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cfg_subsys_reconfig(3)
NAME
cfg_subsys_reconfig - reconfigure attribute values for a subsystem
SYNOPSIS
#include <cfg.h>
cfg_status_t cfg_subsys_reconfig(
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 modifying
attribute values.
attributes
On input, contains a list of attributes whose value you want to modify.
For each attribute, the list includes the attribute name, data type,
and the new value.
On return, contains a status for each attribute. The status indicates
whether the system was able to make the modification and, if not, what
problem caused the error.
nattributes
The number of attributes whose values you are changing.
DESCRIPTION
Use the cfg_subsys_reconfig() routine to modify attribute values for a
subsystem. The modifications made by this routine take effect immediately
because they are made to the in-memory copy of the subsystem. Neither the
kernel nor the subsystem stores a copy of the modifications, so if the
system is rebooted or the subsystem is unconfigured, the modifications are
lost. When the subsystem is once again configured into the kernel, the
value of its attributes are retrieved from the /etc/sysconfigtab database
and the subsystem code.
To reconfigure an individual array element, on input the index field of the
cfg_attr_t structure must be set to the index value of the array element.
To make permanent changes to attribute values, store the new attribute
values in the /etc/sysconfigtab database. See sysconfigtab(4) for
information about that database.
When your application calls the cfg_subsys_reconfig() routine, it passes a
list of attribute names and values. The application passes this information
in an array of structures of type cfg_attr_t. For information about this
structure, see libcfg(3). The following list describes the information that
is passed to the system by your application:
Attribute data type
Attributes can be integer, string, or binary data. To specify the data
type of your attribute you pass one of these attribute data types:
CFG_ATTR_STRTYPE, CFG_ATTR_INTTYPE, CFG_ATTR_UNITTYPE,
CFG_ATTR_LONGTYPE, CFG_ATTR_ULONGTYPE, CFG_ATTR_BINTYPE
Index
For attributes that are themselves a structure, your application must
pass the index for the attribute whose value you want to modify.
Attribute value
The attribute value specifies the new value for the attribute.
Be aware that the system updates attributes in the order in which you
specify them in the attribute list. This order can be important when
one attribute is validated based on another attribute's current
setting. On return, the system supplies the status for each attribute.
The status is returned in the attribute parameter, which is normally an
array of structures of the type cfg_attr_t. For information about this
structure, see libcfg(3). The following table describes the status
values your application might receive from the cfg_subsys_reconfig()
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
reconfigure 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_ELARGE
The new attribute value or length
is too large
CFG_ATTR_ESMALL
The new attribute value or length
is too small
_____________________________________________________
RETURN VALUES
Upon successful completion, cfg_subsys_reconfig() 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_reconfig()
routine:
cfg_attr_t attributes[1];
cfg_status_t retval;
cfg_handle_t handle;
int i;
int nattributes;
/*****************************************************/
/* Initialize attribute names for the request */
strcpy (attributes[0].name, "max-vnodes");
attributes[0].type = CFG_ATTR_INTTYPE;
attributes[0].attr.num.val = 20000;
nattributes = 1;
/***************************************************/
/* Call the cfg_subsys_reconfig routine */
retval = cfg_subsys_reconfig(&handle, "vfs", attributes, nattributes);
if (retval != CFG_SUCCESS)
print_error (retval);
else {
for (i=0; i<1; i++) {
if (attributes[i].status != CFG_ATTR_SUCCESS) {
printf("%s:", attributes[i].name);
switch (attributes[i].status){
case CFG_ATTR_EEXISTS:
printf("unknown attribute\n");
break;
case CFG_ATTR_EOP:
printf("attribute does not allow this operation\n");
break;
.
.
.
default:
printf("unknown error\n");
break;
}
}
}
}
In this example, the application attempts to modify the value of the max-
vnodes attribute. This attribute, which is part of the vfs subsystem is
being set to the value 20000.
On return the application checks the status of the request as a whole and
of the attribute itself. If the request and attribute status both indicate
success, the application continues. Otherwise, an error is displayed.
SEE ALSO
Commands: cfgmgr(8), sysconfig(8)
Routines: libcfg(3)
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