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cfg_subsys_query_all(3)
NAME
cfg_subsys_query_all - determine the value of all attributes for a
subsystem
SYNOPSIS
#include <cfg.h>
cfg_status_t cfg_subsys_query_all(
cfg_handle_t *handle,
caddr_t subsys,
cfg_attr_t **attributes,
int *nattributes );
LIBRARY
Configuration Management Library (libcfg.a)
PARAMETERS
handle
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.
subsys
Specifies the name of the subsystem for which you are getting attribute
values.
attributes
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.
nattributes
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.
For array-type attributes, each individual array element will be returned
in a separate cfg_attr_t structure and the index field will have the index
value of the array element.
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:
Attribute data type
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.
Attribute operations
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).
Attribute status
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 Code Meaning
_____________________________________________________
CFG_ATTR_SUCCESS Successful operation
CFG_ATTR_EEXISTS No attribute by that name exists
CFG_ATTR_EOP
Attribute 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
_____________________________________________________
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.)
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).
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, "vfs", &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);
free(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);
free(attributes[i].attr.str.val);
break;
}
}
/* Free the memory allocated by the configuration management */
/* library */
free(attributes);
}
In this example, the application requests information about all attributes
of the vfs 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.
SEE ALSO
Commands: cfgmgr(8), sysconfig(8)
Routines: cfg_subsys_query(3), libcfg(3)
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