/*
**  OSSP sio - Stream I/O
**  Copyright (c) 2002-2005 Cable & Wireless <http://www.cw.com/>
**  Copyright (c) 2002-2005 The OSSP Project <http://www.ossp.org/>
**  Copyright (c) 2002-2005 Ralf S. Engelschall <rse@engelschall.com>
**
**  This file is part of OSSP sio, a layered stream I/O library
**  which can be found at http://www.ossp.org/pkg/lib/sio/.
**
**  Permission to use, copy, modify, and distribute this software for
**  any purpose with or without fee is hereby granted, provided that
**  the above copyright notice and this permission notice appear in all
**  copies.
**
**  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
**  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
**  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
**  IN NO EVENT SHALL THE AUTHORS AND COPYRIGHT HOLDERS AND THEIR
**  CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
**  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
**  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
**  USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
**  ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
**  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
**  OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
**  SUCH DAMAGE.
**
**  sio.c: stream I/O library implementation
*/

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <stddef.h>
#include <stdlib.h>
#include <string.h>

#include "al.h"
#include "sio.h"
#include "list.h"

/****************************************************************************/

/* unique library identifier */
const char sio_id[] = "OSSP sio";

/* support for OSSP ex based exception throwing */
#ifdef WITH_EX
#define __EX_NS_UCCXX__
#include "ex.h"
#define SIO_RC(rv) \
    (  (rv) != SIO_OK && (ex_catching && !ex_shielding) \
         ? (ex_throw(sio_id, NULL, (rv)), (rv)) : (rv) )
#else
#define SIO_RC(rv) (rv)
#endif /* WITH_EX */

/*
 * node representing either input or output
 * direction of a processing node
 */
struct sio_halfduplex_st;
typedef struct sio_halfduplex_st sio_halfduplex_t;
struct sio_halfduplex_st {
    NODE(sio_halfduplex_t)  hd;                /* link to reader/writer chain */
    sio_stage_t            *stage;             /* back to its stage structure */
    sio_halfduplex_t       *cross;             /* reader <-> writer sibling */
    const char             *tag;               /* debugging help */
    sio_rc_t                rc_with_data;      /* default rc to avoid */
    sio_rc_t                rc_no_data;        /*  decision in strategy() */
    al_t                   *al;                /* reader/writer assembly line */
    sio_rc_t              (*func)(sio_t *, al_t *, void *, sio_rc_t); /* input() or output() */
};

/*
 * processing node
 */
struct sio_stage_st {
    sio_halfduplex_t       reader;      /* reader node, linked into sio_t */
    sio_halfduplex_t       writer;      /* writer node, linked into sio_t */
    void                  *userdata;    /* module private per-instance data */
    sio_module_t          *module;      /* link to module methods */
    sio_mode_t             rw;          /* state of attachment    */
};

/*
 * represent the whole full-duplex pipe
 */
struct sio_st {
    struct {
        LIST(sio_halfduplex_t)  hd;        /* link reader halfduplex nodes */
        al_t                   *al;        /* the reader assembly line     */
    } readers;
    struct {
        LIST(sio_halfduplex_t)  hd;        /* link writer halfduplex nodes */
        al_t                   *al;        /* the writer assembly line     */
    } writers;
    sio_labelnum_t              label_data;   /* unique al_label object    */
    sio_labelnum_t              label_error;  /* to tag data and signals   */
    sio_labelnum_t              label_eof;
    int                         eof_flag;     /* accumulating flags        */
    int                         error_flag;
};

/*
 * AL tags data with unique pointers. Each (!) sio structure has
 * unique (!) labels to tag data, error information and eof
 * information on the global assembly lines
 */
#define SIO_LABEL_DATA(sio)  ((al_label_t)&(sio)->label_data)
#define SIO_LABEL_ERROR(sio) ((al_label_t)&(sio)->label_error)
#define SIO_LABEL_EOF(sio)   ((al_label_t)&(sio)->label_eof)

/****************************************************************************/

/*
 * schedule stages on chain of halfduplex nodes
 */
static
sio_rc_t sio_strategy(sio_t *sio, sio_halfduplex_t *chain)
{
    sio_rc_t rc;
    sio_halfduplex_t *h;

    /*
     * call stage and direct data upstream/downstream
     * according to response code
     *
     * if stage directs SIO_OK, chose default direction
     * depending on data in assembly line
     *
     * if we the stage does not return a direction,
     * simply end the code
     *
     * if we drop off the chain, simply result SIO_OK
     *
     */
    rc = SIO_SCHED_UP;
    h  = chain;
    while (h != NULL) {
        rc = h->func(sio, h->al, h->stage->userdata, rc);

        /* chose default direction */
        if (rc == SIO_OK) {
            if (al_bytes(h->al) > 0)
                rc = h->rc_with_data;
            else
                rc = h->rc_no_data;
        }

        if (rc == SIO_SCHED_UP)
            h = NEXT(h,hd);
        else if (rc == SIO_SCHED_DOWN)
            h = PREV(h,hd);
        else if (rc == SIO_SCHED_CROSS)
            h = h->cross;
        else if (rc == SIO_SCHED_LOOP)
            h = h;
        else
            break;
    }

    if (h == NULL)
        rc = SIO_OK;

    return rc;
}

/**************************************************************************/

/*
 * allocate and intialize sio_t data structure
 *
 */
sio_rc_t sio_create(sio_t **siop)
{
    sio_t *sio;

    /* argument sanity check(s) */
    if (siop == NULL)
        return SIO_RC(SIO_ERR_ARG);

    sio = (sio_t *)malloc(sizeof(sio_t));
    if (sio == NULL)
        return SIO_RC(SIO_ERR_MEM);

    LISTINIT(&sio->readers,hd);
    LISTINIT(&sio->writers,hd);

    /*
     * we only need unique pointers for the labels, but
     * we point the pointers also to symbolic constants
     */
    sio->label_data  = SIO_LN_DATA;
    sio->label_error = SIO_LN_ERROR;
    sio->label_eof   = SIO_LN_EOF;

    sio->eof_flag    = 0;
    sio->error_flag  = 0;

    *siop = sio;

    return SIO_OK;
}

/*
 * destroy sio_t data structure.
 *
 * no deinitialization is done.
 */
sio_rc_t sio_destroy(sio_t *sio)
{
    /* argument sanity check(s) */
    if (sio == NULL)
        return SIO_RC(SIO_ERR_ARG);

    /* see wether all stages are detached */
    if (!ISEMPTY(&sio->readers,hd) ||
        !ISEMPTY(&sio->writers,hd))
        return SIO_RC(SIO_ERR_ARG);

    free(sio);

    return SIO_OK;
}

/*
 * create pair of halfduplex nodes that use methods
 * from module siom.
 */
sio_rc_t sio_create_stage(sio_t *sio, sio_module_t *siom, sio_stage_t **siosp)
{
    sio_rc_t rc;
    sio_stage_t *sios;

    /* argument sanity check(s) */
    if (sio == NULL || siom == NULL || siosp == NULL)
        return SIO_RC(SIO_ERR_ARG);

    sios = (sio_stage_t *)malloc(sizeof(sio_stage_t));
    if (sios == NULL)
        return SIO_RC(SIO_ERR_MEM);

    NODEINIT(&sios->reader,hd);
    NODEINIT(&sios->writer,hd);

    sios->module       = siom;

    sios->userdata     = NULL;
    sios->rw           = SIO_MODE_INVALID;
    sios->reader.func  = sios->module->input;
    sios->reader.stage = sios;
    sios->writer.func  = sios->module->output;
    sios->writer.stage = sios;

    sios->reader.cross = NULL;
    sios->writer.cross = NULL;

    sios->reader.tag   = "reader";
    sios->writer.tag   = "writer";

    /* default rules */
    sios->reader.rc_with_data = SIO_SCHED_DOWN;
    sios->reader.rc_no_data   = SIO_SCHED_UP;
    sios->writer.rc_with_data = SIO_SCHED_UP;
    sios->writer.rc_no_data   = SIO_SCHED_DOWN;

    rc = sios->module->init(sio, &sios->userdata);
    if (rc != SIO_OK) {
        free(sios);
        return SIO_RC(rc);
    }

    *siosp = sios;

    return SIO_RC(rc);
}

/*
 * pass parameters to the configure method of a stage
 */
sio_rc_t sio_configure_stage(sio_t *sio, sio_stage_t *sios,
                             void *obj, void *value)
{
    sio_rc_t rc;

    /* argument sanity check(s) */
    if (sio == NULL || sios == NULL)
        return SIO_RC(SIO_ERR_ARG);

    rc = sios->module->configure(sio, sios->userdata, obj, value);

    return SIO_RC(rc);
}

/*
 *
 */
sio_rc_t sio_destroy_stage(sio_t *sio, sio_stage_t *sios)
{
    sio_rc_t rc;

    /* argument sanity check(s) */
    if (sio == NULL || sios == NULL)
        return SIO_RC(SIO_ERR_ARG);

    /* more sanity checking */
    if (sios->rw != SIO_MODE_INVALID)
        return SIO_RC(SIO_ERR_ARG);

    rc = sios->module->cleanup(sio, sios->userdata);
    free(sios);

    return SIO_OK;
}

/*
 * allocate global assembly lines
 *
 * this is called before a module gets attached
 *
 * the first module attached as a reader allocates
 * the read assembly line
 *
 * the first module attached as a writer allocates
 * the write assembly line
 */
static
sio_rc_t sio_create_al(sio_t *sio, sio_mode_t rw)
{
    al_rc_t arc;
    int freereader = 0;

    if (rw == SIO_MODE_READ || rw == SIO_MODE_READWRITE) {
        if (ISEMPTY(&sio->readers,hd)) {
            arc = al_create(&sio->readers.al);
            if (arc != AL_OK)
                return SIO_ERR_INT;
            freereader = 1;
        }
    }
    if (rw == SIO_MODE_WRITE || rw == SIO_MODE_READWRITE) {
        if (ISEMPTY(&sio->writers,hd)) {
            arc = al_create(&sio->writers.al);
            if (arc != AL_OK) {
                if (freereader)
                    al_destroy(sio->readers.al);
                return SIO_ERR_INT;
            }
        }
    }

    return SIO_OK;
}

/*
 * free global assembly lines
 *
 * this is called after a module has been detached
 *
 * if the detached module was a reader and there are no more
 *   readers then drop read assembly line
 *
 * if the detached module was a writer and there are no more
 *   writers then drop write assembly line
 *
 */
static
sio_rc_t sio_destroy_al(sio_t *sio, sio_mode_t rw)
{
    if (rw == SIO_MODE_READ || rw == SIO_MODE_READWRITE) {
        if (ISEMPTY(&sio->readers,hd)) {
            al_destroy(sio->readers.al);
            sio->readers.al = NULL;
        }
    }
    if (rw == SIO_MODE_WRITE || rw == SIO_MODE_READWRITE) {
        if (ISEMPTY(&sio->writers,hd)) {
            al_destroy(sio->writers.al);
            sio->writers.al = NULL;
        }
    }

    return SIO_OK;
}

/*
 * attach a stage to the read and/or write side of the pipe
 *
 * the stage is attached to the head of the pipe, you
 * have to create your pipes "backwards".
 *
 * prepare assembly lines
 *
 * stages that are reader and writer get a pointer to the
 * sibling side so that the scheduler can cross between
 * reading and writing
 *
 * when a stage is attached to either side its openr and
 * openw methods are called respectively
 *
 */
sio_rc_t sio_attach(sio_t *sio, sio_stage_t *sios, sio_mode_t rw)
{
    sio_rc_t rc;
    int freereader = 0;

    /* argument sanity check(s) */
    if (sio == NULL || sios == NULL)
        return SIO_RC(SIO_ERR_ARG);
    switch (rw) {
    case SIO_MODE_READ:
    case SIO_MODE_WRITE:
    case SIO_MODE_READWRITE:
        break;
    default:
        return SIO_RC(SIO_ERR_ARG);
    }

    /* is module already attached ? */
    if (sios->rw != SIO_MODE_INVALID)
        return SIO_RC(SIO_ERR_ARG);

    /* create assembly lines (if aready existing) */
    rc = sio_create_al(sio, rw);
    if (rc != SIO_OK)
        return SIO_RC(rc);

    if (rw == SIO_MODE_READ || rw == SIO_MODE_READWRITE) {
        rc = sios->module->openr(sio, sio->readers.al, sios->userdata);
        if (rc != SIO_OK) {
            sio_destroy_al(sio, rw);
            return SIO_RC(rc);
        }
        ADDHEAD(&sio->readers,hd,&sios->reader);
        freereader = 1;
    }
    if (rw == SIO_MODE_WRITE || rw == SIO_MODE_READWRITE) {
        rc = sios->module->openw(sio, sio->writers.al, sios->userdata);
        if (rc != SIO_OK) {
            if (freereader) {
                REMOVE(&sio->readers,hd,&sios->reader);
                sios->module->closer(sio, sio->readers.al, sios->userdata);
            }
            sio_destroy_al(sio, rw);
            return SIO_RC(rc);
        }
        ADDHEAD(&sio->writers,hd,&sios->writer);
    }

    if (rw == SIO_MODE_READWRITE) {
        sios->reader.cross = &sios->writer;
        sios->writer.cross = &sios->reader;
    }

    sios->reader.al = sio->readers.al;
    sios->writer.al = sio->writers.al;
    sios->rw        = rw;

    return SIO_OK;
}

/*
 * detach a stage to the read and/or write side of the pipe
 *
 * when a stage is detached from either side its closer and
 * closew methods are called respectively
 *
 * drop assembly lines when possible
 *
 */
sio_rc_t sio_detach(sio_t *sio, sio_stage_t *sios)
{
    sio_rc_t rc, rc2;

    /* argument sanity check(s) */
    if (sio == NULL || sios == NULL)
        return SIO_RC(SIO_ERR_ARG);

    switch (sios->rw) {
    case SIO_MODE_READ:
    case SIO_MODE_WRITE:
    case SIO_MODE_READWRITE:
        break;
    default:
        return SIO_RC(SIO_ERR_ARG);
    }

    rc  = SIO_OK;
    rc2 = SIO_OK;

    if (sios->module->shutdown != NULL &&
        sios->module->shutdown(sio, sios->userdata) == SIO_OK) {

        if (sios->rw == SIO_MODE_WRITE || sios->rw == SIO_MODE_READWRITE) {
            rc = sio_strategy(sio, HEAD(&sio->writers,hd));
            if (rc != SIO_OK) return SIO_RC(rc);
        }
        if (sios->rw == SIO_MODE_READ || sios->rw == SIO_MODE_READWRITE) {
            sio_strategy(sio, HEAD(&sio->readers,hd));
            if (rc != SIO_OK) return SIO_RC(rc);
        }

    }

    if (sios->rw == SIO_MODE_WRITE || sios->rw == SIO_MODE_READWRITE) {
        REMOVE(&sio->writers,hd,&sios->writer);
        rc = sios->module->closew(sio, sio->writers.al, sios->userdata);
    }
    if (sios->rw == SIO_MODE_READ || sios->rw == SIO_MODE_READWRITE) {
        REMOVE(&sio->readers,hd,&sios->reader);
        rc2 = sios->module->closer(sio, sio->readers.al, sios->userdata);
    }

    /* XXX double error handling ? */
    if (rc == SIO_OK)
        rc = rc2;

    if (sios->rw == SIO_MODE_READWRITE) {
        sios->reader.cross = NULL;
        sios->writer.cross = NULL;
    }

    sios->writer.al = NULL;
    sios->reader.al = NULL;

    sio_destroy_al(sio, sios->rw);

    sios->rw = SIO_MODE_INVALID;

    return SIO_RC(rc);
}

/*
 * retrieve data from the input side
 *
 * if there is no data in the reader assembly line
 *  then schedule the input side of the pipe once
 *  if this still doesn't retrieve data then raise
 *  a SIO_ERR_EOF error.
 *
 * retrieve data from the reader assembly line up to
 * the specified byte limit for the first span of
 * the specified label or any data if label == NULL
 *
 */
sio_rc_t sio_input(sio_t *sio, al_t *al, size_t limit, al_label_t label)
{
    sio_rc_t rc;
    sio_halfduplex_t *h;
    al_t *src;
    size_t n;
    size_t datastart, datasize;

    /* argument sanity check(s) */
    if (sio == NULL || al == NULL)
        return SIO_RC(SIO_ERR_ARG);

    h = HEAD(&sio->readers,hd);
    if (h == NULL)
        return SIO_RC(SIO_ERR_ARG);

    src = h->al;
    n = al_bytes(src);
    if (n == 0) {

        rc = sio_strategy(sio, h);
        if (rc != SIO_OK)
            return SIO_RC(rc);

        n = al_bytes(src);
        if (n == 0)
            return SIO_RC(SIO_ERR_EOF);

    }

    /*
     * clamp to requested size
     */
    if (n > limit)
        n = limit;

    while (n > 0) {
        if (label == NULL) {
            datastart = 0;
            datasize  = n;
        } else if (al_spanlabel(src, 0, n, label, &datastart, &datasize) != AL_OK)
            break;

        /*
         * clamp to requested size
         */
        if (datasize > n)
            datasize = n;

        /* XXX - error handling ? */
        (void) al_splice(src, datastart, datasize, NULL, al);

        n -= datasize;
    }

    return SIO_OK;
}

/*
 * pass data to the output side
 *
 * append data to the writer assembly line
 *
 * schedule the output side of the pipe
 *
 */
sio_rc_t sio_output(sio_t *sio, al_t *al)
{
    sio_rc_t rc;
    al_rc_t arc;
    sio_halfduplex_t *h;
    al_t *dst;
    size_t n;

    /* argument sanity check(s) */
    if (sio == NULL || al == NULL)
        return SIO_RC(SIO_ERR_ARG);

    h = HEAD(&sio->writers,hd);
    if (h == NULL)
        return SIO_RC(SIO_ERR_ARG);
    dst = h->al;

    n = al_bytes(dst);
    arc = al_splice(dst, n, 0, al, NULL);
    if (arc != AL_OK)
        return SIO_RC(SIO_ERR_INT);

    rc = sio_strategy(sio, h);

    return SIO_RC(rc);
}

/*
 * schedule the output side of the pipe and
 * signal to flush data buffers
 *
 * current the signalling is done by sending
 * an EOF data chunk. Convention for all
 * buffering modules is to flush data buffers
 * on label boundaries.
 *
 */
sio_rc_t sio_push(sio_t *sio)
{
    sio_rc_t rc;
    al_rc_t arc;
    sio_halfduplex_t *h;
    al_t *dst;
    char eof = '\0';

    /* argument sanity check(s) */
    if (sio == NULL)
        return SIO_RC(SIO_ERR_ARG);

    h = HEAD(&sio->writers,hd);
    if (h == NULL)
        return SIO_RC(SIO_ERR_ARG);
    dst = h->al;

    arc = al_append_bytes(dst, &eof, 1, SIO_LABEL_EOF(sio));
    if (arc != AL_OK)
        return SIO_RC(SIO_ERR_INT);

    rc = sio_strategy(sio, h);

    return SIO_RC(rc);
}

/*
 * retrieve data from the pipe into a buffer much like read()
 *
 * handles error and eof signals
 *
 */
sio_rc_t sio_read(sio_t *sio, char *dst, size_t n, size_t *actualp)
{
    al_rc_t arc;
    sio_rc_t rc;
    al_t *al;

    *actualp = 0;

    if (n == 0)
        return SIO_OK;

    arc = al_create(&al);
    if (arc != AL_OK) return SIO_RC(SIO_ERR_INT);

    rc = sio_input(sio, al, n, SIO_LABEL_DATA(sio));
    if (rc == SIO_OK) {
        if (al_bytes(al) > 0)
            al_flatten(al, 0, n, AL_FORWARD, NULL, dst, actualp);
        else {
            rc = sio_input(sio, al, n, SIO_LABEL_ERROR(sio));
            if (rc == SIO_OK) {
                if (al_bytes(al) > 0)
                    sio->error_flag = 1;
                else {
                    rc = sio_input(sio, al, n, SIO_LABEL_EOF(sio));
                    if (rc == SIO_OK) {
                        if (al_bytes(al) > 0)
                            sio->eof_flag = 1;
                    }
                }
            }
        }
    }

    arc = al_destroy(al);
    if (arc != AL_OK) return SIO_RC(SIO_ERR_INT);

    return SIO_RC(rc);
}

/*
 * send data to the pipe from a buffer much like write()
 */
sio_rc_t sio_write(sio_t *sio, char *src, size_t n, size_t *actualp)
{
    al_rc_t arc;
    sio_rc_t rc;
    al_t *al;

    if (n == 0)
        return SIO_OK;

    arc = al_create(&al);
    if (arc != AL_OK) return SIO_RC(SIO_ERR_INT);

    arc = al_append_bytes(al, src, n, SIO_LABEL_DATA(sio));
    if (arc != AL_OK)
        rc = SIO_ERR_INT;
    else
        rc = sio_output(sio, al);

    *actualp = n - al_bytes(al);

    arc = al_destroy(al);
    if (arc != AL_OK) return SIO_RC(SIO_ERR_INT);

    return SIO_RC(rc);
}

/*
 * query a SIO flag
 *
 * currently this is SIO_FLAG_ERROR and SIO_FLAG_EOF
 * which are set by sio_read()
 *
 */
sio_rc_t sio_flag(sio_t *sio, sio_flag_t fl)
{
    int rc;

    switch (fl) {
    case SIO_FLAG_ERROR:
        rc = sio->error_flag;
        break;
    case SIO_FLAG_EOF:
        rc = sio->eof_flag;
        break;
    default:
        rc = 0;
        break;
    }

    return rc ? SIO_TRUE : SIO_FALSE;
}

/*
 * query and clear a SIO flag
 */
sio_rc_t sio_clearflag(sio_t *sio, sio_flag_t fl)
{
    int rc;

    switch (fl) {
    case SIO_FLAG_ERROR:
        rc = sio->error_flag;
        sio->error_flag = 0;
        break;
    case SIO_FLAG_EOF:
        rc = sio->eof_flag;
        sio->eof_flag = 0;
        break;
    default:
        rc = 0;
        break;
    }

    return rc ? SIO_TRUE : SIO_FALSE;
}

const char *sio_error(sio_rc_t rc)
{
    const char *mess;

    switch (rc) {
    case SIO_OK:          mess = "Everything Ok"; break;
    case SIO_ERR_ARG:     mess = "Invalid Argument"; break;
    case SIO_ERR_MEM:     mess = "Not Enough Memory"; break;
    case SIO_ERR_EOF:     mess = "End Of Data"; break;
    case SIO_ERR_SYS:     mess = "Operating System Error"; break;
    case SIO_ERR_INT:     mess = "Internal Error"; break;
    case SIO_SCHED_UP:    mess = "Invoke Upstream Stage"; break;
    case SIO_SCHED_DOWN:  mess = "Invoke Downstream Stage"; break;
    case SIO_SCHED_CROSS: mess = "Invoke Crossstream Stage"; break;
    case SIO_SCHED_LOOP:  mess = "Loop through current Stage"; break;
    default:              mess = "Invalid Result Code"; break;
    }

    return mess;
}

/*
 * stages need to share the labels that distinguish between
 * data and signals on the pipe
 *
 * this function returns OSSP al labels for SIO specific
 * label numbers defined in sio.h
 *
 */
sio_rc_t sio_label(sio_t *sio, sio_labelnum_t ln, al_label_t *p)
{
    void *label;

    switch (ln) {
    case SIO_LN_DATA:
        label = SIO_LABEL_DATA(sio);
        break;
    case SIO_LN_ERROR:
        label = SIO_LABEL_ERROR(sio);
        break;
    case SIO_LN_EOF:
        label = SIO_LABEL_EOF(sio);
        break;
    default:
        return SIO_ERR_ARG;
    }

    *p = label;
    return SIO_OK;
}