null_code: First cut

Signed-off-by: Tushar Gohad <tushar.gohad@intel.com>

1 files changed, 220 insertions, 0 deletions

diff --git a/src/backends/null/null.c b/src/backends/null/null.c
new file mode 100644
index 0000000..b04cd99
--- /dev/null
+++ b/src/backends/null/null.c
@@ -0,0 +1,220 @@
+/* 
+ * <Copyright>
+ *
+ * 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"
+
+/* Forward declarations */
+struct ec_backend null;
+struct ec_backend_op_stubs null_ops;
+
+struct null_descriptor {
+    /* calls required for init */
+    void* (*init_null_code)(int k, int m, int hd); 
+
+    /* calls required for encode */
+    int (*null_code_encode)(void *code_desc, char **data, char **parity,
+            int blocksize); 
+
+    /* calls required for decode */
+    int (*null_code_decode)(void *code_desc, char **data, char **parity,
+            int *missing_idxs, int blocksize, int decode_parity);
+
+    /* calls required for reconstruct */
+    int (*null_reconstruct)(char **available_fragments, int num_fragments,
+            uint64_t fragment_len, int destination_idx, char* out_fragment);
+
+    /* set of fragments needed to reconstruct at a minimum */
+    int (*null_code_fragments_needed)(void *code_desc, int *missing_idxs,
+            int *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)
+{
+    struct null_descriptor *xdesc =
+        (struct null_descriptor *) desc;
+
+    return 0;
+}
+
+static int null_decode(void *desc, char **data, char **parity,
+        int *missing_idxs, int blocksize)
+{
+    struct null_descriptor *xdesc =
+        (struct null_descriptor *) desc;
+
+    return 0;
+}
+
+static int null_reconstruct(void *desc, char **data, char **parity,
+        int *missing_idxs, int destination_idx, int blocksize)
+{
+    struct null_descriptor *xdesc =
+        (struct null_descriptor *) desc;
+
+    return 0;
+}
+
+static int null_min_fragments(void *desc, int *missing_idxs,
+        int *fragments_needed)
+{
+    struct null_descriptor *xdesc =
+        (struct null_descriptor *) desc;
+
+    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)
+{
+    int k, m, arg1, w;
+    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;
+    }
+
+    xdesc->k = args->uargs.k;
+    xdesc->m = args->uargs.m;
+
+    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;
+        }
+    }
+
+    /* fill in function addresses */
+    xdesc->init_null_code = dlsym(
+            backend_sohandle, "null_code_init");
+    if (NULL == xdesc->init_null_code) {
+        goto error; 
+    }
+
+    xdesc->null_code_encode = dlsym(
+            backend_sohandle, "null_code_encode");
+    if (NULL == xdesc->null_code_encode) {
+        goto error; 
+    }
+
+    xdesc->null_code_decode = dlsym(
+            backend_sohandle, "null_code_decode");
+    if (NULL == xdesc->null_code_decode) {
+        goto error; 
+    }
+
+    xdesc->null_reconstruct = dlsym(
+            backend_sohandle, "null_reconstruct");
+    if (NULL == xdesc->null_reconstruct) {
+        goto error; 
+    }
+
+    xdesc->null_code_fragments_needed = dlsym(
+            backend_sohandle, "null_code_fragments_needed");
+    if (NULL == xdesc->null_code_fragments_needed) {
+        goto error; 
+    }
+
+    return (void *) xdesc;
+
+error:
+    if (NULL != xdesc) {
+        free(xdesc);
+        xdesc = NULL;
+    }
+
+    return NULL;
+}
+
+static int null_exit(void *desc)
+{
+    struct null_descriptor *xdesc = (struct null_descriptor *) desc;
+
+    free (xdesc);
+}
+
+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,
+};
+
+struct ec_backend_common backend_null = {
+    .id                         = EC_BACKEND_NULL,
+    .name                       = "null",
+#if defined(__MACOS__) || defined(__MACOSX__) || defined(__OSX__) || defined(__APPLE__)
+    .soname                     = "libnullcode.dylib",
+#else
+    .soname                     = "libnullcode.so",
+#endif
+    .soversion                  = "1.0",
+    .ops                        = &null_op_stubs,
+};
+