Replace the zlib driver with a NIF

All operations will now yield appropriately, allowing them to be used
freely in concurrent applications. This commit also deprecates the
functions listed below, although they won't raise deprecation
warnings until OTP 21:

zlib:adler32
zlib:crc32
zlib:inflateChunk
zlib:getBufSize
zlib:setBufSize

The behavior of throwing an error when a dictionary is required for
decompression has also been deprecated.

1 files changed, 998 insertions, 0 deletions

diff --git a/erts/emulator/nifs/common/zlib_nif.c b/erts/emulator/nifs/common/zlib_nif.c
new file mode 100644
index 0000000000..cffb3f3f63
--- /dev/null
+++ b/erts/emulator/nifs/common/zlib_nif.c
@@ -0,0 +1,998 @@
+/*
+ * %CopyrightBegin%
+ *
+ * Copyright Ericsson 2017. All Rights Reserved.
+ *
+ * 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.
+ *
+ * %CopyrightEnd%
+ */
+
+#define STATIC_ERLANG_NIF 1
+
+#include <stdio.h>
+#include <zlib.h>
+
+#include "erl_nif.h"
+#include "config.h"
+#include "sys.h"
+
+#ifdef VALGRIND
+#  include <valgrind/memcheck.h>
+#endif
+
+#define INFL_DICT_SZ    (32768)
+
+#ifndef MAX
+#define MAX(X, Y) ((X) > (Y) ? (X) : (Y))
+#endif
+
+#ifndef MIN
+#define MIN(X, Y) ((X) < (Y) ? (X) : (Y))
+#endif
+
+/* NIF interface declarations */
+static int load(ErlNifEnv *env, void** priv_data, ERL_NIF_TERM load_info);
+static int upgrade(ErlNifEnv *env, void** priv_data, void** old_priv_data, ERL_NIF_TERM load_info);
+static void unload(ErlNifEnv *env, void* priv_data);
+
+static ErlNifResourceType *rtype_zlib;
+
+static ERL_NIF_TERM am_ok;
+static ERL_NIF_TERM am_error;
+static ERL_NIF_TERM am_continue;
+static ERL_NIF_TERM am_finished;
+static ERL_NIF_TERM am_empty;
+static ERL_NIF_TERM am_not_supported;
+static ERL_NIF_TERM am_need_dictionary;
+static ERL_NIF_TERM am_stream_end;
+static ERL_NIF_TERM am_stream_error;
+static ERL_NIF_TERM am_data_error;
+static ERL_NIF_TERM am_mem_error;
+static ERL_NIF_TERM am_buf_error;
+static ERL_NIF_TERM am_version_error;
+static ERL_NIF_TERM am_unknown_error;
+
+typedef enum {
+    ST_NONE    = 0,
+    ST_DEFLATE = 1,
+    ST_INFLATE = 2,
+    ST_CLOSED = 3
+} zlib_state;
+
+typedef struct {
+    z_stream s;
+    zlib_state state;
+
+    /* These refer to the plaintext CRC, and are only needed for zlib:crc32/1
+     * which is deprecated. */
+    uLong input_crc;
+    uLong output_crc;
+    int want_input_crc;
+    int want_output_crc;
+
+    int is_raw_stream;
+
+    int eos_seen;
+
+    /* DEPRECATED */
+    int inflateChunk_buffer_size;
+
+    ErlNifPid controlling_process;
+
+    ErlNifIOQueue *input_queue;
+
+    ErlNifEnv *stash_env;
+    ERL_NIF_TERM stash_term;
+} zlib_data_t;
+
+/* The NIFs: */
+
+static ERL_NIF_TERM zlib_open(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]);
+static ERL_NIF_TERM zlib_close(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]);
+static ERL_NIF_TERM zlib_deflateInit(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]);
+static ERL_NIF_TERM zlib_deflateInit2(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]);
+static ERL_NIF_TERM zlib_deflateSetDictionary(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]);
+static ERL_NIF_TERM zlib_deflateReset(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]);
+static ERL_NIF_TERM zlib_deflateEnd(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]);
+static ERL_NIF_TERM zlib_deflateParams(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]);
+static ERL_NIF_TERM zlib_deflate(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]);
+
+static ERL_NIF_TERM zlib_inflateInit(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]);
+static ERL_NIF_TERM zlib_inflateInit2(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]);
+static ERL_NIF_TERM zlib_inflateSetDictionary(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]);
+static ERL_NIF_TERM zlib_inflateGetDictionary(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]);
+static ERL_NIF_TERM zlib_inflateReset(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]);
+static ERL_NIF_TERM zlib_inflateEnd(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]);
+static ERL_NIF_TERM zlib_inflate(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]);
+
+static ERL_NIF_TERM zlib_crc32(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]);
+
+static ERL_NIF_TERM zlib_clearStash(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]);
+static ERL_NIF_TERM zlib_setStash(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]);
+static ERL_NIF_TERM zlib_getStash(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]);
+
+static ERL_NIF_TERM zlib_getBufSize(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]);
+static ERL_NIF_TERM zlib_setBufSize(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]);
+
+static ERL_NIF_TERM zlib_enqueue_input(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]);
+
+static ErlNifFunc nif_funcs[] = {
+    /* deflate */
+    {"deflateInit_nif", 2, zlib_deflateInit},
+    {"deflateInit_nif", 6, zlib_deflateInit2},
+    {"deflateSetDictionary_nif", 2, zlib_deflateSetDictionary},
+    {"deflateReset_nif", 1, zlib_deflateReset},
+    {"deflateEnd_nif", 1, zlib_deflateEnd},
+    {"deflateParams_nif", 3, zlib_deflateParams},
+    {"deflate_nif", 4, zlib_deflate},
+
+    /* inflate */
+    {"inflateInit_nif", 1, zlib_inflateInit},
+    {"inflateInit_nif", 2, zlib_inflateInit2},
+    {"inflateSetDictionary_nif", 2, zlib_inflateSetDictionary},
+    {"inflateGetDictionary_nif", 1, zlib_inflateGetDictionary},
+    {"inflateReset_nif", 1, zlib_inflateReset},
+    {"inflateEnd_nif", 1, zlib_inflateEnd},
+    {"inflate_nif", 4, zlib_inflate},
+
+    /* running checksum */
+    {"crc32_nif", 1, zlib_crc32},
+
+    /* open & close */
+    {"close_nif", 1, zlib_close},
+    {"open_nif", 0, zlib_open},
+
+    /* The stash keeps a single term alive across calls, and is used in
+     * exception_on_need_dict/1 to retain the old error behavior, and for
+     * saving data flushed through deflateParams/3. */
+    {"getStash_nif", 1, zlib_getStash},
+    {"clearStash_nif", 1, zlib_clearStash},
+    {"setStash_nif", 2, zlib_setStash},
+
+    /* DEPRECATED: buffer size for inflateChunk */
+    {"getBufSize_nif", 1, zlib_getBufSize},
+    {"setBufSize_nif", 2, zlib_setBufSize},
+
+    {"enqueue_nif", 2, zlib_enqueue_input},
+};
+
+ERL_NIF_INIT(zlib, nif_funcs, load, NULL, upgrade, unload)
+
+static void gc_zlib(ErlNifEnv *env, void* data);
+
+static int load(ErlNifEnv *env, void** priv_data, ERL_NIF_TERM load_info)
+{
+    am_ok = enif_make_atom(env, "ok");
+    am_error = enif_make_atom(env, "error");
+    am_empty = enif_make_atom(env, "empty");
+    am_continue = enif_make_atom(env, "continue");
+    am_finished = enif_make_atom(env, "finished");
+    am_need_dictionary = enif_make_atom(env, "need_dictionary");
+    am_not_supported = enif_make_atom(env, "not_supported");
+    am_stream_end = enif_make_atom(env, "stream_end");
+    am_stream_error = enif_make_atom(env, "stream_error");
+    am_data_error = enif_make_atom(env, "data_error");
+    am_mem_error = enif_make_atom(env, "mem_error");
+    am_buf_error = enif_make_atom(env, "buf_error");
+    am_version_error = enif_make_atom(env, "version_error");
+    am_unknown_error = enif_make_atom(env, "unknown_error");
+
+    rtype_zlib = enif_open_resource_type(env, NULL,
+            "gc_zlib", gc_zlib, ERL_NIF_RT_CREATE, NULL);
+    *priv_data = NULL;
+
+    return 0;
+}
+
+static void unload(ErlNifEnv *env, void* priv_data)
+{
+
+}
+
+static int upgrade(ErlNifEnv *env, void** priv_data, void** old_priv_data, ERL_NIF_TERM load_info)
+{
+    if(*old_priv_data != NULL) {
+        return -1; /* Don't know how to do that */
+    }
+    if(*priv_data != NULL) {
+        return -1; /* Don't know how to do that */
+    }
+    if(load(env, priv_data, load_info)) {
+        return -1;
+    }
+    return 0;
+}
+
+static void* zlib_alloc(void* data, unsigned int items, unsigned int size)
+{
+    return (void*) enif_alloc(items * size);
+}
+
+static void zlib_free(void* data, void* addr)
+{
+    enif_free(addr);
+}
+
+static ERL_NIF_TERM zlib_return(ErlNifEnv *env, int code) {
+    ERL_NIF_TERM reason;
+    switch(code) {
+    case Z_OK:
+        reason = am_ok;
+        break;
+    case Z_STREAM_END:
+        reason = am_stream_end;
+        break;
+    case Z_ERRNO:
+        reason = enif_make_int(env, errno);
+        //enif_make_tuple2(env, enif_make_int(env, err), reason);
+        break;
+    case Z_STREAM_ERROR:
+        //reason = am_stream_error;
+        reason = enif_raise_exception(env, am_stream_error);
+        break;
+    case Z_DATA_ERROR:
+        //reason = am_data_error;
+        reason = enif_raise_exception(env, am_data_error);
+        break;
+    case Z_MEM_ERROR:
+        reason = am_mem_error;
+        break;
+    case Z_BUF_ERROR:
+        reason = am_buf_error;
+        break;
+    case Z_VERSION_ERROR:
+        reason = am_version_error;
+        break;
+    default:
+        reason = am_unknown_error;
+        break;
+    }
+    return reason;
+}
+
+static void gc_zlib(ErlNifEnv *env, void* data) {
+    zlib_data_t *d = (zlib_data_t*)data;
+
+    if(d->state == ST_DEFLATE) {
+        deflateEnd(&d->s);
+    } else if(d->state == ST_INFLATE) {
+        inflateEnd(&d->s);
+    }
+
+    if(d->state != ST_CLOSED) {
+        enif_ioq_destroy(d->input_queue);
+
+        if(d->stash_env != NULL) {
+            enif_free_env(d->stash_env);
+        }
+
+        d->state = ST_CLOSED;
+    }
+}
+
+static void zlib_reset_input(zlib_data_t *d) {
+    enif_ioq_destroy(d->input_queue);
+    d->input_queue = enif_ioq_create(ERL_NIF_IOQ_NORMAL);
+
+    if(d->stash_env != NULL) {
+        enif_free_env(d->stash_env);
+        d->stash_env = NULL;
+        d->stash_term = NIL;
+    }
+}
+
+static int get_zlib_data(ErlNifEnv* env, ERL_NIF_TERM opaque, zlib_data_t **d) {
+    ErlNifPid current_process;
+
+    if(!enif_get_resource(env, opaque, rtype_zlib, (void **)d)) {
+        return 0;
+    }
+
+    enif_self(env, &current_process);
+
+    return enif_is_identical(enif_make_pid(env, &current_process),
+        enif_make_pid(env, &(*d)->controlling_process));
+}
+
+static int zlib_flush_queue(int (*codec)(z_stream*, int), ErlNifEnv *env,
+        zlib_data_t *d, size_t input_limit, ErlNifBinary *output_buffer, int flush,
+        size_t *bytes_produced, size_t *bytes_consumed, size_t *bytes_remaining) {
+
+    int vec_len, vec_idx;
+    SysIOVec *input_vec;
+    int res;
+
+    input_vec = enif_ioq_peek(d->input_queue, &vec_len);
+    vec_idx = 0;
+    res = Z_OK;
+
+    *bytes_produced = 0;
+    *bytes_consumed = 0;
+
+    d->s.avail_out = output_buffer->size;
+    d->s.next_out = output_buffer->data;
+
+    while(res == Z_OK && vec_idx < vec_len && *bytes_consumed < input_limit) {
+        size_t timeslice_percent, block_consumed, block_size;
+
+        block_size = MIN(input_vec[vec_idx].iov_len, input_limit);
+
+        d->s.next_in = input_vec[vec_idx].iov_base;
+        d->s.avail_in = block_size;
+
+        res = codec(&d->s, Z_NO_FLUSH);
+
+        ASSERT(d->s.avail_in == 0 || d->s.avail_out == 0 || res != Z_OK);
+
+        block_consumed = block_size - d->s.avail_in;
+        *bytes_consumed += block_consumed;
+
+        if(d->want_input_crc) {
+            d->input_crc =
+                crc32(d->input_crc, input_vec[vec_idx].iov_base, block_consumed);
+        }
+
+        timeslice_percent = (100 * block_consumed) / input_limit;
+        if(enif_consume_timeslice(env, MAX(1, timeslice_percent))) {
+            break;
+        }
+
+        vec_idx++;
+    }
+
+    if(!enif_ioq_deq(d->input_queue, *bytes_consumed, bytes_remaining)) {
+        *bytes_remaining = 0;
+        res = Z_BUF_ERROR;
+    }
+
+    if(res == Z_OK && flush != Z_NO_FLUSH && (*bytes_remaining == 0)) {
+        d->s.next_in = NULL;
+        d->s.avail_in = 0;
+
+        res = codec(&d->s, flush);
+    }
+
+    *bytes_produced = output_buffer->size - d->s.avail_out;
+
+    return res;
+}
+
+static ERL_NIF_TERM zlib_codec(int (*codec)(z_stream*, int),
+                               ErlNifEnv *env, zlib_data_t *d,
+                               int input_chunk_size,
+                               int output_chunk_size,
+                               int flush) {
+
+    size_t bytes_produced, bytes_consumed, bytes_remaining;
+    ErlNifBinary output_buffer;
+    int res;
+
+    if(!enif_alloc_binary(output_chunk_size, &output_buffer)) {
+        return zlib_return(env, Z_MEM_ERROR);
+    }
+
+    res = zlib_flush_queue(codec, env, d, input_chunk_size, &output_buffer,
+        flush, &bytes_produced, &bytes_consumed, &bytes_remaining);
+
+    if(res < 0 && res != Z_BUF_ERROR) {
+        enif_release_binary(&output_buffer);
+        return zlib_return(env, res);
+    }
+
+    if(res == Z_STREAM_END) {
+        d->eos_seen = 1;
+    }
+
+    if(d->want_output_crc) {
+        d->output_crc =
+            crc32(d->output_crc, output_buffer.data, bytes_produced);
+    }
+
+    if(bytes_consumed == 0 && bytes_produced == 0 && bytes_remaining != 0) {
+        /* Die if we've made zero progress; this should not happen on
+         * well-formed input. */
+
+        enif_release_binary(&output_buffer);
+        return zlib_return(env, Z_DATA_ERROR);
+    } else {
+        ERL_NIF_TERM flushed_output;
+
+        if(bytes_produced > 0) {
+            if(bytes_produced < output_buffer.size) {
+                enif_realloc_binary(&output_buffer, bytes_produced);
+            }
+
+            flushed_output =
+                enif_make_list1(env, enif_make_binary(env, &output_buffer));
+        } else {
+            enif_release_binary(&output_buffer);
+            flushed_output = enif_make_list(env, 0);
+        }
+
+        if(bytes_remaining == 0 && bytes_produced < output_chunk_size) {
+            return enif_make_tuple2(env, am_finished, flushed_output);
+        } else if(res != Z_NEED_DICT) {
+            return enif_make_tuple2(env, am_continue, flushed_output);
+        }
+
+        return enif_make_tuple3(env, am_need_dictionary,
+            enif_make_int(env, d->s.adler), flushed_output);
+    }
+}
+
+/* zlib nifs */
+
+static ERL_NIF_TERM zlib_getStash(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
+    zlib_data_t *d;
+
+    if(argc != 1 || !get_zlib_data(env, argv[0], &d)) {
+        return enif_make_badarg(env);
+    }
+
+    if(d->stash_env == NULL) {
+        return am_empty;
+    }
+
+    return enif_make_tuple2(env, am_ok, enif_make_copy(env, d->stash_term));
+}
+
+static ERL_NIF_TERM zlib_clearStash(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
+    zlib_data_t *d;
+
+    if(argc != 1 || !get_zlib_data(env, argv[0], &d)) {
+        return enif_make_badarg(env);
+    }
+
+    if(d->stash_env == NULL) {
+        return enif_make_badarg(env);
+    }
+
+    enif_free_env(d->stash_env);
+    d->stash_env = NULL;
+    d->stash_term = NIL;
+
+    return am_ok;
+}
+
+static ERL_NIF_TERM zlib_setStash(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
+    zlib_data_t *d;
+
+    if(argc != 2 || !get_zlib_data(env, argv[0], &d)) {
+        return enif_make_badarg(env);
+    }
+
+    if(d->stash_env != NULL) {
+        return enif_make_badarg(env);
+    }
+
+    d->stash_env = enif_alloc_env();
+    d->stash_term = enif_make_copy(d->stash_env, argv[1]);
+
+    return am_ok;
+}
+
+static ERL_NIF_TERM zlib_open(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
+    zlib_data_t *d;
+    ERL_NIF_TERM result;
+
+    d = (zlib_data_t *) enif_alloc_resource(rtype_zlib, sizeof(zlib_data_t));
+
+    memset(&d->s, 0, sizeof(z_stream));
+
+    enif_self(env, &d->controlling_process);
+
+    d->input_queue = enif_ioq_create(ERL_NIF_IOQ_NORMAL);
+
+    d->s.zalloc = zlib_alloc;
+    d->s.zfree  = zlib_free;
+    d->s.opaque = d;
+    d->s.data_type = Z_BINARY;
+
+    d->state = ST_NONE;
+    d->eos_seen = 0;
+
+    d->want_output_crc = 0;
+    d->want_input_crc = 0;
+    d->is_raw_stream = 0;
+
+    d->output_crc = crc32(0L, Z_NULL, 0);
+    d->input_crc = crc32(0L, Z_NULL, 0);
+
+    d->stash_env = NULL;
+    d->stash_term = NIL;
+
+    d->inflateChunk_buffer_size = 4000;
+
+    result = enif_make_resource(env, d);
+    enif_release_resource(d);
+
+    return result;
+}
+
+static ERL_NIF_TERM zlib_close(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
+    zlib_data_t *d;
+
+    /* strictly speaking not needed since the gc will handle this */
+    if(argc != 1 || !get_zlib_data(env, argv[0], &d)) {
+        return enif_make_badarg(env);
+    }
+
+    if(d->state == ST_CLOSED) {
+        return enif_make_badarg(env);
+    }
+
+    gc_zlib(env, d);
+
+    return am_ok;
+}
+
+/* deflate */
+
+static ERL_NIF_TERM zlib_deflateInit(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
+    zlib_data_t *d;
+    int level, res;
+
+    if(argc != 2 || !get_zlib_data(env, argv[0], &d) ||
+                    !enif_get_int(env, argv[1], &level)) {
+        return enif_make_badarg(env);
+    }
+
+    if(d->state != ST_NONE) {
+        return enif_make_badarg(env);
+    }
+
+    res = deflateInit(&d->s, level);
+
+    if(res == Z_OK) {
+        d->state = ST_DEFLATE;
+        d->eos_seen = 0;
+
+        /* FIXME: crc32/1 is documented as returning "the current calculated
+         * checksum," but failed to mention that the old implementation only
+         * calculated it when WindowBits < 0 (See zlib_deflateInit2).
+         *
+         * We could fix this behavior by setting d->want_input_crc to 1 here,
+         * but we've decided to retain this quirk since the performance hit is
+         * quite significant. */
+        d->want_output_crc = 0;
+        d->want_input_crc = 0;
+
+        d->output_crc = crc32(0L, Z_NULL, 0);
+        d->input_crc = crc32(0L, Z_NULL, 0);
+    }
+
+    return zlib_return(env, res);
+}
+
+static ERL_NIF_TERM zlib_deflateInit2(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
+    zlib_data_t *d;
+    int level, method, windowBits, memLevel, strategy, res;
+
+    if(argc != 6 || !get_zlib_data(env, argv[0], &d) 
+                 || !enif_get_int(env, argv[1], &level)
+                 || !enif_get_int(env, argv[2], &method)
+                 || !enif_get_int(env, argv[3], &windowBits)
+                 || !enif_get_int(env, argv[4], &memLevel)
+                 || !enif_get_int(env, argv[5], &strategy)) {
+        return enif_make_badarg(env);
+    }
+
+    if(d->state != ST_NONE) {
+        return enif_make_badarg(env);
+    }
+
+    res = deflateInit2(&d->s, level, method, windowBits, memLevel, strategy);
+
+    if(res == Z_OK) {
+        d->state = ST_DEFLATE;
+        d->eos_seen = 0;
+
+        d->is_raw_stream = (windowBits < 0);
+
+        d->want_output_crc = 0;
+        d->want_input_crc = d->is_raw_stream;
+
+        d->output_crc = crc32(0L, Z_NULL, 0);
+        d->input_crc = crc32(0L, Z_NULL, 0);
+    }
+
+    return zlib_return(env, res);
+}
+
+static ERL_NIF_TERM zlib_deflateSetDictionary(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
+    zlib_data_t *d;
+    ErlNifBinary bin;
+    int res;
+
+    if(argc != 2 || !get_zlib_data(env, argv[0], &d)
+                 || !enif_inspect_iolist_as_binary(env, argv[1], &bin)) {
+        return enif_make_badarg(env);
+    }
+
+    if(d->state != ST_DEFLATE) {
+        return enif_make_badarg(env);
+    }
+
+    if((res = deflateSetDictionary(&d->s, bin.data, bin.size)) == Z_OK) {
+        uLong checksum = d->s.adler;
+
+        /* d->s.adler is not updated in raw deflate mode, so we'll calculate it
+         * ourselves in case the user wants to rely on that behavior. */
+        if(d->is_raw_stream) {
+            checksum = adler32(0, bin.data, bin.size);
+        }
+
+        return enif_make_int(env, checksum);
+    }
+
+    return zlib_return(env, res);
+}
+
+static ERL_NIF_TERM zlib_deflateReset(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
+    zlib_data_t *d;
+    int res;
+
+    if(argc != 1 || !get_zlib_data(env, argv[0], &d)) {
+        return enif_make_badarg(env);
+    }
+
+    if(d->state != ST_DEFLATE) {
+        return enif_make_badarg(env);
+    }
+
+    res = deflateReset(&d->s);
+
+    d->input_crc = crc32(0L, Z_NULL, 0);
+    d->eos_seen = 0;
+
+    zlib_reset_input(d);
+
+    return zlib_return(env, res);
+}
+
+static ERL_NIF_TERM zlib_deflateEnd(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
+    zlib_data_t *d;
+    int res;
+
+    if(argc != 1 || !get_zlib_data(env, argv[0], &d)) {
+        return enif_make_badarg(env);
+    }
+
+    if(d->state != ST_DEFLATE) {
+        return enif_make_badarg(env);
+    }
+
+    res = deflateEnd(&d->s);
+
+    if(res == Z_OK && enif_ioq_size(d->input_queue) > 0) {
+        res = Z_DATA_ERROR;
+    }
+
+    zlib_reset_input(d);
+    d->state = ST_NONE;
+
+    return zlib_return(env, res);
+}
+
+static ERL_NIF_TERM zlib_deflateParams(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
+    zlib_data_t *d;
+    int res, level, strategy;
+
+    if(argc != 3 || !get_zlib_data(env, argv[0], &d)
+                 || !enif_get_int(env, argv[1], &level)
+                 || !enif_get_int(env, argv[2], &strategy)) {
+        return enif_make_badarg(env);
+    }
+
+    if(d->state != ST_DEFLATE) {
+        return enif_make_badarg(env);
+    }
+
+    /* deflateParams will flush everything currently in the stream, corrupting
+     * the heap unless it's empty. We therefore pretend to have a full output
+     * buffer, forcing a Z_BUF_ERROR if there's anything left to be flushed. */
+    d->s.avail_out = 0;
+    res = deflateParams(&d->s, level, strategy);
+
+    return zlib_return(env, res);
+}
+
+static ERL_NIF_TERM zlib_deflate(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
+    zlib_data_t *d;
+
+    int input_chunk_size, output_chunk_size, flush;
+
+    if(argc != 4 || !get_zlib_data(env, argv[0], &d)
+                 || !enif_get_int(env, argv[1], &input_chunk_size)
+                 || !enif_get_int(env, argv[2], &output_chunk_size)
+                 || !enif_get_int(env, argv[3], &flush)) {
+        return enif_make_badarg(env);
+    }
+
+    if(d->state != ST_DEFLATE) {
+        return enif_make_badarg(env);
+    }
+
+    return zlib_codec(&deflate, env, d, input_chunk_size, output_chunk_size, flush);
+}
+
+/* inflate */
+
+static ERL_NIF_TERM zlib_inflateInit(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
+    zlib_data_t *d;
+    int res;
+
+    if(argc != 1 || !get_zlib_data(env, argv[0], &d)) {
+        return enif_make_badarg(env);
+    }
+
+    if(d->state != ST_NONE) {
+        return enif_make_badarg(env);
+    }
+
+    res = inflateInit(&d->s);
+
+    if(res == Z_OK) {
+        d->state = ST_INFLATE;
+        d->eos_seen = 0;
+
+        d->want_output_crc = 0;
+        d->want_input_crc = 0;
+        d->is_raw_stream = 0;
+
+        d->output_crc = crc32(0L, Z_NULL, 0);
+        d->input_crc = crc32(0L, Z_NULL, 0);
+    }
+
+    return zlib_return(env, res);
+}
+
+static ERL_NIF_TERM zlib_inflateInit2(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
+    zlib_data_t *d;
+    int windowBits, res;
+
+    if(argc != 2 || !get_zlib_data(env, argv[0], &d)
+                 || !enif_get_int(env, argv[1], &windowBits)) {
+        return enif_make_badarg(env);
+    }
+
+    if(d->state != ST_NONE) {
+        return enif_make_badarg(env);
+    }
+
+    res = inflateInit2(&d->s, windowBits);
+
+    if(res == Z_OK) {
+        d->state = ST_INFLATE;
+        d->eos_seen = 0;
+
+        d->is_raw_stream = (windowBits < 0);
+
+        d->want_output_crc = d->is_raw_stream;
+        d->want_input_crc = 0;
+
+        d->output_crc = crc32(0L, Z_NULL, 0);
+        d->input_crc = crc32(0L, Z_NULL, 0);
+    }
+
+    return zlib_return(env, res);
+}
+
+static ERL_NIF_TERM zlib_inflateSetDictionary(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
+    zlib_data_t *d;
+    ErlNifBinary bin;
+    int res;
+
+    if(argc != 2 || !get_zlib_data(env, argv[0], &d)
+                 || !enif_inspect_iolist_as_binary(env, argv[1], &bin)) {
+        return enif_make_badarg(env);
+    }
+
+    if(d->state != ST_INFLATE) {
+        return enif_make_badarg(env);
+    }
+
+    res = inflateSetDictionary(&d->s, bin.data, bin.size);
+
+    return zlib_return(env, res);
+}
+
+#ifdef HAVE_ZLIB_INFLATEGETDICTIONARY
+/* Work around broken build system with runtime version test */
+static int zlib_supports_inflateGetDictionary(void) {
+    static int supportsGetDictionary = -1;
+
+#if defined(__APPLE__) && defined(__MACH__)
+    if(supportsGetDictionary < 0) {
+        unsigned int v[4] = {0, 0, 0, 0};
+        unsigned hexver;
+
+        sscanf(zlibVersion(), "%u.%u.%u.%u", &v[0], &v[1], &v[2], &v[3]);
+
+        hexver = (v[0] << (8*3)) | (v[1] << (8*2)) | (v[2] << (8)) | v[3];
+        supportsGetDictionary = (hexver >= 0x1020701); /* 1.2.7.1 */
+    }
+#endif
+
+    return supportsGetDictionary;
+}
+
+static ERL_NIF_TERM zlib_inflateGetDictionary(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
+    zlib_data_t *d;
+    ErlNifBinary obin;
+    uInt len;
+    int res;
+
+    if(argc != 1 || !get_zlib_data(env, argv[0], &d)) {
+        return enif_make_badarg(env);
+    }
+
+    if(d->state != ST_INFLATE) {
+        return enif_make_badarg(env);
+    }
+
+    if(!zlib_supports_inflateGetDictionary()) {
+        return enif_make_badarg(env);
+    }
+
+    enif_alloc_binary(INFL_DICT_SZ, &obin);
+
+    len = 0;
+    if((res = inflateGetDictionary(&d->s, obin.data, &len)) < 0) {
+        enif_release_binary(&obin);
+        return zlib_return(env, res);
+    }
+
+    enif_realloc_binary(&obin, (size_t)len);
+    return enif_make_binary(env, &obin);
+}
+
+#else /* !HAVE_ZLIB_INFLATEGETDICTIONARY */
+
+static ERL_NIF_TERM zlib_inflateGetDictionary(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
+    return enif_make_badarg(env);
+}
+
+#endif
+
+static ERL_NIF_TERM zlib_inflateReset(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
+    zlib_data_t *d;
+    int res;
+
+    if(argc != 1 || !get_zlib_data(env, argv[0], &d)) {
+        return enif_make_badarg(env);
+    }
+
+    if(d->state != ST_INFLATE) {
+        return enif_make_badarg(env);
+    }
+
+    res = inflateReset(&d->s);
+
+    d->output_crc = crc32(0L, Z_NULL, 0);
+    d->eos_seen = 0;
+
+    zlib_reset_input(d);
+
+    return zlib_return(env, res);
+}
+
+static ERL_NIF_TERM zlib_inflateEnd(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
+    zlib_data_t *d;
+    int res;
+
+    if(argc != 1 || !get_zlib_data(env, argv[0], &d)) {
+        return enif_make_badarg(env);
+    }
+
+    if(d->state != ST_INFLATE) {
+        return enif_make_badarg(env);
+    }
+
+    res = inflateEnd(&d->s);
+
+    if(res == Z_OK && (!d->eos_seen || enif_ioq_size(d->input_queue) > 0)) {
+        res = Z_DATA_ERROR;
+    }
+
+    zlib_reset_input(d);
+    d->state = ST_NONE;
+
+    return zlib_return(env, res);
+}
+
+static ERL_NIF_TERM zlib_inflate(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
+    zlib_data_t *d;
+
+    int input_chunk_size, output_chunk_size, flush;
+
+    if(argc != 4 || !get_zlib_data(env, argv[0], &d)
+                 || !enif_get_int(env, argv[1], &input_chunk_size)
+                 || !enif_get_int(env, argv[2], &output_chunk_size)
+                 || !enif_get_int(env, argv[3], &flush)) {
+        return enif_make_badarg(env);
+    }
+
+    if(d->state != ST_INFLATE) {
+        return enif_make_badarg(env);
+    }
+
+    return zlib_codec(&inflate, env, d, input_chunk_size, output_chunk_size, flush);
+}
+
+static ERL_NIF_TERM zlib_crc32(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
+    zlib_data_t *d;
+
+    if(argc != 1 || !get_zlib_data(env, argv[0], &d)) {
+        return enif_make_badarg(env);
+    }
+
+    if(d->state == ST_DEFLATE) {
+        return enif_make_ulong(env, d->input_crc);
+    } else if(d->state == ST_INFLATE) {
+        return enif_make_ulong(env, d->output_crc);
+    }
+
+    return enif_make_badarg(env);
+}
+
+static ERL_NIF_TERM zlib_getBufSize(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
+    zlib_data_t *d;
+
+    if(argc != 1 || !get_zlib_data(env, argv[0], &d)) {
+        return enif_make_badarg(env);
+    }
+
+    return enif_make_int(env, d->inflateChunk_buffer_size);
+}
+
+static ERL_NIF_TERM zlib_setBufSize(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
+    zlib_data_t *d;
+
+    if(argc != 2 || !get_zlib_data(env, argv[0], &d)
+                 || !enif_get_int(env, argv[1], &d->inflateChunk_buffer_size)) {
+        return enif_make_badarg(env);
+    }
+
+    return am_ok;
+}
+
+static ERL_NIF_TERM zlib_enqueue_input(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
+    zlib_data_t *d;
+
+    ErlNifIOVec prealloc, *iovec = &prealloc;
+    ERL_NIF_TERM tail;
+
+    if(argc != 2 || !get_zlib_data(env, argv[0], &d)) {
+        return enif_make_badarg(env);
+    }
+
+    if(d->state != ST_DEFLATE && d->state != ST_INFLATE) {
+        return enif_make_badarg(env);
+    }
+
+    if(!enif_inspect_iovec(env, 256, argv[1], &tail, &iovec)) {
+        return enif_make_badarg(env);
+    }
+
+    if(!enif_ioq_enqv(d->input_queue, iovec, 0)) {
+        return enif_make_badarg(env);
+    }
+
+    if(!enif_is_empty_list(env, tail)) {
+        return enif_make_tuple2(env, am_continue, tail);
+    }
+
+    return am_ok;
+}