feat(lua): add lua-cjson as vendored dependency

Derived from the openresty lua-cjson fork at commit https://github.com/openresty/lua-cjson/commit/3d93d297092172eac3d52a1b3b6c1d479da5341a

5 files changed, 2233 insertions, 0 deletions

diff --git a/src/cjson/fpconv.c b/src/cjson/fpconv.c
new file mode 100644
index 0000000000..3e480ece0a
--- /dev/null
+++ b/src/cjson/fpconv.c
@@ -0,0 +1,211 @@
+/* fpconv - Floating point conversion routines
+ *
+ * Copyright (c) 2011-2012  Mark Pulford <mark@kyne.com.au>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+/* JSON uses a '.' decimal separator. strtod() / sprintf() under C libraries
+ * with locale support will break when the decimal separator is a comma.
+ *
+ * fpconv_* will around these issues with a translation buffer if required.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <string.h>
+
+#include "fpconv.h"
+
+/* Workaround for MSVC */
+#ifdef _MSC_VER
+#define inline __inline
+#define snprintf sprintf_s
+#endif
+
+/* Lua CJSON assumes the locale is the same for all threads within a
+ * process and doesn't change after initialisation.
+ *
+ * This avoids the need for per thread storage or expensive checks
+ * for call. */
+static char locale_decimal_point = '.';
+
+/* In theory multibyte decimal_points are possible, but
+ * Lua CJSON only supports UTF-8 and known locales only have
+ * single byte decimal points ([.,]).
+ *
+ * localconv() may not be thread safe (=>crash), and nl_langinfo() is
+ * not supported on some platforms. Use sprintf() instead - if the
+ * locale does change, at least Lua CJSON won't crash. */
+static void fpconv_update_locale()
+{
+    char buf[8];
+
+    snprintf(buf, sizeof(buf), "%g", 0.5);
+
+    /* Failing this test might imply the platform has a buggy dtoa
+     * implementation or wide characters */
+    if (buf[0] != '0' || buf[2] != '5' || buf[3] != 0) {
+        fprintf(stderr, "Error: wide characters found or printf() bug.");
+        abort();
+    }
+
+    locale_decimal_point = buf[1];
+}
+
+/* Check for a valid number character: [-+0-9a-yA-Y.]
+ * Eg: -0.6e+5, infinity, 0xF0.F0pF0
+ *
+ * Used to find the probable end of a number. It doesn't matter if
+ * invalid characters are counted - strtod() will find the valid
+ * number if it exists.  The risk is that slightly more memory might
+ * be allocated before a parse error occurs. */
+static inline int valid_number_character(char ch)
+{
+    char lower_ch;
+
+    if ('0' <= ch && ch <= '9')
+        return 1;
+    if (ch == '-' || ch == '+' || ch == '.')
+        return 1;
+
+    /* Hex digits, exponent (e), base (p), "infinity",.. */
+    lower_ch = ch | 0x20;
+    if ('a' <= lower_ch && lower_ch <= 'y')
+        return 1;
+
+    return 0;
+}
+
+/* Calculate the size of the buffer required for a strtod locale
+ * conversion. */
+static int strtod_buffer_size(const char *s)
+{
+    const char *p = s;
+
+    while (valid_number_character(*p))
+        p++;
+
+    return p - s;
+}
+
+/* Similar to strtod(), but must be passed the current locale's decimal point
+ * character. Guaranteed to be called at the start of any valid number in a string */
+double fpconv_strtod(const char *nptr, char **endptr)
+{
+    char localbuf[FPCONV_G_FMT_BUFSIZE];
+    char *buf, *endbuf, *dp;
+    int buflen;
+    double value;
+
+    /* System strtod() is fine when decimal point is '.' */
+    if (locale_decimal_point == '.')
+        return strtod(nptr, endptr);
+
+    buflen = strtod_buffer_size(nptr);
+    if (!buflen) {
+        /* No valid characters found, standard strtod() return */
+        *endptr = (char *)nptr;
+        return 0;
+    }
+
+    /* Duplicate number into buffer */
+    if (buflen >= FPCONV_G_FMT_BUFSIZE) {
+        /* Handle unusually large numbers */
+        buf = malloc(buflen + 1);
+        if (!buf) {
+            fprintf(stderr, "Out of memory");
+            abort();
+        }
+    } else {
+        /* This is the common case.. */
+        buf = localbuf;
+    }
+    memcpy(buf, nptr, buflen);
+    buf[buflen] = 0;
+
+    /* Update decimal point character if found */
+    dp = strchr(buf, '.');
+    if (dp)
+        *dp = locale_decimal_point;
+
+    value = strtod(buf, &endbuf);
+    *endptr = (char *)&nptr[endbuf - buf];
+    if (buflen >= FPCONV_G_FMT_BUFSIZE)
+        free(buf);
+
+    return value;
+}
+
+/* "fmt" must point to a buffer of at least 6 characters */
+static void set_number_format(char *fmt, int precision)
+{
+    int d1, d2, i;
+
+    assert(1 <= precision && precision <= 16);
+
+    /* Create printf format (%.14g) from precision */
+    d1 = precision / 10;
+    d2 = precision % 10;
+    fmt[0] = '%';
+    fmt[1] = '.';
+    i = 2;
+    if (d1) {
+        fmt[i++] = '0' + d1;
+    }
+    fmt[i++] = '0' + d2;
+    fmt[i++] = 'g';
+    fmt[i] = 0;
+}
+
+/* Assumes there is always at least 32 characters available in the target buffer */
+int fpconv_g_fmt(char *str, double num, int precision)
+{
+    char buf[FPCONV_G_FMT_BUFSIZE];
+    char fmt[6];
+    int len;
+    char *b;
+
+    set_number_format(fmt, precision);
+
+    /* Pass through when decimal point character is dot. */
+    if (locale_decimal_point == '.')
+        return snprintf(str, FPCONV_G_FMT_BUFSIZE, fmt, num);
+
+    /* snprintf() to a buffer then translate for other decimal point characters */
+    len = snprintf(buf, FPCONV_G_FMT_BUFSIZE, fmt, num);
+
+    /* Copy into target location. Translate decimal point if required */
+    b = buf;
+    do {
+        *str++ = (*b == locale_decimal_point ? '.' : *b);
+    } while(*b++);
+
+    return len;
+}
+
+void fpconv_init()
+{
+    fpconv_update_locale();
+}
+
+/* vi:ai et sw=4 ts=4:
+ */
diff --git a/src/cjson/fpconv.h b/src/cjson/fpconv.h
new file mode 100644
index 0000000000..7b0d0ee313
--- /dev/null
+++ b/src/cjson/fpconv.h
@@ -0,0 +1,22 @@
+/* Lua CJSON floating point conversion routines */
+
+/* Buffer required to store the largest string representation of a double.
+ *
+ * Longest double printed with %.14g is 21 characters long:
+ * -1.7976931348623e+308 */
+# define FPCONV_G_FMT_BUFSIZE   32
+
+#ifdef USE_INTERNAL_FPCONV
+static inline void fpconv_init()
+{
+    /* Do nothing - not required */
+}
+#else
+extern void fpconv_init();
+#endif
+
+extern int fpconv_g_fmt(char*, double, int);
+extern double fpconv_strtod(const char*, char**);
+
+/* vi:ai et sw=4 ts=4:
+ */
diff --git a/src/cjson/lua_cjson.c b/src/cjson/lua_cjson.c
new file mode 100644
index 0000000000..0c41cabac4
--- /dev/null
+++ b/src/cjson/lua_cjson.c
@@ -0,0 +1,1590 @@
+/* Lua CJSON - JSON support for Lua
+ *
+ * Copyright (c) 2010-2012  Mark Pulford <mark@kyne.com.au>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+/* Caveats:
+ * - JSON "null" values are represented as lightuserdata since Lua
+ *   tables cannot contain "nil". Compare with cjson.null.
+ * - Invalid UTF-8 characters are not detected and will be passed
+ *   untouched. If required, UTF-8 error checking should be done
+ *   outside this library.
+ * - Javascript comments are not part of the JSON spec, and are not
+ *   currently supported.
+ *
+ * Note: Decoding is slower than encoding. Lua spends significant
+ *       time (30%) managing tables when parsing JSON since it is
+ *       difficult to know object/array sizes ahead of time.
+ */
+
+#include <assert.h>
+#include <stdint.h>
+#include <string.h>
+#include <math.h>
+#include <limits.h>
+#include <lua.h>
+#include <lauxlib.h>
+
+#include "strbuf.h"
+#include "fpconv.h"
+
+#ifndef CJSON_MODNAME
+#define CJSON_MODNAME   "cjson"
+#endif
+
+#ifndef CJSON_VERSION
+#define CJSON_VERSION   "2.1.0.9"
+#endif
+
+#ifdef _MSC_VER
+#define snprintf sprintf_s
+
+#ifndef isnan
+#include <float.h>
+#define isnan(x) _isnan(x)
+#endif
+
+#endif
+
+/* Workaround for Solaris platforms missing isinf() */
+#if !defined(isinf) && (defined(USE_INTERNAL_ISINF) || defined(MISSING_ISINF))
+#define isinf(x) (!isnan(x) && isnan((x) - (x)))
+#endif
+
+#define DEFAULT_SPARSE_CONVERT 0
+#define DEFAULT_SPARSE_RATIO 2
+#define DEFAULT_SPARSE_SAFE 10
+#define DEFAULT_ENCODE_MAX_DEPTH 1000
+#define DEFAULT_DECODE_MAX_DEPTH 1000
+#define DEFAULT_ENCODE_INVALID_NUMBERS 0
+#define DEFAULT_DECODE_INVALID_NUMBERS 1
+#define DEFAULT_ENCODE_KEEP_BUFFER 1
+#define DEFAULT_ENCODE_NUMBER_PRECISION 14
+#define DEFAULT_ENCODE_EMPTY_TABLE_AS_OBJECT 1
+#define DEFAULT_DECODE_ARRAY_WITH_ARRAY_MT 0
+#define DEFAULT_ENCODE_ESCAPE_FORWARD_SLASH 1
+
+#ifdef DISABLE_INVALID_NUMBERS
+#undef DEFAULT_DECODE_INVALID_NUMBERS
+#define DEFAULT_DECODE_INVALID_NUMBERS 0
+#endif
+
+#ifdef _MSC_VER
+/* Microsoft C compiler lacks strncasecmp and strcasecmp. */
+#define strncasecmp _strnicmp
+#define strcasecmp _stricmp
+#endif
+
+#if LONG_MAX > ((1UL << 31) - 1)
+#define json_lightudata_mask(ludata)                                         \
+    ((void *) ((uintptr_t) (ludata) & ((1UL << 47) - 1)))
+
+#else
+#define json_lightudata_mask(ludata)    (ludata)
+#endif
+
+#if LUA_VERSION_NUM > 501
+#define lua_objlen(L,i)		lua_rawlen(L, (i))
+#endif
+
+static const char * const *json_empty_array;
+static const char * const *json_array;
+
+typedef enum {
+    T_OBJ_BEGIN,
+    T_OBJ_END,
+    T_ARR_BEGIN,
+    T_ARR_END,
+    T_STRING,
+    T_NUMBER,
+    T_BOOLEAN,
+    T_NULL,
+    T_COLON,
+    T_COMMA,
+    T_END,
+    T_WHITESPACE,
+    T_ERROR,
+    T_UNKNOWN
+} json_token_type_t;
+
+static const char *json_token_type_name[] = {
+    "T_OBJ_BEGIN",
+    "T_OBJ_END",
+    "T_ARR_BEGIN",
+    "T_ARR_END",
+    "T_STRING",
+    "T_NUMBER",
+    "T_BOOLEAN",
+    "T_NULL",
+    "T_COLON",
+    "T_COMMA",
+    "T_END",
+    "T_WHITESPACE",
+    "T_ERROR",
+    "T_UNKNOWN",
+    NULL
+};
+
+typedef struct {
+    json_token_type_t ch2token[256];
+    char escape2char[256];  /* Decoding */
+
+    /* encode_buf is only allocated and used when
+     * encode_keep_buffer is set */
+    strbuf_t encode_buf;
+
+    int encode_sparse_convert;
+    int encode_sparse_ratio;
+    int encode_sparse_safe;
+    int encode_max_depth;
+    int encode_invalid_numbers;     /* 2 => Encode as "null" */
+    int encode_number_precision;
+    int encode_keep_buffer;
+    int encode_empty_table_as_object;
+    int encode_escape_forward_slash;
+
+    int decode_invalid_numbers;
+    int decode_max_depth;
+    int decode_array_with_array_mt;
+} json_config_t;
+
+typedef struct {
+    const char *data;
+    const char *ptr;
+    strbuf_t *tmp;    /* Temporary storage for strings */
+    json_config_t *cfg;
+    int current_depth;
+} json_parse_t;
+
+typedef struct {
+    json_token_type_t type;
+    int index;
+    union {
+        const char *string;
+        double number;
+        int boolean;
+    } value;
+    int string_len;
+} json_token_t;
+
+static const char *char2escape[256] = {
+    "\\u0000", "\\u0001", "\\u0002", "\\u0003",
+    "\\u0004", "\\u0005", "\\u0006", "\\u0007",
+    "\\b", "\\t", "\\n", "\\u000b",
+    "\\f", "\\r", "\\u000e", "\\u000f",
+    "\\u0010", "\\u0011", "\\u0012", "\\u0013",
+    "\\u0014", "\\u0015", "\\u0016", "\\u0017",
+    "\\u0018", "\\u0019", "\\u001a", "\\u001b",
+    "\\u001c", "\\u001d", "\\u001e", "\\u001f",
+    NULL, NULL, "\\\"", NULL, NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, "\\/",
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL, "\\\\", NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, "\\u007f",
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+};
+
+/* ===== CONFIGURATION ===== */
+
+static json_config_t *json_fetch_config(lua_State *l)
+{
+    json_config_t *cfg;
+
+    cfg = lua_touserdata(l, lua_upvalueindex(1));
+    if (!cfg)
+        luaL_error(l, "BUG: Unable to fetch CJSON configuration");
+
+    return cfg;
+}
+
+/* Ensure the correct number of arguments have been provided.
+ * Pad with nil to allow other functions to simply check arg[i]
+ * to find whether an argument was provided */
+static json_config_t *json_arg_init(lua_State *l, int args)
+{
+    luaL_argcheck(l, lua_gettop(l) <= args, args + 1,
+                  "found too many arguments");
+
+    while (lua_gettop(l) < args)
+        lua_pushnil(l);
+
+    return json_fetch_config(l);
+}
+
+/* Process integer options for configuration functions */
+static int json_integer_option(lua_State *l, int optindex, int *setting,
+                               int min, int max)
+{
+    char errmsg[64];
+    int value;
+
+    if (!lua_isnil(l, optindex)) {
+        value = luaL_checkinteger(l, optindex);
+        snprintf(errmsg, sizeof(errmsg), "expected integer between %d and %d", min, max);
+        luaL_argcheck(l, min <= value && value <= max, 1, errmsg);
+        *setting = value;
+    }
+
+    lua_pushinteger(l, *setting);
+
+    return 1;
+}
+
+/* Process enumerated arguments for a configuration function */
+static int json_enum_option(lua_State *l, int optindex, int *setting,
+                            const char **options, int bool_true)
+{
+    static const char *bool_options[] = { "off", "on", NULL };
+
+    if (!options) {
+        options = bool_options;
+        bool_true = 1;
+    }
+
+    if (!lua_isnil(l, optindex)) {
+        if (bool_true && lua_isboolean(l, optindex))
+            *setting = lua_toboolean(l, optindex) * bool_true;
+        else
+            *setting = luaL_checkoption(l, optindex, NULL, options);
+    }
+
+    if (bool_true && (*setting == 0 || *setting == bool_true))
+        lua_pushboolean(l, *setting);
+    else
+        lua_pushstring(l, options[*setting]);
+
+    return 1;
+}
+
+/* Configures handling of extremely sparse arrays:
+ * convert: Convert extremely sparse arrays into objects? Otherwise error.
+ * ratio: 0: always allow sparse; 1: never allow sparse; >1: use ratio
+ * safe: Always use an array when the max index <= safe */
+static int json_cfg_encode_sparse_array(lua_State *l)
+{
+    json_config_t *cfg = json_arg_init(l, 3);
+
+    json_enum_option(l, 1, &cfg->encode_sparse_convert, NULL, 1);
+    json_integer_option(l, 2, &cfg->encode_sparse_ratio, 0, INT_MAX);
+    json_integer_option(l, 3, &cfg->encode_sparse_safe, 0, INT_MAX);
+
+    return 3;
+}
+
+/* Configures the maximum number of nested arrays/objects allowed when
+ * encoding */
+static int json_cfg_encode_max_depth(lua_State *l)
+{
+    json_config_t *cfg = json_arg_init(l, 1);
+
+    return json_integer_option(l, 1, &cfg->encode_max_depth, 1, INT_MAX);
+}
+
+/* Configures the maximum number of nested arrays/objects allowed when
+ * encoding */
+static int json_cfg_decode_max_depth(lua_State *l)
+{
+    json_config_t *cfg = json_arg_init(l, 1);
+
+    return json_integer_option(l, 1, &cfg->decode_max_depth, 1, INT_MAX);
+}
+
+/* Configures number precision when converting doubles to text */
+static int json_cfg_encode_number_precision(lua_State *l)
+{
+    json_config_t *cfg = json_arg_init(l, 1);
+
+    return json_integer_option(l, 1, &cfg->encode_number_precision, 1, 16);
+}
+
+/* Configures how to treat empty table when encode lua table */
+static int json_cfg_encode_empty_table_as_object(lua_State *l)
+{
+    json_config_t *cfg = json_arg_init(l, 1);
+
+    return json_enum_option(l, 1, &cfg->encode_empty_table_as_object, NULL, 1);
+}
+
+/* Configures how to decode arrays */
+static int json_cfg_decode_array_with_array_mt(lua_State *l)
+{
+    json_config_t *cfg = json_arg_init(l, 1);
+
+    json_enum_option(l, 1, &cfg->decode_array_with_array_mt, NULL, 1);
+
+    return 1;
+}
+
+/* Configures JSON encoding buffer persistence */
+static int json_cfg_encode_keep_buffer(lua_State *l)
+{
+    json_config_t *cfg = json_arg_init(l, 1);
+    int old_value;
+
+    old_value = cfg->encode_keep_buffer;
+
+    json_enum_option(l, 1, &cfg->encode_keep_buffer, NULL, 1);
+
+    /* Init / free the buffer if the setting has changed */
+    if (old_value ^ cfg->encode_keep_buffer) {
+        if (cfg->encode_keep_buffer)
+            strbuf_init(&cfg->encode_buf, 0);
+        else
+            strbuf_free(&cfg->encode_buf);
+    }
+
+    return 1;
+}
+
+#if defined(DISABLE_INVALID_NUMBERS) && !defined(USE_INTERNAL_FPCONV)
+void json_verify_invalid_number_setting(lua_State *l, int *setting)
+{
+    if (*setting == 1) {
+        *setting = 0;
+        luaL_error(l, "Infinity, NaN, and/or hexadecimal numbers are not supported.");
+    }
+}
+#else
+#define json_verify_invalid_number_setting(l, s)    do { } while(0)
+#endif
+
+static int json_cfg_encode_invalid_numbers(lua_State *l)
+{
+    static const char *options[] = { "off", "on", "null", NULL };
+    json_config_t *cfg = json_arg_init(l, 1);
+
+    json_enum_option(l, 1, &cfg->encode_invalid_numbers, options, 1);
+
+    json_verify_invalid_number_setting(l, &cfg->encode_invalid_numbers);
+
+    return 1;
+}
+
+static int json_cfg_decode_invalid_numbers(lua_State *l)
+{
+    json_config_t *cfg = json_arg_init(l, 1);
+
+    json_enum_option(l, 1, &cfg->decode_invalid_numbers, NULL, 1);
+
+    json_verify_invalid_number_setting(l, &cfg->encode_invalid_numbers);
+
+    return 1;
+}
+
+static int json_cfg_encode_escape_forward_slash(lua_State *l)
+{
+    int            ret;
+    json_config_t *cfg = json_arg_init(l, 1);
+
+    ret = json_enum_option(l, 1, &cfg->encode_escape_forward_slash, NULL, 1);
+    if (cfg->encode_escape_forward_slash) {
+        char2escape['/'] = "\\/";
+    } else {
+        char2escape['/'] = NULL;
+    }
+    return ret;
+}
+
+static int json_destroy_config(lua_State *l)
+{
+    json_config_t *cfg;
+
+    cfg = lua_touserdata(l, 1);
+    if (cfg)
+        strbuf_free(&cfg->encode_buf);
+    cfg = NULL;
+
+    return 0;
+}
+
+static void json_create_config(lua_State *l)
+{
+    json_config_t *cfg;
+    int i;
+
+    cfg = lua_newuserdata(l, sizeof(*cfg));
+
+    /* Create GC method to clean up strbuf */
+    lua_newtable(l);
+    lua_pushcfunction(l, json_destroy_config);
+    lua_setfield(l, -2, "__gc");
+    lua_setmetatable(l, -2);
+
+    cfg->encode_sparse_convert = DEFAULT_SPARSE_CONVERT;
+    cfg->encode_sparse_ratio = DEFAULT_SPARSE_RATIO;
+    cfg->encode_sparse_safe = DEFAULT_SPARSE_SAFE;
+    cfg->encode_max_depth = DEFAULT_ENCODE_MAX_DEPTH;
+    cfg->decode_max_depth = DEFAULT_DECODE_MAX_DEPTH;
+    cfg->encode_invalid_numbers = DEFAULT_ENCODE_INVALID_NUMBERS;
+    cfg->decode_invalid_numbers = DEFAULT_DECODE_INVALID_NUMBERS;
+    cfg->encode_keep_buffer = DEFAULT_ENCODE_KEEP_BUFFER;
+    cfg->encode_number_precision = DEFAULT_ENCODE_NUMBER_PRECISION;
+    cfg->encode_empty_table_as_object = DEFAULT_ENCODE_EMPTY_TABLE_AS_OBJECT;
+    cfg->decode_array_with_array_mt = DEFAULT_DECODE_ARRAY_WITH_ARRAY_MT;
+    cfg->encode_escape_forward_slash = DEFAULT_ENCODE_ESCAPE_FORWARD_SLASH;
+
+#if DEFAULT_ENCODE_KEEP_BUFFER > 0
+    strbuf_init(&cfg->encode_buf, 0);
+#endif
+
+    /* Decoding init */
+
+    /* Tag all characters as an error */
+    for (i = 0; i < 256; i++)
+        cfg->ch2token[i] = T_ERROR;
+
+    /* Set tokens that require no further processing */
+    cfg->ch2token['{'] = T_OBJ_BEGIN;
+    cfg->ch2token['}'] = T_OBJ_END;
+    cfg->ch2token['['] = T_ARR_BEGIN;
+    cfg->ch2token[']'] = T_ARR_END;
+    cfg->ch2token[','] = T_COMMA;
+    cfg->ch2token[':'] = T_COLON;
+    cfg->ch2token['\0'] = T_END;
+    cfg->ch2token[' '] = T_WHITESPACE;
+    cfg->ch2token['\t'] = T_WHITESPACE;
+    cfg->ch2token['\n'] = T_WHITESPACE;
+    cfg->ch2token['\r'] = T_WHITESPACE;
+
+    /* Update characters that require further processing */
+    cfg->ch2token['f'] = T_UNKNOWN;     /* false? */
+    cfg->ch2token['i'] = T_UNKNOWN;     /* inf, ininity? */
+    cfg->ch2token['I'] = T_UNKNOWN;
+    cfg->ch2token['n'] = T_UNKNOWN;     /* null, nan? */
+    cfg->ch2token['N'] = T_UNKNOWN;
+    cfg->ch2token['t'] = T_UNKNOWN;     /* true? */
+    cfg->ch2token['"'] = T_UNKNOWN;     /* string? */
+    cfg->ch2token['+'] = T_UNKNOWN;     /* number? */
+    cfg->ch2token['-'] = T_UNKNOWN;
+    for (i = 0; i < 10; i++)
+        cfg->ch2token['0' + i] = T_UNKNOWN;
+
+    /* Lookup table for parsing escape characters */
+    for (i = 0; i < 256; i++)
+        cfg->escape2char[i] = 0;          /* String error */
+    cfg->escape2char['"'] = '"';
+    cfg->escape2char['\\'] = '\\';
+    cfg->escape2char['/'] = '/';
+    cfg->escape2char['b'] = '\b';
+    cfg->escape2char['t'] = '\t';
+    cfg->escape2char['n'] = '\n';
+    cfg->escape2char['f'] = '\f';
+    cfg->escape2char['r'] = '\r';
+    cfg->escape2char['u'] = 'u';          /* Unicode parsing required */
+}
+
+/* ===== ENCODING ===== */
+
+static void json_encode_exception(lua_State *l, json_config_t *cfg, strbuf_t *json, int lindex,
+                                  const char *reason)
+{
+    if (!cfg->encode_keep_buffer)
+        strbuf_free(json);
+    luaL_error(l, "Cannot serialise %s: %s",
+                  lua_typename(l, lua_type(l, lindex)), reason);
+}
+
+/* json_append_string args:
+ * - lua_State
+ * - JSON strbuf
+ * - String (Lua stack index)
+ *
+ * Returns nothing. Doesn't remove string from Lua stack */
+static void json_append_string(lua_State *l, strbuf_t *json, int lindex)
+{
+    const char *escstr;
+    unsigned i;
+    const char *str;
+    size_t len;
+
+    str = lua_tolstring(l, lindex, &len);
+
+    /* Worst case is len * 6 (all unicode escapes).
+     * This buffer is reused constantly for small strings
+     * If there are any excess pages, they won't be hit anyway.
+     * This gains ~5% speedup. */
+    strbuf_ensure_empty_length(json, len * 6 + 2);
+
+    strbuf_append_char_unsafe(json, '\"');
+    for (i = 0; i < len; i++) {
+        escstr = char2escape[(unsigned char)str[i]];
+        if (escstr)
+            strbuf_append_string(json, escstr);
+        else
+            strbuf_append_char_unsafe(json, str[i]);
+    }
+    strbuf_append_char_unsafe(json, '\"');
+}
+
+/* Find the size of the array on the top of the Lua stack
+ * -1   object (not a pure array)
+ * >=0  elements in array
+ */
+static int lua_array_length(lua_State *l, json_config_t *cfg, strbuf_t *json)
+{
+    double k;
+    int max;
+    int items;
+
+    max = 0;
+    items = 0;
+
+    lua_pushnil(l);
+    /* table, startkey */
+    while (lua_next(l, -2) != 0) {
+        /* table, key, value */
+        if (lua_type(l, -2) == LUA_TNUMBER &&
+            (k = lua_tonumber(l, -2))) {
+            /* Integer >= 1 ? */
+            if (floor(k) == k && k >= 1) {
+                if (k > max)
+                    max = k;
+                items++;
+                lua_pop(l, 1);
+                continue;
+            }
+        }
+
+        /* Must not be an array (non integer key) */
+        lua_pop(l, 2);
+        return -1;
+    }
+
+    /* Encode excessively sparse arrays as objects (if enabled) */
+    if (cfg->encode_sparse_ratio > 0 &&
+        max > items * cfg->encode_sparse_ratio &&
+        max > cfg->encode_sparse_safe) {
+        if (!cfg->encode_sparse_convert)
+            json_encode_exception(l, cfg, json, -1, "excessively sparse array");
+
+        return -1;
+    }
+
+    return max;
+}
+
+static void json_check_encode_depth(lua_State *l, json_config_t *cfg,
+                                    int current_depth, strbuf_t *json)
+{
+    /* Ensure there are enough slots free to traverse a table (key,
+     * value) and push a string for a potential error message.
+     *
+     * Unlike "decode", the key and value are still on the stack when
+     * lua_checkstack() is called.  Hence an extra slot for luaL_error()
+     * below is required just in case the next check to lua_checkstack()
+     * fails.
+     *
+     * While this won't cause a crash due to the EXTRA_STACK reserve
+     * slots, it would still be an improper use of the API. */
+    if (current_depth <= cfg->encode_max_depth && lua_checkstack(l, 3))
+        return;
+
+    if (!cfg->encode_keep_buffer)
+        strbuf_free(json);
+
+    luaL_error(l, "Cannot serialise, excessive nesting (%d)",
+               current_depth);
+}
+
+static void json_append_data(lua_State *l, json_config_t *cfg,
+                             int current_depth, strbuf_t *json);
+
+/* json_append_array args:
+ * - lua_State
+ * - JSON strbuf
+ * - Size of passwd Lua array (top of stack) */
+static void json_append_array(lua_State *l, json_config_t *cfg, int current_depth,
+                              strbuf_t *json, int array_length)
+{
+    int comma, i;
+
+    strbuf_append_char(json, '[');
+
+    comma = 0;
+    for (i = 1; i <= array_length; i++) {
+        if (comma)
+            strbuf_append_char(json, ',');
+        else
+            comma = 1;
+
+        lua_rawgeti(l, -1, i);
+        json_append_data(l, cfg, current_depth, json);
+        lua_pop(l, 1);
+    }
+
+    strbuf_append_char(json, ']');
+}
+
+static void json_append_number(lua_State *l, json_config_t *cfg,
+                               strbuf_t *json, int lindex)
+{
+    double num = lua_tonumber(l, lindex);
+    int len;
+
+    if (cfg->encode_invalid_numbers == 0) {
+        /* Prevent encoding invalid numbers */
+        if (isinf(num) || isnan(num))
+            json_encode_exception(l, cfg, json, lindex,
+                                  "must not be NaN or Infinity");
+    } else if (cfg->encode_invalid_numbers == 1) {
+        /* Encode NaN/Infinity separately to ensure Javascript compatible
+         * values are used. */
+        if (isnan(num)) {
+            strbuf_append_mem(json, "NaN", 3);
+            return;
+        }
+        if (isinf(num)) {
+            if (num < 0)
+                strbuf_append_mem(json, "-Infinity", 9);
+            else
+                strbuf_append_mem(json, "Infinity", 8);
+            return;
+        }
+    } else {
+        /* Encode invalid numbers as "null" */
+        if (isinf(num) || isnan(num)) {
+            strbuf_append_mem(json, "null", 4);
+            return;
+        }
+    }
+
+    strbuf_ensure_empty_length(json, FPCONV_G_FMT_BUFSIZE);
+    len = fpconv_g_fmt(strbuf_empty_ptr(json), num, cfg->encode_number_precision);
+    strbuf_extend_length(json, len);
+}
+
+static void json_append_object(lua_State *l, json_config_t *cfg,
+                               int current_depth, strbuf_t *json)
+{
+    int comma, keytype;
+
+    /* Object */
+    strbuf_append_char(json, '{');
+
+    lua_pushnil(l);
+    /* table, startkey */
+    comma = 0;
+    while (lua_next(l, -2) != 0) {
+        if (comma)
+            strbuf_append_char(json, ',');
+        else
+            comma = 1;
+
+        /* table, key, value */
+        keytype = lua_type(l, -2);
+        if (keytype == LUA_TNUMBER) {
+            strbuf_append_char(json, '"');
+            json_append_number(l, cfg, json, -2);
+            strbuf_append_mem(json, "\":", 2);
+        } else if (keytype == LUA_TSTRING) {
+            json_append_string(l, json, -2);
+            strbuf_append_char(json, ':');
+        } else {
+            json_encode_exception(l, cfg, json, -2,
+                                  "table key must be a number or string");
+            /* never returns */
+        }
+
+        /* table, key, value */
+        json_append_data(l, cfg, current_depth, json);
+        lua_pop(l, 1);
+        /* table, key */
+    }
+
+    strbuf_append_char(json, '}');
+}
+
+/* Serialise Lua data into JSON string. */
+static void json_append_data(lua_State *l, json_config_t *cfg,
+                             int current_depth, strbuf_t *json)
+{
+    int len;
+    int as_array = 0;
+    int has_metatable;
+
+    switch (lua_type(l, -1)) {
+    case LUA_TSTRING:
+        json_append_string(l, json, -1);
+        break;
+    case LUA_TNUMBER:
+        json_append_number(l, cfg, json, -1);
+        break;
+    case LUA_TBOOLEAN:
+        if (lua_toboolean(l, -1))
+            strbuf_append_mem(json, "true", 4);
+        else
+            strbuf_append_mem(json, "false", 5);
+        break;
+    case LUA_TTABLE:
+        current_depth++;
+        json_check_encode_depth(l, cfg, current_depth, json);
+
+        has_metatable = lua_getmetatable(l, -1);
+
+        if (has_metatable) {
+            lua_pushlightuserdata(l, json_lightudata_mask(&json_array));
+            lua_rawget(l, LUA_REGISTRYINDEX);
+            as_array = lua_rawequal(l, -1, -2);
+            lua_pop(l, 2);
+        }
+
+        if (as_array) {
+            len = lua_objlen(l, -1);
+            json_append_array(l, cfg, current_depth, json, len);
+        } else {
+            len = lua_array_length(l, cfg, json);
+
+            if (len > 0 || (len == 0 && !cfg->encode_empty_table_as_object)) {
+                json_append_array(l, cfg, current_depth, json, len);
+            } else {
+                if (has_metatable) {
+                    lua_getmetatable(l, -1);
+                    lua_pushlightuserdata(l, json_lightudata_mask(
+                                          &json_empty_array));
+                    lua_rawget(l, LUA_REGISTRYINDEX);
+                    as_array = lua_rawequal(l, -1, -2);
+                    lua_pop(l, 2); /* pop pointer + metatable */
+                    if (as_array) {
+                        json_append_array(l, cfg, current_depth, json, 0);
+                        break;
+                    }
+                }
+                json_append_object(l, cfg, current_depth, json);
+            }
+        }