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cfg_subsys_reconfig(3)
Contents
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cfg_subsys_reconfig - reconfigure attribute values for a
subsystem
#include <cfg.h>
cfg_status_t cfg_subsys_reconfig(
cfg_handle_t *handle,
caddr_t subsys,
cfg_attr_t *attributes,
int nattributes );
Configuration Management Library (libcfg.a)
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 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.
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:
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 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 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
------------------------------------------------------
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).
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.
Commands: cfgmgr(8), sysconfig(8)
Routines: libcfg(3)
cfg_subsys_reconfig(3)
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