/*

 * Amanda, The Advanced Maryland Automatic Network Disk Archiver

 * Copyright (c) 2008-2012 Zmanda, Inc.  All Rights Reserved.

 * Copyright (c) 2013-2016 Carbonite, Inc.  All Rights Reserved.

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 2

 * of the License, or (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful, but

 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY

 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * for more details.

 *

 * You should have received a copy of the GNU General Public License along

 * with this program; if not, write to the Free Software Foundation, Inc.,

 * 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA

 *

 * Contact information: Carbonite Inc., 756 N Pastoria Ave

 * Sunnyvale, CA 94085, or: http://www.zmanda.com

 */

#include "amanda.h"

#include "amxfer.h"

#include "simpleprng.h"

/*

 * Class declaration

 *

 * This declaration is entirely private; nothing but xfer_source_pattern() references

 * it directly.

 */

GType xfer_source_pattern_get_type(void);

#define XFER_SOURCE_PATTERN_TYPE (xfer_source_pattern_get_type())

#define XFER_SOURCE_PATTERN(obj) G_TYPE_CHECK_INSTANCE_CAST((obj), xfer_source_pattern_get_type(), XferSourcePattern)

#define XFER_SOURCE_PATTERN_CONST(obj) G_TYPE_CHECK_INSTANCE_CAST((obj), xfer_source_pattern_get_type(), XferSourcePattern const)

#define XFER_SOURCE_PATTERN_CLASS(klass) G_TYPE_CHECK_CLASS_CAST((klass), xfer_source_pattern_get_type(), XferSourcePatternClass)

#define IS_XFER_SOURCE_PATTERN(obj) G_TYPE_CHECK_INSTANCE_TYPE((obj), xfer_source_pattern_get_type ())

#define XFER_SOURCE_PATTERN_GET_CLASS(obj) G_TYPE_INSTANCE_GET_CLASS((obj), xfer_source_pattern_get_type(), XferSourcePatternClass)

static GObjectClass *parent_class = NULL;

/*

 * Main object structure

 */

typedef struct XferSourcePattern {

    XferElement __parent__;

    gboolean limited_length;

    guint64 length;

    size_t pattern_buffer_length;

    size_t current_offset;

    char * pattern;

} XferSourcePattern;

/*

 * Class definition

 */

typedef struct {

    XferElementClass __parent__;

} XferSourcePatternClass;

/*

 * Implementation

 */

/*

 * Utility function to fill a buffer buf of size len with the pattern defined

 * for this instance. We start each copying from the offset where we left the

 * previous one.

 *

 * Note that performance is important: amtapetype uses this very source and

 * source-random.c to determine whether a tape device uses compression, and

 * expects the two to run about the same speed.  This is why this is a byte

 * loop and does not use mempcy() and friends: the random source is also byte

 * per byte.

 */

static void fill_buffer_with_pattern(XferSourcePattern *self, char *buf,

    size_t len)

{

    char *src = self->pattern, *dst = buf;

    size_t plen = self->pattern_buffer_length, offset = self->current_offset;

    size_t pos = 0;

    src += offset;

    while (pos < len) {

        *dst++ = *src++;

        pos++, offset++;

        if (G_LIKELY(offset < plen))

            continue;

        offset = 0;

        src = self->pattern;

    }

    self->current_offset = offset;

}

static gpointer

pull_buffer_impl(

    XferElement *elt,

    size_t *size)

{

    XferSourcePattern *self = (XferSourcePattern *)elt;

    char *rval;

    /* indicate EOF on an cancel */

    if (elt->cancelled) {

	*size = 0;

	return NULL;

    }

    if (self->limited_length) {

        if (self->length == 0) {

            *size = 0;

            return NULL;

        }

        *size = MIN(10240, self->length);

        self->length -= *size;

    } else {

	*size = 10240;

    }

    rval = malloc(*size);

    fill_buffer_with_pattern(self, rval, *size);

    return rval;

}

static gpointer

pull_buffer_static_impl(

    XferElement *elt,

    gpointer buf,

    size_t block_size,

    size_t *size)

{

    XferSourcePattern *self = (XferSourcePattern *)elt;

    /* indicate EOF on an cancel */

    if (elt->cancelled) {

	*size = 0;

	return NULL;

    }

    if (self->limited_length) {

        if (self->length == 0) {

            *size = 0;

            return NULL;

        }

        *size = MIN(10240, self->length);

        *size = MIN(*size, block_size);

        self->length -= *size;

    } else {

	*size = 10240;

    }

    fill_buffer_with_pattern(self, buf, *size);

    return buf;

}

static void

instance_init(

    XferElement *elt)

{

    elt->can_generate_eof = TRUE;

}

static void

class_init(

    XferSourcePatternClass * selfc)

{

    XferElementClass *klass = XFER_ELEMENT_CLASS(selfc);

    static xfer_element_mech_pair_t mech_pairs[] = {

	{ XFER_MECH_NONE, XFER_MECH_PULL_BUFFER, XFER_NROPS(1), XFER_NTHREADS(0), XFER_NALLOC(1) },

	{ XFER_MECH_NONE, XFER_MECH_PULL_BUFFER_STATIC, XFER_NROPS(1), XFER_NTHREADS(0), XFER_NALLOC(0) },

	{ XFER_MECH_NONE, XFER_MECH_NONE, XFER_NROPS(0), XFER_NTHREADS(0), XFER_NALLOC(0) },

    };

    klass->pull_buffer = pull_buffer_impl;

    klass->pull_buffer_static = pull_buffer_static_impl;

    klass->perl_class = "Amanda::Xfer::Source::Pattern";

    klass->mech_pairs = mech_pairs;

    parent_class = g_type_class_peek_parent(selfc);

}

GType

xfer_source_pattern_get_type (void)

{

    static GType type = 0;

    if (G_UNLIKELY(type == 0)) {

        static const GTypeInfo info = {

            sizeof (XferSourcePatternClass),

            (GBaseInitFunc) NULL,

            (GBaseFinalizeFunc) NULL,

            (GClassInitFunc) class_init,

            (GClassFinalizeFunc) NULL,

            NULL /* class_data */,

            sizeof (XferSourcePattern),

            0 /* n_preallocs */,

            (GInstanceInitFunc) instance_init,

            NULL

        };

        type = g_type_register_static (XFER_ELEMENT_TYPE, "XferSourcePattern", &info, 0);

    }

    return type;

}

/* create an element of this class; prototype is in xfer-element.h */

XferElement * xfer_source_pattern(guint64 length, void * pattern,

                                  size_t pattern_length) {

    XferSourcePattern *xsp =

        (XferSourcePattern *)g_object_new(XFER_SOURCE_PATTERN_TYPE, NULL);

    XferElement *elt = XFER_ELEMENT(xsp);

    xsp->length = length;

    xsp->limited_length = (length > 0);

    xsp->pattern = g_memdup(pattern, pattern_length);

    xsp->pattern_buffer_length = pattern_length;

    xsp->current_offset = 0;

    return elt;

}