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encode.c
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encode.c
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// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.
#include <stdio.h>
#include <string.h>
#include <math.h>
#include "erl_nif.h"
#include "erl_nif_compat.h"
#include "yajl/yajl_encode.h"
#if defined(_WIN32) || defined(WIN32) || defined(__WIN32__)
#include <float.h>
#define isnan _isnan
#define isinf !_finite
#define snprintf _snprintf
#endif
#define SUCCESS 0
#define NOMEM 1
#define BADARG 2
typedef struct {
ErlNifEnv* env;
ErlNifBinary bin;
size_t fill_offset;
int error;
} encode_ctx;
static int
ensure_buffer(void* vctx, unsigned int len) {
encode_ctx* ctx = (encode_ctx*)vctx;
if ((ctx->bin.size - ctx->fill_offset) < len) {
if(!enif_realloc_binary_compat(ctx->env, &(ctx->bin), (ctx->bin.size * 2) + len)) {
return NOMEM;
}
}
return SUCCESS;
}
static void
fill_buffer(void* vctx, const char* str, unsigned int len)
{
encode_ctx* ctx = (encode_ctx*)vctx;
if (ctx->error || (ctx->error = ensure_buffer(vctx, len))) {
return;
}
memcpy(ctx->bin.data + ctx->fill_offset, str, len);
ctx->fill_offset += len;
}
/* Json encode the string binary into the ctx.bin,
with surrounding quotes and all */
static int
encode_string(void* vctx, ERL_NIF_TERM binary)
{
encode_ctx* ctx = (encode_ctx*)vctx;
ErlNifBinary bin;
if(!enif_inspect_binary(ctx->env, binary, &bin)) {
return NOMEM;
}
fill_buffer(ctx, "\"", 1);
if (ctx->error) {
return ctx->error;
}
yajl_string_encode2(fill_buffer, ctx, bin.data, bin.size);
fill_buffer(ctx, "\"", 1);
return ctx->error;
}
static ERL_NIF_TERM
no_mem_error(ErlNifEnv* env)
{
return enif_make_tuple(env, 2,
enif_make_atom(env, "error"),
enif_make_atom(env, "insufficient_memory"));
}
ERL_NIF_TERM
final_encode(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
ERL_NIF_TERM head = argv[0];
ERL_NIF_TERM term;
double number;
encode_ctx ctx;
ctx.env = env;
ctx.fill_offset = 0;
ctx.error = 0;
if (!enif_alloc_binary_compat(env, 100, &ctx.bin)) {
return no_mem_error(env);
}
while(enif_get_list_cell(env, head, &term, &head)) {
ErlNifBinary termbin;
const ERL_NIF_TERM* array;
int arity;
int code;
// We scan the list, looking for things to write into the binary, or
// encode and then write into the binary. We encode values that are
// tuples tagged with a type and a value: {Type, Value} where Type
// is a an Integer and Value is what is to be encoded
if (enif_get_tuple(env, term, &arity, &array)) {
// It's a tuple to encode and copy
if (arity != 2 || !enif_get_int(env, array[0], &code)) {
// not arity 2 or the first element isn't an int
ctx.error = BADARG;
goto done;
}
if (code == 0) {
// {0, String}
if (encode_string(&ctx, array[1]) != SUCCESS) {
goto done;
}
}
else {
// {1, Double}
if(!enif_get_double(env, array[1], &number)) {
ctx.error = BADARG;
goto done;
}
// We can't encode these.
if (isnan(number) || isinf(number)) {
ctx.error = BADARG;
goto done;
}
if ((ctx.error = ensure_buffer(&ctx, 32)) != SUCCESS) {
goto done;
}
// write the string into the buffer
snprintf((char*)ctx.bin.data+ctx.fill_offset, 32,
"%.16g", number);
// increment the length
ctx.fill_offset += strlen((char*)ctx.bin.data+ctx.fill_offset);
}
} else if (enif_inspect_binary(env, term, &termbin)) {
// this is a regular binary, copy the contents into the buffer
fill_buffer(&ctx, (char*)termbin.data, termbin.size);
if (ctx.error) {
goto done;
}
}
else {
//not a binary, not a tuple, wtf!
ctx.error = BADARG;
goto done;
}
}
done:
if (ctx.error == NOMEM) {
enif_release_binary_compat(env, &ctx.bin);
return no_mem_error(env);
} else if (ctx.error == BADARG) {
enif_release_binary_compat(env, &ctx.bin);
return enif_make_badarg(env);
}
// Resize the binary to our exact final size
if(!enif_realloc_binary_compat(env, &(ctx.bin), ctx.fill_offset)) {
enif_release_binary_compat(env, &ctx.bin);
return no_mem_error(env);
}
// make the binary term which transfers ownership
return enif_make_binary(env, &ctx.bin);
}