tsoding.frozen/frozen.c

/*
 * Copyright (c) 2004-2013 Sergey Lyubka <[email protected]>
 * Copyright (c) 2018 Cesanta Software Limited
 * 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.
 */

#define _CRT_SECURE_NO_WARNINGS /* Disable deprecation warning in VS2005+ */

#include "frozen.h"

#include <ctype.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#if !defined(WEAK)
#if (defined(__GNUC__) || defined(__TI_COMPILER_VERSION__)) && !defined(_WIN32)
#define WEAK __attribute__((weak))
#else
#define WEAK
#endif
#endif

#ifdef _WIN32
#undef snprintf
#undef vsnprintf
#define snprintf cs_win_snprintf
#define vsnprintf cs_win_vsnprintf
int cs_win_snprintf(char *str, size_t size, const char *format, ...);
int cs_win_vsnprintf(char *str, size_t size, const char *format, va_list ap);
#if _MSC_VER >= 1700
#include <stdint.h>
#else
typedef _int64 int64_t;
typedef unsigned _int64 uint64_t;
#endif
#define PRId64 "I64d"
#define PRIu64 "I64u"
#else /* _WIN32 */
/* <inttypes.h> wants this for C++ */
#ifndef __STDC_FORMAT_MACROS
#define __STDC_FORMAT_MACROS
#endif
#include <inttypes.h>
#endif /* _WIN32 */

#ifndef INT64_FMT
#define INT64_FMT PRId64
#endif
#ifndef UINT64_FMT
#define UINT64_FMT PRIu64
#endif

#ifndef va_copy
#define va_copy(x, y) x = y
#endif

#ifndef JSON_ENABLE_ARRAY
#define JSON_ENABLE_ARRAY 1
#endif

struct frozen {
  const char *end;
  const char *cur;

  const char *cur_name;
  size_t cur_name_len;

  /* For callback API */
  char path[JSON_MAX_PATH_LEN];
  size_t path_len;
  void *callback_data;
  json_walk_callback_t callback;
};

struct fstate {
  const char *ptr;
  size_t path_len;
};

#define SET_STATE(fr, ptr, str, len)              \
  struct fstate fstate = {(ptr), (fr)->path_len}; \
  json_append_to_path((fr), (str), (len));

#define CALL_BACK(fr, tok, value, len)                                        \
  do {                                                                        \
    if ((fr)->callback &&                                                     \
        ((fr)->path_len == 0 || (fr)->path[(fr)->path_len - 1] != '.')) {     \
      struct json_token t = {(value), (int) (len), (tok)};                    \
                                                                              \
      /* Call the callback with the given value and current name */           \
      (fr)->callback((fr)->callback_data, (fr)->cur_name, (fr)->cur_name_len, \
                     (fr)->path, &t);                                         \
                                                                              \
      /* Reset the name */                                                    \
      (fr)->cur_name = NULL;                                                  \
      (fr)->cur_name_len = 0;                                                 \
    }                                                                         \
  } while (0)

static int json_append_to_path(struct frozen *f, const char *str, int size) {
  int n = f->path_len;
  int left = sizeof(f->path) - n - 1;
  if (size > left) size = left;
  memcpy(f->path + n, str, size);
  f->path[n + size] = '\0';
  f->path_len += size;
  return n;
}

static void json_truncate_path(struct frozen *f, size_t len) {
  f->path_len = len;
  f->path[len] = '\0';
}

static int json_parse_object(struct frozen *f);
static int json_parse_value(struct frozen *f);

#define EXPECT(cond, err_code)      \
  do {                              \
    if (!(cond)) return (err_code); \
  } while (0)

#define TRY(expr)          \
  do {                     \
    int _n = expr;         \
    if (_n < 0) return _n; \
  } while (0)

#define END_OF_STRING (-1)

static int json_left(const struct frozen *f) {
  return f->end - f->cur;
}

static int json_isspace(int ch) {
  return ch == ' ' || ch == '\t' || ch == '\r' || ch == '\n';
}

static void json_skip_whitespaces(struct frozen *f) {
  while (f->cur < f->end && json_isspace(*f->cur)) f->cur++;
}

static int json_cur(struct frozen *f) {
  json_skip_whitespaces(f);
  return f->cur >= f->end ? END_OF_STRING : *(unsigned char *) f->cur;
}

static int json_test_and_skip(struct frozen *f, int expected) {
  int ch = json_cur(f);
  if (ch == expected) {
    f->cur++;
    return 0;
  }
  return ch == END_OF_STRING ? JSON_STRING_INCOMPLETE : JSON_STRING_INVALID;
}

static int json_isalpha(int ch) {
  return (ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z');
}

static int json_isdigit(int ch) {
  return ch >= '0' && ch <= '9';
}

static int json_isxdigit(int ch) {
  return json_isdigit(ch) || (ch >= 'a' && ch <= 'f') ||
         (ch >= 'A' && ch <= 'F');
}

static int json_get_escape_len(const char *s, int len) {
  switch (*s) {
    case 'u':
      return len < 6 ? JSON_STRING_INCOMPLETE
                     : json_isxdigit(s[1]) && json_isxdigit(s[2]) &&
                               json_isxdigit(s[3]) && json_isxdigit(s[4])
                           ? 5
                           : JSON_STRING_INVALID;
    case '"':
    case '\\':
    case '/':
    case 'b':
    case 'f':
    case 'n':
    case 'r':
    case 't':
      return len < 2 ? JSON_STRING_INCOMPLETE : 1;
    default:
      return JSON_STRING_INVALID;
  }
}

/* identifier = letter { letter | digit | '_' } */
static int json_parse_identifier(struct frozen *f) {
  EXPECT(json_isalpha(json_cur(f)), JSON_STRING_INVALID);
  {
    SET_STATE(f, f->cur, "", 0);
    while (f->cur < f->end &&
           (*f->cur == '_' || json_isalpha(*f->cur) || json_isdigit(*f->cur))) {
      f->cur++;
    }
    json_truncate_path(f, fstate.path_len);
    CALL_BACK(f, JSON_TYPE_STRING, fstate.ptr, f->cur - fstate.ptr);
  }
  return 0;
}

static int json_get_utf8_char_len(unsigned char ch) {
  if ((ch & 0x80) == 0) return 1;
  switch (ch & 0xf0) {
    case 0xf0:
      return 4;
    case 0xe0:
      return 3;
    default:
      return 2;
  }
}

/* string = '"' { quoted_printable_chars } '"' */
static int json_parse_string(struct frozen *f) {
  int n, ch = 0, len = 0;
  TRY(json_test_and_skip(f, '"'));
  {
    SET_STATE(f, f->cur, "", 0);
    for (; f->cur < f->end; f->cur += len) {
      ch = *(unsigned char *) f->cur;
      len = json_get_utf8_char_len((unsigned char) ch);
      EXPECT(ch >= 32 && len > 0, JSON_STRING_INVALID); /* No control chars */
      EXPECT(len <= json_left(f), JSON_STRING_INCOMPLETE);
      if (ch == '\\') {
        EXPECT((n = json_get_escape_len(f->cur + 1, json_left(f))) > 0, n);
        len += n;
      } else if (ch == '"') {
        json_truncate_path(f, fstate.path_len);
        CALL_BACK(f, JSON_TYPE_STRING, fstate.ptr, f->cur - fstate.ptr);
        f->cur++;
        break;
      };
    }
  }
  return ch == '"' ? 0 : JSON_STRING_INCOMPLETE;
}

/* number = [ '-' ] digit+ [ '.' digit+ ] [ ['e'|'E'] ['+'|'-'] digit+ ] */
static int json_parse_number(struct frozen *f) {
  int ch = json_cur(f);
  SET_STATE(f, f->cur, "", 0);
  if (ch == '-') f->cur++;
  EXPECT(f->cur < f->end, JSON_STRING_INCOMPLETE);
  if (f->cur + 1 < f->end && f->cur[0] == '0' && f->cur[1] == 'x') {
    f->cur += 2;
    EXPECT(f->cur < f->end, JSON_STRING_INCOMPLETE);
    EXPECT(json_isxdigit(f->cur[0]), JSON_STRING_INVALID);
    while (f->cur < f->end && json_isxdigit(f->cur[0])) f->cur++;
  } else {
    EXPECT(json_isdigit(f->cur[0]), JSON_STRING_INVALID);
    while (f->cur < f->end && json_isdigit(f->cur[0])) f->cur++;
    if (f->cur < f->end && f->cur[0] == '.') {
      f->cur++;
      EXPECT(f->cur < f->end, JSON_STRING_INCOMPLETE);
      EXPECT(json_isdigit(f->cur[0]), JSON_STRING_INVALID);
      while (f->cur < f->end && json_isdigit(f->cur[0])) f->cur++;
    }
    if (f->cur < f->end && (f->cur[0] == 'e' || f->cur[0] == 'E')) {
      f->cur++;
      EXPECT(f->cur < f->end, JSON_STRING_INCOMPLETE);
      if ((f->cur[0] == '+' || f->cur[0] == '-')) f->cur++;
      EXPECT(f->cur < f->end, JSON_STRING_INCOMPLETE);
      EXPECT(json_isdigit(f->cur[0]), JSON_STRING_INVALID);
      while (f->cur < f->end && json_isdigit(f->cur[0])) f->cur++;
    }
  }
  json_truncate_path(f, fstate.path_len);
  CALL_BACK(f, JSON_TYPE_NUMBER, fstate.ptr, f->cur - fstate.ptr);
  return 0;
}

#if JSON_ENABLE_ARRAY
/* array = '[' [ value { ',' value } ] ']' */
static int json_parse_array(struct frozen *f) {
  int i = 0, current_path_len;
  char buf[20];
  CALL_BACK(f, JSON_TYPE_ARRAY_START, NULL, 0);
  TRY(json_test_and_skip(f, '['));
  {
    {
      SET_STATE(f, f->cur - 1, "", 0);
      while (json_cur(f) != ']') {
        snprintf(buf, sizeof(buf), "[%d]", i);
        i++;
        current_path_len = json_append_to_path(f, buf, strlen(buf));
        f->cur_name =
            f->path + strlen(f->path) - strlen(buf) + 1 /*opening brace*/;
        f->cur_name_len = strlen(buf) - 2 /*braces*/;
        TRY(json_parse_value(f));
        json_truncate_path(f, current_path_len);
        if (json_cur(f) == ',') f->cur++;
      }
      TRY(json_test_and_skip(f, ']'));
      json_truncate_path(f, fstate.path_len);
      CALL_BACK(f, JSON_TYPE_ARRAY_END, fstate.ptr, f->cur - fstate.ptr);
    }
  }
  return 0;
}
#endif /* JSON_ENABLE_ARRAY */

static int json_expect(struct frozen *f, const char *s, int len,
                       enum json_token_type tok_type) {
  int i, n = json_left(f);
  SET_STATE(f, f->cur, "", 0);
  for (i = 0; i < len; i++) {
    if (i >= n) return JSON_STRING_INCOMPLETE;
    if (f->cur[i] != s[i]) return JSON_STRING_INVALID;
  }
  f->cur += len;
  json_truncate_path(f, fstate.path_len);

  CALL_BACK(f, tok_type, fstate.ptr, f->cur - fstate.ptr);

  return 0;
}

/* value = 'null' | 'true' | 'false' | number | string | array | object */
static int json_parse_value(struct frozen *f) {
  int ch = json_cur(f);

  switch (ch) {
    case '"':
      TRY(json_parse_string(f));
      break;
    case '{':
      TRY(json_parse_object(f));
      break;
#if JSON_ENABLE_ARRAY
    case '[':
      TRY(json_parse_array(f));
      break;
#endif
    case 'n':
      TRY(json_expect(f, "null", 4, JSON_TYPE_NULL));
      break;
    case 't':
      TRY(json_expect(f, "true", 4, JSON_TYPE_TRUE));
      break;
    case 'f':
      TRY(json_expect(f, "false", 5, JSON_TYPE_FALSE));
      break;
    case '-':
    case '0':
    case '1':
    case '2':
    case '3':
    case '4':
    case '5':
    case '6':
    case '7':
    case '8':
    case '9':
      TRY(json_parse_number(f));
      break;
    default:
      return ch == END_OF_STRING ? JSON_STRING_INCOMPLETE : JSON_STRING_INVALID;
  }

  return 0;
}

/* key = identifier | string */
static int json_parse_key(struct frozen *f) {
  int ch = json_cur(f);
  if (json_isalpha(ch)) {
    TRY(json_parse_identifier(f));
  } else if (ch == '"') {
    TRY(json_parse_string(f));
  } else {
    return ch == END_OF_STRING ? JSON_STRING_INCOMPLETE : JSON_STRING_INVALID;
  }
  return 0;
}

/* pair = key ':' value */
static int json_parse_pair(struct frozen *f) {
  int current_path_len;
  const char *tok;
  json_skip_whitespaces(f);
  tok = f->cur;
  TRY(json_parse_key(f));
  {
    f->cur_name = *tok == '"' ? tok + 1 : tok;
    f->cur_name_len = *tok == '"' ? f->cur - tok - 2 : f->cur - tok;
    current_path_len = json_append_to_path(f, f->cur_name, f->cur_name_len);
  }
  TRY(json_test_and_skip(f, ':'));
  TRY(json_parse_value(f));
  json_truncate_path(f, current_path_len);
  return 0;
}

/* object = '{' pair { ',' pair } '}' */
static int json_parse_object(struct frozen *f) {
  CALL_BACK(f, JSON_TYPE_OBJECT_START, NULL, 0);
  TRY(json_test_and_skip(f, '{'));
  {
    SET_STATE(f, f->cur - 1, ".", 1);
    while (json_cur(f) != '}') {
      TRY(json_parse_pair(f));
      if (json_cur(f) == ',') f->cur++;
    }
    TRY(json_test_and_skip(f, '}'));
    json_truncate_path(f, fstate.path_len);
    CALL_BACK(f, JSON_TYPE_OBJECT_END, fstate.ptr, f->cur - fstate.ptr);
  }
  return 0;
}

static int json_doit(struct frozen *f) {
  if (f->cur == 0 || f->end < f->cur) return JSON_STRING_INVALID;
  if (f->end == f->cur) return JSON_STRING_INCOMPLETE;
  return json_parse_value(f);
}

int json_escape(struct json_out *out, const char *p, size_t len) WEAK;
int json_escape(struct json_out *out, const char *p, size_t len) {
  size_t i, cl, n = 0;
  const char *hex_digits = "0123456789abcdef";
  const char *specials = "btnvfr";

  for (i = 0; i < len; i++) {
    unsigned char ch = ((unsigned char *) p)[i];
    if (ch == '"' || ch == '\\') {
      n += out->printer(out, "\\", 1);
      n += out->printer(out, p + i, 1);
    } else if (ch >= '\b' && ch <= '\r') {
      n += out->printer(out, "\\", 1);
      n += out->printer(out, &specials[ch - '\b'], 1);
    } else if (isprint(ch)) {
      n += out->printer(out, p + i, 1);
    } else if ((cl = json_get_utf8_char_len(ch)) == 1) {
      n += out->printer(out, "\\u00", 4);
      n += out->printer(out, &hex_digits[(ch >> 4) % 0xf], 1);
      n += out->printer(out, &hex_digits[ch % 0xf], 1);
    } else {
      n += out->printer(out, p + i, cl);
      i += cl - 1;
    }
  }

  return n;
}

int json_printer_buf(struct json_out *out, const char *buf, size_t len) WEAK;
int json_printer_buf(struct json_out *out, const char *buf, size_t len) {
  size_t avail = out->u.buf.size - out->u.buf.len;
  size_t n = len < avail ? len : avail;
  memcpy(out->u.buf.buf + out->u.buf.len, buf, n);
  out->u.buf.len += n;
  if (out->u.buf.size > 0) {
    size_t idx = out->u.buf.len;
    if (idx >= out->u.buf.size) idx = out->u.buf.size - 1;
    out->u.buf.buf[idx] = '\0';
  }
  return len;
}

int json_printer_file(struct json_out *out, const char *buf, size_t len) WEAK;
int json_printer_file(struct json_out *out, const char *buf, size_t len) {
  return fwrite(buf, 1, len, out->u.fp);
}

#if JSON_ENABLE_BASE64
static int b64idx(int c) {
  if (c < 26) {
    return c + 'A';
  } else if (c < 52) {
    return c - 26 + 'a';
  } else if (c < 62) {
    return c - 52 + '0';
  } else {
    return c == 62 ? '+' : '/';
  }
}

static int b64rev(int c) {
  if (c >= 'A' && c <= 'Z') {
    return c - 'A';
  } else if (c >= 'a' && c <= 'z') {
    return c + 26 - 'a';
  } else if (c >= '0' && c <= '9') {
    return c + 52 - '0';
  } else if (c == '+') {
    return 62;
  } else if (c == '/') {
    return 63;
  } else {
    return 64;
  }
}

static int b64enc(struct json_out *out, const unsigned char *p, int n) {
  char buf[4];
  int i, len = 0;
  for (i = 0; i < n; i += 3) {
    int a = p[i], b = i + 1 < n ? p[i + 1] : 0, c = i + 2 < n ? p[i + 2] : 0;
    buf[0] = b64idx(a >> 2);
    buf[1] = b64idx((a & 3) << 4 | (b >> 4));
    buf[2] = b64idx((b & 15) << 2 | (c >> 6));
    buf[3] = b64idx(c & 63);
    if (i + 1 >= n) buf[2] = '=';
    if (i + 2 >= n) buf[3] = '=';
    len += out->printer(out, buf, sizeof(buf));
  }
  return len;
}

static int b64dec(const char *src, int n, char *dst) {
  const char *end = src + n;
  int len = 0;
  while (src + 3 < end) {
    int a = b64rev(src[0]), b = b64rev(src[1]), c = b64rev(src[2]),
        d = b64rev(src[3]);
    dst[len++] = (a << 2) | (b >> 4);
    if (src[2] != '=') {
      dst[len++] = (b << 4) | (c >> 2);
      if (src[3] != '=') {
        dst[len++] = (c << 6) | d;
      }
    }
    src += 4;
  }
  return len;
}
#endif /* JSON_ENABLE_BASE64 */

static unsigned char hexdec(const char *s) {
#define HEXTOI(x) (x >= '0' && x <= '9' ? x - '0' : x - 'W')
  int a = tolower(*(const unsigned char *) s);
  int b = tolower(*(const unsigned char *) (s + 1));
  return (HEXTOI(a) << 4) | HEXTOI(b);
}

int json_vprintf(struct json_out *out, const char *fmt, va_list xap) WEAK;
int json_vprintf(struct json_out *out, const char *fmt, va_list xap) {
  int len = 0;
  const char *quote = "\"", *null = "null";
  va_list ap;
  va_copy(ap, xap);

  while (*fmt != '\0') {
    if (strchr(":, \r\n\t[]{}\"", *fmt) != NULL) {
      len += out->printer(out, fmt, 1);
      fmt++;
    } else if (fmt[0] == '%') {
      char buf[21];
      size_t skip = 2;

      if (fmt[1] == 'l' && fmt[2] == 'l' && (fmt[3] == 'd' || fmt[3] == 'u')) {
        int64_t val = va_arg(ap, int64_t);
        const char *fmt2 = fmt[3] == 'u' ? "%" UINT64_FMT : "%" INT64_FMT;
        snprintf(buf, sizeof(buf), fmt2, val);
        len += out->printer(out, buf, strlen(buf));
        skip += 2;
      } else if (fmt[1] == 'z' && fmt[2] == 'u') {
        size_t val = va_arg(ap, size_t);
        snprintf(buf, sizeof(buf), "%lu", (unsigned long) val);
        len += out->printer(out, buf, strlen(buf));
        skip += 1;
      } else if (fmt[1] == 'M') {
        json_printf_callback_t f = va_arg(ap, json_printf_callback_t);
        len += f(out, &ap);
      } else if (fmt[1] == 'B') {
        int val = va_arg(ap, int);
        const char *str = val ? "true" : "false";
        len += out->printer(out, str, strlen(str));
      } else if (fmt[1] == 'H') {
#if JSON_ENABLE_HEX
        const char *hex = "0123456789abcdef";
        int i, n = va_arg(ap, int);
        const unsigned char *p = va_arg(ap, const unsigned char *);
        len += out->printer(out, quote, 1);
        for (i = 0; i < n; i++) {
          len += out->printer(out, &hex[(p[i] >> 4) & 0xf], 1);
          len += out->printer(out, &hex[p[i] & 0xf], 1);
        }
        len += out->printer(out, quote, 1);
#endif /* JSON_ENABLE_HEX */
      } else if (fmt[1] == 'V') {
#if JSON_ENABLE_BASE64
        const unsigned char *p = va_arg(ap, const unsigned char *);
        int n = va_arg(ap, int);
        len += out->printer(out, quote, 1);
        len += b64enc(out, p, n);
        len += out->printer(out, quote, 1);
#endif /* JSON_ENABLE_BASE64 */
      } else if (fmt[1] == 'Q' ||
                 (fmt[1] == '.' && fmt[2] == '*' && fmt[3] == 'Q')) {
        size_t l = 0;
        const char *p;

        if (fmt[1] == '.') {
          l = (size_t) va_arg(ap, int);
          skip += 2;
        }
        p = va_arg(ap, char *);

        if (p == NULL) {
          len += out->printer(out, null, 4);
        } else {
          if (fmt[1] == 'Q') {
            l = strlen(p);
          }
          len += out->printer(out, quote, 1);
          len += json_escape(out, p, l);
          len += out->printer(out, quote, 1);
        }
      } else {
        /*
         * we delegate printing to the system printf.
         * The goal here is to delegate all modifiers parsing to the system
         * printf, as you can see below we still have to parse the format
         * types.
         *
         * Currently, %s with strings longer than 20 chars will require
         * double-buffering (an auxiliary buffer will be allocated from heap).
         * TODO(dfrank): reimplement %s and %.*s in order to avoid that.
         */

        const char *end_of_format_specifier = "sdfFeEgGlhuIcx.*-0123456789";
        int n = strspn(fmt + 1, end_of_format_specifier);
        char *pbuf = buf;
        int need_len, size = sizeof(buf);
        char fmt2[20];
        va_list ap_copy;
        strncpy(fmt2, fmt,
                n + 1 > (int) sizeof(fmt2) ? sizeof(fmt2) : (size_t) n + 1);
        fmt2[n + 1] = '\0';

        va_copy(ap_copy, ap);
        need_len = vsnprintf(pbuf, size, fmt2, ap_copy);
        va_end(ap_copy);

        if (need_len < 0) {
          /*
           * Windows & eCos vsnprintf implementation return -1 on overflow
           * instead of needed size.
           */
          pbuf = NULL;
          while (need_len < 0) {
            free(pbuf);
            size *= 2;
            if ((pbuf = (char *) malloc(size)) == NULL) break;
            va_copy(ap_copy, ap);
            need_len = vsnprintf(pbuf, size, fmt2, ap_copy);
            va_end(ap_copy);
          }
        } else if (need_len >= (int) sizeof(buf)) {
          /*
           * resulting string doesn't fit into a stack-allocated buffer `buf`,
           * so we need to allocate a new buffer from heap and use it
           */
          if ((pbuf = (char *) malloc(need_len + 1)) != NULL) {
            va_copy(ap_copy, ap);
            vsnprintf(pbuf, need_len + 1, fmt2, ap_copy);
            va_end(ap_copy);
          }
        }
        if (pbuf == NULL) {
          buf[0] = '\0';
          pbuf = buf;
        }

        /*
         * however we need to parse the type ourselves in order to advance
         * the va_list by the correct amount; there is no portable way to
         * inherit the advancement made by vprintf.
         * 32-bit (linux or windows) passes va_list by value.
         */
        if ((n + 1 == strlen("%" PRId64) && strcmp(fmt2, "%" PRId64) == 0) ||
            (n + 1 == strlen("%" PRIu64) && strcmp(fmt2, "%" PRIu64) == 0)) {
          (void) va_arg(ap, int64_t);
        } else if (strcmp(fmt2, "%.*s") == 0) {
          (void) va_arg(ap, int);
          (void) va_arg(ap, char *);
        } else {
          switch (fmt2[n]) {
            case 'u':
            case 'd':
              (void) va_arg(ap, int);
              break;
            case 'g':
            case 'f':
              (void) va_arg(ap, double);
              break;
            case 'p':
              (void) va_arg(ap, void *);
              break;
            default:
              /* many types are promoted to int */
              (void) va_arg(ap, int);
          }
        }

        len += out->printer(out, pbuf, strlen(pbuf));
        skip = n + 1;

        /* If buffer was allocated from heap, free it */
        if (pbuf != buf) {
          free(pbuf);
          pbuf = NULL;
        }
      }
      fmt += skip;
    } else if (*fmt == '_' || json_isalpha(*fmt)) {
      len += out->printer(out, quote, 1);
      while (*fmt == '_' || json_isalpha(*fmt) || json_isdigit(*fmt)) {
        len += out->printer(out, fmt, 1);
        fmt++;
      }
      len += out->printer(out, quote, 1);
    } else {
      len += out->printer(out, fmt, 1);
      fmt++;
    }
  }
  va_end(ap);

  return len;
}

int json_printf(struct json_out *out, const char *fmt, ...) WEAK;
int json_printf(struct json_out *out, const char *fmt, ...) {
  int n;
  va_list ap;
  va_start(ap, fmt);
  n = json_vprintf(out, fmt, ap);
  va_end(ap);
  return n;
}

int json_printf_array(struct json_out *out, va_list *ap) WEAK;
int json_printf_array(struct json_out *out, va_list *ap) {
  int len = 0;
  char *arr = va_arg(*ap, char *);
  size_t i, arr_size = va_arg(*ap, size_t);
  size_t elem_size = va_arg(*ap, size_t);
  const char *fmt = va_arg(*ap, char *);
  len += json_printf(out, "[", 1);
  for (i = 0; arr != NULL && i < arr_size / elem_size; i++) {
    union {
      int64_t i;
      double d;
    } val;
    memcpy(&val, arr + i * elem_size,
           elem_size > sizeof(val) ? sizeof(val) : elem_size);
    if (i > 0) len += json_printf(out, ", ");
    if (strpbrk(fmt, "efg") != NULL) {
      len += json_printf(out, fmt, val.d);
    } else {
      len += json_printf(out, fmt, val.i);
    }
  }
  len += json_printf(out, "]", 1);
  return len;
}

#ifdef _WIN32
int cs_win_vsnprintf(char *str, size_t size, const char *format,
                     va_list ap) WEAK;
int cs_win_vsnprintf(char *str, size_t size, const char *format, va_list ap) {
  int res = _vsnprintf(str, size, format, ap);
  va_end(ap);
  if (res >= size) {
    str[size - 1] = '\0';
  }
  return res;
}

int cs_win_snprintf(char *str, size_t size, const char *format, ...) WEAK;
int cs_win_snprintf(char *str, size_t size, const char *format, ...) {
  int res;
  va_list ap;
  va_start(ap, format);
  res = vsnprintf(str, size, format, ap);
  va_end(ap);
  return res;
}
#endif /* _WIN32 */

int json_walk(const char *json_string, int json_string_length,
              json_walk_callback_t callback, void *callback_data) WEAK;
int json_walk(const char *json_string, int json_string_length,
              json_walk_callback_t callback, void *callback_data) {
  struct frozen frozen;

  memset(&frozen, 0, sizeof(frozen));
  frozen.end = json_string + json_string_length;
  frozen.cur = json_string;
  frozen.callback_data = callback_data;
  frozen.callback = callback;

  TRY(json_doit(&frozen));

  return frozen.cur - json_string;
}

struct scan_array_info {
  int found;
  char path[JSON_MAX_PATH_LEN];
  struct json_token *token;
};

static void json_scanf_array_elem_cb(void *callback_data, const char *name,
                                     size_t name_len, const char *path,
                                     const struct json_token *token) {
  struct scan_array_info *info = (struct scan_array_info *) callback_data;

  (void) name;
  (void) name_len;

  if (strcmp(path, info->path) == 0) {
    *info->token = *token;
    info->found = 1;
  }
}

int json_scanf_array_elem(const char *s, int len, const char *path, int idx,
                          struct json_token *token) WEAK;
int json_scanf_array_elem(const char *s, int len, const char *path, int idx,
                          struct json_token *token) {
  struct scan_array_info info;
  info.token = token;
  info.found = 0;
  memset(token, 0, sizeof(*token));
  snprintf(info.path, sizeof(info.path), "%s[%d]", path, idx);
  json_walk(s, len, json_scanf_array_elem_cb, &info);
  return info.found ? token->len : -1;
}

struct json_scanf_info {
  int num_conversions;
  char *path;
  const char *fmt;
  void *target;
  void *user_data;
  int type;
};

int json_unescape(const char *src, int slen, char *dst, int dlen) WEAK;
int json_unescape(const char *src, int slen, char *dst, int dlen) {
  char *send = (char *) src + slen, *dend = dst + dlen, *orig_dst = dst, *p;
  const char *esc1 = "\"\\/bfnrt", *esc2 = "\"\\/\b\f\n\r\t";

  while (src < send) {
    if (*src == '\\') {
      if (++src >= send) return JSON_STRING_INCOMPLETE;
      if (*src == 'u') {
        if (send - src < 5) return JSON_STRING_INCOMPLETE;
        /* Here we go: this is a \u.... escape. Process simple one-byte chars */
        if (src[1] == '0' && src[2] == '0') {
          /* This is \u00xx character from the ASCII range */
          if (dst < dend) *dst = hexdec(src + 3);
          src += 4;
        } else {
          /* Complex \uXXXX escapes drag utf8 lib... Do it at some stage */
          return JSON_STRING_INVALID;
        }
      } else if ((p = (char *) strchr(esc1, *src)) != NULL) {
        if (dst < dend) *dst = esc2[p - esc1];
      } else {
        return JSON_STRING_INVALID;
      }
    } else {
      if (dst < dend) *dst = *src;
    }
    dst++;
    src++;
  }

  return dst - orig_dst;
}

static void json_scanf_cb(void *callback_data, const char *name,
                          size_t name_len, const char *path,
                          const struct json_token *token) {
  struct json_scanf_info *info = (struct json_scanf_info *) callback_data;
  char buf[32]; /* Must be enough to hold numbers */

  (void) name;
  (void) name_len;

  if (token->ptr == NULL) {
    /*
     * We're not interested here in the events for which we have no value;
     * namely, JSON_TYPE_OBJECT_START and JSON_TYPE_ARRAY_START
     */
    return;
  }

  if (strcmp(path, info->path) != 0) {
    /* It's not the path we're looking for, so, just ignore this callback */
    return;
  }

  switch (info->type) {
    case 'B':
      info->num_conversions++;
      switch (sizeof(bool)) {
        case sizeof(char):
          *(char *) info->target = (token->type == JSON_TYPE_TRUE ? 1 : 0);
          break;
        case sizeof(int):
          *(int *) info->target = (token->type == JSON_TYPE_TRUE ? 1 : 0);
          break;
        default:
          /* should never be here */
          abort();
      }
      break;
    case 'M': {
      union {
        void *p;
        json_scanner_t f;
      } u = {info->target};
      info->num_conversions++;
      u.f(token->ptr, token->len, info->user_data);
      break;
    }
    case 'Q': {
      char **dst = (char **) info->target;
      if (token->type == JSON_TYPE_NULL) {
        *dst = NULL;
      } else {
        int unescaped_len = json_unescape(token->ptr, token->len, NULL, 0);
        if (unescaped_len >= 0 &&
            (*dst = (char *) malloc(unescaped_len + 1)) != NULL) {
          info->num_conversions++;
          if (json_unescape(token->ptr, token->len, *dst, unescaped_len) ==
              unescaped_len) {
            (*dst)[unescaped_len] = '\0';
          } else {
            free(*dst);
            *dst = NULL;
          }
        }
      }
      break;
    }
    case 'H': {
#if JSON_ENABLE_HEX
      char **dst = (char **) info->user_data;
      int i, len = token->len / 2;
      *(int *) info->target = len;
      if ((*dst = (char *) malloc(len + 1)) != NULL) {
        for (i = 0; i < len; i++) {
          (*dst)[i] = hexdec(token->ptr + 2 * i);
        }
        (*dst)[len] = '\0';
        info->num_conversions++;
      }
#endif /* JSON_ENABLE_HEX */
      break;
    }
    case 'V': {
#if JSON_ENABLE_BASE64
      char **dst = (char **) info->target;
      int len = token->len * 4 / 3 + 2;
      if ((*dst = (char *) malloc(len + 1)) != NULL) {
        int n = b64dec(token->ptr, token->len, *dst);
        (*dst)[n] = '\0';
        *(int *) info->user_data = n;
        info->num_conversions++;
      }
#endif /* JSON_ENABLE_BASE64 */
      break;
    }
    case 'T':
      info->num_conversions++;
      *(struct json_token *) info->target = *token;
      break;
    default:
      if (token->len >= (int) sizeof(buf)) break;
      /* Before converting, copy into tmp buffer in order to 0-terminate it */
      memcpy(buf, token->ptr, token->len);
      buf[token->len] = '\0';
      /* NB: Use of base 0 for %d, %ld, %u and %lu is intentional. */
      if (info->fmt[1] == 'd' || (info->fmt[1] == 'l' && info->fmt[2] == 'd') ||
          info->fmt[1] == 'i') {
        char *endptr = NULL;
        long r = strtol(buf, &endptr, 0 /* base */);
        if (*endptr == '\0') {
          if (info->fmt[1] == 'l') {
            *((long *) info->target) = r;
          } else {
            *((int *) info->target) = (int) r;
          }
          info->num_conversions++;
        }
      } else if (info->fmt[1] == 'u' ||
                 (info->fmt[1] == 'l' && info->fmt[2] == 'u')) {
        char *endptr = NULL;
        unsigned long r = strtoul(buf, &endptr, 0 /* base */);
        if (*endptr == '\0') {
          if (info->fmt[1] == 'l') {
            *((unsigned long *) info->target) = r;
          } else {
            *((unsigned int *) info->target) = (unsigned int) r;
          }
          info->num_conversions++;
        }
      } else {
#if !JSON_MINIMAL
        info->num_conversions += sscanf(buf, info->fmt, info->target);
#endif
      }
      break;
  }
}

int json_vscanf(const char *s, int len, const char *fmt, va_list ap) WEAK;
int json_vscanf(const char *s, int len, const char *fmt, va_list ap) {
  char path[JSON_MAX_PATH_LEN] = "", fmtbuf[20];
  int i = 0;
  char *p = NULL;
  struct json_scanf_info info = {0, path, fmtbuf, NULL, NULL, 0};

  while (fmt[i] != '\0') {
    if (fmt[i] == '{') {
      strcat(path, ".");
      i++;
    } else if (fmt[i] == '}') {
      if ((p = strrchr(path, '.')) != NULL) *p = '\0';
      i++;
    } else if (fmt[i] == '%') {
      info.target = va_arg(ap, void *);
      info.type = fmt[i + 1];
      switch (fmt[i + 1]) {
        case 'M':
        case 'V':
        case 'H':
          info.user_data = va_arg(ap, void *);
        /* FALLTHROUGH */
        case 'B':
        case 'Q':
        case 'T':
          i += 2;
          break;
        default: {
          const char *delims = ", \t\r\n]}";
          int conv_len = strcspn(fmt + i + 1, delims) + 1;
          memcpy(fmtbuf, fmt + i, conv_len);
          fmtbuf[conv_len] = '\0';
          i += conv_len;
          i += strspn(fmt + i, delims);
          break;
        }
      }
      json_walk(s, len, json_scanf_cb, &info);
    } else if (json_isalpha(fmt[i]) || json_get_utf8_char_len(fmt[i]) > 1) {
      char *pe;
      const char *delims = ": \r\n\t";
      int key_len = strcspn(&fmt[i], delims);
      if ((p = strrchr(path, '.')) != NULL) p[1] = '\0';
      pe = path + strlen(path);
      memcpy(pe, fmt + i, key_len);
      pe[key_len] = '\0';
      i += key_len + strspn(fmt + i + key_len, delims);
    } else {
      i++;
    }
  }
  return info.num_conversions;
}

int json_scanf(const char *str, int len, const char *fmt, ...) WEAK;
int json_scanf(const char *str, int len, const char *fmt, ...) {
  int result;
  va_list ap;
  va_start(ap, fmt);
  result = json_vscanf(str, len, fmt, ap);
  va_end(ap);
  return result;
}

int json_vfprintf(const char *file_name, const char *fmt, va_list ap) WEAK;
int json_vfprintf(const char *file_name, const char *fmt, va_list ap) {
  int res = -1;
  FILE *fp = fopen(file_name, "wb");
  if (fp != NULL) {
    struct json_out out = JSON_OUT_FILE(fp);
    res = json_vprintf(&out, fmt, ap);
    fputc('\n', fp);
    fclose(fp);
  }
  return res;
}

int json_fprintf(const char *file_name, const char *fmt, ...) WEAK;
int json_fprintf(const char *file_name, const char *fmt, ...) {
  int result;
  va_list ap;
  va_start(ap, fmt);
  result = json_vfprintf(file_name, fmt, ap);
  va_end(ap);
  return result;
}

char *json_fread(const char *path) WEAK;
char *json_fread(const char *path) {
  FILE *fp;
  char *data = NULL;
  if ((fp = fopen(path, "rb")) == NULL) {
  } else if (fseek(fp, 0, SEEK_END) != 0) {
    fclose(fp);
  } else {
    long size = ftell(fp);
    if (size > 0 && (data = (char *) malloc(size + 1)) != NULL) {
      fseek(fp, 0, SEEK_SET); /* Some platforms might not have rewind(), Oo */
      if (fread(data, 1, size, fp) != (size_t) size) {
        free(data);
        data = NULL;
      } else {
        data[size] = '\0';
      }
    }
    fclose(fp);
  }
  return data;
}

struct json_setf_data {
  const char *json_path;
  const char *base; /* Pointer to the source JSON string */
  int matched;      /* Matched part of json_path */
  int pos;          /* Offset of the mutated value begin */
  int end;          /* Offset of the mutated value end */
  int prev;         /* Offset of the previous token end */
};

static int get_matched_prefix_len(const char *s1, const char *s2) {
  int i = 0;
  while (s1[i] && s2[i] && s1[i] == s2[i]) i++;
  return i;
}

static void json_vsetf_cb(void *userdata, const char *name, size_t name_len,
                          const char *path, const struct json_token *t) {
  struct json_setf_data *data = (struct json_setf_data *) userdata;
  int off, len = get_matched_prefix_len(path, data->json_path);
  if (t->ptr == NULL) return;
  off = t->ptr - data->base;
  if (len > data->matched) data->matched = len;

  /*
   * If there is no exact path match, set the mutation position to tbe end
   * of the object or array
   */
  if (len < data->matched && data->pos == 0 &&
      (t->type == JSON_TYPE_OBJECT_END || t->type == JSON_TYPE_ARRAY_END)) {
    data->pos = data->end = data->prev;
  }

  /* Exact path match. Set mutation position to the value of this token */
  if (strcmp(path, data->json_path) == 0 && t->type != JSON_TYPE_OBJECT_START &&
      t->type != JSON_TYPE_ARRAY_START) {
    data->pos = off;
    data->end = off + t->len;
  }

  /*
   * For deletion, we need to know where the previous value ends, because
   * we don't know where matched value key starts.
   * When the mutation position is not yet set, remember each value end.
   * When the mutation position is already set, but it is at the beginning
   * of the object/array, we catch the end of the object/array and see
   * whether the object/array start is closer then previously stored prev.
   */
  if (data->pos == 0) {
    data->prev = off + t->len; /* pos is not yet set */
  } else if ((t->ptr[0] == '[' || t->ptr[0] == '{') && off + 1 < data->pos &&
             off + 1 > data->prev) {
    data->prev = off + 1;
  }
  (void) name;
  (void) name_len;
}

int json_vsetf(const char *s, int len, struct json_out *out,
               const char *json_path, const char *json_fmt, va_list ap) WEAK;
int json_vsetf(const char *s, int len, struct json_out *out,
               const char *json_path, const char *json_fmt, va_list ap) {
  struct json_setf_data data;
  memset(&data, 0, sizeof(data));
  data.json_path = json_path;
  data.base = s;
  data.end = len;
  json_walk(s, len, json_vsetf_cb, &data);
  if (json_fmt == NULL) {
    /* Deletion codepath */
    json_printf(out, "%.*s", data.prev, s);
    /* Trim comma after the value that begins at object/array start */
    if (s[data.prev - 1] == '{' || s[data.prev - 1] == '[') {
      int i = data.end;
      while (i < len && json_isspace(s[i])) i++;
      if (s[i] == ',') data.end = i + 1; /* Point after comma */
    }
    json_printf(out, "%.*s", len - data.end, s + data.end);
  } else {
    /* Modification codepath */
    int n, off = data.matched, depth = 0;

    /* Print the unchanged beginning */
    json_printf(out, "%.*s", data.pos, s);

    /* Add missing keys */
    while ((n = strcspn(&json_path[off], ".[")) > 0) {
      if (s[data.prev - 1] != '{' && s[data.prev - 1] != '[' && depth == 0) {
        json_printf(out, ",");
      }
      if (off > 0 && json_path[off - 1] != '.') break;
      json_printf(out, "%.*Q:", n, json_path + off);
      off += n;
      if (json_path[off] != '\0') {
        json_printf(out, "%c", json_path[off] == '.' ? '{' : '[');
        depth++;
        off++;
      }
    }
    /* Print the new value */
    json_vprintf(out, json_fmt, ap);

    /* Close brackets/braces of the added missing keys */
    for (; off > data.matched; off--) {
      int ch = json_path[off];
      const char *p = ch == '.' ? "}" : ch == '[' ? "]" : "";
      json_printf(out, "%s", p);
    }

    /* Print the rest of the unchanged string */
    json_printf(out, "%.*s", len - data.end, s + data.end);
  }
  return data.end > data.pos ? 1 : 0;
}

int json_setf(const char *s, int len, struct json_out *out,
              const char *json_path, const char *json_fmt, ...) WEAK;
int json_setf(const char *s, int len, struct json_out *out,
              const char *json_path, const char *json_fmt, ...) {
  int result;
  va_list ap;
  va_start(ap, json_fmt);
  result = json_vsetf(s, len, out, json_path, json_fmt, ap);
  va_end(ap);
  return result;
}

struct prettify_data {
  struct json_out *out;
  int level;
  int last_token;
};

static void indent(struct json_out *out, int level) {
  while (level-- > 0) out->printer(out, "  ", 2);
}

static void print_key(struct prettify_data *pd, const char *path,
                      const char *name, int name_len) {
  if (pd->last_token != JSON_TYPE_INVALID &&
      pd->last_token != JSON_TYPE_ARRAY_START &&
      pd->last_token != JSON_TYPE_OBJECT_START) {
    pd->out->printer(pd->out, ",", 1);
  }
  if (path[0] != '\0') pd->out->printer(pd->out, "\n", 1);
  indent(pd->out, pd->level);
  if (path[0] != '\0' && path[strlen(path) - 1] != ']') {
    pd->out->printer(pd->out, "\"", 1);
    pd->out->printer(pd->out, name, (int) name_len);
    pd->out->printer(pd->out, "\"", 1);
    pd->out->printer(pd->out, ": ", 2);
  }
}

static void prettify_cb(void *userdata, const char *name, size_t name_len,
                        const char *path, const struct json_token *t) {
  struct prettify_data *pd = (struct prettify_data *) userdata;
  switch (t->type) {
    case JSON_TYPE_OBJECT_START:
    case JSON_TYPE_ARRAY_START:
      print_key(pd, path, name, name_len);
      pd->out->printer(pd->out, t->type == JSON_TYPE_ARRAY_START ? "[" : "{",
                       1);
      pd->level++;
      break;
    case JSON_TYPE_OBJECT_END:
    case JSON_TYPE_ARRAY_END:
      pd->level--;
      if (pd->last_token != JSON_TYPE_INVALID &&
          pd->last_token != JSON_TYPE_ARRAY_START &&
          pd->last_token != JSON_TYPE_OBJECT_START) {
        pd->out->printer(pd->out, "\n", 1);
        indent(pd->out, pd->level);
      }
      pd->out->printer(pd->out, t->type == JSON_TYPE_ARRAY_END ? "]" : "}", 1);
      break;
    case JSON_TYPE_NUMBER:
    case JSON_TYPE_NULL:
    case JSON_TYPE_TRUE:
    case JSON_TYPE_FALSE:
    case JSON_TYPE_STRING:
      print_key(pd, path, name, name_len);
      if (t->type == JSON_TYPE_STRING) pd->out->printer(pd->out, "\"", 1);
      pd->out->printer(pd->out, t->ptr, t->len);
      if (t->type == JSON_TYPE_STRING) pd->out->printer(pd->out, "\"", 1);
      break;
    default:
      break;
  }
  pd->last_token = t->type;
}

int json_prettify(const char *s, int len, struct json_out *out) WEAK;
int json_prettify(const char *s, int len, struct json_out *out) {
  struct prettify_data pd = {out, 0, JSON_TYPE_INVALID};
  return json_walk(s, len, prettify_cb, &pd);
}

int json_prettify_file(const char *file_name) WEAK;
int json_prettify_file(const char *file_name) {
  int res = -1;
  char *s = json_fread(file_name);
  FILE *fp;
  if (s != NULL && (fp = fopen(file_name, "wb")) != NULL) {
    struct json_out out = JSON_OUT_FILE(fp);
    res = json_prettify(s, strlen(s), &out);
    if (res < 0) {
      /* On error, restore the old content */
      fclose(fp);
      fp = fopen(file_name, "wb");
      fseek(fp, 0, SEEK_SET);
      fwrite(s, 1, strlen(s), fp);
    } else {
      fputc('\n', fp);
    }
    fclose(fp);
  }
  free(s);
  return res;
}

struct next_data {
  void *handle;            // Passed handle. Changed if a next entry is found
  const char *path;        // Path to the iterated object/array
  int path_len;            // Path length - optimisation
  int found;               // Non-0 if found the next entry
  struct json_token *key;  // Object's key
  struct json_token *val;  // Object's value
  int *idx;                // Array index
};

static void next_set_key(struct next_data *d, const char *name, int name_len,
                         int is_array) {
  if (is_array) {
    /* Array. Set index and reset key  */
    if (d->key != NULL) {
      d->key->len = 0;
      d->key->ptr = NULL;
    }
    if (d->idx != NULL) *d->idx = atoi(name);
  } else {
    /* Object. Set key and make index -1 */
    if (d->key != NULL) {
      d->key->ptr = name;
      d->key->len = name_len;
    }
    if (d->idx != NULL) *d->idx = -1;
  }
}

static void json_next_cb(void *userdata, const char *name, size_t name_len,
                         const char *path, const struct json_token *t) {
  struct next_data *d = (struct next_data *) userdata;
  const char *p = path + d->path_len;
  if (d->found) return;
  if (d->path_len >= (int) strlen(path)) return;
  if (strncmp(d->path, path, d->path_len) != 0) return;
  if (strchr(p + 1, '.') != NULL) return; /* More nested objects - skip */
  if (strchr(p + 1, '[') != NULL) return; /* Ditto for arrays */
  // {OBJECT,ARRAY}_END types do not pass name, _START does. Save key.
  if (t->type == JSON_TYPE_OBJECT_START || t->type == JSON_TYPE_ARRAY_START) {
    next_set_key(d, name, name_len, p[0] == '[');
  } else if (d->handle == NULL || d->handle < (void *) t->ptr) {
    if (t->type != JSON_TYPE_OBJECT_END && t->type != JSON_TYPE_ARRAY_END) {
      next_set_key(d, name, name_len, p[0] == '[');
    }
    if (d->val != NULL) *d->val = *t;
    d->handle = (void *) t->ptr;
    d->found = 1;
  }
}

static void *json_next(const char *s, int len, void *handle, const char *path,
                       struct json_token *key, struct json_token *val, int *i) {
  struct json_token tmpval, *v = val == NULL ? &tmpval : val;
  struct json_token tmpkey, *k = key == NULL ? &tmpkey : key;
  int tmpidx, *pidx = i == NULL ? &tmpidx : i;
  struct next_data data = {handle, path, (int) strlen(path), 0, k, v, pidx};
  json_walk(s, len, json_next_cb, &data);
  return data.found ? data.handle : NULL;
}

void *json_next_key(const char *s, int len, void *handle, const char *path,
                    struct json_token *key, struct json_token *val) WEAK;
void *json_next_key(const char *s, int len, void *handle, const char *path,
                    struct json_token *key, struct json_token *val) {
  return json_next(s, len, handle, path, key, val, NULL);
}

void *json_next_elem(const char *s, int len, void *handle, const char *path,
                     int *idx, struct json_token *val) WEAK;
void *json_next_elem(const char *s, int len, void *handle, const char *path,
                     int *idx, struct json_token *val) {
  return json_next(s, len, handle, path, NULL, val, idx);
}

static int json_sprinter(struct json_out *out, const char *str, size_t len) {
  size_t old_len = out->u.buf.buf == NULL ? 0 : strlen(out->u.buf.buf);
  size_t new_len = len + old_len;
  char *p = (char *) realloc(out->u.buf.buf, new_len + 1);
  if (p != NULL) {
    memcpy(p + old_len, str, len);
    p[new_len] = '\0';
    out->u.buf.buf = p;
  }
  return len;
}

char *json_vasprintf(const char *fmt, va_list ap) WEAK;
char *json_vasprintf(const char *fmt, va_list ap) {
  struct json_out out;
  memset(&out, 0, sizeof(out));
  out.printer = json_sprinter;
  json_vprintf(&out, fmt, ap);
  return out.u.buf.buf;
}

char *json_asprintf(const char *fmt, ...) WEAK;
char *json_asprintf(const char *fmt, ...) {
  char *result = NULL;
  va_list ap;
  va_start(ap, fmt);
  result = json_vasprintf(fmt, ap);
  va_end(ap);
  return result;
}