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/*
* Copyright 2014 Tushar Gohad
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright notice, this
* list of conditions and the following disclaimer in the documentation and/or
* other materials provided with the distribution. THIS SOFTWARE IS PROVIDED BY
* THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS 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 COPYRIGHT HOLDER OR 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.
*
* liberasurecode null backend
*
* vi: set noai tw=79 ts=4 sw=4:
*/
#include <stdio.h>
#include <stdlib.h>
#include "erasurecode.h"
#include "erasurecode_backend.h"
#define NULL_LIB_MAJOR 1
#define NULL_LIB_MINOR 0
#define NULL_LIB_REV 0
#define NULL_LIB_VER_STR "1.0"
#define NULL_LIB_NAME "null"
#if defined(__MACOS__) || defined(__MACOSX__) || defined(__OSX__) || defined(__APPLE__)
#define NULL_SO_NAME "libnullcode.dylib"
#else
#define NULL_SO_NAME "libnullcode.so.1"
#endif
/* Forward declarations */
struct ec_backend null;
struct ec_backend_op_stubs null_ops;
typedef void* (*init_null_code_func)(int, int, int);
typedef int (*null_code_encode_func)(void *, char **, char **, int);
typedef int (*null_code_decode_func)(void *, char **, char **, int *, int, int);
typedef int (*null_reconstruct_func)(char **, int, uint64_t, int, char *);
typedef int (*null_code_fragments_needed_func)(void *, int *, int *, int *);
struct null_descriptor {
/* calls required for init */
init_null_code_func init_null_code;
/* calls required for encode */
null_code_encode_func null_code_encode;
/* calls required for decode */
null_code_decode_func null_code_decode;
/* calls required for reconstruct */
null_reconstruct_func null_reconstruct;
/* set of fragments needed to reconstruct at a minimum */
null_code_fragments_needed_func null_code_fragments_needed;
/* fields needed to hold state */
int *matrix;
int k;
int m;
int w;
int arg1;
};
#define DEFAULT_W 32
static int null_encode(void *desc, char **data, char **parity, int blocksize)
{
return 0;
}
static int null_decode(void *desc, char **data, char **parity,
int *missing_idxs, int blocksize)
{
return 0;
}
static int null_reconstruct(void *desc, char **data, char **parity,
int *missing_idxs, int destination_idx, int blocksize)
{
return 0;
}
static int null_min_fragments(void *desc, int *missing_idxs,
int *fragments_to_exclude, int *fragments_needed)
{
return 0;
}
/**
* Return the element-size, which is the number of bits stored
* on a given device, per codeword. This is usually just 'w'.
*/
static int
null_element_size(void* desc)
{
return DEFAULT_W;
}
static void * null_init(struct ec_backend_args *args, void *backend_sohandle)
{
struct null_descriptor *xdesc = NULL;
/* allocate and fill in null_descriptor */
xdesc = (struct null_descriptor *) malloc(sizeof(struct null_descriptor));
if (NULL == xdesc) {
return NULL;
}
memset(xdesc, 0, sizeof(struct null_descriptor));
xdesc->k = args->uargs.k;
xdesc->m = args->uargs.m;
xdesc->w = args->uargs.w;
if (xdesc->w <= 0)
xdesc->w = DEFAULT_W;
/* Sample on how to pass extra args to the backend */
xdesc->arg1 = args->uargs.priv_args1.null_args.arg1;
/* store w back in args so upper layer can get to it */
args->uargs.w = DEFAULT_W;
/* validate EC arguments */
{
long long max_symbols;
if (xdesc->w != 8 && xdesc->w != 16 && xdesc->w != 32) {
goto error;
}
max_symbols = 1LL << xdesc->w;
if ((xdesc->k + xdesc->m) > max_symbols) {
goto error;
}
}
/*
* ISO C forbids casting a void* to a function pointer.
* Since dlsym return returns a void*, we use this union to
* "transform" the void* to a function pointer.
*/
union {
init_null_code_func initp;
null_code_encode_func encodep;
null_code_decode_func decodep;
null_reconstruct_func reconp;
null_code_fragments_needed_func fragsneededp;
void *vptr;
} func_handle = {.vptr = NULL};
/* fill in function addresses */
func_handle.vptr = NULL;
func_handle.vptr = dlsym(backend_sohandle, "null_code_init");
xdesc->init_null_code = func_handle.initp;
if (NULL == xdesc->init_null_code) {
goto error;
}
func_handle.vptr = NULL;
func_handle.vptr = dlsym(backend_sohandle, "null_code_encode");
xdesc->null_code_encode = func_handle.encodep;
if (NULL == xdesc->null_code_encode) {
goto error;
}
func_handle.vptr = NULL;
func_handle.vptr = dlsym(backend_sohandle, "null_code_decode");
xdesc->null_code_decode = func_handle.decodep;
if (NULL == xdesc->null_code_decode) {
goto error;
}
func_handle.vptr = NULL;
func_handle.vptr = dlsym(backend_sohandle, "null_reconstruct");
xdesc->null_reconstruct = func_handle.reconp;
if (NULL == xdesc->null_reconstruct) {
goto error;
}
func_handle.vptr = NULL;
func_handle.vptr = dlsym(backend_sohandle, "null_code_fragments_needed");
xdesc->null_code_fragments_needed = func_handle.fragsneededp;
if (NULL == xdesc->null_code_fragments_needed) {
goto error;
}
return (void *) xdesc;
error:
free (xdesc);
return NULL;
}
static int null_exit(void *desc)
{
struct null_descriptor *xdesc = (struct null_descriptor *) desc;
free (xdesc);
return 0;
}
static bool null_is_compatible_with(uint32_t version) {
return true;
}
struct ec_backend_op_stubs null_op_stubs = {
.INIT = null_init,
.EXIT = null_exit,
.ENCODE = null_encode,
.DECODE = null_decode,
.FRAGSNEEDED = null_min_fragments,
.RECONSTRUCT = null_reconstruct,
.ELEMENTSIZE = null_element_size,
.ISCOMPATIBLEWITH = null_is_compatible_with,
.GETMETADATASIZE = get_backend_metadata_size_zero,
.GETENCODEOFFSET = get_encode_offset_zero,
};
struct ec_backend_common backend_null = {
.id = EC_BACKEND_NULL,
.name = NULL_LIB_NAME,
.soname = NULL_SO_NAME,
.soversion = NULL_LIB_VER_STR,
.ops = &null_op_stubs,
.ec_backend_version = _VERSION(NULL_LIB_MAJOR, NULL_LIB_MINOR,
NULL_LIB_REV),
};
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