cfg_subsys_reconfig(3)cfg_subsys_reconfig(3)NAMEcfg_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
Structure identifying the means of communication between your applica‐
tion 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 modifying attribute values. 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. 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 immedi‐
ately because they are made to the in-memory copy of the subsystem.
Neither the kernel nor the subsystem stores a copy of the modifica‐
tions, 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 applica‐
tion: 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_LONG‐
TYPE, CFG_ATTR_ULONGTYPE, CFG_ATTR_BINTYPE For attributes that are
themselves a structure, your application must pass the index for the
attribute whose value you want to modify. The attribute value speci‐
fies 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() rou‐
tine:
──────────────────────────────────────────────────────
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 informa‐
tion 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 subsys‐
tem 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)cfg_subsys_reconfig(3)
