

/*******************************************************************************
**
**  sql_field ()  --  Read a named field from a database row,
**                          and return a pointer to the data, and the length
**			    of the returned data.
**
**  This subroutine returns the named field from a selected database row.
**  This subroutine may read binary data that might contain zeroes.   
**
**  Return values:
**
**  The return value is a pointer to the raw database field data, or NULL if
**  the operation failed.  The length of the result is stored in the "length"
**  parameter.
**
**  The caller is responsible for g_free()'ing the allocated storage.
**
**  Since searching through the field table each time we are called is 
**  expensive, accelerators are used to speed up this process for subsequent
**  row lookups on the same query.  The accelerator field, provided by the
**  caller, will be unique for each field name.  We simply store the found
**  row index plus one in the caller's accelerator field.  Then, on
**  subsequent calls, we can skip the search by using the accelerator
**  value minus one for the field index.
**
*******************************************************************************/

static gchar * sql_field (G_sql_query * dbq,   G_sql_accelerator *accel,
			  gchar       * field, gint  * length)
{

EXEC SQL BEGIN DECLARE SECTION;
  int i, type, dec, ind, count, len;
  char name[40];
  static char ch[1024];
  long dat;
  float flt;
  char *cname;
  char *qname;
  char *dname;
EXEC SQL END DECLARE SECTION;

  static char buf [128];
  int j;

  cname = dbq->curname;
  dname = dbq->desname;
  qname = dbq->qidname;

  EXEC SQL GET DESCRIPTOR :dname :count = COUNT;

  if (!*accel)
      for (i = 1; i <= count; i++)
        {
          EXEC SQL GET DESCRIPTOR :dname VALUE :i :type = TYPE, :name = NAME;
          j = strlen(name);
          if (j) j--;
          while(j && name[j] == ' ')
            {
              name[j] = '\0';
              j--;
            }
          if (!g_strcasecmp (field, name))
            *accel = (G_sql_accelerator) i;
        }
  if (!*accel)
    {
      g_print ("Informix backend:  Field %s not found in selected row\n", field);
      return NULL;
    }

  i = (int)(*accel);
  EXEC SQL GET DESCRIPTOR :dname VALUE :i :type = TYPE;
  switch (type)
    {
      case SQLSERIAL:
      case SQLINT:
      case SQLSMINT:
      case SQLDECIMAL:
      case SQLMONEY:
        EXEC SQL GET DESCRIPTOR :dname VALUE :i :ind = INDICATOR, :dec = DATA;
        if (ind == -1)
          {
            *length = 0;
            return NULL;
          }
        g_snprintf(buf, sizeof(buf), "%d", dec);
        *length = strlen(buf);
        return buf;
        break;
      case SQLFLOAT:
        EXEC SQL GET DESCRIPTOR :dname VALUE :i :ind = INDICATOR, :flt = DATA;
        if (ind == -1)
          {
            *length = 0;
            return NULL;
          }
        g_snprintf(buf, sizeof(buf), "%f", flt);
        *length = strlen(buf);
        return buf;
        break;
      case SQLDATE:
        EXEC SQL GET DESCRIPTOR :dname VALUE :i :ind = INDICATOR, :dat = DATA;
        if (ind == -1)
          {
            *length = 0;
            return NULL;
          }
        rfmtdate(dat, "mmm. dd, yyyy", buf);
        *length = strlen(buf);
        return buf;
        break;
      case SQLVCHAR:
      case SQLCHAR:
        EXEC SQL GET DESCRIPTOR :dname VALUE :i :ind = INDICATOR, 
                                                :ch = DATA, :len =LENGTH;
        if (ind == -1)
          {
            *length = 0;
            return NULL;
          }
#if 0
	/* Apparently the len parameter means the length of the field, not
           the lenther of the response in Informix */
        *length = len;
        ch[len] = '\0';
#else
        j = strlen(ch);
        if (j) j--;
        while(j && ch[j] == ' ')
          {
            ch[j] = '\0';
            j--;
          }
        *length = strlen(ch);
#endif
        return ch;
    }
}

/******************************************************************************
**
**  Subroutine to load the plugin.  Set the plugin type to PLUGIN_DATABASE.
**
******************************************************************************/

int 
load_plugin (PluginData * pd)
{
  pd->type = PLUGIN_DATABASE;
  pd->name = g_strdup ("Informix DB backend");
  return 0;
}

/******************************************************************************
**
** Subroutine to unload the plugin
**
******************************************************************************/

void
unload_plugin (PluginData * pd)
{
  g_sql_unregister_backend (&backend);
}

/******************************************************************************
**
**  Subroutine to start the plugin
**
******************************************************************************/

void
start_plugin (PluginData * pd)
{
  g_print ("Starting Informix backend plugin ... ");
  g_sql_register_backend (&backend);
}

/* EOF */