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.TH getdns_context_set_context_update_callback 3 "December 2015" "getdns 1.6.0" getdns
.SH NAME
.B getdns_context_set_context_update_callback 
-- get informed on getdns context updates

.SH LIBRARY
DNS Resolver library (libgetdns, \-lgetdns)

.SH SYNOPSIS
#include <getdns.h>

getdns_return_t
.br
.B getdns_context_set_context_update_callback
(getdns_context ** context,
.RS 3
.br
void (*cbfun)(getdns_context *context, getdns_context_code_t changed_item)
.RE

.SH DESCRIPTION

.LP
Changes to the context such as in response to system files that affect the contet (/etc/resolv.conf etc.) trigger a call to the callback function specified as
.B
cbfun

.HP 3
.I context
a previously initialized context

.HP 3
.I cbfun
callback function to invoked when the specified context changes.  If this 
argument is NULL then updates to the context will not invoke a callback.

.HP
.SH "RETURN VALUES"

Upon successful completion each of these functions return
.B GETDNS_RETURN_GOOD
, otherwise the following error values are returned:

.LP
.B GETDNS_RETURN_GENERIC_ERROR
memory allocation failed or some other untoward thing happened 

.LP
.B GETDNS_RETURN_BAD_CONTEXT 
if the context pointer is invalid

.SH EXAMPLES

TBD

.SH SEE ALSO
.BR libgetdns (3),
.BR getdns_context_create (3),
.BR getdns_context_set (3),
.BR getdns_context_set_context_update_callback (3),