cvs.zerfleddert.de Git - proxmark3-svn/blob - client/jansson/pack_unpack.c

   1 /*
   2  * Copyright (c) 2009-2016 Petri Lehtinen <petri@digip.org>
   3  * Copyright (c) 2011-2012 Graeme Smecher <graeme.smecher@mail.mcgill.ca>
   4  *
   5  * Jansson is free software; you can redistribute it and/or modify
   6  * it under the terms of the MIT license. See LICENSE for details.
   7  */
   8
   9 #include <string.h>
  10 #include "jansson.h"
  11 #include "jansson_private.h"
  12 #include "utf.h"
  13
  14 typedef struct {
  15     int line;
  16     int column;
  17     size_t pos;
  18     char token;
  19 } token_t;
  20
  21 typedef struct {
  22     const char *start;
  23     const char *fmt;
  24     token_t prev_token;
  25     token_t token;
  26     token_t next_token;
  27     json_error_t *error;
  28     size_t flags;
  29     int line;
  30     int column;
  31     size_t pos;
  32     int has_error;
  33 } scanner_t;
  34
  35 #define token(scanner) ((scanner)->token.token)
  36
  37 static const char * const type_names[] = {
  38     "object",
  39     "array",
  40     "string",
  41     "integer",
  42     "real",
  43     "true",
  44     "false",
  45     "null"
  46 };
  47
  48 #define type_name(x) type_names[json_typeof(x)]
  49
  50 static const char unpack_value_starters[] = "{[siIbfFOon";
  51
  52 static void scanner_init(scanner_t *s, json_error_t *error,
  53                          size_t flags, const char *fmt)
  54 {
  55     s->error = error;
  56     s->flags = flags;
  57     s->fmt = s->start = fmt;
  58     memset(&s->prev_token, 0, sizeof(token_t));
  59     memset(&s->token, 0, sizeof(token_t));
  60     memset(&s->next_token, 0, sizeof(token_t));
  61     s->line = 1;
  62     s->column = 0;
  63     s->pos = 0;
  64     s->has_error = 0;
  65 }
  66
  67 static void next_token(scanner_t *s)
  68 {
  69     const char *t;
  70     s->prev_token = s->token;
  71
  72     if(s->next_token.line) {
  73         s->token = s->next_token;
  74         s->next_token.line = 0;
  75         return;
  76     }
  77
  78     t = s->fmt;
  79     s->column++;
  80     s->pos++;
  81
  82     /* skip space and ignored chars */
  83     while(*t == ' ' || *t == '\t' || *t == '\n' || *t == ',' || *t == ':') {
  84         if(*t == '\n') {
  85             s->line++;
  86             s->column = 1;
  87         }
  88         else
  89             s->column++;
  90
  91         s->pos++;
  92         t++;
  93     }
  94
  95     s->token.token = *t;
  96     s->token.line = s->line;
  97     s->token.column = s->column;
  98     s->token.pos = s->pos;
  99
 100     t++;
 101     s->fmt = t;
 102 }
 103
 104 static void prev_token(scanner_t *s)
 105 {
 106     s->next_token = s->token;
 107     s->token = s->prev_token;
 108 }
 109
 110 static void set_error(scanner_t *s, const char *source, enum json_error_code code,
 111                       const char *fmt, ...)
 112 {
 113     va_list ap;
 114     va_start(ap, fmt);
 115
 116     jsonp_error_vset(s->error, s->token.line, s->token.column, s->token.pos,
 117                      code, fmt, ap);
 118
 119     jsonp_error_set_source(s->error, source);
 120
 121     va_end(ap);
 122 }
 123
 124 static json_t *pack(scanner_t *s, va_list *ap);
 125
 126
 127 /* ours will be set to 1 if jsonp_free() must be called for the result
 128    afterwards */
 129 static char *read_string(scanner_t *s, va_list *ap,
 130                          const char *purpose, size_t *out_len, int *ours)
 131 {
 132     char t;
 133     strbuffer_t strbuff;
 134     const char *str;
 135     size_t length;
 136
 137     next_token(s);
 138     t = token(s);
 139     prev_token(s);
 140
 141     *ours = 0;
 142     if(t != '#' && t != '%' && t != '+') {
 143         /* Optimize the simple case */
 144         str = va_arg(*ap, const char *);
 145
 146         if(!str) {
 147             set_error(s, "<args>", json_error_null_value, "NULL string argument");
 148             return NULL;
 149         }
 150
 151         length = strlen(str);
 152
 153         if(!utf8_check_string(str, length)) {
 154             set_error(s, "<args>", json_error_invalid_utf8, "Invalid UTF-8 %s", purpose);
 155             return NULL;
 156         }
 157
 158         *out_len = length;
 159         return (char *)str;
 160     }
 161
 162     strbuffer_init(&strbuff);
 163
 164     while(1) {
 165         str = va_arg(*ap, const char *);
 166         if(!str) {
 167             set_error(s, "<args>", json_error_null_value, "NULL string argument");
 168             s->has_error = 1;
 169         }
 170
 171         next_token(s);
 172
 173         if(token(s) == '#') {
 174             length = va_arg(*ap, int);
 175         }
 176         else if(token(s) == '%') {
 177             length = va_arg(*ap, size_t);
 178         }
 179         else {
 180             prev_token(s);
 181             length = s->has_error ? 0 : strlen(str);
 182         }
 183
 184         if(!s->has_error && strbuffer_append_bytes(&strbuff, str, length) == -1) {
 185             set_error(s, "<internal>", json_error_out_of_memory, "Out of memory");
 186             s->has_error = 1;
 187         }
 188
 189         next_token(s);
 190         if(token(s) != '+') {
 191             prev_token(s);
 192             break;
 193         }
 194     }
 195
 196     if(s->has_error) {
 197         strbuffer_close(&strbuff);
 198         return NULL;
 199     }
 200
 201     if(!utf8_check_string(strbuff.value, strbuff.length)) {
 202         set_error(s, "<args>", json_error_invalid_utf8, "Invalid UTF-8 %s", purpose);
 203         strbuffer_close(&strbuff);
 204         s->has_error = 1;
 205         return NULL;
 206     }
 207
 208     *out_len = strbuff.length;
 209     *ours = 1;
 210     return strbuffer_steal_value(&strbuff);
 211 }
 212
 213 static json_t *pack_object(scanner_t *s, va_list *ap)
 214 {
 215     json_t *object = json_object();
 216     next_token(s);
 217
 218     while(token(s) != '}') {
 219         char *key;
 220         size_t len;
 221         int ours;
 222         json_t *value;
 223
 224         if(!token(s)) {
 225             set_error(s, "<format>", json_error_invalid_format, "Unexpected end of format string");
 226             goto error;
 227         }
 228
 229         if(token(s) != 's') {
 230             set_error(s, "<format>", json_error_invalid_format, "Expected format 's', got '%c'", token(s));
 231             goto error;
 232         }
 233
 234         key = read_string(s, ap, "object key", &len, &ours);
 235         if (!key)
 236             s->has_error = 1;
 237
 238         next_token(s);
 239
 240         value = pack(s, ap);
 241         if(!value) {
 242             if(ours)
 243                 jsonp_free(key);
 244
 245             if(strchr("soO", token(s)) && s->next_token.token == '*') {
 246                 next_token(s);
 247             } else {
 248                 s->has_error = 1;
 249             }
 250
 251             next_token(s);
 252             continue;
 253         }
 254
 255         if(s->has_error)
 256             json_decref(value);
 257
 258         if(!s->has_error && json_object_set_new_nocheck(object, key, value)) {
 259             set_error(s, "<internal>", json_error_out_of_memory, "Unable to add key \"%s\"", key);
 260             s->has_error = 1;
 261         }
 262
 263         if(ours)
 264             jsonp_free(key);
 265
 266         if(strchr("soO", token(s)) && s->next_token.token == '*')
 267             next_token(s);
 268         next_token(s);
 269     }
 270
 271     if(!s->has_error)
 272         return object;
 273
 274 error:
 275     json_decref(object);
 276     return NULL;
 277 }
 278
 279 static json_t *pack_array(scanner_t *s, va_list *ap)
 280 {
 281     json_t *array = json_array();
 282     next_token(s);
 283
 284     while(token(s) != ']') {
 285         json_t *value;
 286
 287         if(!token(s)) {
 288             set_error(s, "<format>", json_error_invalid_format, "Unexpected end of format string");
 289             /* Format string errors are unrecoverable. */
 290             goto error;
 291         }
 292
 293         value = pack(s, ap);
 294         if(!value) {
 295             if(strchr("soO", token(s)) && s->next_token.token == '*') {
 296                 next_token(s);
 297             } else {
 298                 s->has_error = 1;
 299             }
 300
 301             next_token(s);
 302             continue;
 303         }
 304
 305         if(s->has_error)
 306             json_decref(value);
 307
 308         if(!s->has_error && json_array_append_new(array, value)) {
 309             set_error(s, "<internal>", json_error_out_of_memory, "Unable to append to array");
 310             s->has_error = 1;
 311         }
 312
 313         if(strchr("soO", token(s)) && s->next_token.token == '*')
 314             next_token(s);
 315         next_token(s);
 316     }
 317
 318     if(!s->has_error)
 319         return array;
 320
 321 error:
 322     json_decref(array);
 323     return NULL;
 324 }
 325
 326 static json_t *pack_string(scanner_t *s, va_list *ap)
 327 {
 328     char *str;
 329     size_t len;
 330     int ours;
 331     int nullable;
 332
 333     next_token(s);
 334     nullable = token(s) == '?';
 335     if (!nullable)
 336         prev_token(s);
 337
 338     str = read_string(s, ap, "string", &len, &ours);
 339     if (!str) {
 340         return nullable ? json_null() : NULL;
 341     } else if (ours) {
 342         return jsonp_stringn_nocheck_own(str, len);
 343     } else {
 344         return json_stringn_nocheck(str, len);
 345     }
 346 }
 347
 348 static json_t *pack(scanner_t *s, va_list *ap)
 349 {
 350     switch(token(s)) {
 351         case '{':
 352             return pack_object(s, ap);
 353
 354         case '[':
 355             return pack_array(s, ap);
 356
 357         case 's': /* string */
 358             return pack_string(s, ap);
 359
 360         case 'n': /* null */
 361             return json_null();
 362
 363         case 'b': /* boolean */
 364             return va_arg(*ap, int) ? json_true() : json_false();
 365
 366         case 'i': /* integer from int */
 367             return json_integer(va_arg(*ap, int));
 368
 369         case 'I': /* integer from json_int_t */
 370             return json_integer(va_arg(*ap, json_int_t));
 371
 372         case 'f': /* real */
 373             return json_real(va_arg(*ap, double));
 374
 375         case 'O': /* a json_t object; increments refcount */
 376         {
 377             int nullable;
 378             json_t *json;
 379
 380             next_token(s);
 381             nullable = token(s) == '?';
 382             if (!nullable)
 383                 prev_token(s);
 384
 385             json = va_arg(*ap, json_t *);
 386             if (!json && nullable) {
 387                 return json_null();
 388             } else {
 389                 return json_incref(json);
 390             }
 391         }
 392
 393         case 'o': /* a json_t object; doesn't increment refcount */
 394         {
 395             int nullable;
 396             json_t *json;
 397
 398             next_token(s);
 399             nullable = token(s) == '?';
 400             if (!nullable)
 401                 prev_token(s);
 402
 403             json = va_arg(*ap, json_t *);
 404             if (!json && nullable) {
 405                 return json_null();
 406             } else {
 407                 return json;
 408             }
 409         }
 410
 411         default:
 412             set_error(s, "<format>", json_error_invalid_format, "Unexpected format character '%c'",
 413                       token(s));
 414             s->has_error = 1;
 415             return NULL;
 416     }
 417 }
 418
 419 static int unpack(scanner_t *s, json_t *root, va_list *ap);
 420
 421 static int unpack_object(scanner_t *s, json_t *root, va_list *ap)
 422 {
 423     int ret = -1;
 424     int strict = 0;
 425     int gotopt = 0;
 426
 427     /* Use a set (emulated by a hashtable) to check that all object
 428        keys are accessed. Checking that the correct number of keys
 429        were accessed is not enough, as the same key can be unpacked
 430        multiple times.
 431     */
 432     hashtable_t key_set;
 433
 434     if(hashtable_init(&key_set)) {
 435         set_error(s, "<internal>", json_error_out_of_memory, "Out of memory");
 436         return -1;
 437     }
 438
 439     if(root && !json_is_object(root)) {
 440         set_error(s, "<validation>", json_error_wrong_type, "Expected object, got %s",
 441                   type_name(root));
 442         goto out;
 443     }
 444     next_token(s);
 445
 446     while(token(s) != '}') {
 447         const char *key;
 448         json_t *value;
 449         int opt = 0;
 450
 451         if(strict != 0) {
 452             set_error(s, "<format>", json_error_invalid_format, "Expected '}' after '%c', got '%c'",
 453                       (strict == 1 ? '!' : '*'), token(s));
 454             goto out;
 455         }
 456
 457         if(!token(s)) {
 458             set_error(s, "<format>", json_error_invalid_format, "Unexpected end of format string");
 459             goto out;
 460         }
 461
 462         if(token(s) == '!' || token(s) == '*') {
 463             strict = (token(s) == '!' ? 1 : -1);
 464             next_token(s);
 465             continue;
 466         }
 467
 468         if(token(s) != 's') {
 469             set_error(s, "<format>", json_error_invalid_format, "Expected format 's', got '%c'", token(s));
 470             goto out;
 471         }
 472
 473         key = va_arg(*ap, const char *);
 474         if(!key) {
 475             set_error(s, "<args>", json_error_null_value, "NULL object key");
 476             goto out;
 477         }
 478
 479         next_token(s);
 480
 481         if(token(s) == '?') {
 482             opt = gotopt = 1;
 483             next_token(s);
 484         }
 485
 486         if(!root) {
 487             /* skipping */
 488             value = NULL;
 489         }
 490         else {
 491             value = json_object_get(root, key);
 492             if(!value && !opt) {
 493                 set_error(s, "<validation>", json_error_item_not_found, "Object item not found: %s", key);
 494                 goto out;
 495             }
 496         }
 497
 498         if(unpack(s, value, ap))
 499             goto out;
 500
 501         hashtable_set(&key_set, key, json_null());
 502         next_token(s);
 503     }
 504
 505     if(strict == 0 && (s->flags & JSON_STRICT))
 506         strict = 1;
 507
 508     if(root && strict == 1) {
 509         /* We need to check that all non optional items have been parsed */
 510         const char *key;
 511         int have_unrecognized_keys = 0;
 512         strbuffer_t unrecognized_keys;
 513         json_t *value;
 514         long unpacked = 0;
 515         if (gotopt) {
 516             /* We have optional keys, we need to iter on each key */
 517             json_object_foreach(root, key, value) {
 518                 if(!hashtable_get(&key_set, key)) {
 519                     unpacked++;
 520
 521                     /* Save unrecognized keys for the error message */
 522                     if (!have_unrecognized_keys) {
 523                         strbuffer_init(&unrecognized_keys);
 524                         have_unrecognized_keys = 1;
 525                     } else {
 526                         strbuffer_append_bytes(&unrecognized_keys, ", ", 2);
 527                     }
 528                     strbuffer_append_bytes(&unrecognized_keys, key, strlen(key));
 529                 }
 530             }
 531         } else {
 532             /* No optional keys, we can just compare the number of items */
 533             unpacked = (long)json_object_size(root) - (long)key_set.size;
 534         }
 535         if (unpacked) {
 536             if (!gotopt) {
 537                 /* Save unrecognized keys for the error message */
 538                 json_object_foreach(root, key, value) {
 539                     if(!hashtable_get(&key_set, key)) {
 540                         if (!have_unrecognized_keys) {
 541                             strbuffer_init(&unrecognized_keys);
 542                             have_unrecognized_keys = 1;
 543                         } else {
 544                             strbuffer_append_bytes(&unrecognized_keys, ", ", 2);
 545                         }
 546                         strbuffer_append_bytes(&unrecognized_keys, key, strlen(key));
 547                     }
 548                 }
 549             }
 550             set_error(s, "<validation>", json_error_end_of_input_expected,
 551                       "%li object item(s) left unpacked: %s",
 552                       unpacked, strbuffer_value(&unrecognized_keys));
 553             strbuffer_close(&unrecognized_keys);
 554             goto out;
 555         }
 556     }
 557
 558     ret = 0;
 559
 560 out:
 561     hashtable_close(&key_set);
 562     return ret;
 563 }
 564
 565 static int unpack_array(scanner_t *s, json_t *root, va_list *ap)
 566 {
 567     size_t i = 0;
 568     int strict = 0;
 569
 570     if(root && !json_is_array(root)) {
 571         set_error(s, "<validation>", json_error_wrong_type, "Expected array, got %s", type_name(root));
 572         return -1;
 573     }
 574     next_token(s);
 575
 576     while(token(s) != ']') {
 577         json_t *value;
 578
 579         if(strict != 0) {
 580             set_error(s, "<format>", json_error_invalid_format, "Expected ']' after '%c', got '%c'",
 581                       (strict == 1 ? '!' : '*'),
 582                       token(s));
 583             return -1;
 584         }
 585
 586         if(!token(s)) {
 587             set_error(s, "<format>", json_error_invalid_format, "Unexpected end of format string");
 588             return -1;
 589         }
 590
 591         if(token(s) == '!' || token(s) == '*') {
 592             strict = (token(s) == '!' ? 1 : -1);
 593             next_token(s);
 594             continue;
 595         }
 596
 597         if(!strchr(unpack_value_starters, token(s))) {
 598             set_error(s, "<format>", json_error_invalid_format, "Unexpected format character '%c'",
 599                       token(s));
 600             return -1;
 601         }
 602
 603         if(!root) {
 604             /* skipping */
 605             value = NULL;
 606         }
 607         else {
 608             value = json_array_get(root, i);
 609             if(!value) {
 610                 set_error(s, "<validation>", json_error_index_out_of_range, "Array index %lu out of range",
 611                           (unsigned long)i);
 612                 return -1;
 613             }
 614         }
 615
 616         if(unpack(s, value, ap))
 617             return -1;
 618
 619         next_token(s);
 620         i++;
 621     }
 622
 623     if(strict == 0 && (s->flags & JSON_STRICT))
 624         strict = 1;
 625
 626     if(root && strict == 1 && i != json_array_size(root)) {
 627         long diff = (long)json_array_size(root) - (long)i;
 628         set_error(s, "<validation>", json_error_end_of_input_expected, "%li array item(s) left unpacked", diff);
 629         return -1;
 630     }
 631
 632     return 0;
 633 }
 634
 635 static int unpack(scanner_t *s, json_t *root, va_list *ap)
 636 {
 637     switch(token(s))
 638     {
 639         case '{':
 640             return unpack_object(s, root, ap);
 641
 642         case '[':
 643             return unpack_array(s, root, ap);
 644
 645         case 's':
 646             if(root && !json_is_string(root)) {
 647                 set_error(s, "<validation>", json_error_wrong_type, "Expected string, got %s",
 648                           type_name(root));
 649                 return -1;
 650             }
 651
 652             if(!(s->flags & JSON_VALIDATE_ONLY)) {
 653                 const char **str_target;
 654                 size_t *len_target = NULL;
 655
 656                 str_target = va_arg(*ap, const char **);
 657                 if(!str_target) {
 658                     set_error(s, "<args>", json_error_null_value, "NULL string argument");
 659                     return -1;
 660                 }
 661
 662                 next_token(s);
 663
 664                 if(token(s) == '%') {
 665                     len_target = va_arg(*ap, size_t *);
 666                     if(!len_target) {
 667                         set_error(s, "<args>", json_error_null_value, "NULL string length argument");
 668                         return -1;
 669                     }
 670                 }
 671                 else
 672                     prev_token(s);
 673
 674                 if(root) {
 675                     *str_target = json_string_value(root);
 676                     if(len_target)
 677                         *len_target = json_string_length(root);
 678                 }
 679             }
 680             return 0;
 681
 682         case 'i':
 683             if(root && !json_is_integer(root)) {
 684                 set_error(s, "<validation>", json_error_wrong_type, "Expected integer, got %s",
 685                           type_name(root));
 686                 return -1;
 687             }
 688
 689             if(!(s->flags & JSON_VALIDATE_ONLY)) {
 690                 int *target = va_arg(*ap, int*);
 691                 if(root)
 692                     *target = (int)json_integer_value(root);
 693             }
 694
 695             return 0;
 696
 697         case 'I':
 698             if(root && !json_is_integer(root)) {
 699                 set_error(s, "<validation>", json_error_wrong_type, "Expected integer, got %s",
 700                           type_name(root));
 701                 return -1;
 702             }
 703
 704             if(!(s->flags & JSON_VALIDATE_ONLY)) {
 705                 json_int_t *target = va_arg(*ap, json_int_t*);
 706                 if(root)
 707                     *target = json_integer_value(root);
 708             }
 709
 710             return 0;
 711
 712         case 'b':
 713             if(root && !json_is_boolean(root)) {
 714                 set_error(s, "<validation>", json_error_wrong_type, "Expected true or false, got %s",
 715                           type_name(root));
 716                 return -1;
 717             }
 718
 719             if(!(s->flags & JSON_VALIDATE_ONLY)) {
 720                 int *target = va_arg(*ap, int*);
 721                 if(root)
 722                     *target = json_is_true(root);
 723             }
 724
 725             return 0;
 726
 727         case 'f':
 728             if(root && !json_is_real(root)) {
 729                 set_error(s, "<validation>", json_error_wrong_type, "Expected real, got %s",
 730                           type_name(root));
 731                 return -1;
 732             }
 733
 734             if(!(s->flags & JSON_VALIDATE_ONLY)) {
 735                 double *target = va_arg(*ap, double*);
 736                 if(root)
 737                     *target = json_real_value(root);
 738             }
 739
 740             return 0;
 741
 742         case 'F':
 743             if(root && !json_is_number(root)) {
 744                 set_error(s, "<validation>", json_error_wrong_type, "Expected real or integer, got %s",
 745                           type_name(root));
 746                 return -1;
 747             }
 748
 749             if(!(s->flags & JSON_VALIDATE_ONLY)) {
 750                 double *target = va_arg(*ap, double*);
 751                 if(root)
 752                     *target = json_number_value(root);
 753             }
 754
 755             return 0;
 756
 757         case 'O':
 758             if(root && !(s->flags & JSON_VALIDATE_ONLY))
 759                 json_incref(root);
 760             /* Fall through */
 761
 762         case 'o':
 763             if(!(s->flags & JSON_VALIDATE_ONLY)) {
 764                 json_t **target = va_arg(*ap, json_t**);
 765                 if(root)
 766                     *target = root;
 767             }
 768
 769             return 0;
 770
 771         case 'n':
 772             /* Never assign, just validate */
 773             if(root && !json_is_null(root)) {
 774                 set_error(s, "<validation>", json_error_wrong_type, "Expected null, got %s",
 775                           type_name(root));
 776                 return -1;
 777             }
 778             return 0;
 779
 780         default:
 781             set_error(s, "<format>", json_error_invalid_format, "Unexpected format character '%c'",
 782                       token(s));
 783             return -1;
 784     }
 785 }
 786
 787 json_t *json_vpack_ex(json_error_t *error, size_t flags,
 788                       const char *fmt, va_list ap)
 789 {
 790     scanner_t s;
 791     va_list ap_copy;
 792     json_t *value;
 793
 794     if(!fmt || !*fmt) {
 795         jsonp_error_init(error, "<format>");
 796         jsonp_error_set(error, -1, -1, 0, json_error_invalid_argument, "NULL or empty format string");
 797         return NULL;
 798     }
 799     jsonp_error_init(error, NULL);
 800
 801     scanner_init(&s, error, flags, fmt);
 802     next_token(&s);
 803
 804     va_copy(ap_copy, ap);
 805     value = pack(&s, &ap_copy);
 806     va_end(ap_copy);
 807
 808     if(!value)
 809         return NULL;
 810
 811     next_token(&s);
 812     if(token(&s)) {
 813         json_decref(value);
 814         set_error(&s, "<format>", json_error_invalid_format, "Garbage after format string");
 815         return NULL;
 816     }
 817     if(s.has_error) {
 818         json_decref(value);
 819         return NULL;
 820     }
 821
 822     return value;
 823 }
 824
 825 json_t *json_pack_ex(json_error_t *error, size_t flags, const char *fmt, ...)
 826 {
 827     json_t *value;
 828     va_list ap;
 829
 830     va_start(ap, fmt);
 831     value = json_vpack_ex(error, flags, fmt, ap);
 832     va_end(ap);
 833
 834     return value;
 835 }
 836
 837 json_t *json_pack(const char *fmt, ...)
 838 {
 839     json_t *value;
 840     va_list ap;
 841
 842     va_start(ap, fmt);
 843     value = json_vpack_ex(NULL, 0, fmt, ap);
 844     va_end(ap);
 845
 846     return value;
 847 }
 848
 849 int json_vunpack_ex(json_t *root, json_error_t *error, size_t flags,
 850                     const char *fmt, va_list ap)
 851 {
 852     scanner_t s;
 853     va_list ap_copy;
 854
 855     if(!root) {
 856         jsonp_error_init(error, "<root>");
 857         jsonp_error_set(error, -1, -1, 0, json_error_null_value, "NULL root value");
 858         return -1;
 859     }
 860
 861     if(!fmt || !*fmt) {
 862         jsonp_error_init(error, "<format>");
 863         jsonp_error_set(error, -1, -1, 0, json_error_invalid_argument, "NULL or empty format string");
 864         return -1;
 865     }
 866     jsonp_error_init(error, NULL);
 867
 868     scanner_init(&s, error, flags, fmt);
 869     next_token(&s);
 870
 871     va_copy(ap_copy, ap);
 872     if(unpack(&s, root, &ap_copy)) {
 873         va_end(ap_copy);
 874         return -1;
 875     }
 876     va_end(ap_copy);
 877
 878     next_token(&s);
 879     if(token(&s)) {
 880         set_error(&s, "<format>", json_error_invalid_format, "Garbage after format string");
 881         return -1;
 882     }
 883
 884     return 0;
 885 }
 886
 887 int json_unpack_ex(json_t *root, json_error_t *error, size_t flags, const char *fmt, ...)
 888 {
 889     int ret;
 890     va_list ap;
 891
 892     va_start(ap, fmt);
 893     ret = json_vunpack_ex(root, error, flags, fmt, ap);
 894     va_end(ap);
 895
 896     return ret;
 897 }
 898
 899 int json_unpack(json_t *root, const char *fmt, ...)
 900 {
 901     int ret;
 902     va_list ap;
 903
 904     va_start(ap, fmt);
 905     ret = json_vunpack_ex(root, NULL, 0, fmt, ap);
 906     va_end(ap);
 907
 908     return ret;
 909 }