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.TH "LWRES_CONTEXT" "3" "Jun 30, 2000" "SunOS 5.10" "Introduction to Library Functions"
.\" disable hyphenation
.nh
.\" disable justification (adjust text to left margin only)
.ad l
.SH "NAME"
lwres_context_create, lwres_context_destroy, lwres_context_nextserial, lwres_context_initserial, lwres_context_freemem, lwres_context_allocmem, lwres_context_sendrecv \- lightweight resolver context management
.SH "SYNOPSIS"
.nf
#include <lwres/lwres.h>
.fi
.HP 36
\fBlwres_result_t\ \fBlwres_context_create\fR\fR\fB(\fR\fBlwres_context_t\ **\fR\fB\fIcontextp\fR\fR\fB, \fR\fBvoid\ *\fR\fB\fIarg\fR\fR\fB, \fR\fBlwres_malloc_t\ \fR\fB\fImalloc_function\fR\fR\fB, \fR\fBlwres_free_t\ \fR\fB\fIfree_function\fR\fR\fB);\fR
.HP 37
\fBlwres_result_t\ \fBlwres_context_destroy\fR\fR\fB(\fR\fBlwres_context_t\ **\fR\fB\fIcontextp\fR\fR\fB);\fR
.HP 30
\fBvoid\ \fBlwres_context_initserial\fR\fR\fB(\fR\fBlwres_context_t\ *\fR\fB\fIctx\fR\fR\fB, \fR\fBlwres_uint32_t\ \fR\fB\fIserial\fR\fR\fB);\fR
.HP 40
\fBlwres_uint32_t\ \fBlwres_context_nextserial\fR\fR\fB(\fR\fBlwres_context_t\ *\fR\fB\fIctx\fR\fR\fB);\fR
.HP 27
\fBvoid\ \fBlwres_context_freemem\fR\fR\fB(\fR\fBlwres_context_t\ *\fR\fB\fIctx\fR\fR\fB, \fR\fBvoid\ *\fR\fB\fImem\fR\fR\fB, \fR\fBsize_t\ \fR\fB\fIlen\fR\fR\fB);\fR
.HP 28
\fBvoid\ \fBlwres_context_allocmem\fR\fR\fB(\fR\fBlwres_context_t\ *\fR\fB\fIctx\fR\fR\fB, \fR\fBsize_t\ \fR\fB\fIlen\fR\fR\fB);\fR
.HP 30
\fBvoid\ *\ \fBlwres_context_sendrecv\fR\fR\fB(\fR\fBlwres_context_t\ *\fR\fB\fIctx\fR\fR\fB, \fR\fBvoid\ *\fR\fB\fIsendbase\fR\fR\fB, \fR\fBint\ \fR\fB\fIsendlen\fR\fR\fB, \fR\fBvoid\ *\fR\fB\fIrecvbase\fR\fR\fB, \fR\fBint\ \fR\fB\fIrecvlen\fR\fR\fB, \fR\fBint\ *\fR\fB\fIrecvd_len\fR\fR\fB);\fR
.SH "DESCRIPTION"
.PP
\fBlwres_context_create()\fR
creates a
\fBlwres_context_t\fR
structure for use in lightweight resolver operations. It holds a socket and other data needed for communicating with a resolver daemon. The new
\fBlwres_context_t\fR
is returned through
\fIcontextp\fR, a pointer to a
\fBlwres_context_t\fR
pointer. This
\fBlwres_context_t\fR
pointer must initially be NULL, and is modified to point to the newly created
\fBlwres_context_t\fR.
.PP
When the lightweight resolver needs to perform dynamic memory allocation, it will call
\fImalloc_function\fR
to allocate memory and
\fIfree_function\fR
to free it. If
\fImalloc_function\fR
and
\fIfree_function\fR
are NULL, memory is allocated using
\fBmalloc\fR(3). and
\fBfree\fR(3). It is not permitted to have a NULL
\fImalloc_function\fR
and a non\-NULL
\fIfree_function\fR
or vice versa.
\fIarg\fR
is passed as the first parameter to the memory allocation functions. If
\fImalloc_function\fR
and
\fIfree_function\fR
are NULL,
\fIarg\fR
is unused and should be passed as NULL.
.PP
Once memory for the structure has been allocated, it is initialized using
\fBlwres_conf_init\fR(3)
and returned via
\fI*contextp\fR.
.PP
\fBlwres_context_destroy()\fR
destroys a
\fBlwres_context_t\fR, closing its socket.
\fIcontextp\fR
is a pointer to a pointer to the context that is to be destroyed. The pointer will be set to NULL when the context has been destroyed.
.PP
The context holds a serial number that is used to identify resolver request packets and associate responses with the corresponding requests. This serial number is controlled using
\fBlwres_context_initserial()\fR
and
\fBlwres_context_nextserial()\fR.
\fBlwres_context_initserial()\fR
sets the serial number for context
\fI*ctx\fR
to
\fIserial\fR.
\fBlwres_context_nextserial()\fR
increments the serial number and returns the previous value.
.PP
Memory for a lightweight resolver context is allocated and freed using
\fBlwres_context_allocmem()\fR
and
\fBlwres_context_freemem()\fR. These use whatever allocations were defined when the context was created with
\fBlwres_context_create()\fR.
\fBlwres_context_allocmem()\fR
allocates
\fIlen\fR
bytes of memory and if successful returns a pointer to the allocated storage.
\fBlwres_context_freemem()\fR
frees
\fIlen\fR
bytes of space starting at location
\fImem\fR.
.PP
\fBlwres_context_sendrecv()\fR
performs I/O for the context
\fIctx\fR. Data are read and written from the context's socket. It writes data from
\fIsendbase\fR
\(em typically a lightweight resolver query packet \(em and waits for a reply which is copied to the receive buffer at
\fIrecvbase\fR. The number of bytes that were written to this receive buffer is returned in
\fI*recvd_len\fR.
.SH "RETURN VALUES"
.PP
\fBlwres_context_create()\fR
returns
\fBLWRES_R_NOMEMORY\fR
if memory for the
\fBstruct lwres_context\fR
could not be allocated,
\fBLWRES_R_SUCCESS\fR
otherwise.
.PP
Successful calls to the memory allocator
\fBlwres_context_allocmem()\fR
return a pointer to the start of the allocated space. It returns NULL if memory could not be allocated.
.PP
\fBLWRES_R_SUCCESS\fR
is returned when
\fBlwres_context_sendrecv()\fR
completes successfully.
\fBLWRES_R_IOERROR\fR
is returned if an I/O error occurs and
\fBLWRES_R_TIMEOUT\fR
is returned if
\fBlwres_context_sendrecv()\fR
times out waiting for a response.
.SH "SEE ALSO"
.PP
\fBlwres_conf_init\fR(3),
\fBmalloc\fR(3),
\fBfree\fR(3).