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cfg_subsys_query_all

Section: C Library Functions (3)
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NAME

cfg_subsys_query_all - Determine the value of all attributes for a subsystem  

LIBRARY

Configuration Management Library (libcfg.a)  

SYNOPSIS

#include <cfg.h> cfg_status_t cfg_subsys_query_all(
        cfg_handle_t *handle,
        caddr_t subsys,
        cfg_attr_t **attributes,
        int *nattributes);  

PARAMETERS

Structure identifying the means of communication between your application and the configuration management server. For local requests, pass NULL in this parameter. For remote requests, pass the value returned from the cfg_connect() routine. Specifies the name of the subsystem for which you are getting attribute values. Returns information about all attributes for the named subsystem. The information includes the data type of the attribute, the list of operations supported by that attribute, the attribute-specific status of the query operation, the minimum and maximum allowed values for the attribute, and the current value of the attribute. For binary data items, the information includes the size of the attribute's current value. The system allocates memory for this array, which you should free when the information in the array is no longer needed, as shown in the EXAMPLES section. An integer value specifying the number of attributes for which information has been returned.  

DESCRIPTION

Use the cfg_subsys_query_all() routine to get information about all the attributes for a particular subsystem.

When your application calls the cfg_subsys_query_all() routine, it passes the name of the subsystem for which you want information. The system reads the subsystem name and finds and collects the information about its attributes. The system then returns that information to your application.

The information returned from the cfg_subsys_query_all() routine is passed in a structure of type cfg_attr_t. If the subsystem has more than one attribute, an array of structures is returned. For information about this structure, see libcfg(3).

The following list describes the information returned to your application when it calls the cfg_subsys_query_all() routine: Attributes can be integer, string, or binary data. As defined in <sys/sysconfig.h>, the integer data types can be CFG_ATTR_INTTYPE (int), CFG_ATTR_UINTTYPE (uint), CFG_ATTR_LONGTYPE (long), or CFG_ATTR_ULONGTYPE (ulong). The string data type is a character string type named CFG_ATTR_STRTYPE and the binary data type is CFG_ATTR_BINTYPE. The definition of each attribute in the subsystem code determines what operations you can perform on the attribute. The possible operation codes are CFG_OP_QUERY (you can request information about the attribute), CFG_OP_CONFIGURE (you can set the attribute value when the subsystem is initially configured), and CFG_OP_RECONFIGURE (you can modify the value of the attribute). During a query request, each attribute is assigned a status. The following table describes the status values your application might receive from the cfg_subsys_query_all() routine:

Status CodeMeaning

CFG_ATTR_SUCCESSSuccessful operation
CFG_ATTR_EEXISTSNo attribute by that name exists
CFG_ATTR_EOPAttribute does not support the query operation
CFG_ATTR_ESUBSYS Subsystem failure (code within the subsystem returned an error)
CFG_ATTR_EINDEX The index for an indexed attribute is out of range
CFG_ATTR_EMEM Unable to allocate memory to return the attribute value

The value of each attribute is returned in a structure. In addition to the attribute value, this structure returns the minimum and maximum value for the attribute and the disposal routine, if any, to be called once the attribute value is returned. For binary attributes, the length of attribute's current value is also returned. (The disposal routine is used to free kernel memory occupied by string and binary data.)  

EXAMPLES

The following example illustrates the use of the cfg_subsys_query_all() library routine: cfg_attr_t *attributes; cfg_status_t retval; cfg_handle_t handle; int nattributes; int i;

/***************************************************/ /* Call the cfg_subsys_query_all() routine */

retval = cfg_subsys_query_all(&handle, "lvm", &attributes, &nattributes);

if (retval != CFG_SUCCESS)
    print_error (retval);

else {
     /*  Use data returned from the query          */


     for (i=0; i<nattributes; i++) {
         printf ("%s", attributes[i].name);
         if (attributes[i].status != CFG_ATTR_SUCCESS) {
             switch (attributes[i].status){
             case CFG_ATTR_EOP:
               printf("attribute does not allow this operation\n");
               break;
             .
             .
             .
             default:
               printf("unknown error\n");
               break;
             }
             continue;
         }


   /*     Display attribute value to application user   */


         switch (attributes[i].type){
         case CFG_ATTR_INTTYPE:
           printf ("%d\n", (int) attributes[i].attr.num.val);
           break;
         .
         .
         .
         case CFG_ATTR_STRTYPE:
           printf ("%s\n", (int) attributes[i].attr.str.val);
           break;


         case CFG_ATTR_BINTYPE:
           printf ("%d bytes of binary data received\n", (int) \
                attributes[i].attr.bin.val_size);
           break;
         }
       }


  /*  Free the memory allocated by the configuration management  */
  /*  library                                                    */
    free(attributes); }

In this example, the application requests information about all attributes of the lvm subsystem. When the cfg_subsys_query_all() routine returns information about those attributes, the application tests the return status of the routine. The application reports any errors returned. If cfg_subsys_query_all() returns CFG_SUCCESS, the status for each attribute is tested and any errors are reported. The application displays the value of attributes that return CFG_ATTR_SUCCESS.  

RETURN VALUES

Upon successful completion, cfg_subsys_query_all() returns CFG_SUCCESS. Other return values indicate that an error has occurred. For information about handling return values from routines in the configuration management library, see libcfg(3).  

RELATED INFORMATION

Commands: cfgmgr(8), sysconfig(8)

Routines: cfg_subsys_query(3), libcfg(3) delim off


 

Index

NAME
LIBRARY
SYNOPSIS
PARAMETERS
DESCRIPTION
EXAMPLES
RETURN VALUES
RELATED INFORMATION

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Time: 02:42:35 GMT, October 02, 2010